US3390029A - Inorganic oxidizer salt explosive composition containing organic fuel solvent for said salt - Google Patents

Description

United States Patent 3,390,029 INORGANIC OXIDIZER SALT EXPLOSIVE COM- POSITION CONTAINING ORGANIC FUEL SOL- VENT FOR SAID SALT Ralph F. Preckel, La Vale, Md., assignor to Hercules Incorporated, Wilmington, Del., a corporation of Delaware No Drawing. Filed Dec. 13, 1966, Ser. No. 601,825 10 Claims. (Cl. 149-41) ABSTRACT OF THE DISCLOSURE An explosive composition in which inorganic oxidizer salt is suspended in fuel-solvent liquid solution of the salt.

Here again, the system of this invention performs similarly: elevated temperature increases solubility of oxidizer salt so that a normally solid system becomes fluent or mobile; after casting, reprecipitation of part of the disice 5 solved salt gives the effect of solid east explosive. TNT

systems often carry metal fuels and may be modified with polymers, crosslinkable, if desired, and the like. Here, the TNT component is replaced with the perchlorate or nitrate salt slurried in its own nonaqueous solution, generally with increased available explosive energy on either a weight or volume basis, often both; polymer (crosslinking optional) may also be added.

The present invention contemplates, therefore, a group of new products, constituting systems of one or more solid The composition may be fluent or semi'fluent containing oxidizers suspended in a liquid (saturated oxidizer soluthickening agent or non-fluent containing crosslinking agent.

This invention relates to a new class of explosive comtion) for manipulation. In finished form, the system may retain its slurry nature, it may be gelled by use of suitable polymer or it may resemble regular cast military explosives. The gel polymer system may be more or less positions. More particularly, the present invention relates crOSSliIlked to resist Slumping defofmatioll- The meltto a new class of organic fuel-solvent/inorganic oxidizer salt explosive compositions in which the oxidizer is suspended in a fuel-solvent liquid solution of the salt. The solvent is a polar organic substance serving as a supplementary fuel as well as a vehicle for rendering the composition fluent where desired, as for example, for uses presently served by the well-known aqueous slurry blasting agents on explosives including the addition of finely divided high energy metal fuel. However, the compositions cast type system may also be modified with polymer, which may be crosslinkable. Any of the systems may carry high energy fuel, generally a powdered metal or metal hydride.

More specifically, the present invention contemplates an explosive composition comprising at least one oxidizer salt of the group consisting of ammonium nitrate, sodium nitrate, potassium nitrate, calcium nitrate, ammonium perchlorate, sodium perchlorate, and magnesium perchloof the invention may be modified as hereinafter set forth rate, and at least one fuel solvent for said salt of the to embrace uses where a range from fluent to non-fluent compositions is desired.

The prior art includes especially aqueous ammonium nitrate systems in which solid salt is suspended along with sensitizer and perhaps powdered metal fuel. Carbohydrates group consisting of glycol, lactic acid, glycolic acid, formamide, dimethyl formamide, ethylene carbonate and propylene carbonate, said explosive composition having a density of more than 1.8 grams per cc.

Many organic liquids are excellent solvents for oxidizers; ethylene glycol is known to dissolve quantities of salts; correspondingly, many other polar organics can dissolve ionic compounds, the optimum combination of solvent and solute being determined by many considerations of compatibility, energetics in the case of explosive systems, etc. Generally, for explosive use, one wants a powerful solvent which will make little demand on the oxidizer, i.e., it will carry oxygen in its own structure.

To illustrate, Table I which follows demonstrates readwater replaced by organic solvent will produce more enily available systems for practicing the present invention.

TABLE I.OXIDIZER SOLUBILITIES [Grams per 100 g. solution at 20-25 0.]

Solvent M.P., C. B.P., O. p (g./ml.) NH4C10; NaClOi NHiNOa Glycol -17 197 1. 12 15 40 Lactic acid... 26 200+ 1. 25 15 Glycolic acid 77 200+ 1. 49 Solid 40 Formamide 2 200+ 1 13 20 65 Dimethyl formamide 61 153 0. 95 35 50+ 40 Ethylene carbonate 36 243 1. 32 15 ergy per unit weight. With judiciously chosen organic 501- With reference to Table I, it will be appreciated that polar polymers (cellulosics, polyethers, polyesters and the like) dissolve in the pure solvents and in the oxidizer solutions in many cases. Crosslinking by means of appropriate standard systems (diisocyanates, epoxies, etc.)

can be accomplished, taking due account of interference to be expected from both oxidizer and solvent.

