USE OF A TETRAPHENYLPHOSPHONIUM HALOGENATED SALT AS SMOKE-PRODUCING AGENT AND SMOKE-PRODUCING PYROTECHNIC COMPOSITION INCORPORATING SUCH A MATERIAL

Abstract

Disclosed is the use of at least one tetraphenylphosphonium halogenated salt as smoke-producing agent in a pyrotechnic composition designed to ensure masking of a target with regard to electromagnetic radiation in a given wavelengths range. Also disclosed is also a smoke-producing pyrotechnic composition including at least one tetraphenylphosphonium halogenated salt.

Claims

1. A method to mask a target with regard to electromagnetic radiation in a given wavelengths range, comprising providing a pyrotechnic composition comprising at least one tetraphenylphosphonium halogenated salt as a smoke-producing agent, and applying the composition to mask the target.

2. The method according to claim 1, wherein the tetraphenylphosphonium halogenated salt used is tetraphenylphosphonium bromide.

3. The method according to claim 1 in order to obtain masking with a camouflage coefficient above 45% for a duration of at least 90 seconds.

4. Smoke-producing pyrotechnic composition intended to mask a target with regard to electromagnetic radiation in a given wavelengths range and comprising at least one energetic material, such as a reduction-oxidation couple, as well as at least one smoke-producing agent generating masking particles, the composition comprising as smoke-producing agent at least one tetraphenylphosphonium halogenated salt.

5. The composition according to claim 4, comprising as smoke-producing agent tetraphenylphosphonium bromide or tetraphenylphosphonium iodide.

6. The composition according to claim 5, comprising as energetic material a reduction-oxidation couple associating, as a reductant, a metallic powder and, as an oxidant, a fluoropolymer.

7. The composition according to claim 6, wherein the fluoropolymer is a fluoropolymer having in its molecular structure a fluorine percentage above 60%.

8. The composition according to claim 6, comprising at least one reductant selected from among the following bodies: magnesium, aluminium, zirconium, titanium, calcium silicide, boron.

9. The composition according to claim 6, comprising at least one oxidant selected from among the following bodies: vinylidene fluoride and hexafluoropropylene dipolymer, polytetrafluoroethylene, tetrafluoroethylene or their mixtures.

10. The composition according to claim 6, comprising at least one chlorinated compound in a proportion below 10% in mass.

11. The composition according to claim 10, comprising at least one organochlorinated compound with a chlorination rate above 60%.

12. The composition according to claim 4, comprising: 10% to 40% in mass of energetic material, 90% to 60% in mass of smoke-producing agent, 0% to 10% in mass of chlorinated agent, 0% to 8% in mass of binding agent.

13. The composition according to claim 12, wherein the binding agent consists of at least one epoxy-type resin added in a proportion of approximately 5% of the overall mass of the bloc.

14. The composition according to claim 12, comprising: 12% in mass of magnesium powder, 18% in mass of vinylidene fluoride and hexafluoropropylene dipolymer, 63% in mass of tetraphenylphosphonium salt, 7% in mass of chlorinated agent.

15. The composition according to claim 12, comprising: 12% in mass of magnesium powder, 12% in mass of vinylidene fluoride and hexafluoropropylene dipolymer, 69% in mass of tetraphenylphosphonium salt, 7% in mass of chlorinated agent, 5% in mass of epoxy resin.

16. The composition according to claim 12, comprising: 15% in mass of magnesium powder, 15% in mass of vinylidene fluoride and hexafluoropropylene dipolymer, 69% in mass of tetraphenylphosphonium salt, 5% in mass of epoxy resin.

17. The composition according to claim 12, comprising: 15% in mass of magnesium powder, 15% in mass of vinylidene fluoride and hexafluoropropylene dipolymer, 62% in mass of tetraphenylphosphonium salt, 7% in mass of chlorinated agent, 5% in mass of epoxy resin.

18. The composition of claim 12, wherein the mass of the energetic material is 20% to 30%.

19. The composition of claim 18, wherein the mass of the smoke-producing agent is 60% to 70%.

20. The composition of claim 19, wherein the mass of the chlorinated agent is 0 to 7%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] With the intention of better showing the characteristics of the invention, some examples of compositions according to the invention and their use are described hereinafter, by way of an example without any limiting nature, with reference to the accompanying drawings wherein:

[0046] FIG. 1 is a curve showing the evolution over time of the camouflage coefficient Cm for a composition according to example 2 hereunder;

[0047] FIG. 2 shows the evolution over time of the camouflage coefficient Cm for a composition according to example 3 hereunder;

[0048] FIG. 3 shows the evolution over time of the camouflage coefficient Cm for a composition according to example 4 hereunder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] The applicant has created a certain number of compositions according to the invention (proportions of the constituents provided in relation to the total mass of the composition) and has evaluated their masking performances.

