RU2551343C1 - Pyrotechnical composition for active action on supercooled clouds and mists - Google Patents

Abstract

FIELD: demolition works.

SUBSTANCE: pyrotechnical composition contains ammonium perchlorate, combustible binder, a flame arrester and a burning rate regulator, Ag₃CuJ₄ is an ice-forming reagent, the iodating additive which is iodide potassium or iodide ammonium and a process additive. The combustible binder of the composition is polybutadiene rubber with isocyanate hardening system, the flame arrester is (NH₄)₂C₂O₄, and the burning rate regulator is CuO.

EFFECT: improvement of stability, increase of a warranty period of pyrotechnical composition at preservation of crystallising action threshold and yield of active nuclei of crystallisation at low temperatures.

1 tbl, 1 ex

Description

The invention relates to pyrotechnic aerosol-forming compositions intended for active exposure to supercooled clouds and fogs with the aim of dispersing them, preventing hail and causing precipitation from the clouds using ice-forming nuclei obtained by burning the pyrotechnic composition.

Known pyrotechnic compositions intended for exposure to supercooled clouds and mists that contain an oxidizing agent, fuel, ice-forming reagent and processing aids.

As an oxidizing agent in known compositions, perchlorates and nitrates of alkali or alkaline earth metals, as well as ammonium, are used.

As a fuel - organic resins, nitrogen-containing organic compounds, metals.

As an ice-forming reagent, silver iodide and lead iodide are used alone or with the addition of potassium iodide, ammonium iodide.

As technological additives ensuring the manufacturability of the manufacture and processing of pyrotechnic compositions, various oils, graphite, aerosil, titanium oxide, iron oxide and other chemicals are used (US Patent No. 3630950, A01G 15/00, No. 3677841, С06В 15/02; England C C10G 5/00; France патент 1460540, A01G 15/00).

The disadvantages of the above pyrotechnic compositions are low threshold (minus 5 ° C) of ice-forming action, low yield of ice-forming nuclei at temperatures of minus 6-10 ° C.

Known pyrotechnic composition for active action on supercooled clouds and mists (RF patent No. 2175185, A01G 15/00) containing ammonium perchlorate, phenol-formaldehyde resin, an ice-forming reagent in the form of a mixture of finely ground powders of silver iodide and potassium iodide, dicyandiamide and technological additive. The disadvantage of this pyrotechnic composition is the low threshold (minus 5 ° C) of ice-forming action, the low yield of ice-forming nuclei at temperatures of minus 6-10 ° C, as well as the instability of ice-forming characteristics and a small warranty period of storage (warranty period according to the manufacturer’s documentation is 3 years) pyrotechnic composition.

The closest technical solution (prototype) is a pyrotechnic composition for active exposure to supercooled clouds and mists (RF Patent No. 2309439, G01W 1/00) containing ammonium perchlorate, phenol formaldehyde resin, an ice-forming reagent in the form of complex compound 3AgJ · CuJ, dicyandiamide, iodide potassium and technological additive in the following quantitative ratio of components, wt.%:

Ammonium perchlorate from 49 to 60 Phenol formaldehyde resin from 12 to 18 Dicyandiamide from 8 to 12 Potassium iodide from 10 to 14 Complex compound 3AgJ · CuJ from 5 to 20 Technological Additive from 1 to 3

According to the authors of the patent, this pyrotechnic composition provides a sufficiently high yield of active nuclei (about 2.0E + 13 with 1 g of the composition at a temperature of minus 10 ° C) and has a sufficiently high threshold of crystallizing action, up to minus 1.5 ° C. The disadvantage of this composition is the instability of the ice-forming characteristics and the short shelf life of the pyrotechnic composition.

In the process of experimental work, it turned out that the samples made according to this recipe do not have the constancy of characteristics. Moreover, the difference in measured activity during storage even during the warranty period (3 years) increases significantly. The reason for the instability of the ice-forming characteristics and the small warranty period of the pyrotechnic composition is the use of iodine compounds with high hygroscopicity in the formulation. It is known that potassium iodide begins to absorb water from the atmosphere at a relative humidity of 60%, ammonium iodide at a humidity of about 50%, sodium iodide and lithium iodide absorb water at a humidity of less than 40%. The absorption of water by this composition over time, depending on time at different air humidity, was investigated in laboratory conditions. The research results are reflected in the test report.

