EP3753916A1 - Composite pyrotechnical product - Google Patents

Abstract

The invention relates to a composite pyrotechnic product comprising organic energetic charges in a plasticized binder, comprising a crosslinked energetic polymer and at least one energetic plasticizer, said energetic crosslinked polymer consisting of a polyglycidyl azide (PAG), having an average molecular weight in number (Mn) between 700 and 3000 g / mol, obtained by crosslinking, via its terminal hydroxyl functions, with at least one crosslinking agent of polyisocyanate type, in the presence of 150 ppm to 500 ppm of at least one crosslinking catalyst .

Description

Field of the invention

The present invention relates to composite pyrotechnic products, suitable in particular as solid propellants for the propellant charges of tactical missiles. These composite pyrotechnic products have good mechanical properties when cold and at room temperature.

State of the art

Solid propellants are used for rocket or missile propulsion. In this regard, mention may in particular be made of double-base propellants and composite propellants. A solid propellant of the composite type comprises pulverulent solid fillers (oxidizing fillers, with, optionally in addition, reducing fillers) as well as various additives, in particular feasibility additives and performance additives, in a generally plasticized binder (a polymer matrix solid - a crosslinked polymer - energetic or not, generally plasticized). The binder is typically obtained from a liquid polymer (“crosslinkable”), exhibiting chemically reactive terminations, capable of being crosslinked by at least one crosslinking agent (at least bifunctional) which is also liquid. In fact, generally introduced into such a liquid polymer, in an appropriate order, at least one plasticizer and the other ingredients of the propellant, with the exception of said at least one crosslinking agent (and at least one crosslinking catalyst, if such at least one crosslinking catalyst (generally very sensitive to humidity) is used), then finally said at least one crosslinking agent (and said optional at least one crosslinking catalyst used). The charged polymer is then heat treated (“fired”) at a temperature compatible with the energetic materials ( minimum charges) present. The crosslinked polymer constitutes, with the plasticizer (s) present (s), the plasticized binder, which coats all the ingredients and in particular the pulverulent fillers, to finally form a solid body. Solid propellants suitable for rocket engines are described in the patent application WO 2016/066945 . Solid propellants suitable for missiles are described in the patent application WO 2018/055312 . Other solid propellants are described in the applications CN-A-107 721 784 , KR-A-2010 0035522 and CN-A-107 879 868 ; in the first two documents, the propellants contain 500 ppm of crosslinking catalyst, while in the third document the propellants contain a small amount (10 to 20% by mass) of energy charges.

• des performances énergétiques élevées sans particule, à fumée réduite, à température de combustion modérée ;
• des propriétés balistiques adaptées à une large gamme d'applications tactiques ;
• des produits de combustion compatibles avec les concepts avancés (vannage) ;
• un excellent comportement en vieillissement, respectueux de l'environnement, non sensible à l'électricité statique.

The objectives sought for solid propellants are generally the following:

• high energy performance without particles, at reduced smoke, at moderate combustion temperature;
• ballistic properties suitable for a wide range of tactical applications;
• combustion products compatible with advanced concepts (valve);
• excellent aging behavior, environmentally friendly, not sensitive to static electricity.

The development of new solid propellants requires a fine balance so as not to improve one property at the expense of another. Thus, lowering the level of plasticizer in the binder can lead to a drop in energy performance; likewise the choice of the crosslinking agent can have an impact on the energetic properties.

The objective of the present invention is to provide composite pyrotechnic products which have good mechanical properties over a wide range of temperatures, and in particular at cold and at room temperature.

Summary of the invention

It has been demonstrated, against all expectations, that it is possible to obtain composite pyrotechnic products having improved mechanical properties, without impact on their energy performance, by increasing the amount of crosslinking catalyst used.

Thus according to one aspect, the invention relates to a composite pyrotechnic product containing organic energetic charges in a plasticized binder, comprising a crosslinked energetic polymer and at least one energetic plasticizer, said energetic polymer being crosslinked in the presence of 150 to 500 ppm of minus a crosslinking catalyst.

