FR2575461A1 - MOULDABLE EXPLOSIVE COMPOSITION LITTLE SENSITIVE TO EXTERNAL INFLUENCES - Google Patents

Abstract

THE INVENTION RELATES TO EXPLOSIVE COMPOSITIONS. IT RELATES TO A VERY LOW SENSITIVE EXPLOSIVE COMPOSITION, IN THE FORM OF APPROXIMATELY 50 TO 70 BY WEIGHT OF A PARTICULAR EXPLOSIVE WHICH CANNOT BE PRIMED BY LEAD AZOTHYDRIDE SINGLE, 5 TO 35 BY WEIGHT OF A PARTICULAR EXPLOSIVE WHICH MAY BE STARTED BY LEAD AZOTHYDRIDE ALONE, AND 10 TO 40 OF A FLUID BINDER WHICH MAY HARDEN. THE EXPLOSIVE COMPOSITION HAS A VERY HIGH STABILITY UNDER THE ACTION OF EXTERNAL MECHANICAL, ELECTRICAL OR CHEMICAL INFLUENCES. APPLICATION TO EXPLOSIVES INTENDED FOR AMMUNITION.

Description

257S461

  The present invention relates to xpiosive compositions, and in particular compositions that can be

  cast and which pose little risk.

  The untimely detonation of high-energy explosives has been responsible for a number of disasters, especially during military use. Significant opportunities for loss of life and destruction of equipment have prompted militants to impose severe restrictions on devices and facilities

   0 transport, handling and storage of these explosives.

  In view of these considerations, various special formulations have been developed for these explosives in an attempt to combine high performance with low sensitivity to influences such as nuisance jerks, electrostatic shock, and friction. exposure to heat and flames at various temperatures. The formulations developed so far range from. certain types of explosives molded in the molten state. up to explosives that are combined with polymeric binders. Unfortunately, the usefulness of these compositions is limited by their physical and mechanical properties, that is to say that some compositions present difficulties in setting certain desired shapes while others may have a certain difficulty.

  cracking at low temperatures or have poor

  tensile strength or elongation properties or a high modulus. As a result, the range of applications

  of these compositions is limited, and few of them

  satisfaction in the ammunition of universal employment.

  An original explosive composition has been developed according to the invention, this composition combining high performance with low sensitivity to influences.

  while having favorable mechanical properties

  rables and can be poured into molds. The composition is a combination of explosives having low sensitivity and high priming sensitivity, with a fluid binder that can harden and become solid. The binder is present in a relatively large amount relative to known analogous compositions, the amount sufficient for the composition to be cast in the uncured state. Despite the large amount of binder, the composition has sufficiently high performance, when cured, to be comparable to other main charge explosives used by the military. The result is an explosive composition with high performance and low sensitivity, useful

  in the universal job ammunition.

  According to the invention, a main explosive which is relatively insensitive to the initiation of the detonation

  is combined with an explosive sensitizer that is rela-

  sensitive to initiation of detonation. The sensibility

  The initiation can be determined and expressed in a variety of ways known to those skilled in the art. This parameter is expressed in the most advantageous way

  the minimum quantity.or the nature of an intermediate charge

  which, when it detonates under the control of any device, for example by physical shock or

  electric shock, then causes a detonation of the explo-

  sive. The priming sensitivity of the main explosive and the sensitizing explosive may be expressed by

  relative to an intermediate load of lead azide.

  In particular, the main explosive is characterized in that it can not be triggered by an intermediate charge (i.e. a detonator) formed only

  of lead azide, but it requires the contra-

  an additional constituent having a higher speed

  detonation, such as tetryl (trinitrophenylmethyl)

  nitramine) incorporates to the intermediate charge for the detonation to take place. Similarly, the sensitizing explosive is characterized in that it can be initiated by a charge

  intermediate formed of lead azothydride only.

