Smoke-Producing Compositions

Abstract

The present disclosure relates to non-toxic smoke-producing compositions for producing colored smoke. In particular, the smoke-producing compositions are free from organic dyes from the family of anthraquinones (or derivatives). The smoke-producing compositions can be used to prepare pyrotechnic devices suitable for use in the military and civilian fields.

Description

FIELD OF THE INVENTION

The present invention relates to non-toxic smoke-producing compositions for producing colored smoke. The smoke-producing compositions are free from organic dyes of the family of anthraquinones (or derivatives). The smoke-producing compositions can be used to prepare pyrotechnic devices suitable for use in the military and civilian field.

TECHNOLOGICAL BACKGROUND

Smoke-producing compositions for producing colored smoke generally comprise an oxidizing/reducing couple and an organic dye in powder form. The production of colored smoke from such compositions is based on a principle of sublimation. During the combustion of the oxidizing/reducing couple, the heat generated by the combustion causes the organic dye to change from the solid state to the gaseous state. Colored smokes are generated when the organic dye condenses in the atmosphere.

A large number of the organic dyes used in smoke-producing compositions are dyes from the family of anthraquinone (or derivatives) (polycyclic aromatic hydrocarbons, PAHs) which allow the generation of yellow, red, blue or green smokes. Some of these derivatives have or may have a risk to the environment or human health. Moreover, when the compositions comprise organic dyes whose decomposition temperature is less than the combustion temperature of the oxidizing/reducing couple, the dye can be destroyed and generate more or less toxic combustion entities. In compositions containing potassium chlorate as a reducer, these entities can be associated with chlorine atoms and possibly form molecules of the dioxin type. Dioxins, like polycyclic aromatic hydrocarbons, are classified as persistent organic pollutants (POPs). In order to protect human health and the environment against POPs, manufacturers aim at reducing their unintentional production.

However, the production of smoke-producing compositions that do not have a risk to the environment or to human health remains a challenge. Thus, the simple substitution of a dye, the use of which may be controversial, by a dye that does not have the aforementioned disadvantages does not prove to be easy given the number of requirements which a dye must meet in order to allow the production and marketing of high-performance smoke-producing compositions. Thus, the smoke-producing compositions for producing colored smoke must be stable over time and withstand climatic variations, in particular high temperature variations. They must have an acceptable burn time and smoke efficiency. In addition to non-toxicity for humans, they must also meet a large number of environmental requirements (non-toxicity, compliance with REACH regulations, limitation of non-biodegradable inert waste from firing).

Thus, a need remains for the provision of high-performance non-toxic smoke-producing compositions which allow to meet the above requirements and which do not contain organic dyes liable to generate POPs, in particular which do not contain organic dyes from the family of anthraquinone (or derivatives).

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a smoke-producing composition comprising, relative to the total weight of the composition:

• • from 12 to 40% by weight of potassium chlorate;
  • from 12 to 40% by weight of lactose;
  • from 30 to 60% by weight of a non-salified sublimable organic dye in powder form;
    wherein the sublimable organic dye:
  • has a sublimation temperature of less than 450° C., the sublimation temperature being less than the decomposition temperature of the sublimable organic dye;
  • has a decomposition temperature higher than the combustion temperature of the smoke-producing composition; and
  • is selected from the group consisting of dyes from the family of thioxanthenes, nitrobenzamines, perylenes, benzimidozoles, naphthols, terephthalates, phthalocyanines, violanthrones, xanthenes, the dyes Solvent Yellow 14, Solvent Red 25, Pigment Red 1 and Solvent Yellow 56 from the azobenzene family, the dyes Vat Blue 5, Pigment Yellow 154 and Pigment Yellow 175 from the pyrazolinone family, the dyes Pigment Blue 66, Solvent Blue 2 and mixtures thereof.

The present invention also relates to a pyrotechnic device comprising such a smoke-producing composition as well as to its use for civil or military use.

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

DETAILED DESCRIPTION OF THE INVENTION

The research carried out by the inventors has allowed to develop smoke-producing compositions that meet the need expressed.