According to another aspect, the invention relates to a process for preparing said composite pyrotechnic product.

According to another aspect, the invention relates to the use of said composite pyrotechnic product as a solid propellant for a propellant charge of a missile, in particular of a tactical missile.

Brief description of the figure

The figure 1 represents the elongation at break and the mechanical capacity of a composite pyrotechnic product representative of the invention.

Description of the invention

• le polymère énergétique réticulé consiste en un polyazoture de glycidyle (PAG), ayant une masse moléculaire moyenne en nombre (Mn) comprise entre 700 et 3000 g/mol, obtenu par réticulation, via ses fonctions terminales hydroxyles, à l'aide d'au moins un agent de réticulation de type polyisocyanate, en présence d'environ 150 ppm à environ 500 ppm d'au moins un catalyseur de réticulation.

According to one aspect, the present invention relates to novel composite pyrotechnic products exhibiting excellent mechanical properties. These composite products are of the type with a crosslinked energy binder containing organic energy charges. More precisely, the composite products in accordance with the invention contain organic energetic fillers in a plasticized binder, comprising a crosslinked energetic polymer and at least one energetic plasticizer. Characteristically:

• the crosslinked energetic polymer consists of a polyglycidylazide (PAG), having a number average molecular mass (Mn) of between 700 and 3000 g / mol, obtained by crosslinking, via its terminal hydroxyl functions, using at least one polyisocyanate crosslinking agent, in the presence of from about 150 ppm to about 500 ppm of at least one crosslinking catalyst.

The nature of the binder (that of its precursor polymer (energy)) constitutes one of the important elements of the invention. Another important element of the invention is the amount of crosslinking catalyst used.

With reference to the nature of the binder (therefore energetic binder), more particularly to that of its precursor polymer (polyhydroxytelechelic glycidyl azide), the following can be added.

It is in no way excluded from the scope of the invention that a mixture of at least two glycidyl polyazides (having molecular masses (between 700 and 3000 g / mol) and / or different branching rates) is used as precursor polymer of the binder of the products of the invention.

The precursor energetic polymer of the binder of the products of the invention is therefore a poly glycidyl azide (PAG) which has terminal hydroxy functions (a hydroxytelechelic PAG), hence 1) its energetic properties and 2) its ability to be crosslinked with polyisocyanate type crosslinking agents.

Said polymer has an adequate molecular mass (in particular, with reference to its consistency (liquid) and to the consistency of its mixture with essentially the fillers (organic energies) and with reference to the relative content of the crosslinked binder in crosslinking agent (s) ), number-average molecular mass (Mn) of between 700 and 3000 g / mol, advantageously between 1700 and 2300 g / mol.

Crosslinking agents, of the polyisocyanate type (at least bifunctional), suitable for the crosslinking of such a hydroxytelechelic polyglycidylazide (PAG) are known per se. They may in particular be di- or triisocyanates. It is advantageously of polyisocyanates, liquid, chosen from toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), dicyclohexylmethylene diisocyanate (MDCI), hexamethylene diisocyanate (HDI), the trimer of said hexamethylene diisocyanate (in particular sold by the company Bayer trade name Desmodur® N 3300), biuret trihexane isocyanate (BTHI), 3,5,5-trimethyl-1,6-hexamethylene diisocyanate and their mixtures. Particularly preferably, the trimer of hexamethylene diisocyanate is used.

Said crosslinking agents are conventionally used in the necessary and sufficient quantity, to ensure crosslinking of the polymer (not excessive so as not to pollute the crosslinked product obtained). They are conventionally used in an amount such that the bridging ratio (NCO (of the crosslinking agent) / OH (of the polymer)) is between about 0.8 and about 1.4, advantageously between about 0.8 and about 1.1.

The crosslinked energetic polymer generally represents from 9 to 14% by weight of the total composition of the composite pyrotechnic products of the invention.

