Patent GB-1326721-A (GB)
Title: High specific impulse propellants
IPC: C06B45/10
Filed: 1961-08-11
Abstract: 1326721 Propellent compositions AEROJETGENERAL CORP 11 June 1961 25149/61 Heading C1D A solid propellent composition comprises an intimate mixture of a solid inorganic oxidizing salt, a binder and not less than about 5% by weight of aluminium. The binder is preferably a cross-linked urethane type synthetic resin formed by reacting a diol or dithiol with a diisocyanate or diisothiocyanate in the presence of a cross-linking agent having at least three reactive groups. The specification lists many suitable reactants. The diols and dithiols include polyesters prepared from dihydric alcohols and dibasic acids and preferably mixed with olefines, polyalkylene ether glycols, and polysulphides. The polyurethane reaction may take place in the presence of a plasticizer, curing catalyst, and solvent at a temperature of 70‹-180‹ F. Preferably there is used a slight excess of the isocyanate component over the hydroxy component. Other suitable binders are asphalt, synthetic rubber, polysulphides, and phenolaldehyde, polyester, acrylate, and polyalkylene resins. Such binders are described in Specification 579,057 and United States Specifications 2,479,828, 3,012,866 and 3,031,288. A nitrocellulose-plasticizer binder may also be used. If nitro-substituted acrylic resins or polyurethane resins are used, the presence of an oxidizing salt is not necessary. The aluminium is preferably in powder form having spherical particles and may be present in an amount of 11-26% by weight. Solid oxidizing salts specified are the chromates, dichromates, permanganates, nitrates, chlorates, and perchlorates of alkali and alkaline earth metals, ammonia, hydrazine, or guanidine. The propellent may also contain burning rate modifiers, wetting agents, antifoaming agents, and antioxidants. In examples of compositions containing polyurethane type binders, the following ingredients are used in addition to aluminium powder: as urethane reactants, polypropylene glycol, polybutylene glycol, tolylene diisocyanate, hexamethylene diisocyanate, and a prepolymer of polybutylene glycol and tolylene diisocyanate; as cross-linking agents, glycerol monoricinoleate, glycerol triricinoleate, methylene-bis-(orthochloroaniline), polypropylene glycol initiated with 1,2,6-hexanetriol, monohydroxyethyltrihydroxypropylene - diamine, triethanolamine, trimethylolpropane, and hexenetriol; as oxidants, ammonium perchlorate, lithium perchlorate, ammonium nitrate, and nitroguanidine; as burning rate modifiers, copper chromite, carbon black, and calcium oxalate; as plasticizers, dioctyl azelate, isodecyl pelargonate, trioctyl phosphate, and as antioxidants, phenyl betanaphthylamine N,N<SP>1</SP> - di - beta - naphthyl - p - phenylenediamine, and N,N<SP>1</SP>-diphenyl-p-phenylenediamine; as curing catalyst, ferric acetylacetonate; and as wetting agents, lecithin, sorbitan trioleate, sorbitan monooleate-polyoxyethylene derivative mixtures, and a mixture of polyethoxy amines. In Example XVI, the ingredients are plastisol grade nitrocellulose, pentaerythritol trinitrate, aluminium powder, and ammonium perchlorate. Specification 984,960 is referred to.