The smoke-producing compositions of the present invention comprise

• • from 12 to 40% by weight, relative to the total weight of the composition, of potassium chlorate (KClO₃) as oxidant;
  • from 12 to 40% by weight, relative to the total weight of the composition, of lactose as a reducer;
  • from 30 to 60% by weight, relative to the total weight of the composition, of a non-salified sublimable organic dye in powder form;
    in which:
  • the sublimable organic dye has a sublimation temperature less than 450° C., the sublimation temperature being less than its decomposition temperature;
  • the sublimable organic dye has a decomposition temperature higher than the combustion temperature of the smoke-producing composition; and
  • the sublimable organic dye is selected from the group consisting of dyes from the family of thioxanthenes, nitrobenzamines, perylenes, benzimidozoles, naphthols, terephthalates, phthalocyanines, violanthrones, xanthenes, the dyes Solvent Yellow 14, Solvent Red 25, Pigment Red 1 and Solvent Yellow 56 from the azobenzene family, the dyes Vat Blue 5, Pigment Yellow 154 and Pigment Yellow 175 from the pyrazolinone family, the dyes Pigment Blue 66, Solvent Blue 2 and mixtures thereof.

Such smoke-producing compositions have good technical performance: such as good combustion efficiency, good smoke density and pure color. Thus, the smoke-producing compositions of the present invention offer a very good combustion efficiency. Thus, combustion efficiencies above 45% are considered good and above 60% are considered very good. Such efficiencies allow the colored smoke to be visible over 5 km away in calm weather. The smoke density is greater than 5 g/cm³. Thus, the compositions of the present invention allow to obtain excellent smoke densities (greater than 5 g/cm³). The color of the smokes is characterized by measuring the colorimetry (Cylab coordinates) just for information.

Moreover, the smoke-producing compositions of the present invention are advantageously free from components listed to date in Annexes XIV and XVII of the REACH regulations and do not belong to the raw materials classified as toxic (bearing the mentions H314, H318, H300, H310, H311, H330, H331, H370, H372, H334, H350, H340, H360, H410 and H420). The absence of such components, in particular of toxic dyes, limits the risks for users exposed in the shorter or longer term to the smokes generated. Thus, the use of the compositions of the present invention does not have any known risks for human health and the environment.

The absence of dyes from the family of anthraquinone (or derivatives) in the formulation of the smoke-producing compositions of the present invention allows to limit the production of harmful entities during their combustion and the production of non-biodegradable inert waste.

In the present description, unless explicitly stated otherwise, the term “a” designates one or more.

The smoke-producing compositions of the present invention comprise from 12 to 40% by weight, relative to the total weight of the composition, of potassium chlorate (KClO₃) as oxidant. In certain embodiments, the smoke-producing compositions comprise from 15 to 30% by weight of potassium chlorate.

The smoke-producing compositions of the present invention comprise from 12 to 40% by weight, relative to the total weight of the composition, of lactose as a reducer. In certain embodiments, the smoke-producing compositions comprise from 20 to 32% by weight of lactose.

The smoke-producing compositions of the present invention comprise from 30 to 60% by weight, relative to the total weight of the composition, of a non-salified sublimable organic dye in powder form. In certain embodiments, the smoke-producing compositions comprise from 35 to 50% by weight of a non-salified sublimable organic dye in powder form.

The term “sublimable organic dye” refers to the ability of a dye to transition directly from the solid state to the gaseous state.

The term “non-salified” indicates that the organic dye is not in the form of a salt, such as a dye in monosodium or disodium form.

The sublimable organic dyes suitable for use in the context of the present invention must have a decomposition temperature higher than the combustion temperature of the smoke-producing composition. Their decomposition temperature must also be higher than their sublimation temperature. The smoke-producing compositions comprising the oxidizing/reducing couple KClO₃/lactose having a combustion temperature around 200° C., the organic dyes therefore have a decomposition temperature above 200° C.

The sublimable organic dye comes in the form of a powder. Preferably, the particles making up the powder are not nanoparticles, they do not have a nanometric size (1 to 100 nm). The absence of nanoparticle organic dyes limits the health risks for users exposed to the smokes generated. Preferably, the size of the particles does not exceed 200 μm. Such particles provide better dispersion in the smoke cloud.