  In preferred embodiments, when an intermediate filler formed of a combination of lead azuride and atrium is used as the primary explosive, at least about 100% of ttryl is required in the name. when, for the explosive sensitizer,

  less than 0.5 g of lead azide is required.

sairess

  Although attempts to determine the sensitivity

  The method may include the use of a 0.4 g sample of the explosive, compressed to 2.07 x 10 7 Pa, O in a No. 6 capsule. The sample can be performed in a variety of different ways. is started. by Plombombine azide or combined lead azithride

  tetryl, if necessary, in a test bomb to-

  sand containing 200 g of sand larger than 0.595 mm. Priming is detected by measuring the amount of crushed sand to a size less than 0.595 mm. The smallest quantity of lead azide alone or mixture

  tryl.which gives the maximum grinding of the sand (that is,

  ie mass less than 0.595 mrn) is conidreed as an index of the sensitivity of the explosive al: amorgageo The main explosive and the sensitizing explosive may be further characterized by a test value the main explosive having a relatively high value to the shock test and the explosive sensitizer a

relatively low value.

  The term "shock test value" as used herein refers to a numerical value of standard shock tests commonly used in the explosives industry. Such a test is a hammer fall test in which a standard mass falls under the action of gravity on a sample of the explosive from various heights. The lowest height that causes the detonation of the sample is considered an index of sensitivity. Thus, the higher the value, the lower the sensitivity. The value is conveniently expressed in relation to

  a reference such as, for example, trinitrotoluene TNT.

  Thus, the main explosive of the composition according to the invention

  is measured by a shock test value of approxi-

  at 300% and about 150 to 300%

  TINT, and the sensitizing explosive is characterized

  rised by shock value of about 5 to 100%

  and about 30 to 65% of the TNT.

  In preferred embodiments of the invention,

  In addition, the pH value of the centrifugation probe is at least 75% relative to the TNT. Spacing tests are known in the art as indicating the susceptibility of a sample to priming charges and in particular to the detonation pressure (of an intermediate charge) necessary to initiate the detonation of the detonation. explosives sample. Tests generally include the detonation of a standard size sample with an explosive capsule and. an intermediate charge, which are separated from the sample by a stack of acetate cards

  cellulose of standardized thickness (for example 0.025 cm

  CUNE). The number of cards in the pile is changed until the largest number that allows the detonation of the sample after priming by the capsule and the intermediate charge, is determined. This number is then

  considered an index of detonation sensitivity.

  High values of the index indicate a high sensitivity. As in the case of the shock test value, the term "Spacing Test Value" used herein is the index expressed relative to

  TNT considered as a reference.

  In the groups indicated above, a number of particular examples are preferable. Examples of the main explosive are nitroguanidine,

  guanidine nitrate, ammonium picrate, 2,4-diamino-

  1,3,5-trinitrobenzene (DATB), 1,3,5-triamino-2,4-

  3'5 trobenzene (TADB), ethylenediamine dinitrate, potassium perchlorate, potassium nitrate and lead nitrate. The main explosives particularly advantageous are nitroguanidine, ammonium picrate,

  DATB and TATB, the most advantageous being nitro-

  guanidine. Among the sensitizing explosives,

  examples are cyclo-1,3,5-trimethylene-2,4,6-

  trinitramine (RDX), cyclotetramethylenetetranitramine

  (HMX), and 2,4,6-trinitrotoluene (TNT). The RDX is

advantageously.

  The relative proportions of these constituents in the composition are as follows. The main explosive is in the range of approximately 50 to

  %, preferably 35 to 65% by weight, and the

  The sensitizing agent is present at about 5 to about 35% and preferably at about 10 to about 30% by weight, based on

to the total composition.

  The remainder of the composition is a binder or a binder composition, formed of any liquid capable of hardening in solid form, optionally containing other ingredients known for their use with

  binders such as catalysts and stabilizers

  for example. The binder is incorporated in sufficient quantity

  It is intended that the uncured composition can be cast so that it can be molded. Thus, the amount of binder is between about 10 and 40% of the weight of the total explosive composition and preferably between 15 and

About 25% of this weight.

  Examples of materials forming useful binders

  according to the invention are polybutadienes, both

  carboxy and hydroxy compounds, polyethylene glycol, polyethers, polyesters (especially hydroxy-terminated), fluorocarbon polymers, epoxy resins and

  silicone rubbers (in particular two-component).

