MIXABLE EXPLOSIVE MATERIAL

Description

[0001] The invention relates to an explosive composition comprising a crystalline first explosive and a fusible second explosive as a binder, as well as an energetic additive.

[0002] A similar explosive composition, but without an energetic additive, is known as Octol. It is a solid mixture of cyclotetramethylenetetranitramine (HMX) and trinitrotoluene (TNT). The mixture can contain, for example, 70 wt% HMX and 30 wt% TNT ("Octol 70 / 30") or 75 wt% HMX and 25 wt% TNT ("Octol 75 / 25"). Octol is a melt-castable explosive composition, but it is highly sensitive and therefore dangerous to handle.

[0003] Insensitive explosives containing nitroguanidine are known from Ernst-Christian Koch, Defense Technology 15 (2019), pages 467 to 487. The publication also describes an explosive containing guanylurea dinitramide (FOX-12), trinitrotoluene (TNT), and hexogen (RDX).

[0004] US patent 2012 / 305149 A1 discloses an insensitive, melt-castable explosive composition comprising TNT, RDX with a particle size between 315 and 800 µm and oxynitrotriazole with a particle size between 200 and 400 µm.

[0005] Further polymer-bonded cast explosive compositions are known from the publications US 5 067 996 A, DE 38 04 396 C1, US 2005 / 081970 A1, US 2010 / 065170 A1 and SARANGAPANI RADHAKRISHNAN ET AL: "Effect of particle size and shape of NTO on micromeritic characteristics and its explosive formulations", POWDER TECHNOLOGY, Vol. 253, pages 276-283, ISSN: 0032-5910, DOI: 10.1016 / J.POWTEC.2013.11.029.

[0006] The object of the present invention is to provide an alternative explosive active ingredient which, upon detonation, provides a similarly high performance as Octol, but is significantly less sensitive and therefore safer to handle.

[0007] The problem is solved by the features of claim 1. Advantageous embodiments of the invention result from the features of claims 2 to 14.

[0008] According to the invention, the problem is solved by an explosive composition comprising, in addition to a crystalline first explosive and a second explosive as a binder, an energetic additive. An energetic additive is understood to be an additive which, after its ignition or ignition by reaction without external oxidizers such as atmospheric oxygen, releases energy, in particular at least 1 kJ / g. Molecules of such additives typically carry energetic groups such as nitro groups, nitramine groups, or nitrate groups. The second explosive has a melting point or melting range in a temperature range between 70 °C and 120 °C. This makes the explosive composition according to the invention melt-castable.A special feature of the explosive composition according to the invention is that the first explosive and the additive are present in particle form in a mixture in which the particles exhibit a multimodal particle size distribution. In the explosive composition according to the invention, the mixture has a particle size distribution with at least three modes, wherein the mean particle size of the particles of a first mode is 1.4 to 12 times larger than the mean particle size of the particles of a second mode. The second mode can be the one with the smallest mean particle size. Furthermore, the mean particle size of the particles of the first mode is 1.4 to 12 times smaller than the mean particle size of the particles of a third mode. The third mode can be the one with the largest mean particle size.According to the invention, the mean particle size of the particles of the first mode is in the range of 90 µm to 210 µm, wherein the ratio of the weight percent of the particles of the first mode to the weight percent of the particles of the second mode in the explosive active mass is in the range of 1 : 5 to 6 : 1, wherein the ratio of the weight percent of the particles of the first mode to the weight percent of the particles of the third mode in the explosive active mass is in the range of 1 : 1 to 1 : 12.

[0009] The mean particle size is defined as the particle size at which exactly 50% of the particles in this mode are smaller than this particle size. Particle size and particle size distribution can be determined using laser diffraction. For this purpose, the "Mastersizer 3000" instrument from Malvern Panalytical GmbH, Kassel, Germany, can be used. To determine particle size using laser diffraction, the particles to be measured are suspended in a liquid, such as isopropanol, and the scattering of a laser beam passed through the resulting suspension is analyzed. The analysis is performed by comparing a diffraction pattern obtained through laser diffraction with diffraction patterns obtained by calibration using defined suspensions of spherical particles of different sizes. The particle size determined by laser light scattering is a physical equivalent diameter.Alternatively, another physical equivalent diameter can be determined, for example, by determining the settling velocity of the particles in a liquid or in air. When particle size is determined using the settling velocity of particles in air, this is referred to as the aerodynamic diameter, and when particle size is determined using the sedimentation velocity of particles in a liquid, it is referred to as the equivalent diameter in a fluid.