Since at the moment in pyrotechnic industries air humidity is usually not controlled, it is possible that water gets into the pyro composition during production even for relatively low-hygroscopic formulations (RF patent No. 2309439). The second problem is that the water content in the composition depends not only on air humidity and holding time, but also on the type and time of technological operations, especially leading to intensive contact of the composition with ambient air, for example, when mixing components or sieving. Since the checker of the generator after manufacture does not lose its hygroscopic properties (and the components of the binder do not form a single hydrophobic structure), it is also possible that water gets into the volume of the checker during storage in the presence of improper or leaky packaging.

The ingress of water into the structure of the composition has several negative consequences:

initial characteristics of the composition deteriorate: the texture and mechanical properties of the checker, the corrosion of the shells change, cracks appear in the composition, the formulation exfoliates and recrystallizes, etc .;

to a much greater extent, there is a decrease in the ice-forming properties of the generator during storage;

the structure of the charge, the packaging elements, the strength characteristics of the product are violated.

Since in each case the water content in the formulation can vary, the spread of product properties from batch to batch is very significant.

Due to the foregoing, the manufacturer of the means of active exposure is forced to reduce the warranty period of storage of products in specialized storage facilities to three years (Anti-hail rocket "Alazan-6": material of the company / OAO ChPA.VI Chapaev. Http: //www.chapaew .ru /? page =. / 10507/10518/10525/170733 & mode = prod. - 2013), and in the field under a canopy without direct exposure to precipitation and solar radiation - 6 months, which is negligible compared to the warranty periods storage of regular ammunition. However, for ice-forming products, despite such a short shelf life, periodically there is a significant decrease in the activity of anti-hail products, even during the shelf life. The warranty period for the use of the composition should be at least 5 years without any significant reduction in ice-forming activity.

The objective of the present invention is to increase stability, increase the warranty period of the pyrotechnic composition while maintaining the threshold of crystallizing action and the release of active crystallization nuclei at temperatures from minus 2 ° C and below.

The problem is solved in that the pyrotechnic composition for active exposure to supercooled clouds and mists, containing ammonium perchlorate, a flame arrester and a burn rate controller, a fuel-binding agent, Ag ₃ CuJ ₄ as an ice-forming reagent, an iodine additive in the form of potassium iodide or ammonium iodide and technological additive, as a combustible binder it contains polybutadiene rubber with an isocyanate curing system, (NH ₄ ) ₂ C ₂ O ₄ as a flame arrester, and CuO as a burning rate controller, p In the following quantitative ratio of components, wt.%:

In common with the prototype is the presence of the following components in the pyrotechnic composition: ammonium perchlorate, a fuel-binding agent, a flame arrester and a combustion rate controller, an ice-forming reagent - Ag ₃ CuJ ₄ , an iodine additive in the form of potassium or ammonium iodide, and a technological additive.

Distinctive features of the invention: as a fuel-binding binder, the pyrotechnic composition contains polybutadiene rubber with an isocyanate curing system, (NH ₄ ) ₂ C ₂ O ₄ as a flame arrester, and CuO as a combustion rate regulator.

The table shows the changes in the ice-forming activity of the patented composition and the prototype when modeling long-term storage.

The proposed composition is a plastic composition processed by injection methods or pressing methods.

One of the components of the curing system - isocyanate - can react with both -OH groups of polybutadiene rubber, forming a strong hydrophobic matrix that impedes further transport of water into the structure of the composition, and with water, which is almost always present in hygroscopic iodine compounds.

The quantitative ratio “polybutadiene rubber: isocyanate” is determined by the initial moisture content of the pyrotechnic composition and is selected so that, after the polymerization reaction, all OH groups of polybutadiene rubber and H ₂ O, which is inevitably present in the composition, react.

After curing, the resulting mixture of components is a soft rubber-like composition with good mechanical and hydrophobic properties. The use of rubber with an isocyanate curing system completely eliminates the microporosity of the composition, as a result of which the shelf life of the products is significantly increased, their sensitivity to moisture and mechanical stress is reduced, it becomes impossible to transfer the normal combustion mode to detonation at any real pressure maintained by the generator shell. Under test conditions, samples formed without a protective shell were functional even after 24 hours in boiling water and a month immersion in water at a temperature of 20 ° C, while a molded tablet of the prototype composition completely lost its ability to burn after several tens of minutes , and after 10 hours it turns into a homogeneous powdery mass, which is reflected in the test report.

