JPH0641397B2 - Casting explosive composition and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to explosive compositions. More particularly, this invention relates to cast explosive compositions having relatively high density, energy and critical diameter. The term "casting" is fluid when blended at elevated temperatures, but solidifies or solidifies upon cooling to ambient temperature (herein "ambient temperature" means ambient temperature or room temperature). Means a non-flowable or non-extrudable object. This is to "pour" or "cast" the composition while it is being fluidized into a container of the desired shape to solidify into that shape. Although the composition of the present invention is cured, it is still ready for machining into the desired shape.

The composition of the present invention is prepared by increasing the temperature to form a water-in-oil emulsion, which emulsion forms a casting composition when allowed to cool. This composition comprises an inorganic oxidant salt,
An organic liquid fuel that is immiscible with water, about 5% or less of water, any fuel or sensitizer, and an elevated compounding temperature (herein, "compounding temperature" is the temperature at which an emulsion is formed). Therefore, the water-in-oil type emulsion is formed at an ambient temperature or a temperature higher than the crystal precipitation temperature), but at a temperature lower than that or at an ambient temperature, the emulsification is weakened and an inorganic oxidizer salt is crystallized. It contains a special type of emulsifier which allows it to form a casting composition.

Water-in-oil emulsion explosives are well known in the art. For example, U.S. Pat. Nos. 4,356044; 4322,258 and 4,
See No. 141,767. Such an explosive composition comprises a continuous phase of an organic liquid fuel that is immiscible with water and a discontinuous phase of an emulsified aqueous solution of an inorganic oxidant salt. Usually, these explosive compositions contain a density-reducing agent for eager purposes. These compositions have a greasy consistency which makes them water resistant and generally extrudable.

Past efforts have focused on the preparation of stable emulsion detonation compositions and thus preventing or minimizing the formation or destruction of emulsions and the formation of crystallization of the inorganic oxidant salt initially dispersed throughout the continuous fuel phase. It came to me. This is the crystal precipitation temperature of the emulsion that is stable against the destruction of the solution of the oxidant salt, and particularly the emulsion (in the present specification, the "crystal precipitation temperature" means that the oxidant salt melted in the solution starts to precipitate from the solution. This is generally achieved by using about 8% or more water to reduce the temperature (meaning temperature). In contrast, the present invention uses less than about 5% water and an emulsifier of a type that does not form a particularly stable emulsion, thus weakening the emulsion and causing crystallization of the oxidizer salt to form a composition. This is a cast product with a shape.

A low-moisture emulsion emerged from U.S. Pat.No. 4,248,644, in which the melt emulsifies in the form of a "melt in fuel" where the composition is ammonium nitrate as the discontinuous phase and the composition is substantially free of water. An explosive composition is disclosed. However, this composition contains an emulsifier of the type which gives a "greasy consistency" even after cooling to ambient temperature. Thus, the low water itself does not guarantee the formation of the casting composition. The casting composition of the present invention requires low water binding with the special emulsifiers described herein.

The composition of the present invention has advantageous properties. There has been a widespread need for explosive compositions that can be poured into various forms of containers while hot, but that when cooled, can be cast or cured into the form of containers that are relatively gold-free and cast. Previously such types of explosives have been cast from self-cast explosives such as TNT, Composition B, Pentlite and the like. However, these compositions are relatively expensive. The casting compositions of the present invention have physical properties similar to those casting self-explosives containing high density energy. But,
The cost of the ingredients is quite low. Thus, a major benefit of the present invention resides in providing a castable explosive composition containing relatively inexpensive ingredients. In addition to this, whenever the composition loses its greasy toughness upon cooling and precipitation of the oxidizer salt, it retains the appropriate water resistance due to the hardened nature of its surface. Because of the ease of touch, the composition remains fluid for some time even after cooling to reduce the salt crystallization temperature.