It has been understood that the interest of the invention is based on the level of crosslinking of the binder precursor polymer, energetic, this level resulting from the amount of crosslinking catalyst used, namely about 150 ppm to about 500 ppm, advantageously about 150 ppm to about 400 ppm, most preferably about 200 ppm to about 400 ppm. It will be noted here that the amount of crosslinking catalyst is expressed relative to the mass of composite pyrotechnic product. The crosslinking catalyst is advantageously chosen from triphenylbismuth (Biφ ₃ ), tin dibutyldilaurate (DBTL), and mixtures thereof. In one embodiment of the invention, the crosslinking catalyst is a mixture of triphenylbismuth and tin dibutyldilaurate, advantageously in a mass ratio ranging from about 75:25 to about 95: 5, for example 75:25, 80 : 20, 85:15, 90:10 or 95: 5.

Conventionally, the energetic binder is associated with at least one energetic plasticizer. The energetic plasticizer (s) in question is (are) advantageously of the nitrate and / or nitramine type. The energetic plasticizer (s) in question is (are) very advantageously chosen from diethylene glycol dinitrate (DEGDN); triethylene glycol dinitrate (TEGDN); butanetriol trinitrate (BTTN); trimethylolethane trinitrate (TMETN); a mixture of 2,4-dinitro-2,4-diaza-pentane, 2,4-dinitro-2,4-diaza-hexane and 3,5-dinitro-3,5-diaza-heptane (and very particularly DNDA 5.7); nitratoethyl nitramines (in particular methyl-2-nitratoethyl nitramine (methylNENA) and ethyl-2-nitratoethyl nitramine (ethylNENA)); and their mixtures.

The plasticizer (s) of the pyrotechnic products of the invention generally represent (s) from 10 to 30% by mass, more generally from 15 to 25% by mass, of the total composition of said products.

The energetic charges present are organic charges.

The organic energy charges in question are not per se original. These are organic energetic fillers known per se and, for the most part, already packaged according to the prior art in crosslinked energetic polymeric binders (in particular of the PAG type). These are advantageously charges of hexogen (RDX), octogen (HMX), hexanitrohexaazaisowurtzitane (CL20), 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), 5,5'-azotetrazolate dihydrazinium (DHDZT), 5,5'-bis (tetrazolyl) hydrazine (HBT), bis (2,2-dinitropropyl) nitramine (BDNPN), a nitropyrazole or a mixture of these fillers (organic energy ).

Within the composite pyrotechnic products of the invention, there is therefore a type of energy charge, advantageously chosen from the above list, or a mixture of at least two types of energy charge, advantageously chosen from the above list. .

Preferably, there are energetic loads of RDX and / or HMX, more preferably energetic loads of RDX or HMX.

The use of hexogen charges and / or octogen charges is particularly recommended insofar as these two types of charges offer a very satisfactory compromise: security / energy power.

The organic energy charges are conventionally in the form of solid grains, distributed homogeneously within the plasticized crosslinked binder. These solid grains conveniently exhibit, in a manner known per se, several particle size distributions.

The organic energy charges of the composite pyrotechnic products of the invention generally represent from 50 to 70% by mass, more generally from 55 to 65% by mass, of the total composition of said products. It has been understood that said products have a high loading rate.

It should be noted that the presence of metal fillers (aluminum, in particular), within the plasticized binder of the composite pyrotechnic products of the invention, is itself generally excluded. Such metal charges are indeed likely to generate particles during their combustion, ie to generate primary fumes. The presence of inorganic energetic charges (of ammonium perchlorate, in particular), within the plasticized binder of the pyrotechnic products of the invention, is not desired but cannot be totally excluded. In any event, such inorganic energetic charges present are necessarily present in small quantities (<4% by mass). They can be considered as ballistic additives (see below). Their presence may be opportune, with reference to the desired ballistic properties of the product.

