KR102325489B1 - Low-toxicity smoke pyrotechnic compositions for wide-band masking - Google Patents

Abstract

The present invention relates in particular to a smoke chemical composition aimed at protecting land platforms against infrared induced threats. The composition comprises a polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms as fuel in a chemical composition, preferably a smoke chemical composition, and when the composition is combusted, a toxic substance of released gas such as hydrobromic acid The content is less than 350 ppm, preferably less than 300 ppm.

Description

LOW-TOXICITY SMOKE PYROTECHNIC COMPOSITIONS FOR WIDE-BAND MASKING

The present invention relates to a low toxic pyrotechnic composition, preferably aimed at protecting land platforms (eg vehicles or armored vehicles), in particular against infrared induced threats. The composition can prepare an effective camouflage cloud in the infrared and visible region.

Concealment compositions used today generally include a redox couple and a composition that serves as a fuel. Upon combustion, the fuel enables the production of particles of suitable size and shape to ensure effective hiding in the visible and infrared, especially in the spectral window between 3 and 14 μm. These compositions contain a chlorinated compound such as CLONACIRE® (a composition comprising a mixture of naphthalene chloride having a level of substitution greater than 3) or hexachloroethane. They serve either as oxidizers or as particle products.

However, these highly chlorinated compounds form large amounts of toxic substances, especially HCl (gas hydrogen chloride), upon degradation.

According to the evaluation of "the Ministry of Ecology and Sustainable Development and the Ministry of Health, Family and Handicapped People (INERIS sheet, 2003)", the threshold and irreversible effects for the first lethal effect associated with exposure to gaseous HCl for 10 min. Thresholds for this are 1300 ppm (1937 mg/m3, threshold of first lethal effect) and 240 ppm (358 mg/m, threshold of irreversible effect).

Accordingly, there is a need for a chemical composition that exhibits good hiding performance with low toxicity.

The use of bromine compounds in chemical compositions, in particular their application as decoys for the protection of aerial targets against infrared induced threats, is known, but does not address the problem of toxicity of these compounds. The desired effect in this case is generally not concealment smoke, but rather infrared, which mimics the radiation of the motors of an aerial platform.

Also, US 5,389,308 relates to a composition that produces smoke opaque to infrared light comprising magnesium powder, a fluorinated organic polymer, chloroparaffin and an aromatic compound, which may be a brominated aromatic compound such as 8-bromoanthracene, which is non-halogenated. It is disclosed that the compound is preferred because of its low toxicity.

Likewise, US 3,498,925 and US 3,400,082 disclose the use of metal or organometallic compounds in addition to non-halogen compounds to reduce the toxicity of chemical compositions for hiding in visible light. Application US 2012/0267016 concerning a smoke generating composition for concealment in visible light recommends the use of a mixture comprising melamine and polymethylated methyl gallate. In addition, these compositions contain sucrose as a fuel and chlorate as an oxidizing agent. Also, US 4,238,254 describes a chemical composition for concealment in visible light, comprising guanidine nitrate, which produces a basic compound capable of neutralizing hydrogen chloride (HCl) or phosphorus pentoxide produced in smoke.

Accordingly, the prior art consistently teaches that, in order to reduce or eliminate the toxicity of these concealment chemical compositions, any use of halides as oxidizing agents, reducing agents or fuels should be avoided.

Surprisingly, the present application nevertheless discloses that the use as fuel of a polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms in a chemical composition, preferably in a smoke generating chemical composition, while maintaining hiding performance in both visible and infrared light It is mentioned that the toxicity of the chemical composition can be significantly reduced compared to that of the prior art.

A "spectral window" according to the present invention specifies a range of wavelengths. The "polyaromatic" compound according to the present invention designates a C ₁₀ to C ₁₄ hydrocarbon compound consisting of 2 to 3 condensed aromatic rings. In particular, mention may be made of naphthalene, anthracene and phenanthrene as examples of polyaromatic compounds. The polyaromatic compound is preferably naphthalene or anthracene, more preferably naphthalene.

The "polyheteroaromatic" compound according to the present invention denotes a compound composed of 2 to 3 condensed aromatic rings or heteroaromatic rings and containing at least one nitrogen heteroaromatic ring. In particular, mention may be made of quinoline, isoquinoline and naphthyridine as examples of polyheteroaromatic compounds. The polyheteroaromatic compound is preferably a quinoline.