When initially compounded at elevated temperature, the compositions of the present invention are in the form of a water-in-oil emulsion with a greasy consistency. This is advantageous for many reasons. The emulsion morphology is finely and evenly dispersed throughout the continuous fuel phase, increasing the ease of reaction of the oxidant and fuel. The oxidant salt is initially dispersed through the fuel phase as drops of the solution at elevated temperature, and with cooling of the composition the precipitation of salts in the drops is physically blocked resulting in the formation of fine salt crystals, which is Enhances the homogeneity between oxidant and fuel. Another benefit is that the greasy emulsion is liquid and can be pumped and extruded as desired. As the emulsion cools, the crease-like properties are not lost immediately as the crystallization of the salt gradually occurs, thus the composition remains in its emulsified liquid state for a while after cooling below the crystal precipitation temperature of the salt. Retains the tactile sensation of. This makes it feel like an initial texture as an emulsion, even at lower temperatures than the composition. In this way the addition of other ingredients such as solid sensitizers or density reducing agents can be achieved at lower temperatures. Shrinkage and / or voids after addition to the container can be minimized. And the risk to people of high temperature material processing can be reduced. The non-emulsifying composition will cure rapidly after cooling below the crystallization or melting temperature of the components.

The inorganic oxidant salt is used in an amount of about 45% to about 92% by weight of the total composition. The oxidant salt is preferably ammonium nitrate salt, but other salts can be used. Other oxidant salts are selected from the group consisting of ammonium, alkali and alkaline earth metal nitrates, chlorates and perchlorates. Preferably about 10% to about 65% of the total oxidizer salt is added in particulate or granulated form.

The water-immiscible organic liquid fuel which forms the continuous phase of the composition at elevated temperatures is generally present in an amount of about 2% to about 15% by weight of the total composition. The actual amount used may vary depending on the particular immiscible fuel (s) used and other fuels, if any. Immiscible organic liquid fuels may be aliphatic, cycloaliphatic and / or aromatic and may be saturated or unsaturated as long as they are liquid at the compounding temperature. Preferred fuels include mineral oils, waxes, paraffin oils, benzene, toluene, xylenes and mixtures of liquid hydrocarbons commonly referred to as petroleum distillates such as gasoline, kerosene and diesel fuel. Particularly preferred liquid fuels are mineral oil, No. 2 fuel oil, paraffin wax, fine crystalline wax and mixtures thereof.
Aliphatic and aromatic nitro compounds can also be used. Halogenated organic fuels can also be used in amounts up to about 25%. Mixtures of the above can also be used.

Water can be used in an amount of about 5% or less of the total composition. Organic liquids that are miscible with water can partly be replaced by water as a solvent for salts, such liquids acting as fuel for the composition. Liquid fuels that can be mixed are alcohols such as methyl alcohol, glycols such as ethylene glycol, amides such as formamide,
And similar nitrogen-containing liquids. The use of small amounts of water is an important direction of the present invention.

Optionally and in addition to the immiscible organic fuel, solid or other liquid fuel or both may be used in selected amounts.
Examples of solid fuels that may be used are finely ground aluminum particles; finely ground carbonaceous material such as Gilsonite or coal; finely ground vegetable granules such as flour; and sulfur. Liquid fuels include fuels that are miscible with water as described above. Specifically selected solid fuels can be used in amounts up to about 5% by weight to increase the density and energy of the composition. Granular, finely divided or paint grade aluminum can also be used, finely divided ones being preferred.

Depending on the case, a sharpening agent can be used, and the temperature is about 150 mm at 5 ℃
Gives a not-greater critical diameter. The critical diameter is the minimum diameter at which a given temperature will ensure that an explosive will explode at a given temperature. At relatively high densities of 1.50 g / cc or higher, sensitizers are commonly used to provide moderate sensitivity. The sensitizer may be selected from the group consisting of particulate metals, molecular explosives and mixtures of these components. About 50% by weight of granular aluminum or other metal particles
It can be used in an amount up to. The aluminum particles may be paint grade, finely divided or granular. Examples of granular molecular explosives are pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RD
X), trinitrotoluene (TNT), cyclotetramethylene tetranitramine (HMX) and nitrocellulose.
Other types of molecular explosives are water-soluble salts such as amine nitrates or perhydrochlorides including monomethylamine or ethylenediamine nitrates and alkanolamine salts such as ethanolamine nitrates or perchlorates.

Molecular explosives can be used in amounts ranging from about 10 to about 70% by weight, preferably up to about 45%. Preferred sensitizers are RDX, alone or in combination with finely ground aluminum.