  Preferred binders are those which remain elastomeric in the cured state even at low temperatures such as, for example, up to - 73 C. Thus, polybutadienes and rubbers

  two-component silicone are preferable.

  The binders can be cured by any suitable device, for example by heating, radiation and

  catalysts. Thermosetting binders are preferable.

  In a variant, metal powders, for

  aluminum, can be incorporated into the composi-

  to increase the explosion pressure. The size

  particle size, giving the best results, is less than or equal to 149 ei m and preferably between

  between about 2 and 100 pm. The powder usually forms

  10 to 30% of the weight of the composition.

  It is preferred that the two components have different particle sizes so that the mixing of the explosive components remains homogeneous during preparation and casting. The best results are

  usually obtained with a ratio of the particular dimensions

  between 5/1 and 20/1, preferably between

  1 conference of about 10/1. it is particularly advantageous

  that the sensitizing agent has a particular dimension

  lai -: acfenne between about 0.5 and 50 Dm and pre-

  -ference between about 1 and 2C mi so that the composition as a whole has sufficient sensitivity to detonate properly. The preferred dimension range for RDX is between about 2 and 8 Mm. The explosive

  in general has a relative particle size

  fat, ranging from about 20 to 1000 μm. Variations in the particle size of the explosive sensitizer

  as well as variations in the amount of explosive

  The user affects the relative sensitivity of the composition as a whole. Thus, the composition can be finely adjusted by adjusting these parameters in the ranges

previously indicated.

  The compositions according to the present invention give an energy comparable to that of explosives such as 2,4,6-trinitrotoluene (TNT), aluminum-containing TNT-based explosives, composition B (combination of TNT and cyclo-1,3,5-trimethylene-2,4,6-trinitramine,

  that is, RDX), and explosive D (ammonium picrate).

  Performance can be characterized by

  meters such as detonation velocity, tonal pressure and critical diameter. In practice, in

  ro of realization -refered of the invention, the const, _i-

  A.exposites are chosen so that they give the explosion a detonation velocity of at least 6.5 km / s, and preferably at least 7.0 km / s. At least approximately 175 kilobars detonation and at least 200 kilobars Dreence *, a confined diameter, in confined trials, less than 10.2 cm and preferably less than 10.2 cm. maximum value l of about 5%, 08 cm, and a critical diameter in tests

  not conferred with a maximum value of less than 15,2 cm

  Viron e- preferably at about 11.4 cm.

  The examples which follow are given purely for illustrative purposes and in no way limit the scope.

d5 the invention.

EXAMPLE i

  An explosive composition was prepared with the following ingredients: Ingredient% by weight Nitroguanid-isne particle size 60 iVm 60 Cycleo-1,35-trimethylene-2,4,6-trinitratmine, 20 particulate dim-ion 4 uIm Diisocyanate binder The ingredients were combined at 49 ° C., passed through a tap opening into an empty chamber at a pressure of 0.08 to 0.14 bar. and cured at 57 ° C for three to six days. The result was a white molded composition having a density of 1.49 g / cm 3 '; possessing the following mechanical properties: Temperature Resistance to Elongation Modulus tensile C aMl105 Pa m% in% n / a, 10 6Pa __ __o

71 6.3 51 51 1.96

8.8 56 57 2.71

- 54 37.5 47 56 31.15

  - A. C.ract..stiqces of I.ex.osif the detonation life under steady state was measured in an iron tube of 12.7 cm diameter. re and 63, ci. one end, plugged at one end, having boreholes su> its length at intervals

  25.4 mrm near one end blocked. The composition

  The ionization probe was poured into the tube, ionization probes being introduced into the holes and connected to a capacitor and a 9 V accumulator battery. Five probes were used in total. The detonation was triggered by a P-3 primer, an Atlas Giant explosive capsule and an 80-gram pentolite disc, with a 0.8 cm buffer of PBXN-106 to prevent loss of control. The detonation velocity was measured with a

  "Nicolet" oscilloscope giving a result of 7.35 mm / ps.

