Low-toxicity smoke-producing pyrotechnic compositions for wideband masking

Abstract

The present invention relates to smoke-producing pyrotechnic compositions for protecting land-based platforms. The compositions comprise a monocyclic aromatic or monocyclic heteroaromatic compound substituted with at least one halogen atom as the fuel in a pyrotechnic composition, preferably a smoke-producing pyrotechnic composition, such that, when the composition combusts, the content of toxic substances in the emitted gases, such as hydrobromic acid, is less than 350 ppm, preferably less than 110 ppm.

Description

[0001] LOW-TOXICITY BROAD-BAND PYROTECHNIC SMOKE COMPOSITIONS FOR MASKING

[0002] FIELD OF INVENTION

[0003] The present invention relates to low toxicity pyrotechnic compositions advantageously intended for the protection of land platforms or infrastructure. The compositions make it possible to produce an effective camouflage cloud in the multispectral range, in particular visible, near-infrared, infrared and millimeter.

[0004] TECHNOLOGICAL BACKGROUND

[0005] Current masking compositions generally include an oxidizing / reducing agent and a fuel compound. During combustion, the fuel's degradation generates particles of a shape and size suitable for effective masking in the visible and infrared regions, particularly in the spectral range between 0.3 and 14 pm. These compositions include chlorinated compounds (compositions containing a mixture of chlorinated naphthalenes with a substitution ratio greater than 3) or hexachloroethane. These act as either oxidizing agents or particle-generating products. However, these highly chlorinated compounds, upon decomposition, form toxic products, especially large quantities of hydrochloric acid (HCl).

[0006] According to assessments by the Ministry of Ecology and Sustainable Development and the Ministry of Health, Family and Persons with Disabilities (INERIS Fact Sheet, 2003), the threshold for the first lethal effects and the threshold for irreversible effects associated with gaseous HCl for 10 minutes of exposure are 1300 ppm (threshold for the first lethal effects, or 1937 mg / m³). 3 ), and 240 ppm (threshold of irreversible effects, or 358 mg / m³ 3 ).

[0007] The use of brominated compounds in pyrotechnic compositions is already known, particularly for decoy applications, although the issue of the toxicity of these compositions has not been addressed. The desired effects in this case are generally not masking smoke but infrared radiation mimicking the radiation from the engines of aerial platforms.

[0008] US 5,389,308 discloses compositions that generate infrared-opaque smoke and include magnesium powder, a fluorinated organic polymer, chloroparaffin, and an aromatic compound, which may be a brominated aromatic compound such as 8-bromoanthracene. US 5,389,308 teaches that non-halogenated compounds are preferred because of their lower toxicity. US 3,498,925 and US 3,400,082 teach the use of metallic or organometallic, but non-halogenated, compounds to reduce the toxicity of pyrotechnic compositions for visible-light masking.

[0009] US patent application 2012 / 0267016, which concerns smoke compositions for visible-light masking, recommends the use of a mixture comprising melamine and polymethyl methylgallate. Furthermore, these compositions include sucrose as a fuel and chlorate as an oxidant.

[0010] US 4,238,254 describes pyrotechnic compositions for masking in the visible spectrum, including guanidine nitrate, which produces basic compounds capable of neutralizing hydrogen chloride (HCl) or phosphorus pentoxide produced in fumes.

[0011] Prior art therefore consistently teaches that, in order to reduce the toxicity of pyrotechnic masking compositions, it is necessary to avoid any use of halogenated products, such as chlorine, whether as an oxidizer, reducer or fuel.

[0012] In view of the above, there remains a need for the provision of pyrotechnic compositions with good masking performance and low toxicity.

[0013] BRIEF DESCRIPTION OF THE INVENTION

[0014] The present invention relates to the use of a monocyclic aromatic compound, or monocyclic heteroaromatic compound, substituted by at least one halogen atom as a fuel in a pyrotechnic composition, preferably a smoke-producing one, not containing a chlorinated compound, in which the toxic substance content of the gases emitted during the combustion of the composition is less than 350 ppm, preferably less than 110 ppm.