The composite pyrotechnic products of the invention are moreover likely to contain, and generally contain, in their binder (crosslinked precursor polymer), in addition to the plasticizer (s) and organic energy fillers, at least one ballistic additive. We can more accurately speak of at least one other ballistic additive, the crosslinking catalyst being able to be fully analyzed as an additive in its own right. Crosslinking catalysts have presently been isolated from other additives, insofar as they are present with reference to the technical problem presently considered.

Among the ballistic additives suitably present, the following conventional additives are preferred: stabilizers for the energetic plasticizer (s) present, ballistic catalysts and anti-glare agents. Thus, according to an advantageous variant, the composite pyrotechnic products of the invention therefore contain in their composition, in addition to the crosslinked polymer (PAG), the plasticizer (s) and the organic energy charges, at least one ballistic additive; said at least one ballistic additive comprising at least one agent for stabilizing the plasticizer (s) present and / or at least one ballistic catalyst and / or at least one anti-glare agent. Mention may be made, by way of stabilizing agent of the plasticizer (s), of aromatic amines, such in particular 2-nitrodiphenylamine (2-NDPA) and N-methylparanitroaniline (MNA). Present, it is generally present at a content of about 1% by mass. By way of ballistic catalyst, mention may be made of conventional ballistic catalysts, such as in particular lead salts and oxides, and bismuth citrate. Said bismuth citrate, in particular because of its lower toxicity, is preferred. Said at least one ballistic catalyst is generally present in the composition of the pyrotechnic products of the invention at a content of approximately 1% to approximately 6% by mass, very generally at a content of approximately 3% to approximately 5% by mass . By way of anti-glare agent, mention may be made of compounds based on alkali metals, sodium (Na ₂ SO ₄ , etc.) and especially potassium (K ₂ SO ₄ , KNO ₃ , K ₃ AlF ₆ , C ₄ H ₅ KO ₆ , etc.). Advantageously, the anti-glare agent is cryolite potassium (= potassium aluminum fluoride; (K ₃ AlF ₆ )), monobasic potassium tartrate (C ₄ H ₅ KO ₆ ) (said monobasic potassium tartrate possibly being in the form of the L- enantiomer or D- or in racemic form These specific potassium salts are commercially available at conventional particle sizes (powders with grains generally having a d ₅₀ between 1 and 300 µm). Present, the anti-glare agent is generally available at a content of about 1% to about 5% by mass.

Other ballistic additives capable of being present in the composition of the composite pyrotechnic products of the invention may in particular consist of inorganic energetic charges (see above).

The ballistic additives which may be present (in view of the above comments, it has been understood that generally several types of additive are present) generally represent at most approximately 10% by mass of the composition of the composite pyrotechnic products of the invention. They very generally represent approximately 0.1% to approximately 10% by mass (often approximately 1.5% to approximately 10% by mass) of the composition of said composite pyrotechnic products of the invention.

• de environ 50% à environ 70%, avantageusement de environ 55% à environ 65%, de charges énergétiques organiques,
• de environ 9% à environ 4 % de polymère énergétique (de type PAG hydroxytéléchélique) réticulé (via ses fonctions terminales hydroxy par au moins un polyisocyanate),
• de environ 10% à environ 30%, avantageusement de environ 15% à environ 25%, d'au moins un plastifiant énergétique,
• de 0 à environ 10%, avantageusement de environ 0,1% à environ 10%, d'au moins un additif balistique.

In one embodiment, the composition of the composite pyrotechnic products of the invention, expressed in percentages by mass, contains:

• from about 50% to about 70%, advantageously from about 55% to about 65%, of organic energy loads,
• from about 9% to about 4% of energetic polymer (of the hydroxytelechelic PAG type) crosslinked ( via its terminal hydroxyl functions by at least one polyisocyanate),
• from about 10% to about 30%, advantageously from about 15% to about 25%, of at least one energetic plasticizer,
• from 0 to about 10%, preferably from about 0.1% to about 10%, of at least one ballistic additive.