[0010] By varying the particle sizes within the explosive composition, a very high density can be achieved. Because the average particle size of the second mode is no more than 12 times smaller than the average particle size of the first mode, the molten explosive composition is prevented from becoming too viscous to be easily handled by pouring. If the particles are too small, a highly viscous melt results.

[0011] Because the additive is energetic, it prevents the explosive's performance from being excessively reduced by the additive. The very dense packing of the particles, achieved through the specific particle size distribution in at least three modes, reduces the sensitivity of the explosive. This sensitivity can be further reduced if the additive is an insensitive additive. The insensitivity of the additive, the explosive, or any other component of the explosive can be determined using a gap test. This test measures the height of a standardized water column, referred to as the "gap," that is sufficient to transmit a shock wave generated in the water column by the detonation of a standard explosive charge to the explosive or explosive component under test in such a way that it either detonates reliably or fails to detonate reliably.The values ​​are usually given in millimeters of water column. The lower the value, the more insensitive the active substance or component being tested. In a typical standard test, the threshold gap for an insensitive substance is 15 mm. If the gap is equal to or less than 15 mm and the substance does not reproducibly detonate, it is classified as insensitive. Such insensitive additives are known. These can include, for example, nitroguanidine, guanylurea dinitramide (FOX-12; GUDN; CAS No. 217464-38-5), guanidine dinitrate, nitrotriazolone (NTO), triaminotrinitrobenzene (TATB), or dihydroxylammonium 5,5'-bistetrazol-1,1'-diolate (TKX-50). Alternatively, the additive can comprise at least one of the substances mentioned. The absolute density of the aggregate can be at least 1.74 g / cm³, in particular at least 1.75 g / cm³.The additive thus reduces the density of the explosive composition, which is usually aimed for at the highest possible level, only minimally. Additionally, the explosive composition may contain a wax, plastic, or resin with a melting point or range between 80 °C and 120 °C. This allows for a cost-effective reduction in sensitivity, although this typically results in a decrease in the explosive composition's performance.

[0012] The particles of the first mode can be particles of the aggregate. According to the invention, the average particle size of the particles of the first mode is in the range of 90 µm to 210 µm, in particular 100 µm to 190 µm, and in particular 110 µm to 180 µm.

[0013] According to the invention, the ratio of the weight percent of particles of the first mode to the weight percent of particles of the second mode in the explosive active mass is in the range of 1 : 5 to 6 : 1, in particular 2 : 1 to 5 : 1.

[0014] The ratio of the weight percent of particles of the second mode to the weight percent of particles of the third mode in the explosive active mass can be in the range of 1:2 to 1:6, in particular 1:3 to 1:5.

[0015] According to the invention, the ratio of the weight percent of particles of the first mode to the weight percent of particles of the third mode in the explosive active mass is in the range of 1 : 1 to 1 : 12, in particular 1 : 2 to 1 : 11, in particular 1 : 3 to 1 : 5.

[0016] Due to the specific particle size distribution of the explosive composition according to the invention, the ratio of the weight percentages of the particles of the first, second, and third modes in the explosive composition can be selected such that the explosive composition has a density of more than 99%, in particular more than 99.1%, in particular more than 99.2%, in particular more than 99.3%, in particular more than 99.4%, of the theoretical maximum density and / or an absolute density of at least 1.77 g / cm³, in particular at least 1.78 g / cm³, in particular at least 1.79 g / cm³, in particular at least 1.80 g / cm³. The higher the density in relation to the theoretical maximum density, the less sensitive the explosive composition.To achieve the highest possible density and high insensitivity, the mean particle size of the particles of the first mode is, according to the invention, 1.4 to 12 times, in particular 1.5 to 8 times, larger than the mean particle size of the particles of the second mode. Alternatively or simultaneously, the mean particle size of the particles of the first mode is, according to the invention, 1.4 to 12 times, in particular 1.5 to 8 times, smaller than the mean particle size of the particles of the third mode.

[0017] In one embodiment of the explosive active ingredient according to the invention, the particle size distribution has three or four modes.