Thus, preferably, the sublimable organic dye is in the form of a powder whose particles have a size greater than 1 μm, generally a size varying from 6 to 200 μm as measured by counting under a microscope (zoom X84). It is understood that, within this size range, the average particle size may vary depending on the organic dye selected.

The examples of specific dyes useful in the present invention are referred to by their generic name as referenced in the “Color Index International” database (2020).

An example of dyes from the thioxanthene family, suitable for use in the context of the present invention, includes the dye Solvent Yellow 98.

Examples of dyes from the nitrobenzamine family, suitable for use in the context of the present invention include the dyes Pigment Yellow 65 and Pigment Green 8.

An example of dyes from the perylene family, suitable for use in the context of the present invention includes the dye Solvent Green 5.

Examples of dyes from the benzimidazole family, suitable for use in the context of the present invention include the dyes Solvent Red 196 and Pigment Red 194.

Examples of dyes from the azobenzene family, suitable for use in the context of the present invention include the dyes Solvent Yellow 14, Solvent Red 25, Pigment Red 1, Solvent Yellow 56 and Pigment Red 170, in particular dyes from the naphthol subfamily including Solvent Yellow 14, Solvent Red 25, Pigment Red 1 and Pigment Red 170. In certain embodiments, the dye from the azobenzene family is selected from Solvent Yellow 14 and Solvent Yellow 56.

Examples of dyes from the terephthalate family, suitable for use in the context of the present invention include the dyes Solvent Yellow 155 and Pigment Yellow 175.

Examples of dyes from the phthalocyanine family, suitable for use in the context of the present invention include the dyes Pigment Green 7, Solvent Blue 70 and Solvent Blue 67.

Examples of dyes from the violanthrone family, suitable for use in the context of the present invention include the dyes Vat blue 20, Vat green 1, Vat blue 16 and Vat green 2 (also called Pigment Green 54).

An example of a dye from the xanthene family, suitable for use in the context of the present invention includes the dye Solvent Green 4.

Examples of dyes from the pyrazolinone family, suitable for use in the context of the present invention include Vat Blue 5, Pigment Yellow 154 and Pigment Yellow 175.

Thus, in certain embodiments, the non-salified sublimable organic dye is selected from the group consisting of Solvent Green 4, Pigment Yellow 65, Pigment Green 8, Solvent Green 5, Solvent Red 196, Pigment Red 194, Solvent Yellow 14, Solvent Red 25, Pigment Red 1, Solvent Yellow 56, Pigment Red 170, Solvent Yellow 155, Pigment Yellow 175, Pigment Green 7, Solvent Yellow 98, Solvent Blue 70, Solvent Blue 67, Vat Blue 20, Vat Green 1, Vat Green 2, Vat Blue 16, Vat Blue 5, Pigment Yellow 154, Pigment Yellow 175, Pigment Blue 66, Solvent Blue 2 and mixtures thereof.

Such organic dyes have a decomposition temperature higher than the combustion temperature of the smoke-producing composition and higher than their sublimation temperature. Such organic dyes do not have toxicity. Thus, the smoke-producing compositions comprising such dyes do not represent a danger for humans exposed in the shorter or longer term to the generated smokes.

In certain embodiments, the organic dye is selected from the group consisting of Solvent Green 5, Pigment Red 194, Solvent Yellow 14, Solvent Red 25, Pigment Green 7, Solvent Yellow 98, Vat Green 1, Vat Green 2, Pigment Blue 66 and mixtures thereof.

The smoke-producing compositions of the present invention may further comprise additives commonly employed in the technical field, such as binders, phlegmatizers, combustion regulators, moisture absorbers, flame inhibitors and mixtures thereof.

In certain embodiments, the smoke-producing compositions comprise from 0.5 to 10%, preferably from 5 to 10%, by weight relative to the total weight of the composition, of a phlegmatizer and/or from 0.5 to 8%, preferably from 1 to 3%, relative to the total weight of the composition, of a binder.

The smoke-producing compositions of the present invention may comprise from 1 to 18% by weight of optional additives relative to the total weight of the composition. The sum of the percentages by weight of oxidant, reducer, organic dye and optional additives is then equal to 100%.