[0015] The present invention also relates to a pyrotechnic composition, preferably a smoke-producing one, comprising, relative to the total weight of the composition:

[0016] 5 to 30%, preferably 5 to 20%, by weight of a reducer;

[0017] 5 to 30%, preferably 5 to 15%, by weight of an oxidant;

[0018] - 40 to 90%, preferably 50 to 90% or 60 to 80%, by weight of a fuel, comprising a monocyclic aromatic compound, or monocyclic heteroaromatic compound, substituted by at least one halogen atom.

[0019] The present invention also relates to a pyrotechnic device comprising a container in which is housed a payload of a pyrotechnic composition according to the invention.

[0020] Finally, the present invention also relates to a masking method comprising the production of a smoke screen using a pyrotechnic composition or a pyrotechnic device according to the invention. In one application, the proposed smoke composition is used for the disengagement of infantry sections in contact, by the establishment of a multispectral masking screen in a simple and agile manner.

[0021] At present, the disengagement and withdrawal of a group or combat section in contact can be ensured by artillery fire using smoke shells, when the pieces are available and with a time to put the effects into effect of 15 minutes under the best conditions.

[0022] The masking screen can notably be achieved by means of an aerial drone equipped with a smoke canister or several smoke canisters or cartridges, allowing a ground combat section to disengage quickly and safely under the cover of instant, dense and multispectral masking.

[0023] This solution provides additional answers to the needs of infantrymen:

[0024] Responsiveness and availability: the drone setup time is short (5 min installation and 5 min deployment) and therefore allows for greater responsiveness.

[0025] Positioning of the smoke screen: a drone with smoke can be placed as close as possible to the desired area, precisely, and without risk to the section that is disengaging.

[0026] Masking performance: the compositions used in smoke canisters or cartridges are more effective in multispectral masking than the compositions used in current smoke shells (red phosphorus or composition masking only in the visible).

[0027] Toxicity of fumes: the proposed composition is non-toxic to humans and has a low environmental impact.

[0028] Thus, the invention also proposes a system for implementing the masking process comprising at least one drone and at least one pot or cartridge of the pyrotechnic composition, said pot or cartridge being carried by the drone, a piloting interface being adapted to allow a remote operator to pilot the drone to a given area on the ground and to trigger or release it.

[0029] Other aspects of the invention are as described below and in the claims.

[0030] FIGURES

[0031] Figure 1: Curve representing the evolution of transmittance for the 8-12 pm optical window during laboratory chamber shots. The x-axis represents time in seconds, the y-axis represents transmittance in %.

[0032] Figure 2: Curve representing the evolution of transmittance for the 3-5 pm optical window during laboratory chamber shots. The x-axis represents time in seconds, the y-axis represents transmittance in %.

[0033] Figure 3: Curve representing the evolution of the camouflage coefficient for the optical window 8-12 pm for the compositions of example 5 and example 6. The x-axis represents time in seconds, the y-axis represents the camouflage coefficient in %.

[0034] DEFINITIONS

[0035] For the purposes of this invention, "spectral window" means a range of wavelengths.

[0036] For the purposes of this invention, a monocyclic aromatic hydrocarbon compound is defined as a monocyclic aromatic hydrocarbon compound, the ring comprising 6 to 10 carbon atoms, for example benzene (6-carbon ring).

[0037] For the purposes of this invention, a monocyclic heteroaromatic compound is defined as a monocyclic aromatic compound with 5 to 10 links comprising at least one heteroatom, preferably 1 to 3 heteroatoms, chosen from nitrogen, sulfur or oxygen, the other atoms of the ring being carbon atoms.

[0038] For the purposes of this invention, "chlorinated compound" means an organic compound comprising at least one chlorine atom, in particular a compound comprising at least one carbon-chlorine (C-Cl) bond.

[0039] DETAILED DESCRIPTION OF THE INVENTION

[0040] Surprisingly, the inventors found that the use of a monocyclic aromatic compound, or monocyclic heteroaromatic compound, substituted by at least one halogen atom, preferably at least two halogen atoms, as a fuel in a pyrotechnic composition, preferably a smoke-producing one, makes it possible to significantly reduce the toxicity of pyrotechnic compositions compared to those of the prior art, while retaining their masking performance in both the visible and infrared ranges.