Emulsifiers are a key ingredient in the compositions of this invention. The emulsifier must be capable of forming a water-in-oil emulsion at elevated compounding temperatures. In addition to this, the emulsifier must be one that weakens the emulsification by cooling and precipitates the inorganic oxidant salt in the solution at a temperature below the crystal precipitation temperature of the solution. Thus, the emulsion should be such that it is inherently unstable in the composition and causes salt precipitation so that the composition may be cast. The emulsifiers found to give compositions with these properties include aliphatic amines having the formula: : RNH ₂ , where R has a chain length in the range of 4 to 22 carbon atoms. Acid salts of such fatty amines, disodium ethoxylated nonylphenol half-esters of sulfosuccinic acid; complex organic phosphate esters (SYn Fac9214); and sucrose stearate (sucrose stearic acid) These examples are anions, Represents the grade of cationic and nonionic emulsifiers. Emulsifiers form water-in-oil emulsions at elevated compounding temperatures, but also weaken emulsification at ambient temperatures, precipitating inorganic oxidizer salts to give casting compositions. The emulsifier is used in an amount of about 0.2 to about 5% by weight. The emulsifier preferably contains saturated hydrocarbon chains as its lipophilic part, although unsaturated forms can also be used. The unsaturated form may not form castings as easily or as quickly as the saturated form, but tends to form a more stable emulsion than the saturated form. It is desirable that the salt of the aliphatic amine or its emulsifier has a chain length of 14 to 18 carbon atoms, and the aliphatic amine is an alkylammonium composed of saturated molecules having a chain length of 14 to 18 carbon atoms. More preferably, it is a salt. The aliphatic amine emulsifiers of the present invention are also capable of acting as crystalline modifiers in that they control the crystal growth of the oxidant salt and prevent the formation of larger desensitizing crystals.

Although it is desirable for the compositions of the present invention to have a high density, the composition can be reduced from its natural density by the addition of density-reducing agents such as plastics or glass spheres and small hollow particles exemplifying perlite. You can
In addition to this, bubbles can be mixed into the composition during formation or small amounts of chemical outgassing agents such as sodium nitrite can be introduced. It chemically decomposes into bubbles in the composition. The use of density reducing agents to increase sensitivity is well known in the art.

The compositions of the present invention are first formulated by melting, or if water is present, by raising the temperature above the salt crystallization temperature to form a solution of the oxidizer salt (s). This melt or solution is then added to a solution of emulsifier and immiscible organic liquid fuel, which, if treated at ambient temperature or elevated temperature and sufficiently vigorous, melts the oxidizer salt as a continuous organic liquid fuel phase. Or it produces an emulsion of the solution. Usually this can be substantially achieved by constantly rapid stirring. Stirring should be continued until the formulation is uniform. Any solids, particulate fuel and / or oxidant salt and other ingredients, if any, are then added and agitated through the formulation by conventional equipment. The compounding method can also be accomplished in a continuous manner as is known in the art. It is desirable to add any solid particulate fuel, such as any particulate oxidant salt or aluminum particles, at ambient temperature, which results when the entire composition is cooled to a temperature below the oxidant salt freezing or crystallization temperature. . As previously said, crystallization of the oxidant salt occurs at temperatures below the crystal precipitation temperature over a certain period of time,
The resulting composition was left in liquid form for ease of handling, even when containing up to 60% solids. The rate of curing depends on the refining rate of the original emulsion and the amount and strength of shear,
This is what is received during processing while it is below the crystal precipitation temperature. The emulsifier and liquid fuel type also affect the cure rate. It is advantageous to pre-dissolve the emulsifier in the organic liquid fuel before adding it to the oxidant salt melt or solution. This method allows the emulsion to form quickly and with minimal agitation. The emulsifier may be added separately and just prior to emulsification, which is optional or if, for example, the emulsifier deteriorates at the elevated temperature of the fuel.

The following table further illustrates the invention.

In Table 1, Examples A and B are prepared by the method described above and are representative compositions of the present invention. Example A contains a large amount of dry AN (ammonium nitrate) granules (50%) and no aluminum. In contrast, Example B contains a smaller amount of grit, but contains 39% finely ground aluminum, which gives Example B a much higher density and much greater energy. The remaining examples show variations on the components. Examples GL and O contain glass microballoons and thus have a relatively small density but high sensitivity. Example L is 40%
Contains dry potassium perchlorate. Examples of other emulsifiers found to be capable of producing casting compositions according to the invention are disodium ethoxylated nonylphenol half esters of sulfosuccinic acid (Syn Fac9214) and sucrose stearate. All these examples are manufactured in the same way as described above.