It is understood that the advantageous ranges indicated above can quite be considered independently of one another. Preferably, they are in combination with one another.

In the context of this embodiment, said composition is generally free of any other ingredient (in particular of any metallic filler) and therefore consists of the ingredients listed above, present in the amounts indicated above.

The preparation of the composite pyrotechnic products in accordance with the invention does not pose any particular difficulties. It can in particular be implemented by the method specified below, which constitutes another aspect of the invention. This is a process by analogy, which characteristically involves the at least one crosslinking catalyst in the preparation of a propellant with a crosslinked hydroxytelechelic PAG type binder.

• la constitution d'une pâte homogène par
  1. a) incorporation, avec agitation, à une température comprise entre environ 35°C et environ 55°C, dans un polyazoture de glycidyle adéquat (PAG hydroxytéléchélique présentant une masse moléculaire en nombre telle que précisée ci-dessus), d'au moins un plastifiant énergétique, des charges énergétiques organiques et des autres ingrédients constitutifs du produit pyrotechnique composite recherché à l'exception d'un quelconque agent de réticulation et d'un quelconque catalyseur de réticulation, et
  2. b) agitation du mélange résultant, sous vide partiel, à une température comprise entre environ 35°C et environ 55°C ;
• l'incorporation dans ladite pâte homogène constituée, sous vide partiel et à une température comprise entre environ 35°C et environ 55°C, dudit au moins un agent de réticulation et d'environ 150 ppm à environ 500 pm dudit au moins un catalyseur de réticulation, suivie d'une agitation du mélange constitué ;
• la coulée dudit mélange constitué dans au moins une structure ; et
• le traitement thermique dudit mélange constitué agité coulé dans ladite au moins une structure.

The present invention therefore also relates to a process for preparing a composite pyrotechnic product, as described above. This process includes:

• the constitution of a homogeneous paste by
  1. a) incorporation, with stirring, at a temperature of between approximately 35 ° C and approximately 55 ° C, in a suitable poly glycidylazide (hydroxytelechelic PAG having a number molecular mass as specified above), of at least one energetic plasticizer, organic energetic charges and other constituent ingredients of the desired composite pyrotechnic product with the exception of any crosslinking agent and any crosslinking catalyst, and
  2. b) stirring the resulting mixture, under partial vacuum, at a temperature between about 35 ° C and about 55 ° C;
• the incorporation into said homogeneous paste consisting, under partial vacuum and at a temperature between approximately 35 ° C and approximately 55 ° C, of said at least one crosslinking agent and of approximately 150 ppm to approximately 500 μm of said at least one catalyst crosslinking, followed by stirring of the mixture formed;
• casting said mixture formed in at least one structure; and
• heat treatment of said stirred mixture cast in said at least one structure.

The mentioned partial vacuum is intended for degassing the medium above which it is applied. It is generally around 10 mm Hg. We note incidentally that it is not necessarily of constant intensity.

The heat treatment (of crosslinking (of the hydroxytelechelic PAG)) is generally carried out at a temperature between approximately 30 ° C and approximately 60 ° C (30 ° C ≤ T ≤ 60 ° C), for several days.

The composite pyrotechnic products in accordance with the invention are suitable in particular as solid propellants for propellant charges of missiles, in particular of tactical missiles. Their use for this purpose is particularly recommended. It forms an integral part of the present invention.

• ils possèdent d'excellentes propriétés mécaniques à froid et à température ambiante, sans baisse de performance énergétique ;
• ils peuvent être fabriqués de manière satisfaisante et compatible avec une montée en maturité à échelle industrielle.

The composite pyrotechnic products in accordance with the invention have in particular the following advantages:

• they have excellent mechanical properties at cold temperature and at room temperature, with no decrease in energy performance;
• they can be manufactured satisfactorily and compatible with a rise in maturity on an industrial scale.

The invention will be better understood with the aid of the examples below, given purely by way of illustration.