[0041] Thus, the present invention relates to the use of a monocyclic aromatic compound or a monocyclic heteroaromatic compound, the compound being substituted by at least one halogen atom, preferably at least two halogen atoms, as a fuel in a pyrotechnic composition, preferably a smoke agent, such that the toxic substance content of the gases emitted during combustion of the composition is less than 350 ppm, preferably less than 110 ppm. To determine the toxicity of a pyrotechnic composition, the potentially toxic species emitted during combustion of the smoke agent are identified. The quantities emitted during combustion are evaluated using thermodynamic calculation codes. For each identified toxic species, the thresholds for first lethal effects and the thresholds for irreversible effects are searched in the literature.These two thresholds are assessed based on the duration of the subject's exposure to the toxic substance, for example gaseous HBr.

[0042] According to the report by the Expert Group of Toxicologists of the Ministry of Ecology, Energy, Sustainable Development and Spatial Planning (April 15, 2008), the threshold for the first lethal effects and the threshold for irreversible effects associated with gaseous HBr for 10 minutes of exposure are 3290 ppm (threshold for the first lethal effects, or 11054 mg / m³). 3 ), and 366 ppm (threshold of irreversible effects, or 1228 mg / m³ 3 ).

[0043] Fuels

[0044] The fuel used in the formulation of pyrotechnic compositions, preferably smoke-producing, comprises one or more monocyclic aromatic or monocyclic heteroaromatic compounds, the aromatic or heteroaromatic compound(s) being substituted by at least one halogen atom, preferably by at least two halogen atoms, typically by two halogen atoms.

[0045] The monocyclic aromatic or monocyclic heteroaromatic compound may be substituted by one to six halogen atoms or by one to four halogen atoms, for example by one to six bromine atoms or by one to four bromine atoms, preferably by one or two bromine atoms. The monocyclic aromatic or monocyclic heteroaromatic compound may be substituted by one or more substituents other than a halogen atom, for example by one or more substituents selected from the group consisting of alkyls in positions O1-O4, alkenyls in positions O2-O4, a hydroxyl group, and an amino group.

[0046] The compounds useful within the framework of the invention are chemically stable compounds.

[0047] Advantageously, the aromatic or heteroaromatic monocyclic compounds useful within the scope of the invention do not include chlorinated substituents.

[0048] Preferably, the aromatic or heteroaromatic monocyclic compounds useful in the context of the invention do not include any other substituents.

[0049] Advantageously, the fuel is a dibromobenzene, more particularly 1,4-dibromobenzene (CAS number: [106-37-6]).

[0050] Pyrotechnic compositions and pyrotechnic devices

[0051] The present invention also relates to a pyrotechnic composition, preferably smoke-producing, comprising at least one reducing agent, one oxidizing agent and at least one monocyclic aromatic or monocyclic heteroaromatic compound substituted by at least one halogen atom, preferably at least two halogen atoms as a fuel, and optionally a binder, in the following proportions, expressed relative to the total weight of the composition:

[0052] 5 to 30%, preferably 5 to 20%, by weight of a reducer;

[0053] 5 to 30%, preferably 5 to 15%, by weight of an oxidant;

[0054] - 40 to 90%, preferably 50 to 90% or 60 to 80%, by weight of a fuel, comprising a monocyclic aromatic or monocyclic heteroaromatic compound substituted by at least one halogen atom, preferably at least two halogen atoms; optionally 1 to 10% by weight of additives; and

[0055] optionally 2% to 25% by weight of a binder, possibly mixed with a plasticizer.

[0056] The sum of the proportions of reducer, oxidant, fuel, any binder and additives is preferably 100%.

[0057] The monocyclic aromatic compound or monocyclic heteroaromatic compound substituted by at least one halogen atom can be as previously described.

[0058] Preferably, the pyrotechnic composition, preferably smoke-producing, does not contain any chlorinated compound.

