United States Patent (19) 11 4,343,663 Breza, deceased et al. 45 Aug. 10, 1982 54 RESIN-BONDED WATER-BEARING 56 References Cited EXPLOSIVE U.S. PATENT DOCUMENTS 75 Inventors: Cyril J. Breza, deceased, late of 4,141,767 2/1979 Sudweeks et al. ...................... 149/2 Hagerstown, Md., by Therese H. 4,151,022 4/1979 Donaghue ............ ... 49/19.4 Breza, executrix; William E. 4,216,040 8/1980 Sudweeks et al. .................... 149/21 Schaefer, Hagerstown, Md. Primary Examiner-Stephen J. Lechert, Jr. 73 Assignee: E. I. Du Pont de Nemours and Attorney, Agent, or Firm-Diamond C. Ascani Company, Wilmington, Del. 57 ABSTRACT Self-supporting water-bearing explosive products, e.g., 21 Appl. No.: 164,143 for use as primers and in blasting and seismic charges, 22 Filed: Jun, 30, 1980 contain discrete cells of an aqueous solution of an inor ganic oxidizing salt and/or of an amine salt encapsu 51 Int. Cl. .............................................. CO6B 45/18 lated by a crosslinked (thermoset) resin matrix. The 52 U.S.C. .......................................... 149/4; 149/11; products are sensitized by a dispersed solid high explo 149/18; 149/19.5; 149/1991; 149/19.92; sive and/or gas bubbles or voids. Preferred primers are 149/19.93; 149/20, 149/21; 149/38; 149/46; sensitized by PETN and are rigid. The products are 149/47; 149/61; 149/62; 149/70; 149/92; made by crosslinking a liquid polymer in the continuous 149/93; 102/204; 252/313 R phase of an emulsion which contains the aqueous solu 58 Field of Search .................. 149/4, 11, 2, 18, 19.5, tion as a discontinuous phase. 149/19.91, 19.92, 19.93, 20, 21, 38, 46, 47, 61, 62, 70, 92,93; 102/204; 252/313 R 3 Claims, 1 Drawing Figure ss3. U.S. Patent Aug. 10, 1982 4,343,663 4,343,663 1. 2 agents. Primers are very high-energy, usually compact, RESIN-BONDED WATER-BEARING EXPLOSIVE explosive products which are used to initiate the deto nation of adjacent non-cap-sensitive blasting agents in BACKGROUND OF THE INVENTION boreholes, e.g., adjacent chub cartridges or a detonable 1. Field of the Invention mixture of ammonium nitrate and fuel oil (ANFO). One The present invention relates to water-bearing explo type of primer in common use is a packaged cylindrical sives which contain an aqueous solution of at least one charge of castable explosive weighing 0.45 kilogram or salt of an inorganic oxidizing acid as a dispersed phase less and designed to be detonated by detonating cord or within a continuous organic fuel phase, and to a method a blasting cap. Primers this small in size need rigidity to of preparing such explosives. 10 assure satisfactory performance. Preferably, rigidity is 2. Description of the Prior Art Water-bearing explosives in the form of semi-solid present in the explosive charge itself so that rigid con colloidal dispersions are available in film-wrapped car tainment is not required. Heretofore, water-bearing tridges or bags, as well as in bulk form for pouring or blasting agents used in primer cartridges have been pumping into boreholes. In the water gel or slurry type 15 non-self-supporting, non-rigid compositions. Co-pend of water-bearing explosive, a solid or liquid fuel is dis ing, co-assigned U.S. patent application Ser. No. 27,882. persed or dissolved in a continuous thickened or gelled filed Apr. 6, 1979, describes a primer cartridge of this aqueous solution of an inorganic oxidizing salt. In the kind. water-in-oil emulsion type, an aqueous solution of an Even for non-primer uses, self-supportability or rigid inorganic oxidizing salt is a discontinuous phase dis 20 ity, and the absence of thermoplasticity, in a water-bear persed in a continuous carbonaceous fuel or oil phase. ing explosive are desirable from the point of view of In U.S. Pat. No. 3,447,978, Bluhm describes emulsion product stability during storage and use as it may be blasting agents in which the continuous phase is a car affected by such variables as temperature, pressure, and bonaceous fuel component which forms a water-in-oil ambient moisture. type emulsion with an aqueous ammonium nitrate solu 25 tion component when a water-in-oil type emulsifying SUMMARY OF THE INVENTION agent is present, and which has a gas occlusion tempera This invention provides a self-supporting water-bear ture of 21-88' C. The firmness of Bluhm's emulsion ing explosive product comprising system is said to be variable depending on the physical (a) a mass of crosslinked organic resin, e.g., the reac consistency of the carbonaceous fuel used, the latter 30 being required to be thick enough to prevent an oc tion product of an unsaturated polymerizable polyester cluded gas sensitizing component from agglomerating resin, a monomeric polymerizable ethylenic compound, and being expelled from the emulsion at ambient tem and a crosslinking catalyst, forming a