Example 1

Hydroxytelechelic poly glycidyl azide (PAG) (marketed by the company EURENCO (Mn = 1900 g / mol) then plasticizers (BTTN / TMETN, 30/70 mixture by mass), stabilizing agents (MNA) were introduced into a mixer. / 2-NDPA, 75/25 mass mixture) of said plasticizers and ballistic additives. The mixture was kneaded for 15 min at a temperature of 40 ° C. The organic energy charges (mixture) were then added to said mixture, with stirring. by mass of 2/3 RDX 0-100 and 1/3 RDX M3C) per portion, then the ballistic catalyst (bismuth citrate) in portions. Stirring was then continued for 2 hours 30 minutes, still at a temperature of 40 ° C and under a vacuum of 10 mm Hg (which allowed the degassing of the medium), to obtain a homogeneous paste. The crosslinking catalyst (20 ppm DBTL + 200 ppm Biφ ₃ ) was then added to said homogeneous paste and the medium was further stirred 30 min before the addition of the binder crosslinking agent (trimer of hexamethylene diisocyanate sold by the company Bayer under the trade name Desmodur®N 3300). The medium was stirred for a further 15 min (still at 40 ° C. and under vacuum). There was thus obtained 2 kg of propellant paste, the composition of which is shown in Table 1. A sample was taken from each of the propellant pastes thus prepared for the determination of the pot life. The rest of the propellant paste was then poured into a suitable structure and then subjected to a heat treatment (baking at a temperature of 50 ° C. for 14 days).

Comparative example

The procedure of Example 1 was repeated but using a mixture of 5 ppm of DBTL and 50 ppm of Biφ ₃ as a crosslinking catalyst. The composition of the propellant paste obtained is shown in Table 1. Table 1 Compound (% mass) Ex. 1 Ex. Comp PAG 9.0 9.0 BTTN / TMETN 20.2 20.2 MNA / 2-NDPA 0.7 0.7 RDX 61.5 61.5 Bi citrate 4 4 DBTL 20 ppm 5 ppm Biφ ₃ 200 ppm 50 ppm Ballistic additives 2.6 2.5 Desmodur® N 3300 2.0 2.1

Example 2

The pot life (which makes it possible to assess the feasibility of the process for obtaining the propellants) was determined by measuring the viscosity of the propellant paste in question (containing the crosslinking agent and the crosslinking catalyst) at over time, using a Brookfield viscometer (with body n ° 3 (mobile C) rotated at 1 revolution / min), at a temperature of 40 ° C. The time for which the viscosity reached 1500 Pa.s was recorded in order to determine whether the propellant met the industrialization criterion, that is to say if said time recorded was greater than 10 h. The results are shown in Table 2. Table 2 Ex. 1 Ex. Comp Pot life > 8 p.m. ≈ 70h

Example 3

The different mechanical properties of the propellant blocks obtained according to the above examples were evaluated over a wide temperature range: modulus of elasticity (E), stress (Sm), elongation at break (em) and mechanical capacity (shown by the product Sm * em) as a function of t / a _T (time-temperature equivalence). The measurements were carried out by uniaxial traction in accordance with Standard NFT70-315.

The results are presented in Table 3 below and on the figure 1 . Table 3 Ex. 1 Ex. Comp + 20 ° C 50 mm / min E (Mpa) 8.8 4.1 Sm (Mpa) 0.74 0.50 em (%) 42 40 Sm / E 0.08 0.12 Sm * em 31 20 -20 ° C 50 mm / min E (Mpa) 13.0 7.2 Sm (Mpa) 0.99 0.73 em (%) 36 33 Sm / E 0.08 0.12 Sm * em 36 24 -20 ° C 500 mm / min E (Mpa) 21.6 14.2 Sm (Mpa) 1.45 1.37 em (%) 40 33 Sm / E 0.07 0.10 Sm * em 58 45 -46 ° C 500 mm / min E (Mpa) 869 342 Sm (Mpa) 11.4 11.6 em (%) 8 6 Sm / E 0.01 0.03 Sm * em 91 64

