EP0072276B1 - Pourable pyrotechnic composition of the coloured or non-coloured flame, smoke-producing type, comprising a chlorinated binder - Google Patents

Description

The technical sector of the present invention is that of flowable pyrotechnic compositions of the smoke smoke type with or without a colored flame, the binder of which is a resin with a high chlorine content.

Most of the known white smoke or colored flame pyrotechnic compositions are mixtures of pulverulent constituents or dry granules, consolidated by compression at high pressure, with a small proportion of agglomerating binder.

To obtain a white smoke or a colored flame, it is also known to use a chlorine-donating substance, generally a chlorinated organic compound, with a high chlorine content, the role of which is to allow the abundant formation of sublimable metal chlorides intended to produce either white (or gray) smoke or a flame color.

Thus, American patent US-A-2,939,779 describes a composition of this type in which the chlorine donor consists of hexachloroethane; a low percentage plastic binder of less than 10% ensures the cohesion of the whole. Compositions of this type present risks of fragmentation of the charge by impact during their use. On the other hand, during prolonged storage, their permeability to humidity changes their characteristics and makes them unsuitable for proper operation.

In US patent US-A-2 997 375, the use of polyvinyl chloride in a pyrotechnic composition has been proposed. This type of composition has never been able to be really used because these chlorinated resins being thermoplastic, it is necessary to use exclusively metallic perchlorates, dangerous in an industrial implementation.

French patent FR-A-2153431 has also proposed a pyrotechnic composition containing polyvinyl chloride and optionally an additional chlorine donor consisting of a salt of the ammonium chloride type. The polyvinyl chloride must be dissolved in a plasticizer, but in this case, the acceptable proportion of plasticizer can hardly exceed 15% by mass of the total of the composition. Beyond this value, the plasticizer acts as an excessive diluent and the performance of the composition is all the more reduced. Thus, the plasticizer being the only liquid constituent of the composition, its low percentage makes problematic the mixing and the flowability of this composition.

As for P.V.C., its proportion can hardly exceed 15 to 16% without causing a decrease in the percentages of active materials (oxidant and zinc oxide) which would be detrimental to the operation and the desired effect. Thus, the binder obtained is relatively poor in halogen (30% of the total binder and 10% of the composition) whereas the optimal yield of the composition requires about 30% by mass of the composition, 12 to 13% of which come from the oxidizing perchlorate. (ammonium perchlorate), the rest to be supplied by the binder. In addition, the “setting of this binder requires a“ cooking ”of several hours at approximately 150 ° C., a temperature too high for a pyrotechnic composition whose reaction begins to manifest from approximately 200 ° C. The risk in manufacturing is therefore significant.

The object of the present invention is to provide a new smoke-producing pyrotechnic composition and a new improved pyrotechnic composition with colored flame, the operating temperature of which can be adapted as necessary from 350 ° C. to 500 ° C. to produce smoke with a combustion without flame, up to around 1000 ° C or more to produce combustions with colored flame.

Another object of the present invention is also to provide a new smoke or colored flame pyrotechnic composition which can be easily kneaded and poured (or extruded) at ordinary temperature or close to 0 ° C., to obtain by the polymerization of a resin , a load of great compactness and great structural cohesion in order to avoid its fragmentation by shocks or vibrations.

Another object of the invention is also to provide a pyrotechnic composition free from any solvent, which would adversely affect the conservation of its properties by modifying its pyrotechnic behavior in an undesirable manner over time, and capable of being cast in various forms and in all capabilities.

Another object of the invention is also to provide a pyrotechnic composition in which the binder constitutes, in addition to its role of charge consolidator and regulator of combustion rate, an abundant chlorine donor necessary for obtaining the desired effects , this halogen being able to constitute from 30% to at least up to 70% by mass of the binder.

Another object of the invention is also to provide a pyrotechnic composition, the binder of which can be hardened by polymerization at ordinary temperature or at a moderately high temperature not exceeding 80 ° C. maximum.

The subject of the invention is therefore a flowable pyrotechnic composition comprising in particular an redox couple and a chlorinated binder, characterized in that the binder is constituted by the association of a polymerizable chlorinated monomer and a chlorinated polymer copolymerized or not , the resulting mixture being subjected to a polymerization at ordinary temperature from 20 to 25 ° C approximately said binder then containing approximately 30 to 70% by mass of chlorine.

The monomer may be a chlorinated alkylene, the number of carbon atoms of which is between 2 and 5, the chlorinated polymer being of the perchlorinated type.

The chlorinated alkylene can be dichloro-1,1-ethylene, and the chlorinated polymer polypropylene or polyethylene perchlorinated.

The binder can comprise 50 to 80% by mass of chlorinated monomer, the rest being constituted by the chlorinated polymer.

Advantageously, the binder can comprise approximately 70% of chlorinated monomer and 30% of chlorinated polymer.

The binder can also comprise approximately 50 to 60% by mass of chlorinated monomer, 20 to 25% by mass of chlorinated polymer and 15 to 20% by mass of another monomer such as allyldiglycol carbonate.