  2. The confined critical diameter was determined on a card spacing device (without card) using a J-2 priming capsule, an intermediate charge of g of pentolite, a mild steel control plate 1.3 cm

  thick, and cylindrical samples of the composition

  having a length to diameter ratio of 4.0. When using 2.5, 2.8 and 3.0 cm diameter samples, the smallest diameter supporting detonation

  : g likes permanent was 2.8 cim.

  3. The unconfined critical diameter was measured with an "Atlas" primer and an intermediate load of composition B mounted on the test sample which was cylindrical in shape with a length-to-diameter ratio.

  4.0. When using samples with diamonds

  7.6, 10.2, 11.4 and 12.7 cm, it was found that the smallest diameter maintaining the detonation

  steady state was 11.4 cm.

  B. Safety features 1. Shock tests were performed on two types of equipment. The first was an apparatus of the Bureau of Mines, implementing a mass of 2 kg. Twenty tests were performed at the maximum height of 100 cm; none has produced a detonation. By way of comparison, it should be noted that the 50% firing point for RDX explosives

  Category 11/1, on this device, is 30-33 cm.

  The second apparatus had a mass of 2.4 kg and a maximum fall height of 320 cm, with two types of surfaces, a bare surface of sandblasted tool steel and a garnet paper surface. The tests were carried out on both surfaces and the detonation did not take place under any circumstances (twenty tests per surface). For comparison, the 0o firing point of 50% of RDX 11/1 explosives, on the first surface, is 32 cm, and on the second

surface, at 28 cm.

  2. Frictional sensitivity was determined in a sliding friction test with a force of 1110 N and a speed of 2.4 m / s. No detonation occurred in twenty attempts. For comparison, the. pentaerythritol tetranitrate (PETN) tests with the same apparatus gave the following values for the

  maximum pressure giving twenty consecutive negative results

  for the indicated anvil speed: Anvil speed Pressure force

2,4,445

1.8 890

0.9 3 115

  25. 3. The electrostatic sensitivity was determined with a disruptive discharge of 0.25 J. No priming was

  occurred in twenty consecutive trials.

  4. Sensitivity to detonation has been determined

  by placing a 5.08 cm cube on the side of the sample

  sample on a lead cylinder and the disposition of a No. 8 primer at the surface of the sample, by detonation of the primer and inspection of the cylinder deformation (flattening) following the detonation. In each of five tests, the force of the explosion only punctured a hole about 0.64 cm in the cube and grated its surface. However, no deformation of the cylinder

  did not occur in any of these trials.

  5. Card spacing tests included a standard Naval Ordnance Laboratory (NOL) test employing a sample of 14.0 cm in length and 4.76 cm in diameter, with a square shaped steel control plate 15.2 cm side and 0.95 cm thick, two pentolite pellets 5.08 cm in diameter and one

  J-2, and a larger scale test with a sample

  28.6 cm long and 7.5 cm in diameter, a square steel control plate 20.3 cm square and 3 cm thick, a pentolite pellet 8.9 cm thick. diameter and an intermediate load "Atlas". In the NOL test, the spacing of cards, for a 50% firing point,

  was 0.76 c. In the larger scale test, the

  The spacing at 50 D was 2.4-2.5 cm.

  6. Balise impact tests were performed with 12.7 cm x 50.8 cm samples embedded in closed steel sleeves. The bullets used were 50-gauge armor piercing bays. In three trials, bullets were fired at the side of the specimen. The balls passed through the sample and exited the opposite side of the tube in all cases. In three additional tests, the bullets were fired at the end of the sample. In two of

  case, the ball was trapped in the sample. In the third

  In the second case, the ball traveled about 30.5 cm in the sample.

  then left the tube by the side. In all six trials, the sample burned slowly for 30 to min after the shock of the bullet. The subsequent examination

  indicated the presence of a black residue in the

  No reaction or risk of fragmentation of any kind

  did not manifest itself in any of the six trials.

  7. "Susan" essays were made with a

  gun of 7.62 cm-50 and a test arrangement and a

  standard projectile shovel "Susan". For a typing speed of 330 m / s, the energy supplied was equivalent

  to 40.0 g of TNT (overpressure of 1.68 × 10 Pa).