A "chlorinated compound" according to the invention designates an organic compound comprising at least one chlorine atom, in particular a compound comprising at least one carbon-chlorine (C-Cl) bond.

The present invention relates only to chemically stable compounds.

Preferably, the polyaromatic or polyheteroaromatic compounds substituted with 1 to 3 bromine atoms according to the invention do not contain chlorine substituents.

Preferably, the polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms does not contain any other substituents.

To determine the toxicity of the chemical composition, the potentially toxic species released upon combustion of the smoke generating composition are determined. Emissions during combustion are estimated by thermodynamic calculations. For each identified toxic species, thresholds of first lethal and irreversible effects are taken from the literature. These two thresholds are evaluated as a function of the subject's exposure time to a toxic substance, here gaseous HBr.

According to a report by the "Toxicology Expert Group of the Ministry of Ecology, Energy, Sustainable Development and Developments of the Territory" (April 15, 2008), the threshold and irreversibility of the first lethal effect on exposure to gaseous HBr for 10 minutes The threshold of effect is 3290 ppm (11054 mg/m3, threshold of first lethal effect) and 366 ppm (1228 mg/m, threshold of irreversible effect).

The present invention therefore relates first of all to the use as fuel of a polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms in a chemical composition, preferably in a smoke generating chemical composition, so that upon combustion of said composition, The concentration of toxic substances such as hydrogen bromide in the gas is less than 350 ppm, preferably less than 300 ppm.

The present invention also relates to a chemical composition, preferably smoke production, comprising at least one polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms as at least a reducing agent, a binder and a fuel, and optionally an oxidizing agent in the following proportions: It relates to a chemical composition:

with respect to the total weight of the composition,

- 5 to 25% by weight of a reducing agent,

- from 2 to 25% by weight of a binder optionally mixed with a plasticizer, and

- 50 to 90% by weight of a fuel comprising at least one polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms,

- optionally 5 to 15% by weight of an oxidizing agent,

- optionally from 2 to 10% by weight of additives.

The invention also relates to a chemical device comprising said composition. The present invention also relates to the transmission of infrared light between a target and a threat using a chemical composition, preferably a smoke generating chemical composition, comprising as fuel a polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms. A method of target concealment comprising the manufacture of a blocking smoke screen.

Accordingly, the present invention relates to the use of a polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms as previously defined as fuel in a chemical composition, preferably a smoke generating chemical composition, wherein upon combustion of said composition, the emission The concentration of toxic substances, in particular hydrogen bromide, in the gas to be produced is less than 350 ppm, preferably less than 300 ppm.

Preferably, the combustion of the composition provides a camouflage coefficient of greater than 50%, preferably greater than 60%, in a spectral window of 8 to 12 μm, generally for 15 seconds, preferably for 20 seconds. do.

Preferably, the combustion of the composition provides a camouflage coefficient of greater than 60%, preferably greater than 70%, in a spectral window of 3-5 μm, generally for 15 seconds, preferably for 20 seconds.

The "disguise coefficient" according to the present invention is expressed as a percentage and specifies the ratio (Cm)(t) calculated at time t according to the formula:

during the meal,

Nb(t) and Nb' are, respectively, a numerical level with and without an effect on a hot source;

Nn(t) and Nn' are, respectively, a numerical level with and without an effect on a cold source.

Gastrointestinal parameters are usually measured under controlled and reproducible conditions. The measuring instruments used are:

- a black-body type heat source exhibiting a temperature adjusted to around 200 °C;

- Cold source (usually steel plate at ambient temperature)

etc. is an emitter.

And, the receptor measuring means is:

- thermal cameras operating in band 2 (3-5 μm spectral window);

- Thermal camera operating in band 3 (8-12 μm spectral window)

etc.

Preferably, the smoke generating composition does not contain chlorinated compounds. Preferably, the polyaromatic or polyheteroaromatic compound is substituted with two bromine atoms; more preferably dibromonaphthalene or dibromoquinoline; More preferably, they are 1,4-dibromonaphthalene, 1,8-dibromoquinoline, or 4,7-dibromoquinoline.

