||||||||||||| s USOO545.535A United States Patent (19) 11 Patent Number: 5,145,535 Patrick (45) Date of Patent: Sep. 8, 1992 54 METHOD FOR INTERMOLECULAR 4,221,616 9/1980 McLean .................................. 149/2 EXPLOSIVE WITH VISCOSTY MODFER 4,331,490 5/1982 Palgrave et al. ... ... 49/46 4,718,954 1/1988 Machacer et al. .. ... 149/46 75) Inventor: Michael A. Patrick, Shalinar, Fla. 4,764,316 8/1988 Brown et al. ....... 264/3. 73) Assignee: United States of America as 4,948,438 8/1990 Patrick et al. ......................... 49/38 represented by the Secretary of the Primary Examiner-Stephen J. Lechert, Jr. Air Force, Washington, D.C. Attorney, Agent, or Firm-Charles E. Bricker; Donald J. 21 Appl. No.: 660,307 Singer 22 Filed: Feb. 25, 1991 57 ABSTRACT 51 Int. C.5 D03D 23/00 A method for improving the disperion of particulate 52 U s Ci so 8 s a ... 149/105 6; 149/43: materials in intermolecular explosive compositions 8 Ys 149/45;see 8 sea as & 8 149/46;s a s a sea 8 esse 8 see49/61: was a s 149/75;ows 149/76s which comprises dry blending at least one fuel com 149/77. 149/83. 149/85. 149/88. 149/92. pound and at least one oxidizer compound, 3. viscosity 264/3.1; 264/3.4 modifier and a dispersable particulate material, melt 58 Field of Search .................. 149/1096,43, 45,46, blending the resulting dry blend, and thereafter casting 149/61, 75, 76, 77, 83, 85, 88, 92; 264/3.1, 34 the melt into a suitable form, casing or mold. The vis cosity modifier suitable for use in the invention is a 56) References Cited cationic salt of carboxymethylcellulose ether. The vis U.S. PATENT DOCUMENTS cosity modifier is added in an amount sufficient to 3,861,138 1/1975 Bridgeforth et al. ................. 60/217 achieve a desired melt viscosity. 3,956,038 5/1976 Duguet et al. ............ 4,063,975 12/1977 Fossan et al. ......................... 49/92 10 Claims, No Drawings 5,145,535 1. 2 as silicates to prevent settling of the particulates during METHOD FOR INTERMOLECULAR EXPLOSIVE the casting and subsequent steps. Loading techniques WITH VISCOSITY MODIFTER used heretofore are either inadequate to keep the partic ulates in suspension or result in lowered explosive per RIGHTS OF THE GOVERNMENT 5 formance. The invention described herein may be manufactured Accordingly, it is an object of this invention to pro and used by or for the Government of the United States vide a method for improving the dispersion of particu for all governmental purposes without the payment of late materials in intermolecular explosive compositions. any royalty. Other objects and advantages of the present invention 10 will be apparent to those skilled in the art from a read BACKGROUND OF THE INVENTION ing of the following description of the invention. This invention relates to explosives, particularly to explosive compositions based upon ammonium nitrate. SUMMARY OF THE INVENTION Traditional general-purpose explosives comprise tri In accordance with the present invention there is nitrotoluene (TNT), which has several disadvantages. It 5 provided a method for improving the dispersion of a is a Class-A explosive, requiring special mixing and particulate materials in intermolecular explosive com handling procedures and storage facilities, all accord positions which comprises dry blending at least one fuel ingly increasing the cost of use. The preparation of this compound and at least one oxidizer compound, a vis explosive is through nitrate substitution of toluene by a cosity modifier and a dispersable particulate material, mixed acid consisting of concentrated nitric acid and 20 melt blending the resulting dry blend, and thereafter sulphuric acid. The cost of concentrated nitric acid is casting the melt into a suitable form, casing or mold. moderately expensive and any excess nitric acid in the The viscosity modifier is added in an amount sufficient product destabilizes the explosive and presents corro to achieve a desired melt viscosity. sion problems. Trinitrotoluene is not water soluble and The oxidizing compounds suitable for use in the in bomb disposal cannot be done economically by steam or 25 vention include the nitrate, chlorate and perchlorate hot water. salts of lithium, sodium, potassium, magnesium, cal Intermolecular explosives are melt castable energetic cium, strontium, barium, copper, zinc, manganese and materials comprising separate fuel and oxidizer compo lead, as well as ammonium nitrate, ammonium chlorate nents, often as eutectic mixtures. It is known to produce and ammonium perchlorate, including mixtures thereof. cast high explosive compositions by solidification of a 30 The fuel compounds suitable for use in the invention molten mixture of ammonium nitrate (AN) and ethyl include the nitrate or perchlorate adducts of ethanol enediamine dinitrate (EDDN). A binary mixture of amine, ethylenediamine and higher homologs; aliphatic ethylenediamine dinitrate and ammonium nitrate is amides such as formamide, acetamide and urea; urea water soluble, thereby having several advantages over nitrate and urea