MXPA98005654A - Explosive compositions detonating with microesphe - Google Patents

Abstract

An explosive explosive solid composition, sensitive to detonators and molded used as a reinforcer or initiator and as an explosive seismic composition. The solid and molded explosive composition contains dispersed microspheres that give the composition important advantages

Description

EXPLOSIVE COMPOSITIONS DETONANTES WITH MICROSPHERES.

The invention relates to an explosive composition that is sensitive to detonators and a molded solid form is presented. More particularly, the invention relates to an explosive composition sensitive to detonators, molded and solid as a reinforcer or initiator and as a seismic explosive in normal and small size.

BACKGROUND OF THE INVENTION Most explosive compositions sensitive to detonators and form Molded solid used as an initiator are made of molecular explosives such as PETN, TNT, RDX or combinations thereof such as pentolite and composition B. These Molecular explosive products have a relatively high density (1.6 g / cc or greater) and are formed from melted solids at high temperatures. The solid melts at high temperatures are emptied into containers and the desired mold is allowed to cool down. The steps melting, casting and molding involve hazards due to the high temperatures required and the presence of molecular explosives. Recently, a novel solid, molded explosive composition was invented that allows the mixing, emptying and molding of non-explosive ingredients to be carried out at room temperature. The ingredients are simply mixed at room temperature to form a pulp that can be emptied ^^ 20 in containers to allow it to heal over time in a form sensitive to detonators, molded and solid. (See patent pending USSN 08 / 201,341). In fact, when the non-explosive ingredients are mixed at room temperature for the first time, the mixture is typically not sensitive to the detonators but upon curing, also at room temperature (except for the increase in temperature due to the heat of hydration and solvation as HE described below), the mixture is molded and its sensitivity increases until it becomes sensitive to the detonators. The safety advantage of these compositions is obvious. Not only non-explosive ingredients are mixed at room temperature instead of high temperatures, but the composition increases its sensitivity only after the mixing stage and simply by being allowed to cure. These recent compositions refer to sodium oxides of sodium perchlorate, to low volatility polyhydric alcohol such as diethylene glycol and a small amount of water. The present invention is an improvement over these novel compositions, which we will call "molded compositions" hereinafter. Although the molded compositions remain sensitive to detonators at high densities (1.78 g / cc or greater), as are molecular explosives, the compositions molded tend to need greater extension distances to achieve the final detonation velocity than compositions based on molecular explosives that need shorter extension distances. (Extension distance is defined as the distance along a load of cylindrical explosive that is required for the load to reach its steady state speed or the terminal velocity of detonation, measured from its point of * 10 initiation). This molded composition also has comparatively greater (unrestricted) critical diameters than molecular explosives. (The critical diameter is defined as the minimum diameter at which the detonation wave is supported by an explosive). Moreover, by decreasing the diameter of the load, the speed of detonation of the molded composition may decrease to a level (less than 5000 m / sec.) Which is not acceptable. Preferred a short extension distance, a small critical diameter and a typical detonation velocity for reinforced or seismic loads. These characteristics are particularly important for small-sized explosives (less than half a kilo), booster or small hole seismic initiators. Another problem of molded compositions compared to explosives >; 20 molecular has to do with the sensitivity of the impact. Molded compositions may be more sensitive to initiation impact than molecular explosive products, depending on the impact stimuli. This difference in sensitivity to impact can > have importance in security. In summary, there is a need for the molded compositions to have a smaller extension distance, small critical diameters, higher terminal velocity in smaller diameters and reduced impact sensitivity. This invention satisfies those needs. It has been found in this invention that adding a relatively small amount of microspheres and dispersing them in the molded composition not only decreases the distance extension to a relatively very small (2 50 mm), but also the critical diameter is decreased to 2 1,27 cm. In addition, the sensitivity of the impact (to initiation with rifle bullet and air cannon) is significantly reduced when microspheres are added. This effect is surprising since normally with the addition to an explosive of microspheres or air voids, even to a molecular explosive, the sensitivity to detonation (and impact) of the charge increases, particularly in charges having small critical diameters. 5 A possible explanation for this phenomenon is that the microspheres act as "energy absorbers" in localized and unpaired regions within the explosive matrix, where the energy created by an impact is dissipated or interrupted before reactions of the ingredients of some importance. The fact that the extension distance of the detonation also decreases seems to indicate that the sensitivity to * 10 l initiation and the sensitivity to impact of these detonating compositions occur by different mechanisms. With respect to initiation sensitivity, once the detonation process has started by a source of energy and localized blow (destructive detonator), the microspheres facilitate the propagation of the detonation wave in such a way that they reach their terminal speed more quickly (shorter distances). The microspheres perform this function by serving as hot spots (adiabatically compressible gas cavities). However, for impact sensitivity, the microspheres prevent the transition to detonation in the product by dissipating or interrupting the relatively low energy delivered by the source of the impact. In contrast, products based on explosives Molecules tend to have excellent detonating properties (such as a minimum extension distance, small critical diameters and high speeds even with small diameter loads) at high densities and do not need the presence of hot spots to help propagate the wave of detonation. Another property of the triggering composition of this application is that the time of Molding or curing is generally reduced when using microspheres or glass. This is advantageous since the total manufacturing time can be decreased. All these benefits are combined to make the mold composition useful for small reinforcement applications (less than half a kilo) or for applications of small hole seismic explosives (one sixth of a kilo), in which the products have long loading small and small diameters.