[0059] Typically, the reducing agent is selected from the group consisting of magnesium, aluminum, zirconium, titanium, silicon, boron, and mixtures thereof. The reducing agent may be, for example, in the form of a metal powder. Preferably, the reducing agent consists primarily of magnesium powder or a mixture of zirconium and magnesium.

[0060] Typically, the oxidant is selected from the group consisting of fluoroelastomers (such as polytetrafluoroethylene, poly(carbon monofluoride) (PMF), polyvinylidene fluoride, vinylidene fluoride copolymer, hexafluoropropylene, perfluoromethyl vinyl ether, tetrafluoroethylene, or mixtures thereof), potassium chlorate, ammonium chlorate, potassium perchlorate, ammonium perchlorate, potassium nitrate, ammonium nitrate, and mixtures thereof. Preferably, the oxidant does not contain silver salts, such as silver iodate.

[0061] In some embodiments, the composition includes a binder. A binder is typically introduced into the compositions to improve the mechanical strength of the pyrotechnic device prepared from these compositions. In these embodiments, the binder is typically selected from the group consisting of phenolic polymers, epoxy resins, polyesters, and polybutadiene.

[0062] In particular, when the binder is an epoxy resin, the oxidant is advantageously chosen from polytetrafluoroethylene, poly(carbon monofluoride) (PMF), polyvinylidene fluoride or a copolymer of vinylidene fluoride, hexafluoropropylene, perfluoromethyl vinyl ether and / or tetrafluoroethylene (such as VITON®) or mixtures thereof.

[0063] The pyrotechnic composition, preferably smoke-producing, typically comprises the following proportions, expressed as a percentage of the total weight of the composition:

[0064] 5 to 30%, preferably 5 to 20%, by weight of a reducer;

[0065] 5 to 30%, preferably 5 to 15%, by weight of an oxidant;

[0066] 50 to 90%, preferably 60 to 80%, by weight of a fuel comprising a monocyclic aromatic compound, or monocyclic heteroaromatic compound, substituted by at least one halogen atom, preferably at least two halogen atoms; and 2 to 25%, preferably 2 to 5%, by weight of a binder, possibly in a mixture with a plasticizer.

[0067] optionally 1 to 10% by weight of additives.

[0068] The sum of the proportions of reducer, oxidant, binder or binder and plasticizer, fuel and additives is preferably 100%.

[0069] Additives can include hardeners, flame retardants, flame inhibitors, and thickeners. Flame retardants are often chosen from diatomaceous earth and graphite. Sodium bicarbonate is a preferred flame inhibitor. Preferred additives include flame retardants and flame inhibitors.

[0070] The combustion of pyrotechnic compositions provides camouflage in the spectral window 8 to 12 pm and / or 3 to 5 pm.

[0071] Pyrotechnic compositions exhibit low toxicity. They can be advantageously used for the protection of land-based platforms or infrastructure, particularly against infrared-guided threats. These compositions produce an effective camouflage cloud in the multispectral range, specifically visible, near-infrared, infrared, and millimeter wavelengths.

[0072] The compositions described above are useful for preparing pyrotechnic devices. Thus, the present invention also relates to a pyrotechnic device comprising a composition according to the invention.

[0073] The pyrotechnic device typically comprises a container housing the pyrotechnic composition payload according to the invention. Preferably, the pyrotechnic composition according to the invention is shaped by compression or casting. The container is typically a smoke canister or cartridge suitable for launching by a launcher or manually.

[0074] Advantageously, the combustion of the composition provides an average camouflage coefficient in the spectral window 8 to 12 pm of at least 30% for a duration of at least 20 s, typically for a duration of 30 s.

[0075] It should be noted here that masking in band II is always greater than in band III by +20 to +30% as can be seen on the box shots in figures 1 and 2.

[0076] For the purposes of this invention, "camouflage coefficient" means the ratio Cm(t) expressed as a percentage, calculated at time t according to the following formula:

[0077]

[0078] in which

[0079] Nb(t) and Nb' are the numerical levels with and without effect on the hot source, respectively; Nn(t) and Nn' are the numerical levels with and without effect on the cold source, respectively. "Camouflage time" refers to the duration during which the camouflage coefficient is greater than 10% of its maximum value.