C. Thermal Properties

  1. A differential thermal analysis was carried out

  * I binds to several vitses of heating, under conditions

  adiaatiqes conrflLincesg and gave the following results.

  Pitch of Peak of Start of Peak of Ignition I-a.a .. Reaction Reaction Rai o L_.on C ('n> ___e_eiotic @ exotanic tt exotanic t (C)

170 173 194

your. i66 174 188

172 178 193

172 177 192

171 177 192

  The results of the tests indicate that the start of the exothermic reaction is reproducible at about 175 ° C regardless of the heating rate. This is quite contrary to the predictions: it is generally expected that the slower heating rates will give a better result.

  lower reaction start temperature.

  2. A test for determining the period before explosion was carried out by cutting the hardened explosive into 6.35 mm diameter blanks, then cutting the cylinder with a microtome in the form of flat plates and introducing the platelets in an empty primer

  of aluminum with a plug designed to give a

  geometric constant. The charged primers were then dropped into a preheated bath, and the

  time before explosion was measured at temperatures

  lower and lower until no explosion

  appears (time equal to infinity) o. The lowest time

  The rate at which an explosion occurred was 75 ° C. 3. Vacuum stability was determined with a sample of 0.5, at an absolute pressure of about torr, and by heating at 38 ° C for 48 hours. The rate of release of gas at the end of this period

was 0D107 cm3 / g.

  4. A growth test was performed to determine the effect of temperature on irreversible growth. Following the test procedure, the sample was subjected to thirty cycles between - 54 C and + 122 C. No trasm of exsiudazion was observed, and the variation

  The solute content was 0.02% only.

  5. Slow cooking tests were carried out using cups 12.7 cm in diameter and 50.8 cm in length, heated from 38 C at a rate of 3.3 C per hour 'reaction or until an i Ju

The temperature of 149 C is reached.

  The temperatures measured at the time of the reaction, one for every three, were as follows: - Reaction temperature Internal temperature (C) Surface temperature (C)

136,197

142 143

15.140 To 146

  In no case was the reaction violent.

  6. Rapid cooking tests were carried out using a wood fire and kerosene at temperatures ranging from 427 to 816 ° C., the samples being molded in tubes sealed with cast iron caps. Three tests were carried out. In all cases: the caps failed about 3 min

  afterwards, and the explosive burned vigorously for 30 seconds.

  vircn. There was no violent reaction in one

any of these tests.

  7 .. A cubic sample of 5.08 cm side was placed on a bed of ash impregnated with kerosene and the ash was lit with an electric spark so

  ignition and unconfined combustion are studied.

  Two tests were carried out. In both cases, the cube burned regularly to its totality in about 200 seconds without explosion. The test was then repeated with four cubes of 5.08 cm side, glued by a ribbon so that they form a single line. The cubes burned this time for 214 seconds, without exploding. In all these tests, the

  was so soft that it was difficult to distinguish

  to prevent the combustion of the sample from that of sawdust

impregnated with kerosene.

  8. The thermal stability was determined by placing a 5.08 cm cubic sample in a constant temperature oven of 75 C, resistant

  explosions for 48 hours, no explosion,

  Nmation or change of configuration of the sample

did not appear.

EXAMPLE 2

  An explosive composition was prepared with the formulation and casting procedure of Example 1, with the following ingredients: Ingredient% by weight Ammonium pore, particle size 140 pm Cyclo-1,3,5-trimethylene -2,4,6-trinitramine, 4 mM particle size] Hydroxy-terminated polybutadiene diisocyanate binder, molecular weight 2,600, with diethanololamide Explosion and stability characteristics were determined using the procedures outlined in US Pat.

  Example 1, and gave the following results.

  A. Explosive properties 1. Detonation velocity in steady state condition:

6.9 mm / s.

  2. Critical diameter confined: 3.8 cm.

B. Security features

1] Shock, 2 kg: greater than 100 cm.

  2. Friction with slip (1110 N, 2.4 m / s)

no detonation in twenty tries.

  Friction, rotary (4000 g, 2000 rpm): not

detonation in ten attempts.

  3. Electrostatic sensitivity 0.25 J: no detonation

nation in twenty trials.