In Table II which follows a number of examples of calculated properties of explosive systems in accordance with the invention are shown.

TABLE II.CALCULATED PROPERTIES OF EXPLOSIVES Explosive (Percent by weight) Density Energy Det. Vel.

(g./cc.) (caL/g.) in m./sec.

TNT 1. 1, 070 6, 000 Commercial Explosive 1. 5+ 1, 6, 450 65 AP, 25 Al, 10 dimethyl-iorrnamide 1.88 1, 685 6, 790 65 AP, 25 Al, 10 ethylene carbonate. 2 05 l, 770 5, 590 65 AP, 25 A1, 10 formic acid 1. 97 l, 665 7, 025 65 AP, 25 Al, 10 lactic acid 1. 98 1, 695 6, 920 65 AP, 25 Al, 10 glycolic acid. 2. 07 1, 680 6, 990 65 AP, 25 Al, 10 formamide 1. 96 ca 1, 670 ca 6, 900

tjl,390,029

A number of examples were tested for critical diameter for propagation of detonation. Each of the systems contained 60 or 70% ammonium perchlorate {AP}, 30 or aluminum (Al) of 20 micron particle size and 10% dirnethylformamide (DMF). In addition systems retaining the 7 to l (and 7 to 2) ratio of AP to solvent were tested and one trial was made in which the oxidizer was AP and 30 HMX with 17 Al, 22 DMF. Each of the systems was thickened with 0.5% cellulose acetate (CA). In every case, negative propagation results were obtained at 2.6" diameter, at 5" diameter, including tests in Sch. steel pipe, using pentolite boosters of 1 lb. weight. In a subsequent test, two 220 lb. charges at 72 AP, 16 Al, 12 DMF and 0.5 added CA were cast in Sch. 40 pipe and initiated under 12 ft. water with 5 lb. pentolite in direct contact. Both these latter charges detonated high order with detonation velocities in the order of calculated properties. It is thus established that the AP/Al/solvent system is far more capable of propagation than AP/Al/nonsolvent (composite rocket propellant, for example), which regularly has a critical diameter of at least 20".

As shown above, the new system of this invention contemplates an oxidizer or mixture of oxidizers in a matrix of solution thereof in a fuel solvent; supplementary solid fuels (powdered metals or hydrides) may also be dispersed in the matrix. Moreover, the invention contemplates the highly desirable performance of high density systems wherein the explosive composition has a density of more than 1.8 grams per cc. Depending on whether the composition is to be fluent, semi-fluent or non-fluent the system may contain a linear polymer for thickening and the polymer may be crosslinked to establish physical properties required for shell rocket or bomb warhead filling and the like. The preferred solvents are generally polar, including glycols and polyols, amides and substituted amides, acids and substituted acids. Generally, the best solvents will be of low molecular weight.

From the foregoing it is evident that there are several factors which will influence conditions for the most satisfactory operation of the invention, the actual requirements of which are determined by the raw materials and the intermediate and the finished products desired.

For example, the salt is an inorganic oxidizer salt or mixture of salts of the group consisting of ammonium nitrate, sodium nitrate, potassium nitrate, calcium nitrate, ammonium perchlorate, sodium perchlorate and magnesium perchlorate present in an amount of from about 60 to about 90% by weight of the composition. For a fluent explosive composition, the oxidizer salt is suspended in the fuel solvent in an amount of from about to about i 80% by weight. The fuel solvent, or mixture of solvents, as previously pointed out, is generally polar and of the group consisting of glycol, lactic acid, glycolic acid, formamide, dimethyl formamide, ethylene carbonate and propylene carbonate present in an amount of from about 5 i to about 40% by weight of the composition and preferably from about 5 to about 20% by weight. For semifluent explosives, thickening agents such as cellulose acetate, long chain polyalkylene glycols, polyvinyl alcohol, carboxymethylcellulose, bydroxyalkylcelluloses, and the like, are incorporated in an amount of from about 0.1 to about 1.0% by weight of the compositions. For nonfiuent explosives, crosslinking agents such as the diisocyanates, epoxies, polyfunctional aziridines and anhydrides, and the like, are incorporated in an amount of from about 0.1 to about 1.0% by weight of the composition. Also, as previously pointed out, the utilization of a linear polymer as the thickening agent together with a crosslinking agent for the polymer gives a particularly eflicacious system where a non-fiuent end product is de- I sired. The metal fuels include any finely divided high potential preferably light metal or hydride such as berryllium, magnesium, aluminum, silicon, titanium, zirconium and mixtures and alloys thereof incorporated in an amount of from 10 to 25% by weight of the composition.