* In brief, the present application relates to the addition of microspheres to the molded compositions resulting in the surprising and important advantages described above.

DETAILED DESCRIPTION OF THE INVENTION The composition of this invention preferably comprises sodium perchlorate in amounts of 50 to 80% by weight of the composition, diethylene glycol in amounts of 10 to 40%, water from 0% to 10% and microspheres of 0, 01% to 4% depending on the type of microspheres. Diethylene glycol can contain small amounts of homologous glycols. 10 Sodium perchlorate is added dry, particulate or crystalline form, although a small amount can also be dissolved in diethylene glycol and / or water. Minor amounts of other inorganic oxidizing salts selected from the group consisting of ammonium, alkali metal and alkaline earth nitrates, chlorates and perchlorates can be added. A thickening agent is preferably added to the composition to influence its 1 geology and manner of molding and time. A preferred thickener is Xanthan gum, although the thickening agent can be selected from the group consisting of galactomanic gums, biopolymer gums, reduced molecular weight guar gum, polyacrylamides and synthetic analog thickeners, flours and starches. Generally the thickening agents are used in amounts ranging from 0.02 to 0.2% but the flours and starches can be used in larger amounts, and in this case they also function as fuels. Mixtures of thickening agents can also be used. The microspheres are preferably plastic microspheres having a non-polar surface including vinyl monomers of homo-, co- or terpolymers. A preferred composition of the plastic microspheres is a thermoplastic copolymer of acrylonitrile and vinylidene chloride. In addition, the microspheres can be made of silica (based on siliacates), ceramics (aluminosilicate), glass such as borosilicate soda-lime glass, polystyrene, pearlite or mineral pearlite material. Moreover, the surface of any of these spheres can be modified with organic monomers or vinyls of homo-, co- or terpolymers or other monomers, or with polymers of inorganic monomers. The microspheres are preferably used in amounts of 0.05 to 1.6% by weight, and the plastic microspheres are preferably used in amounts less than 0.5%.