It can be seen from reading the table above that a significant increase in the amount of crosslinking catalyst during the preparation of the propellant paste (x4) results in a notable increase in the stress Sm and the modulus E at + 20 ° C for a tensile speed of 50 mm / min without degrading the elongation em. The mechanical capacity is therefore markedly improved. When cold (-20 ° C to 5 mm / min and -20 ° C to 500 mm / min), the observed effect is even more interesting: the increase in stress and modulus is cumulative with that of elongation . The figure 1 shows the order of magnitude of the gains in elongation and mechanical capacity for the various conditions tested.

Claims (13)

Composite pyrotechnic product containing organic energetic charges in a plasticized binder, comprising a crosslinked energetic polymer and at least one energetic plasticizer, said energetic crosslinked polymer consisting of a polyglycidylazide (PAG), having a number average molecular weight (Mn) included between 700 and 3000 g / mol, obtained by crosslinking, via its terminal hydroxyl functions, with at least one polyisocyanate type crosslinking agent, in the presence of 150 ppm to 400 ppm of at least one crosslinking catalyst, organic energy charges representing from 50 to 70% by mass of the composition of the composite pyrotechnic product. Composite pyrotechnic product according to claim 1, in which the polyglycidylazide (PAG) has a number molecular weight (Mn) of between 1700 and 2300 g / mol. Composite pyrotechnic product according to Claim 1 or Claim 2, in which said at least one energetic plasticizer is of the nitrate and / or nitramine type. Composite pyrotechnic product according to any one of claims 1 to 3, in which said organic energetic charges are selected from hexogen charges, octogen charges, and mixtures of such charges. Composite pyrotechnic product according to any one of claims 1 to 4, in which the crosslinking catalyst is chosen from tin dibutyldilaurate, triphenylbismuth and their mixtures. A pyrotechnic product according to claim 5, wherein the crosslinking catalyst is a mixture of triphenylbismuth and dibutyldilaurate tin. A composite pyrotechnic product according to any one of claims 1 to 6, wherein the amount of crosslinking catalyst is 200 ppm to 400 ppm. Composite pyrotechnic product according to any one of claims 1 to 7, which further contains at least one ballistic additive. Composite pyrotechnic product according to claim 8, in which said at least one ballistic additive is chosen from an agent for stabilizing the energetic plasticizer (s), a ballistic catalyst and their mixtures. A composite pyrotechnic product according to claim 8 or claim 9, which contains bismuth citrate as a ballistic catalyst. Composite pyrotechnic product according to any one of claims 1 to 10, the composition of which, expressed in percentages by mass, contains: - from 50 to 70%, advantageously from 55 to 65%, of organic energy charges, - from 9 to 14% of crosslinked energetic polymer, - from 10 to 30%, advantageously from 15 to 25%, of energetic plasticizer (s), - From 0 to 10%, advantageously from 0.1 to 10%, of at least one ballistic additive. Use of the composite pyrotechnic product according to any one of Claims 1 to 11, as a solid propellant for a propellant charge of a missile, in particular of a tactical missile. A process for preparing a composite pyrotechnic product according to any one of claims 1 to 11, which comprises: - the constitution of a homogeneous paste by a) incorporation, at a temperature between 35 ° C and 55 ° C, in said poly glycidylazide, of said at least one energetic plasticizer, organic energetic charges and other constituent ingredients of the desired composite pyrotechnic product with the exception of any crosslinking agent and any crosslinking catalyst, and b) stirring the resulting mixture, under partial vacuum, at a temperature between 35 ° C and 55 ° C; - the incorporation into said homogeneous paste consisting, under partial vacuum and at a temperature between 35 ° C and 55 ° C, of said at least one crosslinking agent and at least one crosslinking catalyst, followed by stirring of the mixture formed; the casting of said stirred mixture formed in at least one structure; and the heat treatment of said stirred mixture cast in said at least one structure.

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