3,732,130 United States Patent Office Patented May 8, 1973 2 3,732,130 tion, the formulations are still based primarily upon GUN PROPELLANT CONTAINING NONENER. itsellulose With or without nitroglycerine as indicated GETIC PLASTICIZER, NATROCELLULOSE AND abOWe. TRAMNOGUANDENE NITRATE The early single-base gun propellant, utilizing nitro Joseph E. Flanagan, Woodland Hills, and Vernon E. 5 cellulose with 13.15% nitrogen content, has a mass im Haury, Santa Susana, Calif., assignors to North Ameri petus of 357,000 ft.-lbs./lb. and an isochoric flame tem can Rockwell Corporation perature of 3292. K. Incorporation of 20 weight percent No Drawing. Filed Oct. 14, 1971, Ser. No. 192,717 of nitroglycerin gives the standard double-base propel Int, C. C06d 5/06 lant with a mass impetus of 378,000 ft.-lbs./lb. and an U.S. C. 149-18 10 Claims O isochoric flame temperature of 3592 K. As mentioned previously, the high flame temperature of the double ABSTRACT OF THE DISCLOSURE base system is very undesirable since it severely limits the barrel life of the gun due to barrel erosion. To over Non-metallized gun propellant systems are provided come this critical problem, triple-base gun propellants containing triaminoguanidine nitrate oxidizer alone or in 15 were developed in which nitroguanidine was incorporated combination with other oxidizers such as cyclotrimethyl as a coolant into the nitrocellulose-nitroglycerine system. ene trinitramine or cyclotetramethylene tetranitramine. Representative conventional triple base propellants are the The binder system is based on nitrocellulose and a non M30 (impetus=364,000 ft.-lbs./Ib.; Ty=3040 K.) and energetic plasticizer such as polyethylene glycol. the M31 (impetus=335,000 ft.-lbs./lb.: T-2597 K.) 20 The concurrently filed application of Haury et al., CROSS-REFERENCE TO RELATED APPLICATION Supra, discloses non-metallized gun propellants containing plasticized nitrocellulose binder and triaminoguanidine This application is related to application Ser. No. nitrate oxidizer alone or in combination with other oxi 192,718 filed concurrently herewith by V. E. Haury, a dizers such as cyclotrimethylene trinitramine or cyclo co-inventor herein, and M. B. Frankel for Gun Propel 25 tetramethylene tetranitramine. The plasticized nitrocellu lant Containing Nitroplasticized Nitrocellulose and Tri lose binder is typically a highly nitroplasticized nitrocellu aminoguanidine Nitrate. lose binder and the plasticizer is preferably a blend of tri BACKGROUND OF THE INVENTION methylolethane trinitrate and triethylene glycol dinitrate. This invention relates to "gun propellants' which are These highly nitroplasticized nitrocellulose-based gun generically defined herein as propellants for propelling 30 propellants have a mass impetus which is generally above projectiles. Specifically, this invention is concerned with that of the standard double-base system and an isochoric gun propellants containing plasticized nitrocellulose flame temperature which is typically below 3000 K. binder in which the plasticizer is non-energetic and tri SUMMARY OF THE INVENTION aminoguanidine nitrate oxidizer alone or in combination 35 It has now been discovered that improved triamino with other oxidizers such as cyclotrimethylene tri guanidine nitrate containing nitrocellulose-based gun pro nitramine or cyclotetramethylene tetranitramine. pellants can be formulated using non-energetic plasti Gun propellants are referred to as low explosives to cizers such as polyethylene glycol. Secondary oxidizers distinguish them from detonating high explosives and such as cyclotrimethylene trinitramine and cyclotetra differ from high explosives in that the rate of energy 40 methylene tetranitramine can be added to the propellant release by autocombustion is controlled within certain composition if desired. The present gun propellant sys limitations. The first real gun propellant was made from tems are highly flexible and permit the formulation of potassium nitrate, sulfur and charcoal and was referred propellants with a wide range of mass impetus character to as black powder. Nitrocellulose forms the basis for all istics and low flame temperatures, usually well below modern gunpowders and