W "Preferably the density of the explosive composition containing microspheres is less than 7g / cc. In the optimum preparation, the particles of sodium perchlorate or the crystals (" solid portion ") are mixed with a water solution (if use) and diethylene glycol ("liquid portion"), and a microsphere pulp in diethylene glycol and water (if used) and a shaping agent (if used) ("second liquid portion"). is used, it is preferably pre-hydrated in the liquid portion before adding the other portions Although the preferred method of formulation is to add the liquid portion and the second liquid portion separately to the solid portion, these liquid portions can be combined and then added to the solid portion After adding the portions, simple mixing occurs sufficiently to form a uniform pulp, which can then be added into the mold (s) desired to cure. Curing is not fully understood, but a possible explanation is offered below. During mixing, a small amount of sodium perchlorate dissolves in the liquid portion thanks to the relatively high solubility of sodium perchlorate in water, and its low but significant solubility in diethylene glycol; however, a complete dissolution does not occur. Instead, a pulp of solid sodium perchlorate results in the liquid portion, and this suspension can be stabilized if thickeners are present. As the liquid portion absorbs particles or crystals in the sodium perchlorate, the mixture begins to thicken immediately and generates heat. Water, diethylene glycol and sodium perchlorate anhydride molecules form a sodium perchlorate monohydrate (which is a known hydrate) and a diethylene glycol solvate with sodium perchlorate. (This solvate has been observed in single-crystal X-ray crystallography examinations). The more water molecules and diethylene glycol are penetrated or absorbed in the sodium perchlorate crystals, the more hydrates and solvate are formed and the temperature of the mixture increases due to the heats of hydration and solvation generated in these processes. The rate and degree of temperature rise depends on many factors, such as the size and configuration of the sample, how well the mixture has been isolated to prevent the loss of heat to the medium, and how quickly the liquid is absorbed in the crystals. A The typical temperature increase of a semi-insulated mixture that occurs in 40 to 70 minutes can be 40 ° C. Then, the curing process can be monitored by observing the increase in temperature, the time required to reach the maximum temperature rise and the time required for the mixture to be molded (in other words, for the surface of the mixture to put on). firm). This invention can be better understood by referring to the examples shown in Tables 1-6. Tables 1-5 contain comparative examples between molded compositions containing microspheres and molded compositions without microspheres. Tables 1-3 contain a comparison of detonation results; Table 4 contains a comparison of molding times, for example, the time required following the mixing of the ingredients for the composition to mold (when the surface of the composition becomes firm) and Table 5 contains a comparison of impact sensitivities. Table 6 contains results of representative detonations of small sized molded compositions containing microspheres. In these tables the following keys apply: NaP = sodium perchlorate NHCN = calcium nitrate Norsk Hydro DEG = diethylene glycol D, # 8 = detonation velocity when initiated with a detonated power N ° 8.

Table 1 illustrates the difference between extension distances between the compositions * Molding containing plastic microspheres and those that do not. The compositions contain Norsk Hydro calcium nitrate which acts as a shaping agent. These differences in extension distances are best seen when comparing detonation velocities in the 50-100mm distance segment (distance along the measured load). from the end of the detonator). As can be seen, the presence of plastic microspheres significantly reduces the distance required before the terminal detonation velocity is reached. Without the plastic microspheres (columns 1 and 4), the terminal velocity was not reached until the increase 150-200mm, and where the microspheres were present, the terminal velocity was reached in the increment of 100-150mm for the 50mm samples in diameter and the increase 50-100mm for the sample of 75mm. In addition, the speed for the 50-100mm increase was also greater in the 50mm diameter loads when the microspheres were present. Table 2 shows that the presence of plastic or glass microspheres improve the terminal velocity of the molded compositions in 38mm and smaller load diameters and also lower the critical diameter. Table 3 contains additional comparative data for a detonating composition. An examination of these data again illustrates the effect of the microspheres in relation to the extension distance. When the microspheres are present the extension distance is essentially completed in the 50-100mm segment, and when the microspheres are not present the extension distance is not completed until the 100-150mm segment of the load or more. In addition Table 3 shows that at each diameter tested to less than 38mm, the presence of microspheres improved the terminal detonation velocity of the charge. This table also shows the effect of the microspheres in reducing the critical diameter of the molded composition. Table 4 illustrates the advantages of including plastic or glass microspheres to improve the molding properties of the molded compositions. A comparison of the results shown in the table indicates that the presence of plastic microspheres dramatically increases the speed of molding of the product, as evidenced by the shorter time of molding, an increase in the temperature rise of the product during molding and a Less time required to reach the maximum temperature. The glass microspheres were also effective to increase the molding speed. a Table 5 shows a comparison of the impact sensitivity between molded compositions containing plastic or glass microspheres and those that do not. The result shows a reduction in sensitivity to impact when the »> plastic microspheres in Example 2. As can be seen from the data in the table, the sensitivity to the drop impact test was reduced a little (an increase in H50 from 17.40cm to 18.49cm) (H50 means the high in centimeters where there is a 50% chance of a reaction when a weight of 2.0 kg is dropped on about milligrams of sample), and the impact of the bullet (with a .22-caliber rifle bullet) and the impact sensitivity of the air cannon were dramatically reduced when the microspheres were added. (The airgun impact test involves an apparatus that uses compressed air to accelerate a charge through a barrel and impact it on a concrete surface at a certain speed depending on the air pressure).