Examples of binders suitable for use in the context of the present invention include gum arabic, epoxy resin, shellac and polyethylene wax.

Examples of phlegmatizers suitable for use in the context of the present invention include talc, kaolin (white clay made from aluminum silicate), kieselguhr, micronized silica and realgar.

Examples of combustion regulators suitable for use within the context of the present invention include hydrated alumina, paranitraniline, graphite and auramine N65.

Examples of flame inhibitor suitable for use in the context of the present invention include sodium hydrogencarbonate and calcium carbonate.

The person skilled in the art, on the basis of his technical knowledge, will be able to select the components and proportions of the components of the composition in order to reconcile, for example, chemical compatibility, volume ratio between dye/pyrotechnic composition (oxidant, reducer and additives) and/or combustion rate.

In certain embodiments, the smoke-producing compositions of the present invention comprise:

• • from 12 to 40%, preferably from 15 to 30% by weight, relative to the total weight of the composition, of oxidant (potassium chlorate);
  • from 12 to 40%, preferably from 20 to 32% by weight, relative to the total weight of the composition, of a reducer (lactose);
  • from 30 to 60%, preferably from 35 to 50% by weight, relative to the total weight of the composition, of a non-salified sublimable organic dye in powder form;
  • optionally from 1 to 18% by weight, relative to the total weight of the composition, of additives, typically selected from the group consisting of binders, phlegmatizers, flame inhibitors, moisture absorbers, combustion regulators and mixtures thereof. The proportions of oxidant, reducer, organic dye and additives are chosen so that the sum of the percentages is equal to 100%.

In certain embodiments, the smoke-producing compositions of the present invention comprise:

• • from 12 to 40%, preferably from 15 to 30% by weight, relative to the total weight of the composition, of potassium chlorate (KClO₃);
  • from 12 to 40%, preferably from 20 to 32% by weight, relative to the total weight of the composition, of lactose;
  • from 30 to 60%, preferably from 35 to 50% by weight, relative to the total weight of the composition, of a non-salified sublimable organic dye in powder form;
  • from 0.5 to 10%, preferably from 5 to 10%, by weight relative to the total weight of the composition, of a phlegmatizer;
  • from 0.5 to 8%, preferably from 1 to 3%, relative to the total weight of the composition, of a binder;

The sum of the percentages by weight of oxidant, reducer, organic dye, phlegmatizer and binder being equal to 100%.

In these embodiments, the sublimable organic dye can be as described above.

The smoke-producing compositions of the present invention can be produced according to methods well known to the person skilled in the art. Thus, the method described in the “Examples” section can easily be transposed on a large scale.

The smoke-producing compositions of the present invention can be used to produce pyrotechnic devices generating colored smoke, such as colored smoke grenades, signaling smokes (for example SNCF signals), training smokes, etc.

Thus, the present invention also relates to pyrotechnic devices comprising a smoke-producing composition according to the present invention.

The smokes generated can be yellow, red, blue or green depending on the use and the needs.

Pyrotechnic devices can be used in the civilian (for example paintball, demonstration, football match, . . . ) or military field.

They can allow to make position marking, to alert or to inform according to the color of the smoke.

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

EXAMPLES

Methods

The technical performance of the smoke-producing compositions, such as the density of the smoke, the duration of combustion, the combustion efficiency and the intensity of the color of the smoke are evaluated at room temperature (20-25° C.) in an experimental device comprising:

• • a 0.635 m³ box fitted with a filter disposed at the smoke outlet;
  • a visible camera allowing to measure the combustion time;
  • a thermocouple allowing to measure the combustion temperature.

The produced models are weighed before and after combustion, thus allowing to determine the mass of the composition before combustion (mass_{composition before combustion}) and the mass of the composition after combustion (mass_{combustion residue}).

Smoke Density

The smoke density (d), expressed in grams per cubic centimeter, is determined by the following relationship:

$d=\frac{{\mathrm{mass}}_{\mathrm{composition}\mathrm{before}\mathrm{combustion}}-{\mathrm{mass}}_{\mathrm{combustion}\mathrm{residue}}}{{\mathrm{Volume}}_{\mathrm{box}}\left(0.635m^3\right)}$

Combustion Time

The combustion time is measured by means of the camera.