[0018] The first explosive could be cyclotetramethylenetetranitramine (HMX), 1,1-diamino-2,2-dinitroethylene (DADNE, FOX-7), hexogen (RDX), 3,3'-diamino-4,4'-azoxyfurazan (DAAF), or 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105). However, the first explosive could also be any other crystalline explosive whose detonation pressure is higher than that of cyclotetramethylenetetranitramine (hexogen) and whose detonation velocity is higher than that of hexogen in a detonation of the other crystalline explosive and hexogen.

[0019] The second explosive could be trinitrotoluene (TNT), 1-methyl-2,4,5-trinitroimidazole (MTNI), bis(1,2,4-oxadiazolyl)furoxane (BOF), N-methyltetranitropyrrole (MTNP), bis(1,2,4-oxadiazole)bis(methylene)dinitrate (BITN), 3,3-bis-isoxazole-5,5'-bis-methylendinitrate (BIDN), 3-(4-aminofurazan-3-yl)-4-(4-nitrofurazan-3-yl)furazan (ANTF), 1,3,3-trinitroacetidine (TNAZ), an ammonium nitrate-containing eutectic mixture, or ammonium dinitramine (ADN).

[0020] In one embodiment of the explosive composition according to the invention, the particles of the first mode consist of the additive. The particles of the second and third modes can each consist of the first explosive. However, it is also possible that the particles of the second mode or the third mode consist of the additive, or that the particles of the first and third modes or of the first and second modes consist of the explosive. Any other combination of the composition of the particles of the individual modes is possible. It is even possible for particles of different compositions to belong to the same mode of particle size distribution.

[0021] The invention is explained in more detail below using exemplary embodiments. The figures shown are: Fig. 1 a diagram of the particle size distribution of guanylurea dinitramide (GUDN), Fig. 2 a diagram of the particle size distribution of nitroguanidine (NQ), Fig. 3 a diagram of the particle size distribution of HMX of specification NSO137 and Fig. 4 a diagram of the particle size distribution of HMX of classification Grade B Class 2.

[0022] To produce the explosive active ingredient according to the invention, the particle size distributions of the particles of potential components of an explosive active ingredient according to the invention were determined using the "Mastersizer 3000" particle size analyzer from Malvern Panalytical GmbH in a suspension of the particles in isopropanol. The measurements were carried out several times in each case to detect any artificial falsification of the measurement results. The results of the measurements are presented in the Figures 1 to 4The following is shown. All measurement curves obtained with the same substance are presented in the same figure. In order of Figures 1 to 4 These figures show the results of particle size determinations for guanylurea dinitramide, nitroguanidine, HMX NSO137, and HMX Grade B Class 2. The mean particle size determined—that is, the particle size at which 50% of all particles in the measured sample are smaller than this value—is 164 µm for guanylurea dinitramide, 115 µm for nitroguanidine, 244 µm for HMX NSO137, and 9.87 µm for HMX Grade B Class 2. Since the measurement curves determined for each substance are almost identical, artificial distortion of the measurements, for example by air bubbles, can be ruled out.

[0023] Trinitrotoluene (TNT) was used as the fusible explosive with a melting point of 80.1 °C. To produce the explosive compositions according to the invention, the components listed in Table 1 below were mixed in the specified weight percentage ratios to obtain the respective mixtures. The resulting mixtures were each melted in a water bath, homogeneously blended, and then poured into the test specimens. The test specimens were used to determine the actual density, to perform the gap test, and to determine the detonation properties. Table 1 Mixture No. Components Mixing ratio [wt.%] 5 GUDN 5 TNT 30 HMX NSO137 51 HMX Grade B Class 2 14 7 Nitroguanidine 15 TNT 33 HMX NSO137 41 HMX Grade B Class 2 11

[0024] To perform the gap test, tablets containing 24 g of the explosive material, each with a diameter of 21 mm, were manufactured and used in the gap test. The measured values ​​are given in millimeters of water column in Table 2 below. The first value under "Gap Test GO" indicates the value at which the explosive material under test reliably detonates, and the value under "Gap Test NOGO" indicates the value at which the explosive material under test reliably fails to detonate. The lower these values, the less sensitive the explosive material. Table 2 composition Gap Test GO Gap test NOGO Octol 70 / 30 (reference) 17 mm 18 mm GUDN / TNT / HMX NS0137 / HMX Grade B Class 2 (V5) 14 mm 15 mm NQ / TNT / HMX NSO137 / HMX Grade B Class 2 (V7) 13 mm 15 mm