When glass microspheres were added, the impact sensitivity of the bullet was also dramatically reduced. Table 6 contains representative data of molded compositions containing plastic microspheres in ideal configurations for small load applications, for example, small reinforcers or initiators and mini seismic explosives (2 half kilo). As shown in Table 6, excellent sensitivities were obtained at initiation and detonation rates (approximately 6000 mejtros / second) even at loads as small as 38 mm in diameter by 89 mm in length. In addition, a demonstration of the short distance of extension and the explosive energy available in these products is checked by the capacity 10 of the composition molded with microspheres with a diameter of 38 mm to strike a steel plate of 9.5 mm, when the end of the detonator was only 19 mm from the steel plate witness. Due to the solid nature of the compositions, their relatively high density and sensitivity, and other molding detonation parameters, they are particularly useful as reinforcers or primers or as seismic explosives. In addition, the improved properties due to the presence of microspheres make these compositions ideal for use in small sizes. The molded compositions are reliably sensitive to detonators. Although the present invention has been described with reference to certain illustrative examples and preferred forms, various modifications will be apparent to those skilled in the art and any modification will be contemplated within the scope of this invention as set forth in the claims.

TABL. 1 Diameter 50 mm Diameter 75 mm 1 2 3 4 5 6 NaP 67.90 67.75 67.90 67.90 67.75 67.70 NHCN 3.77 3.76 3.76 3.77 3.76 3.76 SD 24.52 24.47 24.45 24.52 24.47 24.45 H20 3.78 3.77 3.77 3.78 3.77 3.77 Rubber Xantan 0.03 '0.03 0.03 0.03 0.03 0.03 Plastic microspheres - 0.22 0.29 - 0.22 0.29 Density (gr./cc) 1,79 Before molding 1,78 1,64 1,57 1,79 1,64 1,57 After molding 1.59 1.52 1.78 1.59 1.52 Results at 20 ° C D, # 8 (kmVseg.) 