is typically combined today 45 3000 K. when measured at constant volume. with nitroglycerine to form a smokeless powder. "Smoke In accordance with the foregoing, it is an object of less powder' refers to colloided nitrocellulose either alone this invention to provide improved solid propellants and or in admixture with nitroglycerine or other materials. particularly improved solid propellants for propelling Smokeless powders are not in reality powders in the com projectiles. mon sense of the word, nor are they Smokeless, except 50 A further object of the invention is to provide gun when compared with black powder. Modern powders may propellants with low flame temperatures in order to avoid take many forms including flakes, strips, pellets and excessive gun barrel erosion. cylinders. However, the cylindrical grain is most com A still further object of the invention is to provide gun monly employed for military purposes. "Single-base propellant compositions which can be formulated with a powders' generally refer to colloided nitrocellulose in the 55 wide range of mass impetus. absence of nitroglycerine or other plasticizer. The termi An additional object of the invention is to provide gun nology "double-base powder' generally refers to powders propellant compositions which evolve non-corrosive com containing nitrocellulose and nitroglycerine or other bustion products when burned and yet are capable of plasticizer. These double-base powders usually contain manufacture by standard equipment into non-, mono- or from 15 to 40% nitroglycerin. Although double-base pow 60 multi-perforated gun-type grains. ders have many desirable characteristics, they also have many undesirable performance features including a high DESCRIPTION OF THE PREFERRED burning temperature which causes excessive barrel erosion EMBODIMENTS when compared with single-base powders. Additionally, The present gun propellants do not contain metal fuels nitroglycerine is hazardous to handle. 65 since metal particles in the propellant exhaust lead to Since the beginning of the twentieth century, the funda undesirable gun barrel erosion. The gun propellants pref mental nature of solid propellant compositions used in erably contain only carbon-hydrogen-oxygen-nitrogen in small arms ammunition and the like has remained sub order to obtain an all gaseous, non-corrosive combustion stantially unchanged. While improvements have been product. The components of the gun propellant composi made, such as the introduction of ball propellant, cool O tions are preferably high nitrogen and hydrogen contain burning extruded compositions, and the utilization of ing materials which have low carbon and oxygen content deterrents and geometries to improve control of gas evolu in order to avoid high average molecular weight exhaust 3,732,130 3 4. products since a low molecular weight of the combustion used, that the molecular weight of this component not products is desirable to increase the value of the specific exceed about 4000. The plasticizer will usually be present impulse. in about 5 to 20 weight percent of the gun propellant Triaminoguanidine nitrate (TAGN) is a dense, nonhy composition. groscopie, thermally stable solid and is readily prepared Conventional stabilizers are added to the gun propellants in high yields from guanidine nitrate and hydrazine (Dia to insure acceptable stability, or in other words, accept mond, L. H., Derivatives of Hydrazine, Publication No. able resistance to chemical deterioration. Illustrative sta 10, 466, University Microfilms, Ann Arbor, Mich., 1954). bilizers include nitrodiphenylamine (NDPA) and ethyl It can also be prepared by the aqueous fusion of calcium centralite (EC) (N,N'-diethylcarbonilide). The quantity cyanamide and hydrazine nitrate and also by reacting a of stabilizer added to the propellant is typically /2 to 1/2 mixture of hydrazine nitrate and hydrazine hydrate with O weight percent. dicyandiamide (U.S. Pat. 3,285,958). TAGN functions The propellants of this invention may be manufactured as an oxidizer and coolant in the propellent System and utilizing conventional smokeless powder equipment. The has been found to allow the attainment of higher mass individual grains