Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
  • C06B45/04—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive
  • C06B45/06—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component
  • C06B45/10—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component the organic component containing a resin
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
  • C06B21/0008—Compounding the ingredient
  • C06B21/0025—Compounding the ingredient the ingredient being a polymer bonded explosive or thermic component

Definitions

• the present invention relates to composite pyrotechnic products, which are suitable especially as propellant powders for barrel weapons (more particularly for tank artillery). It concerns composite pyrotechnic products, containing a high content of energetic charges in a binder. Said products are particularly advantageous, especially in terms of force (of energetic power), of vulnerability (see below a reminder regarding this notion, which is familiar to those skilled in the art), and of field of application as regards the nature of the charges they may contain. They may conveniently be optimized in terms of erosivity.
• a subject of the present invention is also a process for preparing said composite pyrotechnic products. Said process is particularly easy to perform.
• “Homogeneous” propellant powders constituted by one or more gelatinized energetic bases having a homogeneous appearance are known.
• “smokeless” powders based on nitrocellulose alone or based on a nitrocellulose-nitroglycerine mixture In order to improve the energy performance of these “homogeneous” powders, it is sought to incorporate therein organic (pulverulent) energetic charges. These charged powders no longer have a homogeneous appearance, but a heterogeneous appearance in which are distinguished, on the one hand, the energetic binder, and, on the other hand, the charges.
• Such charged powders are referred to as “composite” or “heterogeneous” powders. Such charged powders are described, for example, in French patent application FR 2 488 246.
• Vulnerability refers to the property that the powders have of being able to ignite and deflagrate under the, effect of an undesired, random physical phenomenon, for instance the impact of a projectile. Vulnerability is a major defect for powders intended to be transported on combat tanks. The development of modern combat machines thus led those skilled in the art to seek sparingly vulnerable propellant powders.
• composite powders with an inert binder were proposed (constituted mainly of organic energetic charges in a synthetic resin). Such powders are markedly less vulnerable than homogeneous or composite powders with an energetic binder (nitrocellulose). However, since they contain an inert binder, these powders must, in order to deliver the necessary energy during their ignition, contain very high levels of charges, often in the region of 80% of the total weight of the powder. Composite powders with an inert binder thus have the characteristic of containing very little binder relative to their pulverulent charge.
• the precursor mixtures of these powders must, however, be able to be worked (in particular be able to be calendered or drawn through a die of relatively small diameter, usually comprising pins intended to create channels present in the final powder strand), and the powders must conserve their geometrical shape over time. It is particularly in reference to the production of these composite propellant powders with an inert binder for barrel weapons that those skilled in the art came up against and are still coming up against serious difficulties.
• thermoplastic binders thermosetting binders obtained from oligomers
• thermoplastic inert binders allow, in theory, while raising temperature, mechanical working of the product to give it the desired geometry.
• the working temperature at which the binder is deformable
• Patent application EP 0 036 481 describes a process for manufacturing composite explosives with a thermoplastic binder.
• Patent application IN 498/DEL/2001 describes a process for preparing propergol containing hexogen charges (RDX) in a thermoplastic binder.
• Composite products with a thermoplastic binder are generally not entirely satisfactory, since their mechanical properties are too sensitive to thermal variations.
• thermosetting inert binders obtained from oligomers
• polyurethane binders such as (crosslinkable) polyurethane binders
• thermosetting binders
• the technique under consideration thus comprises two polymerization or crosslinking steps, more precisely a first step of pre-crosslinking (or first crosslinking phase) with an amount of isocyanate that allows the production of a partially polymerized (crosslinked) paste, having mechanical strength and cohesion suitable for the implementation of the rest of the process (especially extrusion) and a second step of crosslinking leading to the final product with the desired crosslinked binder.
• said technique overcomes the two types of difficulty mentioned above (difficulty due to the lack of mechanical strength and cohesion of the product to be extruded and problem of the “pot life”).
• composite pyrotechnic products that are especially suitable as propellant powders for barrel weapons, of novel type.
• These (novel) composite pyrotechnic products contain a high content of charges in a binder of a novel type (this binder is neither a thermoplastic binder, nor a thermoset (thermocrosslinked) binder).
• Said (novel) composite pyrotechnic products are particularly valuable in terms of force (they contain a high content of energetic charges), of vulnerability (they do not contain any nitrocellulose and may advantageously contain sparingly vulnerable energetic charges) and of production process (their production process is particularly easy to perform (in particular, it comprises no crosslinking step and therefore does not involve the use of crosslinking agent(s)) and they may also be optimized in terms of erosivity (they may advantageously contain EDNA charges in total or partial replacement for RDX charges).
• the present invention thus relates to novel composite pyrotechnic products. Characteristically, their compositions, expressed as weight percentages, contain:
• the composite pyrotechnic products of the invention thus contain a high content of organic energetic charges in a binder of a novel type: a binder, of non-crosslinked gum (“raw rubber”) type. It is seen later that said binder may contain a plasticizer.