The present invention also relates to a chemical composition, preferably smoke production, comprising at least one polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms as at least a reducing agent, a binder and a fuel, and optionally an oxidizing agent in the following proportions: It relates to a chemical composition:

with respect to the total weight of the composition,

- 5 to 25% by weight of reducing agent, preferably 10 to 20% by weight,

- from 2 to 25% by weight of a binder optionally mixed with a plasticizer, and

- 50 to 90% by weight, preferably 60 to 80% by weight of a fuel comprising at least one polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms,

- optionally 5 to 15% by weight of an oxidizing agent,

- optionally from 2 to 10% by weight of additives.

If necessary, the weight of the binder is adjusted so that the percentage of the various additives is 100%. In this method, the percentage of binder is adjusted for the mass percentage of reducing agent, fuel, and optionally oxidizing agent and additive to obtain 100%.

Preferably, the composition is free of chlorinated compounds.

Preferably, the polyaromatic or polyheteroaromatic compound is substituted with two bromine atoms. Preferably, the polyaromatic or polyheteroaromatic compound is substituted with two bromine atoms; more preferably dibromonaphthalene or dibromoquinoline; More preferably, they are 1,4-dibromonaphthalene, 1,8-dibromoquinoline, or 4,7-dibromoquinoline.

In general, the reducing agent is selected from magnesium, aluminum, zirconium, titanium, silicon or boron, or mixtures thereof, for example as metal powder. Preferably, the reducing agent consists essentially of magnesium powder or a powder of a mixture of zirconium and magnesium.

In the first embodiment, the binder also serves as an oxidizing agent. In this embodiment, the composition does not include an oxidizing agent, nor a binder.

In this first embodiment, the chemical composition according to the invention, preferably the smoke-generating chemical composition, preferably comprises:

with respect to the total weight of the composition,

- 5 to 25% by weight of a reducing agent,

- 5 to 25% by weight, preferably 10 to 15% by weight of a binder optionally mixed with a plasticizer, and

- 50 to 90% by weight, preferably 60 to 70% by weight of a fuel comprising at least one polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms,

- optionally 2 to 10% by weight of additives

includes

The binder is then a fluoroelastomer or a mixture thereof, preferably polytetrafluoroethylene, poly(carbon monofluoride) (PMF) or vinylidenefluoride, hexafluoropropylene, perfluoromethylvinylether and/or copolymers of tetrafluoroethylene (eg VITON®) or mixtures thereof.

In the second embodiment, the binder does not act as an oxidizing agent. In this embodiment, the composition according to the invention comprises 5 to 15% by weight of an oxidizing agent, preferably selected from potassium chlorate, ammonium chlorate, potassium perchlorate, ammonium perchlorate, potassium nitrate or ammonium nitrate, or mixtures thereof. The oxidizing agent may also be a fluoroelastomer or mixtures thereof, preferably polytetrafluoroethylene, poly(carbonmonofluoride) (PMF) or vinylidenefluoride, hexafluoropropylene, perfluoromethylvinylether and/or tetrafluoroethylene. copolymers of fluoroethylene or mixtures thereof.

The binder is selected from phenolic polymers, epoxy resins or polybutadiene. In particular, when the binder is an epoxy resin, the oxidizing agent is advantageously a fluoroelastomer or a mixture thereof, advantageously polytetrafluoroethylene, poly(carbonmonofluoride) (PMF) or vinylidenefluoride, hexafluoropropylene , copolymers of perfluoromethylvinylether and/or tetrafluoroethylene or mixtures thereof.

In this second embodiment, the chemical composition according to the invention, preferably the smoke-generating chemical composition, preferably comprises:

with respect to the total weight of the composition,

- 5 to 25% by weight of reducing agent, preferably 10 to 20% by weight;

- from 2 to 10% by weight, preferably from 3 to 5% by weight of a binder optionally mixed with a plasticizer;

- 5 to 15% by weight of an oxidizing agent, preferably 10 to 15% by weight; and

- 50 to 90% by weight, preferably 60 to 80% by weight of a fuel comprising at least one polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms;

- optionally 2 to 10% by weight of additives

includes

The composition according to the invention may also contain additives, for example hardeners, flame retardants or flame suppressants. The flame retardant is selected in particular from diatomaceous earth or graphite. An example of a preferred flame retardant is sodium hydrogen carbonate. Preferred additives are flame retardants and flame suppressants.