are of conventional size and may be non impetus and lower flame temperatures than can be ob perforated, mono-perforated or multi-perforated, such as tained by the use of conventional coolants such as nitro 5 grains containing seven perforations. The grains may be guanidine and oxamide. TAGN is used alone or in con cylindrical or rosette in configuration. junction with other oxidizers such as cyclotrimethylene Table I lists the composition of eight preferred gun trinitramine and cyclotetramethylene tetranitramine. Vari propellants falling within the scope of the present inven ous non-energetic plasticizers can be employed depending tion along with their mass impetus and flame tempera upon the mass impetus required and the flame tempera 20 ture. The table illustrates that the present gun propellant ture and physical properties of the propellant grain de systems are highly flexible and permit the formulation sired. Conventional stabilizers are added to the binder of propellants with a wide range of mass impetus and low system as will be discussed below. flame temperatures. In fact, all of the illustrated gun The TAGN will normally comprise from 40 to 80 25 propellant formulations have theoretical isochoric flame weight percent of the propellant composition. It is gen temperatures well below 3000 K. TABLE Weight percent Gun propellant formula tion number------2 3. 4. 5 6 7 8 Oxidizer: TAGN------60, O 54.0 46.0 70.0 6, 0 65. O 70.0 600 HMX------14.0 200 28.0 ------Binder: NC (12.6% N) 20, 0 7.5 15.0 24.0 60 29.0 9.0 19, O Plasticizer: FEG (M.We 400)------5,0 7.5 0.0 5.0 7.0 5.0 100 50 Stabilizer: NPDA.------i. 0 .0 0 1.0 1.0 1.0 1.0 . 0 IX103 (ft.-bs.fb.) (called.). ------374.2 372.3 372.3 356, 35.1 355. 337.8 315.0 Tv, K. (caled.)------2, 623 2,587 2,580 2,439 2,325 2,459 2, 29 2,049 erally preferred that the solid propellant composition con The following example demonstrates the preparation tain about 50 to 70 weight percent TAGN with the re 40 of a preferred composition of the present invention: mainder of the composition comprising plasticized nitro EXAMPLE cellulose binder. As previously stated, the TAGN oxidizer Ingredient: Weight percent can either be used alone or in combination with other oxidizers. It is generally preferred to reduce the amount TAGN ------75.5 of TAGN employed by the amount of secondary oxidizer HMX ------7.5 added. Cyclotrimethylene trinitramine (RDX) and cyclo 45 NC (12.6% N) ------13.0 tetramethylene tetranitramine (HMX) are the preferred PEG (M.W. 400) ------4.0 secondary oxidizers since they have relatively high nitro NDPA ------0.5 gen and hydrogen contents and relatively low carbon and The ingredients were thoroughly mixed in a 50 cc. oxygen contents, relatively high positive heats of forma horizontal mixer at ambient temperature to form a 50 tion, high density, satisfactory thermostability and rea 50 gram batch of propellant and then pressed into strips. sonable impact sensitivity as well as being nonhygro The strips were cured at 30° C. for 48 hours. Impact scopic. The gun propellants ordinarily will contain from sensitivity, thermal stability (Taliani) and autoignition about 0 to 30 weight percent RDX or HMX, and prefer characteristics of the propellant were measured. These ably about 15 to 25 weight percent. physical properties as well as some thermodynamic prop The gun propellant binder is plasticized nitrocellulose. 55 erties of the propellant are summarized in Table II. The nitrocellulose (NC) content of the composition will normally vary in the range of 10 to 30% by weight and TABLE II will preferably be in the range of 15 to 25% by weight. Thermodynamic properties The weight percent of nitrogen in the nitrocellulose will 60 Mass impetus (calcd.) ------ft.