[0025] "V5" designates mixture no. 5 and "V7" mixture no. 7. In the gap test, the limiting gap size for an insensitive explosive is 15 mm. If the gap is equal to or less than 15 mm and the explosive reproducibly fails to detonate, it is classified as insensitive. Table 2 above clearly shows that Octol 70 / 30, used as a reference, is not insensitive, while mixtures no. 5 and 7 are classified as insensitive.

[0026] The results of density measurements are shown in Table 3 below. "Density relative to TMD [%]" denotes the percentage density of the respective explosive mass in relation to the theoretical maximum density of the respective explosive mass. Table 3 composition Density [g / cm³< ] Density relative to TMD [%] Octol 70 / 30 (reference) 1,8281 99,8940 GUDN / TNT / HMX NSO137 / HMX Grade B Class 2 (V5) 1,8021 99,4547 NQ / TNT / HMX NSO137 / HMX Grade B Class 2 (V7) 1,7804 99,4610

[0027] Table 3 above shows that the measured density in each case reaches almost 100% of the theoretical maximum density. In contrast to Octol 70 / 30, however, the explosive composition according to the invention is insensitive to this. The high density indicates that the particles in the respective explosive composition achieve a nearly optimal packing density. The absolute densities, at 1.8021 g / cm³ and 1.7804 g / cm³, are relatively close to the density of Octol 70 / 30. Consequently, very similar detonation characteristics were achieved as with Octol 70 / 30.

[0028] To investigate the detonation properties of mixtures No. 5 and 7, the mixtures were melted and cast into strands with a diameter of 50 mm. Two of these castings were bonded together to form a test specimen with a measuring length of 300 mm. Holes were drilled into the assembled test specimen at 45 mm intervals. Measuring probes for detonation measurement were inserted into these holes. A total of seven measuring probes were placed throughout the assembled test specimen to ensure a uniform detonation front over the 300 mm measuring length. A tablet of an HWC booster (94.5 wt% hexagen, 4.5 wt% wax, 1 wt% graphite) was bonded to the top of the test specimen and detonated using an electric detonator. The resulting measurements are presented in Tables 4 to 7 below. Table 4 Sample identity GUDN / TNT / HMX NSO137 / HMX Grade B Class 2 (V5) Target density [g / cm³< ] (TMD) 1,812 Detonation pressure [kbar] (calculated) for TMD 323,334 Detonation velocity [m / s] (calculated) at TMD 8442,185 Resolution [µs] 0,1 remark HMX mixture: NSO137 [51%] & Grade B Class 2 [14%] Table 5 Probe number Measurement time [µs] Detonation velocity [m / s] 1 - 2 5,6 8040 2 - 3 5,3 8490 3 - 4 5,5 8180 4 - 5 4,9 9184 5 - 6 5,4 8333 6 - 7 5,5 8180 8401,166667 Table 6 Sample identity NQ / TNT / HMX NSO137 / HMX Grade B Class 2 (V7) Target density [g / cm³< ] (TMD) 1,790 Detonation pressure [kbar] (calculated) for TMD 306,909 Detonation velocity [m / s] (calculated) at TMD 8357,565 Resolution [µs] 0,2 remark HMX mixture: NSO137 [41%] & Grade B Class 2 [11%] Table 7 Probe number Measurement time [µs] Detonation velocity [m / s] 1 - 2 5,4 8333 2 - 3 5,6 8040 3 - 4 5,4 8333 4 - 5 5,6 8040 5 - 6 5,4 8333 6 - 7 5,2 8650 8288,166667

[0029] The corresponding data for the density, detonation pressure and detonation velocity for Octol 70 / 30 are given in Table 8 below. Table 8 composition Density [g / cm³< ] Density relative to TMD [%] Detonation pressure (calculated) [kbar] Detonation velocity (calculated) [m / s] Octol 70 / 30 1,8281 99,894 332,773 8509,194

[0030] A comparison of the data for mixtures No. 5 and No. 7 according to the invention with the corresponding data for Octol 70 / 30 shows that the maximum detonation velocities of the mixtures according to the invention almost reach the detonation velocity of Octol 70 / 30. However, given that the explosive compositions according to the invention are insensitive, achieving such detonation velocities is surprising.