[0080] Camouflage coefficient and camouflage time are typically measured under controlled and reproducible conditions. The measuring devices used are emitting devices such as:

[0081] - a blackbody type hot source with a regulated temperature of around 200°C,

[0082] - a cold source (typically a steel plate at room temperature); and receiving measurement means such as:

[0083] - a thermal camera working in band 2 (spectral window 3-5 pm);

[0084] - a thermal camera working in band 3 (spectral window 8-12 pm).

[0085] Target masking method

[0086] The pyrotechnic compositions described above can be useful in a target masking process.

[0087] Thus, the present invention also relates to a masking method comprising the production of a smoke screen using a pyrotechnic composition, preferably a smoke-producing one, comprising a monocyclic aromatic or monocyclic heteroaromatic compound substituted by at least one halogen atom, preferably at least two halogen atoms, as a fuel. The masking method may also include the production of a smoke screen using a device comprising a container in which a payload of said pyrotechnic composition is housed.

[0088] The smoke screen's primary purpose is to prevent the transmission of infrared radiation between a target and a threat.

[0089] The pyrotechnic composition and the monocyclic aromatic or monocyclic heteroaromatic compound substituted by at least one halogen atom may be as previously described.

[0090] The following examples are given for illustrative purposes only, but should in no way be considered as limiting the present invention.

[0091] EXAMPLES

[0092] Example 1: Evaluation of masking performance in the laboratory

[0093] Description of the tested compositions:

[0094] The tested compositions contain 1,4-dibromobenzene as a fuel. This fuel, combined with the redox couple, ensures broadband masking performance.

[0095] Four compositions were tested: two compositions formatted by compression (Example 1 and Example 2) and two compositions formatted by pouring (Example 3 and Example 4).

[0096] Compression-formed compositions contain a binder in addition to the three other main components. The formulations of the compositions are as described in Table 1. [Table 1] Composition formulations Example 1 to Example 4

[0097]

[0098] Description of the test equipment:

[0099] The test device is a hermetically sealed chamber of 0.565 m 3 allowing the generation of a smoke cloud at a known concentration and the measurement of masking performance in band II and band III.

[0100] Description of the measuring methods:

[0101] The measurement methods consist of emitting sources which are:

[0102] a blackbody type hot spring with a regulated temperature of around 200°C,

[0103] a cold source (typically a steel plate at room temperature); and receiver measurement devices positioned opposite the sources, which are:

[0104] a thermal camera working in band 2 (spectral window 3-5 pm);

[0105] a thermal camera working in band 3 (spectral window 8-12 pm).

[0106] Description of the smoke grenade deployment procedure:

[0107] The smoke curtain is generated by a model smoke generator weighing a few grams and is homogenized in the box using a fan to obtain stable IR masking measurements under controlled and reproducible conditions.

[0108] Description of the data processing method:

[0109] For each pot tested, the following values ​​are calculated from the luminance recordings obtained with the band 2 and band 3 thermal cameras.

[0110] Ct = Transmittance coefficient (expressed as a percentage), also called transmittance, calculated according to the following formula:

[0111]

[0112] in which:

[0113] Nb(t) and Nb' are the numerical levels with and without effect on the hot source, respectively; Nn(t) and Nn' are the numerical levels with and without effect on the cold source, respectively. In this test configuration, the closer the transmittance is to 0%, the better the masking performance.

[0114] Results of the masking performance of strip and strip III:

[0115]

[0116] The results show that the compositions of the invention have masking efficiency in the spectral windows of 8-12 pm (Figure 1) and 3-5 pm (Figure 2), with increased efficiency in the 3-5 pm spectral range (Table 2). With the same forming configuration, the compositions of the invention have performance equal to or even superior to the reference compositions (Reference 1 for the compressed version and Reference 2 for the cast version).

[0117] The references are the pyrotechnic smoke compositions currently used to produce an effective camouflage cloud in the multispectral range, particularly visible, near-infrared, infrared and millimeter ranges, and described in patent application WO 2015 / 132266.