• the composite pyrotechnic products of the invention thus contain a high content of organic energetic charges: from 78% to 90% by weight, advantageously from 80% to 86% by weight.
• the charges under consideration are organic charges of any type (not selected, as in the context of thermocrosslinkable binders, taking into account the crosslinking reaction to ultimately by implemented); mineral charges having been set aside insofar as they generate solid particles) are not per se original. They are organic energetic charges that are known per se and, for the most part, are already conditioned according to the prior art in a conventional organic polymeric binder (such as PBHT), especially crosslinked.
• organic charges of any type not selected, as in the context of thermocrosslinkable binders, taking into account the crosslinking reaction to ultimately by implemented
• mineral charges having been set aside insofar as they generate solid particles are not per se original. They are organic energetic charges that are known per se and, for the most part, are already conditioned according to the prior art in a conventional organic polymeric binder (such as PBHT), especially crosslinked.
• PBHT organic polymeric binder
• the charges are advantageously hexogen (RDX), octogen (HMX), nitroguanidine (NGU), ethylene dinitramine (EDNA), N-guanylurea dinitramide (FOX 12 (GUDN)), 1,1-diamino-2,2-dinitroethylene (FOX 7 (DADE)), bis(triaminoguanidinium) 5,5′-azotetrazolate (TAGZT), dihydrazinium 5,5′-azotetrazolate (DHDZT), 5,5′-bis(tetrazolyl)hydrazine (HBT), bis(2,2-dinitropropyl)nitramine (BDNPN), a nitropyrazole, or a mixture of these energetic charges.
• RDX hexogen
• HMX octogen
• NGU nitroguanidine
• EDNA ethylene dinitramine
• GUDN N-guanylurea dinitramide
• FOX 7 DADE
• EDNA organic energetic charges are preferably found therein.
• a mixture of EDNA charges and of RDX charges is particularly preferably found therein. It is in no way excluded to find only RDX charges or only EDNA charges, but, as indicated above, mixtures of EDNA charges and of RDX charges make it possible to achieve an optimum with reference to the force/erosivity compromise. It has been understood that the more said mixtures contain RDX, the more energetic they are, but the more erosive they are.
• Energetic charges are in the form of solid grains homogeneously distributed in the binder. These solid grains advantageously have, in a manner known per se, several particle size distributions.
• novel binder is based on a gum of the type mentioned. According to one variant, it consists essentially of said gum (at least one additive being present in small amount), or even it consists of said gum. According to another variant, it consists essentially of said gum and at least one plasticizer (at least one additive being present in small amount), or even it consists of said gum and at least one plasticizer.
• Such a gum is perfectly suitable for the purposes of the invention, insofar as, in the proportions indicated (from 10 to 22% only, remembering that products with a high charge rate are under consideration), 1) it allows the (charges+gum) mixture to be mechanically worked at low temperature, i.e. at a temperature below 120° C., or even below 100° C. (which is entirely compatible with the stability of the charges present), and does so without the use of solvent; and 2) it gives the final product the required mechanical hold and cohesion.
• the inventors have, to their credit, identified (selected) this type of gum, which is perfectly suitable for the purposes of the invention. Other types of gum were tested and do not give satisfactory results (as regards the possibility of working the mixture at low temperature and/or as regards the properties of the final product).
• Said gum generally consists of a polyurethane-polyester or a polyurethane-polyether gum, but mixtures of at least two gums (at least two polyurethane-polyester gums, at least two polyurethane-polyether gums or at least one polyurethane-polyester gum and at least one polyurethane-polyether gum; such mixtures of gums (gums within the meaning of the invention) constituting a gum within the meaning of the invention) having the required properties (recalled above) may be used.
• Said gum advantageously consists of a polyurethane-polyester gum.
• composition of the composite pyrotechnic products of the invention is thus liable to contain at least one plasticizer.
• Such an at least one (energetic or non-energetic) plasticizer is generally present in a proportion of from 2% to 8% by weight (of the total composition).
• Such an at least one plasticizer advantageously consists, with reference to the force of the product, of at least one energetic plasticizer.
• composition of the composite pyrotechnic products of the invention thus advantageously contains at least one energetic plasticizer (one energetic plasticizer, at least two energetic plasticizers, or at least one energetic plasticizer and at least one non-energetic plasticizer), and very advantageously contains one energetic plasticizer.
• the energetic plasticizer(s) under consideration are advantageously of nitrate and/or nitramine type.
• the energetic plasticizer(s) under consideration are very advantageously chosen from diethylene glycol dinitrate (DEGDN), triethylene glycol dinitrate (TEGDN), butanetriol trinitrate (1317N), trimethylolethane trinitrate (TMETN), a mixture of 2,4-dinitro-2,4-diazapentane, 2,4-dinitro-2,4-diazahexane and 3,5-dinitro-3,5-diazaheptane (and most particularly DNDA 5,7), nitratoethylnitramines (especially methyl-2-nitratoethyl nitramine (methylNENA) and ethyl-2-nitratoethyl nitramine (ethylNENA)), and mixtures thereof.