  4. Sensitivity to detonation, primer # 8: no

detonation in five attempts.

  5. NOL card spacing tests: 1.5-1.6 cm.

C. Thermal properties

  1. Differential thermal analysis, start of reaction

exothermic temperature: 208 C.

  2. Unconfined ignition and combustion, a single cube of 5.08 cm side: burns 4 min without explosion, four cubes of 5.08 cm side burn 5 min without explosion. 3. Thermal stability, 5.08 cm cube,

  48 h, 75 C: no explosion, no inflammation or change

configuration.

EXAMPLE 3

  This example illustrates the effect of the variation in

  particle size and the amount of explosive

  the reader about the sensitivity of the composition in its

  appears. This sensitivity is expressed by the results of the NOL card spacing test described in Example 1 in the characters. The sensors and sensing and binding agents are those used in Example 1. The results of the following are given in the following in the form of the number of cards. , ilises, each card having a thickness of 0.0254 cm. The notation "minus" indicates the absence of priming

  the indication "plus" indicates priming.

  Test result NOL card spacing Composition without binder (% I by weight) Nitroguanidine RDX n cards -60 m 150 m 15 am Less More

58 10 - 12 70.50 0

58 15 - 7 80 70.75

- - 20 70 50

-58 2 - 20 50.70 42

58 a - 17 55.70 4u56 - - 24 75 70

58 - - 22 50.70 35

58 22 - - 100 85.95

- 20 - 45.70 40

50 - - 30 70 50.60

60.70. 50

15 - - 50.70 30

iVEfNDiCATIONS

  i Explosive mixture moldable by casting,

isee in that it includes

  about 50 to 75% by weight of a particularly explosive

* an area that can not be initiated by a single primer

  auemen: t formed of lead azothydride,

  (b) 5 to 35% by weight of an explosive

  which can be triggered by a primer forms only leadg azimide and tc) 10 to 40% by weight of a fluid binder

which can harden in solid form.

  2. Composition according to claim 1, in which

  constituent (a) can not be initiated by a

  combination of lead azimide and tetryl in the

  the amount of detergent is less than about 0110 g, and component (b) can be initiated by less than 0.5 g

of lead azide.

  Composition according to claim 1, characterized

  in that component (a) has a shock test value of between about 110 and 500% relative to TNT, and component (b) has a value under test

  shock between 25 and 100% compared to TNT.

  4. Composition according to claim 1, containing about 55% of component (a), about 10 to 30% of component (b) and about 15 to 25% of component (c)

  5. The corimposition according to claim 1, characterized

  in that the average particle size of component (b) is about 0.5 to about 50 μm in diameter.

  6. Composition according to claim 1, characterized

  in that it comprises about 10 to 30% by weight of aluminum

  powdered minium having a lower particle size

at 149 pim. -

  7. Composition according to claim 1, characterized

  in that component (a) is selected from the group consisting of nitroguanidine, nitrate of

  guanidine, ammonium picrate, 2,4-diamino-1,3,5-tri-

  nitrobenzene, 1,3,5-triamino-2,4,6-trinitrobenzene, ethylene diamine dinitrate, potassium perchlorate,

  potassium nitrate, lead nitrate and their

  ianges, and component (b) is selected from the group consisting of cyclo-1,3,5-trimethylene-2,4,6-trinitramine, clcyclotetramethylenetetranitramine, 2,4,6-trihotrotoluene

and their mixtures.

  8. Composition according to claim 1, characterized

  tered in that the fluid flier. is selected from the group consisting of hydroxy terminated polybutadienes; carboxy terminated polybutadienes and

silicone rubbers.

  9. Composition according to claim 1, characterized

  it has a detonation velocity of at least 6.5 km / s and a confined critical diameter of not more than 10.16 cm. 10. An explosive casting composition, characterized in that it comprises: (a) from 55 to 65% by weight of nitroguanidine,

  (b) about 10 to about 30% by weight of 1,3,5-cyclo-trimethyl-

  thylene-2,4,6-trinitramine, and (c) from about 15 to about 25% by weight of a polyr binder

hydroxy-terminated butadiene.