perchlorate; nitroguanidine, guanidine trinitrotoluene such as safer storage as a non-explosive 35 nitrate and perchlorate, and triaminoguanidine nitrate water solution and cheaper disposal. However, the and perchlorate; polyols such as ethylene glycol, glyc binary mixture has a high melting point, has stability erol and higher homologs; ammonium and metal salts of problems, and is expensive. carboxylic acids such as formic, acetic and higher acids; Annonium nitrate is a hazardous material to manu sulfur-containing compounds such as dimethylsulfox facture on an industrial scale, to handle in large 40 ide; and mixtures thereof. amounts, and to store in great masses, especially for The viscosity modifier suitable for use in the inven relatively long periods of time. The shock sensitivity of tion is a cationic salt of carboxymethylcellulose ether. ammonium nitrate increases seriously after exposure to Typically, the sodium slat is used but other salts such as a few temperature cycles through the 32.3° C. (90 F) potassium may be used as well. The quantity of viscos transition point of AN. (UP to 32.3°C. the stable crystal 45 ity modifier added to the melt is sufficient to achieve a form is orthorhombic bipyrimidal; from 32.3° C. to 84 desired melt viscosity, i.e., sufficient to maintain the C. the stable crystal form is orthorhombic). particulate material in suspension, generally about 0.1 to It is known to add potassium nitrate (KN) to an AN 3.0 wt %. MEDDN mixture to improve its stability. The problems The particulate material comprises at least one other associated with the binary mixture remain and the 50 amount of chloride impurities is increased by the addi fuel-rich or oxidizer-rich component, such as, for exam tional chloride impurities found in potassium nitrate ple, nitroguanidine, RDX, HMX (cyclo-1,3,5,7-tet (KN). If these impurities are not removed, the explosive ranethylene-2,4,6,8-tetranitramine), ammonium per has serious corrosion problems. If the impurities are chlorate, aluminum powder, or the like. removed the cost of the explosive increases greatly. 55 If particulate agglomeration occurs, small quantities Other explosives compositions based upon ammo of surfactants or dispersing agents can be employed nium nitrate include AN/TNT/RDX (cyclotrimethyl without adversely affecting the action of the viscosity enetrinitramine), AN/MeNQ (methyl nitroguanidine), modifier. AN/EDDN/KN/Al, AN/EDDN/KN/NQ (ni The following examples illustrate the invention: troguanidine) and the like. EXAMPLE Many intermolecular explosives require the addition of particulate materials, such as monomolecular explo The following compositions were prepared: sives, aluminum, or the like, to increase performance, to adjust sensitivity, or to tailor properties for specific Ingredient Parts (wt) applications. Melt castable explosives generally have 65 Composition 1 extremely low viscosities while in the melt state. Ac Ethylenedianine Dinitrate 35.88 cordingly, loading such explosives with particulate Annonium Nitrate 35.88 materials requires the addition of thickening agents such Potassium Nitrate 6.24 5,145,535 4. at least one other fuel or oxidizer-rich component dif -continued ferent from said fuel compound and said oxidizer com Ingredient Parts (wt) pound. Aluminum Powder (Alcoa 1401) 20.00 Carboxymethylcellulose ether, Nasalt" 2.00 2. The method of claim 1 wherein said viscosity mod Composition 2 ifier is added in an amount sufficient to achieve a de Methylnitroguanidine 35.10 sired melt viscosity. Ammonium Nitrate 30.58 3. The method of claim 1 wherein said oxidizer com Sodium Nitrate 3.5 pound is selected from the group consisting of the ni Nitroguanidine 8.8 Aluminum Powder (Alcoa 1401) 20.00 trate, chlorate and perchlorate salts of lithium, sodium, Carboxymethylcellulose ether, Nasalt 2.00 10 potassium, magnesium, calcium, strontium, barium, copper, zinc, manganese and lead, and ammonium ni Available from EM Science, Cherry Hill, NJ trate, ammonium chlorate and ammonium perchlorate. Both of the compositions were dry blended, melted, 4. The method of claim 1 wherein said fuel compound with mixing at 105-110' C., evacuated for 15 minutes is selected from the group consisting of the nitrate and at 15 inches Hg, and cast into test items at 95'-100° C. 15 perchlorate adducts of ethanolamine, ethylenediamine It is important that the viscosity modifier is dispersed and higher homologs, aliphatic amides, urea nitrate, within the explosives ingredients prior to melting. Add urea perchlorate, nitroguanidine, guanidine nitrate and ing the viscosity modifier directly to a melt of explo perchlorate, triaminoguanidine nitrate and perchlorate, sives ingredients results in extensive clumping, incom polyols, ammonium and metal salts of carboxylic acids, plete solubilization and extended kettle residence. 20 and sulfur-containing compounds. No incompatibility has been observed between the 5. The method of claim 1 wherein said viscosity mod viscosity modifier and the ammonium nitrate-based ifier is a cationic salt of carboxymethylcellulose ether.