Patent GB-714214-A (GB)
Title: Fire-retardant cellulose and cellulose ether bodies and compositions for use in producing the same
IPC: D01F2/00
Filed: 1952-06-27
Abstract: An aqueous cellulosic composition comprises cellulose, cellulose xanthate or a cellulose ether in an aqueous solvent therefor and, uniformly dispersed therein, a neutral or alkaline reaction product of phosphorus oxychloride and ammonia in a proportion sufficient to impart afterglow-resisting and fire-resisting properties to dry products obtained from the composition.  The proportion of the reaction product used may be 3-25 per cent. of the weight of the cellulose or cellulose derivative.  The cellulose solvent may be an aqueous solution of calcium thiocyanate, sodium zincate, urea and sodium zincate, trimethyl or triethyl benzyl ammonium hydroxide, or zinc chloride. Cellulose xanthate solutions in water or dilute alkali or cuprammonium cellulose solutions may be used.  Cellulose ethers such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose and hydroxyethyl cellulose may be used in solution in water or dilute sodium hydroxide.  The solution may contain 5-10 per cent. of cellulose or cellulose derivative.  It may also contain titanium oxide, zinc oxide, mineral oil or other delustrant, or a surface active substance to inhibit clogging of spinning orifices, or a dye or pigment.  It may contain an inert fire retardant such as antimony oxide.  The phosphorus oxychloride and ammonia condensation products may be made by the methods described in Specifications 683,572 and 700,822.  A spinning solution containing a neutral to alkaline water-soluble reaction product of phosphorus oxychloride and ammonia coagulates and hardens in acidic aqueous coagulating baths, and simultaneously the reaction product is precipitated and rendered insoluble.  Spinning compositions containing a water-insoluble reaction product of phosphorus oxychloride and ammonia (a polyphosphorylamide) coagulate and harden in acidic aqueous coagulating baths to form regenerated cellulose or cellulose ether products which have the particles of the reaction product uniformly dispersed therein. The filaments or other products may be washed to remove water-soluble impurities without removing appreciable amounts of the phosphorylamide.  Regenerated cellulose products obtained from viscose may be desulphurized with ammonium or sodium sulphide solutions without removing appreciable amounts of the phosphorylamide.  Fine filaments and coarser filaments, such as artificial horsehair or straw, and also foils, tubes, and rods may be obtained.  The filaments and fibres may be woven or knitted to form fire-resistant and after-glow resistant fabrics.  Textile material or paper may be impregnated or coated with the aqueous cellulosic composition and then treated with a coagulating liquid, e.g. a dilute acid, so as to regenerate the cellulose or precipitate the cellulose ether on or in the textile material or paper.  If desired, a non-acidic coagulating bath may be used, but in that case it may be necessary to subject the coagulated filaments or other articles to a heat treatment at 100-200 DEG C. to obtain a permanent fire- and afterglow-resistant effect.  U.S.A. Specification 2,009,015 also is referred to.