[0118] [Table 2] results

[0119]

[0120] Example 2: Evaluation of masking performance with a pyrotechnic device. Description of the compositions tested:

[0121] The tested compositions contain 1,4-dibromobenzene as a fuel. This fuel, combined with the redox couple, ensures broadband masking performance. In both example compositions, the binder used is an epoxy resin combined with its hardener. The formulations of the compositions are as described in Table 3.

[0122] [Table 3] Formulations of the compositions Example 5 and Example 6

[0123]

[0124] The compositions tested are compressed into cylindrical smoke canisters or cartridges.

[0125] Description of the test equipment:

[0126] The test method allows the smoke cloud to be moved at a controlled speed so as to pass in a controlled and reproducible manner in front of the measuring means described below.

[0127] Description of the measuring methods:

[0128] The measurement methods consist of emitting sources which are:

[0129] a blackbody type hot spring with a regulated temperature of around 200°C,

[0130] a cold source (typically a steel plate at room temperature); and receiver measurement devices positioned opposite the sources, which are:

[0131] - a thermal camera working in band 3 (spectral window 8-12 pm).

[0132] Description of the smoke grenade deployment procedure:

[0133] The smoke curtain moves and passes in front of the measuring devices, thus allowing the infrared performance of the smoke generator to be measured under controlled and reproducible conditions.

[0134] Description of the data processing method:

[0135] For each pot tested, the following values ​​are calculated from the luminance recordings obtained with the 3cm band thermal cameras. = Camouflage coefficient (expressed as a percentage) calculated according to the following formula:

[0136]

[0137] in which

[0138] Nb(t) and Nb' are the numerical levels respectively with and without effect on the hot source; Nn(t) and Nn' are the numerical levels respectively with and without effect on the cold source.

[0139] Masking performance results:

[0140] The results obtained for examples 5 and 6 in the spectral window 8-12 pm are shown in Figure 3. The average camouflage coefficient is calculated over the camouflage duration during which the camouflage coefficient is greater than 10% of its maximum value.

[0141] Example 5 has an average camouflage coefficient of 47.1% in the spectral window 8 to 12 pm, with a camouflage duration of 24.2 s (Figure 3). Example 6, with a higher quantity of 1,4-dibromobenzene, provides a longer camouflage duration while maintaining a good average camouflage coefficient (Figure 3).

[0142] The results are presented in Table 4.

[0143] [Table 4] results

[0144]

[0145] Example 3: Toxicity assessment

[0146] The enthalpy of formation of 1,4-dibromobenzene was determined to be 51.5 kJ / mol using data from the literature. A simulation of the combustion of 1,4-dibromobenzene, allowing for the determination of the species emitted during combustion, was performed using the SIAME software. The thermodynamic calculation was carried out in the absence of atmospheric oxygen, under initial conditions equivalent to standard pressure and temperature. The mass fractions of the emitted species resulting from this calculation show primarily one toxic species, HBr. Its mass fraction is given by the SIAME calculation as being 0.125 for the composition of the invention generating the largest quantity of HBr. Based on this result, the maximum concentration of HBr near the source of the smoke, i.e., the burning smoke canister, can be estimated at 110 ppm.This concentration decreases rapidly due to dilution as soon as one moves away from this source.

[0147] Toxicity thresholds described in the literature for the HBr molecule:

[0148] The available data concerning gaseous HBr (report of the Group of Expert Toxicology of the Ministry of Ecology, Energy, Sustainable Development and Spatial Planning of April 15, 2008) describe the thresholds of the first lethal effects and the thresholds of irreversible effects associated with exposure times (tables 5 and 6).

[0149] [Table 5] thresholds of the first lethal effects

[0150]

[0151] [Table 6] Thresholds of the first irreversible effects

[0152]

[0153] Application to assist the disengagement of infantry sections in contact

[0154] The smoke grenades just described are advantageously used for the disengagement of infantry sections in contact, by setting up a multispectral masking screen in a simple and agile way.