EXAMPLE 1

[0050] 12% in mass of magnesium powder, [0051] 18% in mass of vinylidene fluoride and hexafluoropropylene dipolymer, [0052] 63% in mass of tetraphenylphosphonium salt, [0053] 7% in mass of chlorinated agent.

[0054] This composition is formed into a block without binding agent. The bloc is created by compression at the compression rate specified above (17 mega Pascals for a diameter of 125 mm). Such compression rate is sufficient to ensure the cohesion of the block.

EXAMPLE 2

[0055] 12% in mass of magnesium powder, [0056] 12% in mass of vinylidene fluoride and hexafluoropropylene dipolymer, [0057] 69% in mass of tetraphenylphosphonium salt, [0058] 7% in mass of chlorinated agent, [0059] 5% in mass of epoxy resin.

EXAMPLE 3

[0060] 15% in mass of magnesium powder, [0061] 15% in mass of vinylidene fluoride and hexafluoropropylene dipolymer, [0062] 69% in mass of tetraphenylphosphonium salt, [0063] 5% in mass of epoxy resin.

EXAMPLE 4

[0064] 15% in mass of magnesium powder, [0065] 15% in mass of vinylidene fluoride and hexafluoropropylene dipolymer, [0066] 62% in mass of tetraphenylphosphonium salt, [0067] 7% in mass of chlorinated agent, [0068] 5% in mass of epoxy resin.

[0069] For each composition a smoke-producing block of approximately 800 grammes was created.

[0070] This block was positioned in an optronic tunnel at a distance of 6 meters from the optical measurement line.

[0071] The combustion of the block occurs in the manner of a cigarette. Initiation thus happens at the level of the free upper surface of the bloc which is gradually consumed from its upper surface to its lower surface (bearing surface).

[0072] The generated smoke cloud was displaced by a fan at a controlled speed of 3 m/s in such a way as to make it pass in front of the means of measurement.

[0073] The means of measurement include: [0074] a hot source that has a regulated temperature of around 160 C.; [0075] a cold source (consisting of the steel wall of the optronic tunnel); [0076] a thermal camera observing in band 3 (spectral window of 8 to 12 m).

[0077] Masking is evaluated by comparing the effect of the smoke passing in front of the thermal sources (cold and hot) on the temperature seen by the thermal camera.

[0078] For each batch tested, the camouflage coefficients Cm (in percentage points) are calculated by applying the following formula:

[00001]$C_m\left(t\right)=100\left(1-\frac{\left(\mathrm{Nb}\left(t\right)-\mathrm{Nn}\left(t\right)\right)}{\left({\mathrm{Nb}}^{}-{\mathrm{Nn}}^{}\right)}\right)$

[0079] Formula in which: [0080] Nb(t) and Nb are the numerical levels measured by the camera at the hot source, with smoke (Nb(t)) and without smoke (Nb); [0081] Nn(t) and Nn are the numerical levels measured by the camera at the cold source, with smoke (Nn(t)) and without smoke (Nn).

[0082] As stated above, the annexed figures show the evolution over time on the x-axis and the camouflage coefficient Cm on the Y-axis for different examples of compositions.

[0083] FIG. 1 corresponds to the composition according to example 2, FIG. 2 corresponds to the composition according to example 3 and FIG. 3 corresponds to the composition according to example 4.

[0084] When considering all the figures, it is noticeable that the masking compositions according to the invention provide a camouflage coefficient above 45% for a duration of at least 90 seconds, which is particularly advantageous.

[0085] Furthermore, the masking performances are very similar for the different compositions, which indicates a certain operational stability even with a few % of formulation deviations.

[0086] It is also noticeable that the smoke-screen deploys quickly. It takes between 3 seconds and 10 seconds.

[0087] It was also noted, in other tests, that the rate of combustion depends on the magnesium content. Thus, the rate of combustion increases as the magnesium content increases. For example, a magnesium content of 15% provides a combustion duration for the bloc of nearly 52 seconds, whilst a magnesium content of 12% provides a combustion duration of 88 seconds.

[0088] This is not particularly visible on the figures that show the results of firing tunnel tests.

[0089] Moreover, it was observed that adding Dechlorane increased the masking duration in the case of outdoor combustion.

It is obvious that the invention is by no means limited to the examples described above, but that numerous modifications can be made to the smoke-producing pyrotechnic composition and its use described above, without departing from the scope of the invention as defined in the following claims.