-lbs./lb. 375,200 normally be in the range of 12.5 to 13.5% as is conven Tv K. (calcd.) ------2552 tional in smokeless powder formulations. The exact non-energetic plasticizer employed for the Physical properties nitrocellulose binder will depend upon the mass impetus Impact sensitivity (RDX=125) ------in-lbs 33 of the gun propellant composition which is required, the Thermal stability, Taliani: flame temperature desired and the physical properties of 65 Temperature ------C. 65 the final propellant grain which must be attained. The Ml/gas/g/hr. ------0.002 preferred non-energetic plasticizers are the polyalkylene Autoignition (5 Sec.) ------C. 190 glycols such as polyethylene glycol (PEG) and polypro Further verification of the effectiveness of the present pylene glycol and their alkyl ether derivatives such as 70 propellant formulations was made by firings in a small butyl carbitol (diethylene glycol butylether). It is pre volume (2.0 cubic inch) impetus bomb. Thin strips of ferred that the plasticizer be liquid so that the propellant propellant formulation No. 5 in Table I (0.03 inch) were can be easily formulated. For example, it is generally pre cut into small discs (0.3 inch diameter) and placed in the ferred that the molecular weight of the polyethylene gly impetus bomb. Hot-wire ignition was utilized so that no col not exceed about 600 and, if polypropylene glycol is 75 correction was necessary for the igniter. The maximum 3,732,130 5 6 pressure rise of the ignited propellant was 92% that of comprising a cured intimate mixture of, by weight, 40 to the theoretical pressure rise. By comparison, standard 80% triaminoguanidine nitrate, 0 to 30% of cyclotri M-10 propellant (by weight about 97% nitrocellulose methylene trinitramine or cyclotetramethylene tetrani (13.15% N), 1% diphenylamine, 0.1% graphite, 1.5% tramine, 10 to 30% of nitrocellulose and from 5 to 20% ethyl alcohol and 0.5% water) will yield only about 85% of a non-energetic plasticizer for said nitrocellulose. of the expected pressure rise. 5. The solid gun propellant composition of claim 4 in As further illustrative of the present invention, propel which the plasticizer is a polyalkylene glycol. lant formulation No. 7 in Table I was formed into a 7 6. The solid gun propellant composition of claim 5 in perforated grain containing 12 grams and was fired in a which the polyalkylene glycol is polyethylene glycol or 20 mm. Mann. barrel. The length of the propellant grain polypropylene glycol. was 0.17 in., the diameter was 0.19 in. and the perforations O 7. The solid gun propellant composition of claim 5 in were 0.026 in. A maximum pressure of 23 k.p.s. i. was ob which the polyalkylene glycol is an alkyl ether substituted tained in this firing. These tests demonstrated that, al polyalkylene glycol. though the weight and size of the propellant charge were 8. The solid gun propellant composition of claim 7 not optimized, smooth ignition and combustion were ob in which the alkyl ether substituted polyalkylene glycol is tained. 5 butyl carbitol. It will be obvious to those skilled in the art that other 9. The solid gun propellant composition of claim 4 in non-energetic plasticizers as well as other stabilizers and which the composition is in the form of a multi-perfo secondary oxidizers can be substituted for the illustrated rated grain. ingredients. For example, the secondary oxidizer could be 10. The solid gun propellant composition of claim 9 in methylene or ethylene dinitramine rather than RDX or 20 which the grain has seven perforations. HMX. The above description is for the purpose of illustration References Cited and clarification only and it is intended that the scope of UNITED STATES PATENTS the invention not be limited except by reference to the appended claims. 25 2,929,699 3/1960 Audrieth et al. -- 149-92 X We claim: 3,110,258 11/1963 Weber ------149-92 X 1. A non-metallized solid gun propellant composition 3,338,762 8/1967 Oja ------149-36 X comprising a cured intimate mixture of triaminoguanidine 3,400,025 9/1968 Hopper et al. ------149-18 nitrate, non-energetic plasticizer and nitrocellulose. 3,447,983 6/1969 Camp et al. ------149-18 2. The solid gun propellant composition of claim 1 in 30 3,506,505 4/1970 Herzog et al. ------149-100X which the composition contains, by weight, 40 to 80% of 3,639,183 2/1972 Crescenzo et al ----- 149-92 X triaminoguanidine nitrate. CARL D. QUARFORTH, Primary Examiner 3. The solid gun propellant composition of claim 1 in which the composition contains, by weight, 50 to 70% of E. A. MILLER, Assistant Examiner triaminoguanidine nitrate. U.S. C1. X.R. 4. A non-metallized solid gun propellant composition 149-36, 92, 100