[0155] In addition to existing artillery or non-multispectral individual means, the deployment of masking can be carried out rapidly using a light aerial drone equipped with a smoke grenade canister or several smoke grenade canisters or cartridges. The drone, under which the smoke grenade charge is installed, is transportable in a backpack and deployable in less than 5 minutes.

[0156] An operator at the regimental level pilots the drone and releases the smoke grenade canister(s) or cartridge(s). Deployment and piloting of the drone on-site can be very rapid (less than 5 minutes). Guidance can be manual or based on coordinates.

[0157] Upon arrival on site, the masking time can last up to 5 minutes for an estimated front of 100m wide and approximately 3m to 5m high.

[0158] Following this step, the drone returns to its starting point or to a specified area for quick recovery and reconditioning.

[0159] Drone:

[0160] Typically, the drone can be a latest generation drone with an operational autonomy of up to 1 hour thanks to its “smart battery” system.

[0161] It is foldable, can be carried in a backpack, and can be deployed in less than 5 minutes. It is designed for use by forces in the field.

[0162] The drone incorporates GNSS sensors and antennas and can carry payloads of up to 4 kg. Its maximum range is 10 km with a speed of 10 m / s (~40 km / h).

[0163] Its rapid deployment allows for maximum responsiveness in the field.

[0164] It is modular and can carry different formats of smoke charge connected via a quick coupler, a camera to enable effective masking delivery, and is equipped with a hardened communication system, insensitive to the radio environment.

[0165] It can communicate and operate with other drones in Master-Slave mode or in swarm mode.

[0166] Smoke generator module:

[0167] After the drone is deployed, a smoke charge consisting of either a single 4 kg smoke canister or several canisters or individual cartridges, attached to the drone via a mechanical and electrical connection system, can be deployed quickly and safely.

[0168] The smoke charge consists of a smoke composition of the type described above capable of producing multispectral masking for 5 minutes.

[0169] The smoke generator's architecture (pot, cartridge) is designed for easy handling when reloading or at the end of use.

[0170] This composition is non-toxic, allowing infantrymen to move around in smoke if necessary, without risk.

[0171] Smoke production is immediate upon initiation and masking is established in less than 5 seconds. The smoke jet, emitted during the operation of the charge, quickly generates masking of the ground over a length of several tens of meters and up to at least 3 m in height, or even up to 5 m or more.

[0172] Control interfaces:

[0173] The drone is remotely piloted by a single operator positioned behind the unit, close to the combat unit. The operator can maintain direct line of sight to the area to be protected or can use the drone's camera to deliver the footage.

[0174] Receiving the deployment request via radio link from the infantry or the command center, the operator deploys his drone, attaches the smoke module and initiates the rally in less than 5 minutes.

[0175] The smoke grenade is activated by the pilot when he arrives on site.

[0176] Depending on the aerological conditions, the pilot can seed an area by moving the drone or by remaining stationary, or even drop the individual payloads one by one.

[0177] The smoke sequence produces an instant effect with a 5-minute duration. The system includes the option to release the smoke during or after operation, allowing for a rapid return if needed for replenishment or for another mission.

[0178] The system is designed to produce a 100m masking front in less than 20 seconds.

[0179] This combines the agility of a portable drone with the effectiveness of pyrotechnic effects to contribute to the safety of ground units. The three components of the system are designed and selected to provide a real operational advantage:

[0180] The system is easy to transport. Designed for regimental-level operation, it can be rapidly deployed to support a section or even a group of infantrymen. The infantry operator can pilot the drone in the field using direct line of sight or an onboard camera.

[0181] The high-capacity, multispectral smoke charge is easily connected to the drone's initiation box. The system allows for deployment, if necessary.

[0182] The permanent availability of the solution, its elongation capabilities, its implementation time (effect implemented in less than 10 minutes) and its non-toxicity are the major advantages of this masking solution.

[0183] The positioning of the multispectral mask is independent of the range of the munitions and gives the Forces great flexibility of use.