The binder may further comprise a hardener of the organic peroxide type in a proportion of approximately 3 to 4% of the total mass of binder.

Applied to the production of smoke, the pyrotechnic composition can comprise approximately 30 to 35% by mass of zinc oxide, 25 to 35% by mass of ammonium perchlorate and 30 to 40% by mass of binder.

Applied to the production of smoke with a colored flame, the pyrotechnic composition can comprise approximately 40 to 60% of nitrate and / or ammonium perchlorate of strontium or barium, 10 to 20% by mass of a thermogenic agent chosen from the group consisting by magnesium, boron, calcium disilicide, 30 to 40% by mass of binder.

The pyrotechnic compositions according to the invention may comprise a plasticizer chosen for example from the family of phthalic esters, in small proportion.

As indicated above, the combination of a chlorinated polymer belonging to the family known as chlorinated rubbers surprisingly produces a binder or resin usable in pyrotechnic compositions, whose mechanical resistance is considerably improved and makes it capable of consolidating a charge and with less shrinkage. Of course, the binder must be added in sufficient quantity.

In the invention, the best results have been obtained with dichloro-1,1-ethylene. However, other monomers can be used satisfactorily and there may be mentioned.

Dichloro 1,1-ethylene or vinylidene chloride is a highly mobile liquid with a low boiling point (31.6 ° C at normal pressure). Used as it is, it is not very capable of making it possible to obtain a flowable composition because its viscosity is practically zero and therefore does not play the role of lubricant for solid particles during the preparation of the composition. In addition, the mass polymerization of the monomer alone gives a friable and cracked polymer as a result of significant shrinkage and whose mechanical properties are very poor and make this product not very capable of playing a charge consolidating role, at least if the polymerization takes place at atmospheric pressure. The desired viscosity is then obtained by dissolving in the monomer the chlorinated soluble polymer such as polypropylene, polyethylene, perchlorinated, more generally a compound of the family of "chlorinated rubbers".

The mixture of vinylidene chloride and perchlorinated polymer is produced in the preferred proportion of 70% by mass of monomer and 30% of polymer. The hardening is obtained by dissolving in the resin a suitable proportion, 3 to 4% approximately, of a hardener of the family of organic peroxides, such as benzoyl peroxide or better, isopropyl or butyl-cyclohexyl percarbonate. The constituents of the pyrotechnic charge, such as nitrates, perchlorates, metal oxides, powdered metal, are incorporated into the liquid resin at a temperature below 20 ° C, if possible close to 10 ° C, the whole being kneaded for a few moments and then poured into molds.

The curing of the composition is carried out at ordinary temperature, around 20 to 25 ° C, in a closed envelope or under a protective liquid layer in order to avoid significant losses of monomer by evaporation.

A solid and compact pyrotechnic composition is thus obtained, the binder of which is a resin with a high chlorine content, containing approximately 70% of this halogen.

The binder thus obtained can be modified in its composition in various ways depending on the desired effect. Thus, a modification of the resin may be desired in order to increase the consolidation and to regulate the rate of combustion of the composition. This modification can consist in adding to the resin before hardening another conventional monomer compatible with it, to obtain a copolymerization, for example using a liquid monomer of low viscosity such as allyldiglycol carbonate.

The monomer is perfectly soluble and compatible with the chlorinated resin and hardens with the same catalyst. The desired proportion of this monomer was 15 to 20% by mass of the total resin, but may vary beyond these limits.

With 20% of this monomer, the halogen content is approximately 56%, the equivalent of pure polyvinyl chloride. Another reason for the choice of this monomer is its high oxygen content (41%) which advantageously limits the excess of reducing agent often harmful to the desired effect. However, other resins substituted for this monomer can be envisaged.

In the case of the modified resin, the polymerization is carried out under the same conditions at the same temperature. However, it may be desired to improve the curing by terminating the polymerization phase at a substantially higher temperature, from 30 to 80 ° C. for a period of 2 to 4 hours.

It is also possible to partially replace the chlorinated monomer with a plasticizer from the family of substituted phthalic esters compatible with the resin, in particular butyl glycol phthalate compatible with chlorinated rubbers, in order to give the hardened composition a more elastic consistency making it possible to avoid its rupture in the event of a violent impact, or carrying out loads without an envelope.

• - chlorure de vinylidène : 55 %
• ― polypropylène ou polyéthylène perchlorés : 23,5 %
• ― carbonate d'allyldiglycol : 18,5 %
• - catalyseur (peroxyde organique) : 3 %

Thus, the modified resin has the preferred composition as follows:

• - vinylidene chloride: 55%
• - perchlorinated polypropylene or polyethylene: 23.5%
• - allyldiglycol carbonate: 18.5%
• - catalyst (organic peroxide): 3%

To prepare the binder, proceed as follows: the vinylidene chloride catalyst is added at a temperature between 0 ° C and 10 ° C with gentle stirring. The dissolution is immediate. The chlorinated polymer is then added with stirring. Dissolution is rapid at first and then becomes slightly slower as the viscosity of the solution increases. After complete dissolution, the second monomer is optionally added with stirring. The dissolution is practically immediate.