The invention also relates to a chemical device comprising a container in which a useful charge of the chemical composition according to the invention is accommodated. Preferably, the chemical composition according to the invention is shaped by compression. Containers are generally smoke grenades or grenades that can be hand-thrown or fired from a launcher.

The present invention also relates to the production of a smoke screen preventing the transmission of infrared light between a threat and a target using a chemical composition, preferably a smoke generating chemical composition, comprising a polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms as fuel. It relates to a target concealment method comprising a.

Preferably, the chemical composition is as defined above.

1 is a curve showing the evolution of camouflage coefficients for a 3 to 5 μm optical window for Composition 1. FIG. The x-axis represents time in seconds; The y-axis represents the camouflage coefficient in %.
FIG. 2 is a curve showing the evolution of camouflage coefficients for an 8-12 μm optical window for Composition 1. FIG. The x-axis represents time in seconds; The y-axis represents the camouflage coefficient in %.
3 is a curve showing the evolution of the camouflage coefficient for a 3-5 μm optical window for composition 2. The x-axis represents time in seconds; The y-axis represents the camouflage coefficient in %.
4 is a curve showing the evolution of the camouflage coefficient for an 8-12 μm optical window for Composition 2. The x-axis represents time in seconds; The y-axis represents the camouflage coefficient in %.

The following examples are provided to illustrate the present invention, but should not be construed as limiting its scope in any case.

Example 1: Toxicity Assessment

The enthalpy of formation of 1,4-dibromonaphthalene was defined as equivalent to 27.6 kcal/mol using Hyperchem software and literature data.

An experiment of the combustion of 1,4-dibromonaphthalene, which can identify the species emitted during combustion, was performed with Coppelia software. Thermodynamic calculations were performed under a pressure of 2 atmospheres and at a temperature of 2000 K in the absence of atmospheric oxygen. According to this calculation, the mass fraction of the emitted species represents predominantly one toxic species, HBr. Its mass fraction is given as 0.3436 by Coppelia calculations.

From this result, it can be inferred that the maximum concentration of HBr close to the source of smoke, that is, burning smoke grenade, is 300 ppm. This concentration drops rapidly with dilution as it moves away from this source.

HBr Toxicity thresholds described in the literature for:

Available data on gaseous HBr (report from the "Toxicology Expert Group of the Ministry of Ecology, Energy, Sustainable Development and Development of the Territory, 15 April 2008") are based on the threshold of first lethal effects related to exposure time and State the threshold of the irreversible effect.

Example 2: Evaluation of hiding performance

Description of the experimental composition :

The experimental composition contained 1,4-dibromonaphthalene as fuel. This precise fuel for redox couple can guarantee broadband concealment performance.

In the case of composition 1, the binder used is a Viton® type fluorinated polymer. This binder also serves as an oxidizing agent in the composition. The reducing agent used is magnesium. 1,4-dibromonaphthalene constitutes about 70% by mass of the composition; Viton® binder represents 11% by mass of the composition; The reducing agent is 19% by mass of the mixture.

In the case of composition 2, the binder used is an epoxy resin in combination with its curing agent. The oxidizing agent used in the composition is a polytetrafluoroethylene type fluorinated polymer. The reducing agent used is magnesium. A flame retardant, graphite, is also used in the composition. 1,4-dibromonaphthalene constitutes 68 mass % of this composition, with respect to the composition, 3 mass % of a binder, 17 mass % of a reducing agent, 10 mass % of an oxidizing agent, and 2 mass % of a combustion retardant are represented.

The test composition is compressed in the form of a cylindrical smoke generating port. The mass of the composition in each pot is about 400 g.

Description of the experimental method:

The experimental method makes it possible for the smoke cloud to travel at a controlled speed and pass in front of the measuring means described below in a controlled and reproducible way.

Description of the means of measurement:

Measures are:

- a blackbody heat source exhibiting a temperature adjusted to around 200 °C;

- Cold source (usually steel plate at ambient temperature)

Includes phosphorus emission sources.