• DEGDN diethylene glycol dinitrate
• TAGDN triethylene glycol dinitrate
• TMETN trimethylolethane trinitrate
• at least one formulation agent candelilla wax and/or paraffin wax, for example
• the composite pyrotechnic products of the invention are entirely suitable as propellant powders for barrel weapons. Said composite pyrotechnic products of the invention thus consist advantageously of such powders.
• the composite pyrotechnic products of the invention, as described above, are also suitable, especially, as tactical propergol, explosive composition and gas generator.
• the major advantage of the products of the invention becomes apparent from the foregoing text.
• the products are advantageous per se (in terms of force, vulnerability and wide field of application with reference to the nature of the charges) and insofar as they may be obtained via a process that is simple to perform (much easier to perform than the processes of the prior art).
• Said process constitutes the second subject of the present invention. It comprises:
• the charges+the gum the essential constituent ingredients of the desired composite pyrotechnic products: the charges+the gum.
• at least one plasticizer and at least one additive especially such as a formulation agent and/or stabilizer may be used.
• a pasty mixture is thus prepared, which is the precursor of the targeted final product.
• a pasty mixture is advantageously prepared with a twin-screw extruder (by extrusion) or with a two-roll mill, depending on the amounts to be used. It is generally prepared at a temperature of between 60° C. and 120° C. (inclusive of extreme values). It is often prepared at a temperature of 80° C. It is understood that this mixing temperature depends on the type of gum and the presence or absence of at least one plasticizer.
• the product in the desired form is prepared (n products are thus generally prepared).
• Said third step is thus analyzed as a step of forming the paste.
• This forming may especially comprise spinning or calendering. After such spinning (performed in a press cylinder, having an outlet orifice of more or less substantial diameter), the spun product is generally chopped into strands (of the desired length).
• Such strands which are suitable as propellant powders for barrel weapons, generally have a length of from 2 to 20 mm, for a diameter of from 1 to 20 mm (more generally for a diameter of from 2 to 15 mm).
• the calendered product in the form of a plate (such a plate generally has a thickness of from 10 to 20 mm), is generally chopped into platelets.
• steps b and c of said process may comprise:
• EDNA ethylene dinitramine
• nitric acid was introduced into a jacketed 50 cm 3 reactor. The nitrating bath was then cooled to a reaction temperature at 0° C. Once the bath reached at 0° C., the introduction of imidazolidone was commenced. This reagent was introduced slowly so as not to exceed 20° C. The DNEU precipitated as soon as its concentration in the medium was greater than 23% by weight. The introduction of imidazolidone into the heterogeneous medium (nitrating bath+solid DNEU) was continued.
• the mixture was poured into a bath of cold water at about 5° C. with stirring.
• the solid was then separated from the mother liquors by filtration, and washed several times with distilled water to neutral pH, then drained by suction. It was then taken up, in wet form, for the synthesis of EDNA.
• the decarboxylation step was performed by addition of DNEU to a hot aqueous solution buffered with sodium acetate. Evolution of gas (of CO 2 ) was observed, which necessitates portionwise introduction of the powder.
• the mixture was maintained at a stage of 95° C. to complete the formation of EDNA.
• the reaction medium was then cooled to make the EDNA precipitate.
• the suspension was then filtered and then dried. A yield of 85% was obtained.
• Trioxyethylene glycol dinitrate (TEGDN) was obtained by nitration in sulfonitric medium of trioxyethylene glycol.
• Composite pyrotechnic products of the invention of three types were prepared and tested. Their weight composition and their force (measured or calculated) are given, respectively, in Tables 1, 2 and 3 below. Below each of said Tables 1, 2 and 3, other characteristics of said products are indicated.
• Step b of the process of the invention the pasty mixtures were obtained in a two-roll mill, in a manner known per se.
• the gum was first introduced between the rollers of the two-roll mill (rolling mill), brought to a temperature of 65° C. It was thus softened.
• a charges+plasticizer mixture (prepared beforehand in a container) was added. Candelilla wax was then subsequently added to the resulting mixture.
• Step c of the process of the invention the pasty mixtures obtained were introduced into a press cylinder heated to 80° C. to perform spinning at a pressure of between 280 and 320 bar. After chopping, powder strands were obtained (diameter: 10 mm, length: 11 mm).

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• 2013
  • 2013-11-22 FR FR1302707A patent/FR3013705B1/fr active Active
• 2014
  • 2014-11-21 PL PL14809915T patent/PL3071537T3/pl unknown
  • 2014-11-21 EP EP14809915.3A patent/EP3071537B1/de active Active
  • 2014-11-21 US US15/038,116 patent/US20160289133A1/en not_active Abandoned
  • 2014-11-21 WO PCT/FR2014/000250 patent/WO2015075327A1/fr active Application Filing
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