This resin can thus be stored ready for use for several weeks at a temperature below 0 ° C, or for a few days at a temperature between 0 ° C and 10 ° C.

The chlorine content of this resin is approximately 56% by mass, the equivalent of pure polyvinyl chloride.

A few examples of the use of the resin described above are given below by way of illustration for the preparation of flowable pyrotechnic compositions.

The solid constituents nitrates, perchlorates, oxides are previously ground and sieved to 0.2 mm and are cooled to 0 ° C with the powdered metal which must be used if necessary.

These constituents are introduced into the resin at a temperature less than or equal to 10 ° C by kneading. The composition obtained is then poured into the desired envelope, generally made of aluminum.

It is left to polymerize at room temperature (approximately 20 ° C.) for 24 hours, then it is terminated at a higher temperature for 8 hours at 25 ° C., 4 hours at 30 ° C. The mechanical strength of the load can be improved by terminating the operation by baking at 50 ° or 70 ° C for a few hours, but this is not essential if one is satisfied with a simple hardening.

The volatility of the chlorinated monomer, although its vapor pressure is lowered by dilution, is nevertheless high and requires that the envelope is closed, or that a layer of 5 to 15 mm of a solution is poured onto the cast composition. sparingly soluble in resin and which by evaporation leaves a waterproof plastic film. We used an acetone solution of polyvinyl nitrate but other solutions such as polyvinyl chloroacetate in solution in ethyl acetate can be used.

Example I

A white smoke composition consists of 32% ammonium perchlorate, 32% zinc oxide and 36% resin; 200 g of this composition are poured into a cylindrical aluminum envelope 55 mm in diameter.

This composition, initiated by a conventional ignition composition (or directly with the flame of a match), burns without flame for 30 seconds, producing abundant very opaque white smoke.

Example II

A composition with a red flame consists of 54% strontium nitrate, 12% magnesium, 34% resin, 100 g of this composition are loaded into an aluminum tube 32 mm in diameter which burns for 50 s with a Red flame.

Example III

A composition with a green flame consists of 55% barium nitrate, 12% magnesium and 33% resin. 100 g of this composition are loaded into an aluminum tube 32 mm in diameter and burns for 50 s with a green flame.

Example IV

A composition with a green flame consists of 15% barium perchlorate, 40% barium nitrate, 12% magnesium, 33% resin. 100 g of this composition are loaded into an aluminum tube 32 mm in diameter and burns for 40 s with a green flame.

Example V

A red flame composition is made up of 46% strontium nitrate, 16% calcium disilicide and 32% chlorinated resin. This composition burns with a very red flame.

Claims (10)

1. Castable pyrotechnic composition comprising in particular an oxidation - reduction pair and a chlorinated binder, characterised in that the binder is constituted by the association of a polymerisable chlorinated monomer and a copolymerised or non-copolymerised chlorinated polymer, the resulting mixture being subjected to polymerisation at ordinary temperature of 20 to 25 °C, said binder then containing about 30 to 70 % by weight of chlorine.

2. Pyrotechnic composition according to Claim 1, characterised in that the monomer is a chlorinated alkylene in which the number of carbon atoms is between 2 and 5, the chlorinated polymer being perchlorinated.

3. Pyrotechnic composition according to Claim 2, characterised in that the chlorinated alkylene is 1,1-dichloro-ethylene and the chlorinated polymer perchlorinated polypropylene or polyethylene.

4. Pyrotechnic composition according to any one of Claims 1 to 3, characterised in that the binder comprises about 50 to 80 % by weight of the chlorinated monomer, the remainder consisting of the chlorinated polymer.

5. Pyrotechnic composition according to Claim 4, characterised in that the binder comprises about 70 % of chlorinated monomer and 30 % of chlorinated polymer.

6. Pyrotechnic composition according to any of Claims 1 to 4, characterised in that the binder comprises about 50 to 60 % by weight of the chlorinated monomer, 20 to 25 % by weight of the chlorinated polymer and 15 to 20 % by weight of another monomer, such as ally diglycol carbonate.

7. Pyrotechnic composition according to any of Claims 1 to 6, characterised in that it comprises an organic peroxyde type hardener in a proportion of about 3 to 4% of the total weight of the binder.

8. Pyrotechnic composition according to any Claims 1 to 7 of the smoke-producting type, characterised in that it comprises about 30 to 35 % by weight of zinc oxide, 20 to 35 % by weight of ammonium perchlorate and 30 to 40 % by weight of binder.

9. Pyrotechnic composition according to any of Claims 1 to 7 of the smoke-producing type with a coloured flame, characterised in that it comprises about 40 to 60 % of ammonium, strontium or barium nitrate and or perchlorate, 10 to 20% by weight of a heat-generating agent chosen from the group constituted by magnesium, boron, calcium disilicide, 30 to 40 % by weight of binder.

10. Pyrotechnic composition according to any of Claims 1 to 9, it comprises a plasticiser chosen, for example, from the phtalic esters family.