50-100 mm 3.3 5.7 5.8 4.4 6.3 6.0 100-150 mm 5.0 6.3 6.2 6.2 6.0 5.8 150-200 mm 6.3 6.2 5.9 6.8 6.1 6.3 200-250 mm 6.5 5.9 6.1 7.2 6.3 6.0 250-300 mm 6.1 6.1 5.9 7.0 6.2 6.0 twenty TABLE 2 1 2 3 4 5 NaP 67.90 67.75 71.30 71.14 70.16 NHCN 3.77 3.76 - - - DEG 24.52 24.47 24.67 24.62 24.62 H20 3, 78 3.77 3.99 3.98 3.98 Xantan rubber 0.03 0.03 0.04 0.04 0.04 Plastic microspheres 0.22 Oxygen balance (%) -0.01 -0.39 +0.02 -0.37 -0.51 Density (gr./cc) 1.74 1.57 1.78 1.57 Results to 20 ° C 15 MB, 75mm, Det / Triggering Fault # 1 / # 0,5 # 0,5 / - # 0,5 / - # l / # 0,5 # 1 / # 0,5 Wick 7,5gr / 4gr 7.5gr / 4gr - - - do, Det / Fail (mm) 19/12 12 / - 19/12 12 / - 12 / - D, # 8 (km./seg.) 75 mm 6.4 6 , 2 - 6.3 6.3 63 mm 6.1 6.1 - 6.3 50 mm 6.2 6.1 6.3 6.3 6.0 < H r 38 mm 4.9 5.8 6.0 6.2 5.9 32 mm 4.3 5.6 5.6 5.9 5.7 22 mm 4.0 5.3 5.2 5.2 5.4 19 mm 3.1 4.1 4.9 5.4 5.0 12 mm Fault Det. Fault 4.4 4.2 TABLE 3 50 mm diameter 38 i mm 32 i MI 25 i nm 19 i tim 12 i mu 1 2 3 4 5 6 7 8 9 10 11 12 13 NaP 71.30 71.18 70.16 71.30 71.14 71.30 71.14 71.30 71.14 71.30 71.14 71.30 71.14 SD 24.67 24.62 24.62 24.67 24.62 24.67 24.62 24.67 24.62 24.67 24.62 24.67 24.62 H20 3.99 3.98 3.93 3.99 3.98 3.99 3.98 3.99 3.98 3.99 3.98 3.99 3.98 Rubber Xantan 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.04 Plastic microspheres 0.22 0.22 0.22 0.22 0.22 0.22 0.22 Glass microspheres., 20 Results at 20 ° CD, Posidet (Km / sec) 50 - 100 mm 5.4 6.2 6.2 5.0 5.9 4.6 5.6 4.2 5.4 4 , 1 5.0 Fault 4.3 75 - 125 mm 5.4 6.1 6.1 5.3 6.0 5.0 5.8 4.5 5.5 4.1 5, 1 Failure 4.4 100 - 150 mm 5.9 6.3 6.2 5.6 6.3 5.1 5.9 4.9 5.3 4.3 5.1 Failure 4.2 125 - 175 mm 6.1 6, 4 6.2 5.8 6.1 5.5 6.0 5.0 5.5 4.3 5.2 Failure 4.5 150 - 200 m 6.4 6.4 6.3 6.1 6, 1 5.6 5.9 5.3 5.6 4.5 5.2 Failure 4.3 175 - 225 mm 6.5 6.3 6.4 6.1 6.2 5.8 5.9 5.2 5.6 4.4 5.3 Failure 4.4 Average of 3 points (125 - 225 mm) 6.3 - - 6.0 - 5.6 - 5.2 - 4.4 - Fail - Average of 5 points (75 - 225 mm) - 6.3 6.2 - 6.2 - 5.9 - 5.5 - 5.2 - 4.4 o LO O ro -4Á '* TABLE 4 1 2 3 4 5 NaP 71.30 70.98 71.30 70.98 70.34 SD 24.67 24.56 25.33 25.21 24.11 H20 3.99 3.97 3.33 3.32 3.91 Rubber Xantan 0.04 0.04 0.04 0.04 0.04 Plastic microspheres 0.45 _, 0.45 ~ - Glass microspheres - - - - 1.60 Density (gr./cc) 1.75 1.38 1.67 1.42 1.54 Results Molding time (min) * 25.5 5.0 55.5 9.5 19.0 Increase in Temp Y 22.1 40.1 10.9 40.6 33.9 (° C) Time to increase Temp. max (hrs) 1.23 0.33 > 2.00 0.57 0.66 * The surface of the sample is firm.