And, the receptor measuring device is:

- thermal cameras operating in band 2 (3-5 μm spectral window);

- Thermal camera operating in band 3 (8-12 μm spectral window)

It is located opposite the phosphorus source.

Description of the use of smoke pots:

A cloud of smoke moves and passes in front of a measuring instrument where the infrared performance of the smoke generating port can be measured under controlled and reproducible conditions.

Description of the data processing method:

For each experimental port, the following values are calculated from luminance measurements obtained by band 2 and band 3 thermal cameras.

Cm = Gastrointestinal coefficient (expressed as a percentage) calculated according to the following formula:

during the meal,

Nb(t) and Nb' are, respectively, a numerical level with and without an effect on a heat source;

Nn(t) and Nn' are, respectively, a numerical level with and without an effect on a cold source.

The results obtained for Compositions 1 and 2 of 3 to 5 μm and 8 to 12 μm spectral windows are shown in FIGS. 1 to 4 .

For both Composition 1 and Composition 2, it can be seen that combustion of the composition provides a camouflage coefficient of greater than 50% for at least 20 seconds in the 3 to 5 μm and 8 to 12 μm spectral windows.

More specifically, Composition 1 provides a camouflage coefficient of greater than 70% for at least 15 seconds in a 3-5 μm spectral window and a camouflage coefficient of 60% for at least 15 seconds in an 8-12 μm spectral window.

Composition 2 ensures a camouflage coefficient of greater than 70% for at least 30 seconds in a 3-5 μm spectral window and a camouflage coefficient of 60% for at least 20 seconds in an 8-12 μm spectral window.

Claims (20)

delete delete delete delete delete delete At least one polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms as at least a reducing agent, a binder and a fuel, and optionally an oxidizing agent in the following proportions:
with respect to the total weight of the composition,
- 5 to 25% by weight of a reducing agent,
- from 2 to 25% by weight of a binder optionally mixed with a plasticizer, and
- 50 to 90% by weight of a fuel comprising at least one polyaromatic or polyheteroaromatic compound substituted with 1 to 3 bromine atoms,
- optionally 5 to 15% by weight of an oxidizing agent, and
- optionally 2 to 10% by weight of additives
As a chemical composition (pyrotechnic composition) comprising,
The sum of the components does not exceed 100% by weight,
Wherein the chemical composition does not contain a chlorinated compound. 8. The method of claim 7,
wherein the polyaromatic or polyheteroaromatic compound is substituted with two bromine atoms. 8. The method of claim 7,
wherein the polyaromatic or polyheteroaromatic compound is dibromonaphthalene or dibromoquinoline. 8. The method of claim 7,
The reducing agent is selected from magnesium, aluminum, zirconium, titanium, silicon or boron, or mixtures thereof. 8. The method of claim 7,
The oxidizing agent is selected from potassium chlorate, ammonium chlorate, potassium perchlorate, ammonium perchlorate, potassium nitrate or ammonium nitrate, a fluoroelastomer or mixtures thereof. 12. The method of claim 11,
The composition, characterized in that the binder is selected from phenolic polymers, epoxy resins or polybutadiene. 8. The method of claim 7,
A composition, characterized in that the binder also serves as an oxidizing agent. A chemical device comprising a container capable of being fired from a launcher or thrown by hand, comprising:
A chemical device, wherein a useful charge of the chemical composition according to claim 7 is lodged. A method of concealing a target comprising the preparation of a smoke screen that blocks the transmission of infrared light between a target and a threat using a chemical composition comprising a polyaromatic or polyheteroaromatic compound substituted with one to three bromine atoms as fuel, the method comprising:
The chemical composition is the chemical composition according to claim 7, the target concealment method. 8. The method of claim 7,
A chemical composition, characterized in that the chemical composition is a smoke generating chemical composition. 11. The method of claim 10,
The composition, characterized in that the reducing agent consists of magnesium powder or a powder of a mixture of zirconium and magnesium. 14. The method of claim 13,
The binder is selected from polytetrafluoroethylene, poly(carbon monofluoride), or copolymers of vinylidenefluoride, hexafluoropropylene, perfluoromethylvinylether and/or tetrafluoroethylene, or mixtures thereof. characterized in that, the composition. 16. The method of claim 15,
A method for concealing a target, characterized in that the chemical composition is a smoke generating chemical composition. delete

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