Combustion Efficiency

The combustion efficiency, expressed as a percentage, is determined by the following relationship:

$r=\frac{{\mathrm{mass}}_{\mathrm{composition}\mathrm{before}\mathrm{combustion}}-{\mathrm{mass}}_{\mathrm{combustion}\mathrm{residue}}}{{\mathrm{mass}}_{\mathrm{composition}\mathrm{after}\mathrm{combustion}}}$

Colorimetry

Colorimetry allows to characterize a color by numerical values L*a*b* (CIELAB). L*a*b* color space (CIELAB) is a system adopted by the International Commission on Illumination in 1976.

L* a* b* are measured in the space

• • L*: saturation
  • a*: red/green component
  • b*: blue/yellow component

The evolution or color difference (DE) can be followed by the relationship:

DE=[(DL*)²+(Da*)²+(Db*)²]^1/2

where DL*, Da*, db* are the color difference values between the sample and the reference.

The color intensity is measured by a colorimeter disposed directly on the fume recovery filter (sublimated dye deposition on the filter).

Examples of Production of Smoke-Producing Compositions

The smoke-producing compositions were produced from the following raw materials:

• • Potassium Chlorate, CAS No: 3811-04-9;
  • Lactose, CAS No: 63-42-3;
  • Talc (Mg₃Si₄O₁₀(OH)₂), Cas No: 14807-96-6;
  • Gum Arabic, CAS No: 9000-01-5;
  • Sublimable organic dyes:
    • Pigment Red 194 (PR194), CAS No: 4216-02-8;
    • Pigment green 7 (PG7), CAS No: 1328-53-6;
    • Pigment Blue 66 (PB66), CAS No: 482-89-3;
    • Solvent yellow 14 (SY14), CAS No: 842-07-9;
    • Solvent yellow 98 (SY98), CAS No: 27870-92-4

The formulations of the smoke-producing compositions produced are as presented in Table 1. The percentages indicated are percentages by weight expressed relative to the total weight of the smoke-producing composition.

TABLE 1
Formulations of smoke-producing compositions
	CF1	CF2	CF3	CF4	CF5
Potassium	25.5%	20.4%	20.4%	20.6%	20.6%
chlorate
Lactose	23.7%	27.7%	27.7%	27.6%	27.6%
Talc	7.5%	7.5%	7.5%	7.5%	7.5%
Gum	1.3%	1.4%	1.4%	1.4%	1.4%
Dye(s)	PR194	PG7	PB66	SY14	SY98
	42%	43%	43%	42.9%	42.9%

The smoke-producing compositions were produced according to the detailed protocol presented below.

Preparation of Raw Materials

• • A gummed water solution was produced at 7.5% in demineralized water.
  • The oxidant and the reducer were baked at 50° C.-48 hours before mixing.
  • The oxidant and the reducer were stored in sealed jars, at 30° C.+/−5° C.
  • The oxidant and the reducer were crumbled at 500 μm,

Preparation of Smoke-Producing Compositions

• • The dye, the reducer and the phlegmatizer were weighed into the mixing vessel.
  • They were mixed until a homogeneous color powder was obtained.
  • The binder was introduced into the preparation, then mixed until a homogeneous color powder was obtained.
  • The oxidant was in turn introduced to the mixture and it was mixed until a homogeneous color powder was obtained.

Fractionation/Granulation

• • The mixture was poured into a large 630 μm sieve, then the composition was granulated manually on the 630 μm sieve. The composition under the sieve was retained.

Drying:

• • The composition was placed in a ventilated oven at 40° C. for a minimum of 2 days.

Grinding/Storage:

• • The composition was sifted through a 200 μm sieve, then it was stored in sealed and well-identified 200 g bags.

Production of Models

• • In a bakelite hoop, 5 g of PTFE was introduced (to be used as a background).
  • The height H1 was measured. It corresponds to the height available in the hoop.
  • 5 g of the smoke-producing composition were introduced into the hoop as well as 0.5 g of BNP (ignition composition).
  • The whole was compressed to a pressure of 500 Kg.
  • The height H2 was measured. It corresponds to the height available in the fret.
  • The height of the composition H3 was calculated according to the following formula: H3=H1-H2.
  • The hoop was then disposed in a metal case allowing pressurization.