Claims

1. Active material for explosive, comprising a crystalline first explosive, a second explosive as binder and an energetic adjuvant, where the second explosive has a melting point or melting range in a temperature range between 70°C and 120°C, where the first explosive and the adjuvant are in the form of particles in a mixture which has a particle size distribution exhibiting at least three modes, with a mean particle size of a first mode being 1.4 to 12 times greater than a mean particle size of a second mode and 1.4 to 12 times smaller than a mean particle size of a third mode, where the mean particle size of the particles of the first mode is in the range from 90 µm to 210 µm, where a ratio of the weight-percentage fraction of the particles of the first mode to the weight-percentage fraction of the particles of the second mode in the active material for explosive is in the range from 1: 5 to 6: 1, where a ratio of the weight-percentage fraction of the particles of the first mode to the weight-percentage fraction of the particles of the third mode in the active material for explosive is in the range from 1: 1 to 1: 12.

2. Active material for explosive according to Claim 1, where the mean particle size of the particles of the first mode is in the range from 110 µm to 190 µm.

3. Active material for explosive according to Claim 1 or 2, where a ratio of the weight-percentage fraction of the particles of the second mode to the weight-percentage fraction of the particles of the third mode in the active material for explosive is in the range from 1: 2 to 1: 6, more particularly 1: 3 to 1: 5.

4. Active material for explosive according to any of the preceding claims, where a ratio of the weight-percentage fraction of the particles of the first mode to the weight-percentage fraction of the particles of the third mode in the active material for explosive is in the range from 1: 2 to 1: 11.

5. Active material for explosive according to any of the preceding claims, where a ratio of the weight-percentage fraction of the particles of the first, second and third modes in the active material for explosive is selected such that the active material for explosive has a density of more than 99% of the theoretical maximum density and / or has a density of at least 1.77 g / cm3.

6. Active material for explosive according to any of the preceding claims, where the mean particle size of the first mode is 1.5 to 8 times greater than the mean particle size of the second mode and / or is smaller than the mean particle size of the third mode.

7. Active material for explosive according to any of the preceding claims, where the particle size distribution has three or four modes.

8. Active material for explosive according to any of the preceding claims, where the first explosive is cyclotetramethylenetetranitramine (HMX), 1,1-diamino-2,2-dinitroethylene (DADNE, FOX-7), hexogen (RDX), 3,3'-diamino-4,4'-azoxyfurazan (DAAF) or 2,6-diamino-3,5-dinitropyrazine 1-oxide (LLM-105).

9. Active material for explosive according to any of the preceding claims, where the second explosive is trinitrotoluene (TNT), 1-methyl-2,4,5-trinitroimidazole (MTNI), bis(1,2,4-oxadiazolyl)furoxan (BOF), N-methyltetranitropyrrole (MTNP), bis(1,2,4-oxadiazole)bis(methylene) dinitrate (BITN), 3,3-bisisoxazole-5,5'-bismethylene dinitrate (BIDN), 3-(4-aminofurazan-3-yl)-4-(4-nitrofurazan-3-yl)furazan (ANTF), 1,3,3-trinitroazetidine (TNAZ), a eutectic mixture comprising ammonium nitrate, or ammonium dinitramine (ADN).

10. Active material for explosive according to any of the preceding claims, where the particles of the first mode consist of the adjuvant.

11. Active material for explosive according to any of the preceding claims, where the particles of the second and third modes each consist of the first explosive.

12. Active material for explosive according to any of the preceding claims, where the adjuvant is or comprises nitroguanidine, guanylurea dinitramid (FOX-12; GUDN; CAS No. 217464-38-5), guanidine nitrate, nitrotriazolone (NTO), triaminotrinitrobenzene (TATB) or dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50).

13. Active material for explosive according to any of the preceding claims, where the density of the adjuvant is at least 1.74 g / cm3, more particularly at least 1.75 g / cm3.

14. Active material for explosive according to any of the preceding claims, further comprising a wax, plastic or resin which has a melting point or melting range in a temperature range from 80°C to 120°C.