TABLE 5 1 2 3 NaP 71.30 71.18 70.16 SD 24.67 24.62 24.62 H20 3.99 3.98 3.93 Xantan rubber 0.04 0.04 0.04 Plastic microspheres - 0.18 - Glass microspheres 1.20 Results at 20 ° C Drop weight test (cm) 10 H50 17.40 18.49 12.83"min 15.24 15.24 10.16 Friction test Minimum load (kg. ) 1 16.0 16.0 8.0 Quantities of tests required for a positive test 15 Bullet impact test Caliber 22 (135 Joules) 3 Det. 12 4 5 Reaction 20 0 1 Fault 8 56 34 Tests 40 60 40 - * "22/250 (1765 Joules) 3 Det. 4 6 Reaction 6 0 Fault 0 0 Tests 10 6 25 Air cannon test Det 34 2 12 Reaction 0 2 0 Fault 87 56 28 Tests 121 60 40 'One load trun in kg. required for at least one positive result in six tests. 2 Loads of 910 grams > 75 mm in diameter. - 'Energy of impact TABLE 6 NaP 71.12 71.12 71.12 SDR 24.62 24.62 24.62 H20 3.98 3.98 3.98 Xantan rubber 0.04 0.04 0.04 Plastic microspheres 0.24 0.24 0 , 24 Density (gr./cc) 1.60 1.65 1.59 Length (mm) 89 178 160 Results at 20 ° C MB (Det./Falla) # 0.5 / - # 0.5 / - # l / # 0.5 D, Posidet (km./sec.) 6.0 6.2 6.4 Test of hitting plate2 Trigger up3 (hole size, mm) 25.4 x 9.5 25.4 x 25.4 25.4 x 25.4 Trigger down 4 (hole size, mm) 51.8 6.4 31 , 8 25.4 31.8? 31.8 End distance of the < fl_ ^ detonator to the plate (mm) 19 108 90 Average of 20 loads 2 Steel plate of 9.5 mm J The detonator points in the opposite direction to the plate (end of the detonator to 70 mm of the blade) 25 * The detonator points towards the plate

Claims (13)

1. - An explosive composition sensitive to the detonators, molded and solid comprising oxidizing salts of sodium perchlorate, diethylene glycol, water in optional form, CHARACTERIZED because it contains dispersed microspheres.

2. - A composition according to claim 1 CHARACTERIZED because the microspheres are made of glass, plastic, perlite, polystyrene, ceramic or mineral.

3. A composition according to claim 2 characterized in that the microspheres are plastic.

4. - A composition according to claim 3 CHARACTERIZED because the microspheres have their modified surface with polymeric organic coatings or • ^ inorganic.

5. - A composition according to claim 1 CHARACTERIZED because it also has a thickening agent.

6. A composition according to claim 1 characterized in that the sodium perchlorate is 50 to 80% by weight of the composition, the diethylene glycol is 10 to 40%, the water from 0 to 10% and the microspheres from 0.01 to 4%.

7. - A composition according to claim 6 CHARACTERIZED because the 2 microspheres are present in amounts of 0.05 to 1.6% by weight.

8. - A composition according to claim 6 CHARACTERIZED because the microspheres are made of glass, plastic, perlite, polystyrene, ceramic or mineral. 30 9 ..

TJna composition according to claim 8 CHARACTERIZED because the microspheres are plastic.

10. - A composition according to claim 9 CHARACTERIZED because the microspheres have their surface modified with polimepcos organic or inorganic coatings. eleven - .

11 - A composition according to claim 6 CHARACTERIZED because it has a density less than 1.7 gr./cc. ,

12. - A composition according to claim 9 CHARACTERIZED because the plastic microspheres are present in an amount less than 0.5%.

13. A composition according to claim 6 CHARACTERIZED because it also contains a small amount of thickening agent. fifteen - ^^ * "20 25 30