Claims

DEMANDS 1. Use of a monocyclic aromatic compound, or monocyclic heteroaromatic compound, substituted by at least one halogen atom as a fuel in a pyrotechnic composition, preferably a smoke composition, not containing a chlorinated compound, composition, in which the toxic substance content of the gases emitted during combustion of the composition is less than 350 ppm, preferably less than 110 ppm.

2. Use according to claim 1, characterized in that the combustion of the pyrotechnic composition provides camouflage in the spectral window 8 to 12 pm, and / or 3 to 5 pm.

3. Use according to claim 1 or 2, characterized in that the combustion of the pyrotechnic composition provides an average camouflage coefficient in the spectral window 8 to 12 pm of at least 30% for a duration of at least 20 s, typically for a duration of 30 s.

4. Use according to any one of claims 1 to 3, characterized in that the monocyclic aromatic or monocyclic heteroaromatic compound is substituted by one to six bromine atoms.

5. Use according to claim 4, characterized in that the monocyclic aromatic or monocyclic heteroaromatic compound is substituted by one or two bromine atoms.

6. Use according to any one of claims 1 to 5, characterized in that the monocyclic aromatic or monocyclic heteroaromatic compound is a dibromobenzene, preferably 1,4-dibromobenzene.

7. Pyrotechnic composition, preferably smoke-producing, comprising, in relation to the total weight of the composition: 5 to 30%, preferably 5 to 20%, by weight of a reducer; 5 to 30%, preferably 5 to 15%, by weight of an oxidant; 40 to 90%, preferably 60 to 80%, by weight of a fuel comprising a monocyclic aromatic compound, or monocyclic heteroaromatic compound, substituted by at least one halogen atom, preferably at least two halogen atoms; and optionally 2 to 25%, preferably 2 to 5%, by weight of a binder, possibly mixed with a plasticizer; Optionally, 1 to 10% by weight of additives, said pyrotechnic composition not containing any chlorinated compound.

8. Composition according to claim 7, characterized in that the monocyclic aromatic or monocyclic heteroaromatic compound is substituted by one to six bromine atoms.

9. Composition according to claim 7, characterized in that the monocyclic aromatic or monocyclic heteroaromatic compound is substituted by one or two bromine atoms.

10. Composition according to any one of claims 7 to 9, characterized in that the monocyclic aromatic or monocyclic heteroaromatic compound is a dibromobenzene, preferably 1,4-dibromobenzene.

11. Composition according to any one of claims 7 to 10, characterized in that the reducing agent is selected from the group consisting of magnesium, aluminum, zirconium, titanium, silicon, boron and mixtures thereof.

12. Composition according to any one of claims 7 to 11, characterized in that the oxidant is selected from the group consisting of fluoroelastomers, potassium chlorate, ammonium chlorate, potassium perchlorate, ammonium perchlorate, potassium nitrate, ammonium nitrate and mixtures thereof.

13. Pyrotechnic device comprising a container in which is housed a payload of a pyrotechnic composition according to any one of claims 7 to 12.

14. A masking method according to claim 13, wherein an operator pilots a drone carrying at least one pot or cartridge of said composition to a given area where masking is to occur, and then triggers or drops said pot or cartridge.

15. Method according to claim 14, wherein the guidance is manual or based on coordinates.

16. A method according to any one of claims 13 to 15, wherein the smoke screen generates a masking of the ground over a length of several tens of meters and up to at least 3 m in height.

17. A method according to any one of claims 13 to 16, wherein the drone is previously deployed in the field by the operator, who attaches at least one pot or cartridge of the pyrotechnic composition via a connection system.

18. A method according to any one of claims 14 to 17, wherein after triggering or dropping, the drone returns to its starting point or to a specified area for recovery and reconditioning.

19. System for implementing the masking method according to any one of claims 14 to 18, comprising at least one drone and at least one pot or cartridge of a pyrotechnic composition according to any one of claims 7 to 12, said pot or cartridge being carried by the drone, the system also comprising a piloting interface adapted to allow a remote operator to pilot the drone to a given area on the ground and to trigger or release it.

20. System according to claim 19 comprising at least one camera mounted on the drone.

21. System according to any one of claims 19 or 20, wherein the drone is foldable, transportable in a backpack and deployable.

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