Performance Evaluation of Smoke-Producing Compositions

The performance of the smoke-producing compositions was evaluated according to the methods described above. The results obtained with certain smoke-producing compositions are shown in Table 2.

TABLE 2
Performance of smoke-producing compositions
	Combustion		Combustion	Cilab
	efficiency	Smoke density	rate	coordinates (L,
	(%)	(g/cm3)	(mm/s)	a, b)-colorimetry
CF1	68.5	6.2	0.4	36.2; 20.1; 6.2
CF2	Not measured	20.69; −7.4; −4.25
CF3	60	5.43	0.39	33.3; 2; −3
Burning rate is obtained Vc = (Height of loading in the hoop)/(Combustion duration)
The smoke-producing compositions of the present invention are non-toxic and effective.

Claims

1. A smoke-producing composition comprising, relative to the total weight of the composition: wherein the sublimable organic dye:

from 12 to 40% by weight of potassium chlorate;

from 12 to 40% by weight of lactose;

from 30 to 60% by weight of a non-salified sublimable organic dye in powder form;

has a sublimation temperature of less than 450° C., the sublimation temperature being less than the decomposition temperature of the sublimable organic dye;

has a decomposition temperature higher than the combustion temperature of the smoke-producing composition; and

is selected from the group consisting of dyes from the family of thioxanthenes, nitrobenzamines, perylenes, benzimidozoles, naphthols, terephthalates, phthalocyanines, violanthrones, xanthenes, the dyes Solvent Yellow 14, Solvent Red 25, Pigment Red 1 and Solvent Yellow 56 from the azobenzene family, the dyes Vat Blue 5, Pigment Yellow 154 and Pigment Yellow 175 from the pyrazolinone family, the dyes Pigment Blue 66, Solvent Blue 2 and mixtures thereof.

2. The smoke-producing composition according to claim 1, wherein the sublimable organic dye is selected from the group consisting of Solvent Green 4, Pigment Yellow 65, Pigment Green 8, Solvent Green 5, Solvent Red 196, Pigment Red 194, Solvent Yellow 14, Solvent Red 25, Pigment Red 1, Solvent Yellow 56, Pigment Red 170, Solvent Yellow 155, Pigment Yellow 175, Pigment Green 7, Solvent Yellow 98, Solvent Blue 70, Solvent Blue 67, Vat Blue 20, Vat Green 1, Vat Green 2, Vat Blue 16, Vat Blue 5, Pigment Yellow 154, Pigment Yellow 175, Pigment Blue 66, Solvent Blue 2 and mixtures thereof.

3. The smoke-producing composition according to claim 1, wherein the sublimable organic dye is selected from the group consisting of Solvent Green 5, Pigment Red 194, Solvent Yellow 14, Solvent Red 25, Pigment Green 7, Solvent Yellow 98, Vat Green 1, Vat Green 2, Pigment Blue 66 and mixtures thereof.

4. The smoke-producing composition according to claim 1 further comprising additives selected from the group consisting of binders, phlegmatizers, combustion regulators, moisture absorbers, flame inhibitors and mixtures thereof.

5. The smoke-producing composition according to claim 1 further comprising from 0.5 to 8% by weight, relative to the total weight of the composition, of a binder.

6. The smoke-producing composition according to claim 1 further comprising from 0.5 to 10% by weight, relative to the total weight of the composition, of a phlegmatizer.

7. The smoke-producing composition according to claim 1, wherein the sublimable organic dye is a powder whose particle size does not exceed 200 μm.

8. The smoke-producing composition according to claim 1, wherein the decomposition temperature of the dye is higher than 200° C.

9. The smoke-producing composition according to claim 1 comprising:

from 15 to 30% by weight of potassium chlorate;

from 20 to 32% by weight of lactose;

from 35 to 50% by weight of the sublimable organic dye.

10. A pyrotechnic device comprising a smoke-producing composition according to claim 1.

11. The pyrotechnic device according to claim 10 selected from smoke grenades, signaling smoke or training smokes.

12. Use of a pyrotechnic device according to claim 10 for civil or military use.