it will be appreciated that the particle size of the ox- :ldizer salt and the metal fuel may vary considerably but these constituents are preferably utilized having a particle size of from about 150 to about 400 mesh (U.S. Sieve Series) and from about 5.0 to about 50 microns for ease in solubilizing and ease of suspending, respectively.

The advantages of the invention are multifold in that while physically similar to aqueous explosive systems in many respects, the water replaced by organic solvent in accordance with this invention produces more energy per unit weight. Furthermore, the present invention provides for the tailoring of end products to obtain fluent, semi-fluent and non-fluent products as desired in a facile and economical manner and in most instances by simple incorporation of additional thickening and/or crosslinking agents to a basic formulation. Still further, the present invention provides explosive compositions meeting the requirements of blasting agents, conventional explosives, military explosives and rocket propellant.

it will be seen, therefore, that this invention may be carried out by the use of various modifications and changes without departing from its spirit and scope with only such limitations placed thereon as are imposed by the appended claims.

What i claim and desire to protect by Letters Patent are:

l. An explosive composition consisting essentially of:

la) at least one oxidizer salt of the group consisting of ammonium nitrate, sodium nitrate, potassium nitrate, calcium nitrate, ammonium perchlorate, sodium perchlorate. and magnesium perchlorate, and

lb) at least one fuel solvent for said salt of the group consisting of glycol, lactic acid, glycoiic acid, formamide, d'imethyl formamide, ethylene carbonate and propylene carbon-ate, said explosive composition having a density of more than 1.8 grams per cc.

it. The explosive composition of claim 1 in which the oxidizer salt is suspended in the fuel solvent in amount to tender the composition a fluent explosive.

The explosive composition of claim 1 in which the composition contains a thickening agent to render the composition a semi-fluent explosive.

ll. The explosive composition of claim 1 in which the composition contains a crosslinking agent to render the composition a non-fluent explosive.

5. The explosive composition of claim 1 in which the composition contains at least one finely divided metal fuel.

l5. An explosive composition consisting essentially of:

la) from about 60 to about 90% by weight of at least one oxidizer salt of the group consisting of ammonium nitrate, sodium nitrate, potassium nitrate, calcium nitrate, ammonium perchlorate, sodium perchlorate, and magnesium perchlorate, and

lb) from about 5 to about 40% by weight of at least one fuel solvent for said salt of the group consisting of glycol, lactic acid, glycolic acid, formamide, dimethyl formamide, ethylene carbonate and propylcne carbonate, said explosive composition having a density of more than 1.8 grams per cc.

7. The explosive composition of claim 6 in which the oxidizer salt is suspended in the fuel solvent in an amount of from about 50 to about by weight to render the composition a fluent explosive.

B. The explosive composition of claim 6 in which the composition contains from about 0.1 to about 1% by Weight of a thickening agent to render the composition a semi-fluent explosive.

19. The explosive composition of claim 6 in which the composition contains from about 0.1 to about 1% by weight of a crosslinking agent to render the composition a non-fluent explosive.

l0. The explosive composition of claim 6 in which the composition contains from about 10 to about 25% by Weight of at least one finely divided metal fuel.

tlReferences on following page) References Cited UNITED STATES PATENTS Olstowski et a1 14946 X E110 149-39 X Clay et a1 14944 X Grant 14944 X Cook et al 14941 X BENJAMIN R. PADGETT, Primary Examiner.

S. I. LECHERT, ]R., Assistaht Examiner.