continuous ma perature, yet sufficiently fluid at manufacturing temper trix; atures to permit formation of the emulsion. Bluhm's 35 (b) an aqueous solution of at least one salt of an inor carbonaceous fuel component must have the ability to ganic oxidizing acid forming a discontinuous phase provide this consistency differential with variations in dispersed within, and encapsulated by, the continuous temperature. matrix, which salt is derived from nitric or perchloric Bluhm's fuel component becomes thinner when acid and a base selected from the group consisting of heated and thicker when cooled. After this fuel compo 40 ammonia, amines, and alkali and alkaline-earth metal nent has been thinned to a liquid by heating and the hydroxides, preferred salts being ammonium nitrate, emulsion allowed to form, the thickened consistency of sodium nitrate, and monomethylamine nitrate; and the emulsion needed for gas retention is achieved by (c) dispersed in the matrix and/or the aqueous solu cooling. If insufficient gas has been occluded, the emul tion, a sensitizer adapted to induce or enhance the deto sion is heated again (and thinned) for the introduction of 45 nability of the solution-containing resin matrix. additional quantities of gas, and the final thickened In one embodiment of the invention, the explosive consistency is achieved by cooling. Bluhm achieves this product is a primer, and at least a portion of the sensi temperature-responsive consistency differential by tizer is a solid high explosive, e.g., pentaerythritol tetra using an all-wax carbonaceous fuel component, or wax nitrate (PETN), dispersed in the matrix and/or the and oil, wax and a polymeric material, or wax and a 50 polymer-modified oil. While the emulsion can be a de aqueous solution. formable paste or solid at storage temperatures, varying In an alternative embodiment, the explosive product from very soft to firm depending especially on the phys is adapted to form a main explosive charge, e.g., a blast ical consistency of the carbonaceous fuel used, the de ing or seismic charge, in which case the sensitizer can be gree of softness or firmness of the water-in-oil emulsion 55 totally non-explosive, e.g., a dispersion of gas bubbles or explosives of the prior art has been temperature voids, or, at least in part, a dispersed solid high explo dependent and hence subject to variation with changing sive. ambient conditions. A preferred explosive primer of the invention com Although film-packaged water-bearing explosives prises are easy to handle and load into boreholes, in some (a) a preferably cylindrical mass of crosslinked or circumstances there is need for water-bearing explosive ganic resin forming a continuous matrix; charges that are per se self-supporting and preferably (b) an aqueous solution of at least one salt of an inor rigid, i.e., substantially non-deformable or non-slumping ganic oxidizing acid forming a discontinuous phase when, without rigid confinement, and even upon expo dispersed within, and encapsulated by, the continuous sure to elevated temperatures, they are stacked in stor 65 matrix, which salt is derived from nitric or perchloric age or in a column loaded in a borehole, or are loaded acid and a base selected from the group consisting of in an irregularly shaped borehole. Such rigidity is espe ammonia, amines, and alkali and alkaline-earth metal cially important, for example, in primers for blasting hydroxides; and 4,343,663 3 4 (c) a solid high explosive sensitizer selected from the persed cells of the solution. By virtue of the polymer group consisting of organic nitrate esters and nitramines crosslinking reaction that has taken place, the matrix dispersed in the matrix and/or the aqueous solution; has a "locked-in' firmness, and the explosive product the primer having at least one perforation therein for thus is readily distinguishable from explosive products receiving an initiating device, preferably two perfora whose physical consistency is temperature-dependent. tions parallel to the longitudinal axis of a cylindrical The explosive product of the invention combines the mass, one perforation extending from one end of the well-known advantageous features of water-bearing cylindrical mass to the other, and the other perforation explosives, e.g., superior safety and cost performance extending completely or only partly through the mass. characteristics, and self-supporting explosives such as If desired, the primer may have a protective peripheral 10 cast or plastic-bonded explosives, e.g., resistance to the coating or covering, e.g., a spiral paper wrap. kind of deformation that occurs with pastes and gels, This invention also provides a method of producing a and the elimination of the need for supportive, shape resin-bonded water-bearing explosive product compris affording packaging.