Table II illustrates sensitized compositions having a critical diameter of no greater than about 150 mm at a temperature of 5 ° C. Example A
Contains RDX as a single sensitizer and has a density of 1.65 g / cc, but was still more sensitive than No. 12 detonator with a diameter as small as 25 mm. Example B is RDX and 30 as a composite sharpener
% Pulverized aluminum and had a density of 1.81 g / cc and was capable of blasting with the same small diameter. Example B has extremely high energy (2211 cal / g) due to the presence of aluminum
Had. When blending Example B, the emulsion is
Formed (a combination of AN (ammonium nitrate) and SN (sodium nitrate)} salts had a crystal precipitation temperature of 120 ° C.)}, and in a specific example aluminum and RDX at ambient temperature of about 70 ° C. The addition was allowed to cool to 80 ° C. The resulting composition was still grease-like to the touch even after more than one hour after mixing in the solid.
Examples CE show the change in composition. Examples F and G contain potassium nitrate as an additional oxidant salt, and Example G contains a large amount of sensitizer (70
% RDX). Other examples of emulsifiers found to produce casting compositions in accordance with the present invention are disodium ethoxylated nonylphenol half-esters of sulfo-succinic acid; complex organophosphate esters (Syn Fac9214).
including.

The composition of the present invention is also applicable to the most common explosives. When first compounded, the composition is extrudable,
And / or it can be pumped so that it can be filled into containers of different configurations for different applications. The sensitized findings have physical and chemical properties similar to casting self-explosives and thus can be used for boosters, munitions filling, artillery shells, etc.

It will be apparent to those skilled in the art that the present invention has been described with respect to certain illustrative examples and preferred embodiments or that various variations can be made. Any such variations are considered to be within the scope of the invention as described in the appended claims.

Claims (14)

[Claims] 1. An explosive composition comprising an inorganic oxidizer salt; an organic liquid fuel immiscible with water; and 5% by weight or less of the total composition of water, in oil at a higher compounding temperature. Form an aqueous emulsion, weaken the emulsification of the emulsion,
A casting explosive composition, wherein the inorganic oxidizer salt comprises an emulsifier that crystallizes at ambient temperature to form a casting composition. 2. An aliphatic emulsifier having the formula: RNH ₂ wherein R has a chain length in the range of 14 to 22 carbon atoms; an acid addition salt of such an aliphatic amine; A composition according to claim 1 selected from the group consisting of disodium ethoxylated nonylphenol half esters of succinic acid; complex organophosphate esters and sucrose stearate. 3. A composition according to claim 2 in which the emulsifier is saturated. 4. A composition according to claim 2 wherein the emulsifier has a chain length in the range of 14-18 carbon atoms. 5. The composition according to claim 3, wherein the emulsifier is alkyl ammonium acetate. 6. The composition of claim 1 wherein the composition includes a sensitizer to provide a critical diameter at a temperature of about 5 ° C. of not more than about 150 mm. 7. A sharpening agent is TNT, RDX, PETN, HM.
A composition according to claim 6 selected from X, granular aluminum, nitrocellulose, and mixtures thereof. 8. The composition of claim 7 wherein the sensitizer comprises RDX in an amount of at least about 10% by weight of the total composition. 9. A composition according to claim 7, wherein the sensitizer comprises a mixture of RDX and granular aluminum. 10. A composition according to claim 9 wherein RDX is present in an amount of at least about 10% and aluminum is present in an amount of at least about 20%. 11. A method according to claim 1, which contains up to 20% of an additional inorganic oxidant salt selected from the group consisting of ammonium, alkali and alkaline earth metal salts of nitric acid, chloric acid and perchloric acid. The composition according to. 12. A composition according to claim 1 containing up to about 40% of an additional oxidant salt selected from the group consisting of ammonium, alkali and alkaline earth metal salts of perchloric acid. 13. A composition according to claim 1 which contains a density reducing agent to reduce the density of the composition. 14. (a) an inorganic oxidant salt and 5% or less of water,
A water-in-oil emulsion containing an organic liquid fuel immiscible with water, and an emulsifier, wherein the emulsion is formed in the emulsion at a temperature equal to or higher than the crystallization temperature of the inorganic oxidizer salt. A step of forming a water-in-water emulsion, (b) cooling the emulsion to an environmental temperature below the crystal precipitation temperature, and (c) adding an emulsifier to the oil at an elevated compounding temperature in oil A method for producing a cast explosive composition, which comprises forming a water-type emulsion, which weakens the emulsification and precipitates an inorganic oxidizer salt at ambient temperature to produce a casting composition.