An example of a pyrotechnic composition for active exposure to supercooled clouds and mists.

The pyrotechnic composition contains ammonium perchlorate (NH ₄ ClO ₄ ), a flame arrester [(NH ₄ ) ₂ C ₂ O ₄ ] and a combustion rate regulator (CuO), a fuel-binding agent in the form of polybutadiene rubber, an ice-forming reagent (Ag ₃ CuJ ₄ ), and iodine additive (NH ₄ J) and technological additive.

Polybutadiene rubber is a two-component composition of low molecular weight rubber. First component: OH-terminated polybutadiene rubber, Krasol LBH 3000, manufacturer Sartomer USA, number of functional groups (-OH) 1.9, molecular weight 3000, second component: Voranate ™ M 229 Dow Chemical isocyanate, average molecular weight 360 cu , the number of functional groups (-NCO) is 2.7.

The pyrotechnic composition has the following quantitative ratio of components, wt.%:

NH ₄ ClO ₄ 47% Ag ₃ CuJ ₄ fifteen% NH ₄ J fourteen% (NH ₄ ) ₂ C ₂ O ₄ 2% CuO 2% Polybutadiene rubber twenty%

In order to better match the experimental conditions with the production ones, ammonium iodide with a water content of 2% was used as an iodine additive.

To fully undergo the polymerization reaction, the ratio of the components of the polybutadiene rubber must be maintained so that the number of functional groups of Krasol LBH 3000 is equal to the number of functional groups of M229 isocyanate in the following reaction:

But since the isocyanate reacts not only with the terminal groups of LBH 3000 (ROH), but also with water of hydrated ammonium iodide,

the total rubber weight and the ratio of Krasol LBH 3000 and M229 reagents is calculated as follows:

M _rubber = M _LBH + M _{M229 (LBH)} + M _{M229 (H2O)} ;

Where

M _rubber - total weight of rubber added to the formulation

M _LBH - mass of polybutadiene Krasol LBH 3000;

M _{M229 (LBH)} is the mass of M229 isocyanate required for the polymerization reaction with LBH 3000;

M _{M229 (H2O)} is the mass of M229 isocyanate required to react with water.

The mass of M229 isocyanate required for the polymerization reaction with LBH 3000 is calculated based on the ratio:

$$M_{M229(LBH)}=\frac{M_{LBH}*N{f}_{LBH}*M{B}_{M229}}{M{B}_{LBH}*N{f}_{m229}}$$

Where

MB _LBH - molecular weight Krasol LBH 3000;

Nf _LBH is the number of functional groups Krasol LBH 3000;

MB _M229 — Molecular Weight of M229 Isocyanate;

Nf _M229 is the number of functional groups of M229 isocyanate.

The mass of M229 isocyanate required for the reaction with water is calculated based on the ratio:

$$M_{M229(H2O)}=\frac{M_{H2O}*M{B}_{M229}}{M{B}_{H2O}*N{f}_{m229}}$$

Where

M _H2O is the mass of water in the composition.

MB _H2O is the molecular weight of water (18).

Accordingly, after substituting the corresponding values, the mass of Krasol LBH 3000 is determined as:

, $$M_{LBH}=\frac{M_{\mathrm{to}\mathrm{but}\mathrm{at}h\mathrm{at}\mathrm{to}\mathrm{but}}-7.\mathrm{four}\mathrm{one}*M_{H2O}}{\mathrm{one}.08\mathrm{one}}$$

,

and the mass of the isocyanate M229 as:

M _M299 = M _rubber - _MLBH .

And accordingly, for the considered formulation with ammonium iodide at 2% humidity:

Polybutadiene LBH 3000 16.44% Isocyanate M229 3.55%

In the manufacture of the composition, the components of the formulation, with the exception of polybutadiene rubber and a combustion rate controller (CuO), are crushed together with subsequent mixing with pre-prepared polybutadiene rubber. The finished mixture is kneaded, packaged in appropriate containers and left at a temperature of 20 ° C for a week to undergo polymerization.

Climatic tests showed that the patented composition is characterized by large values of ice-forming activity compared to the prototype (even in the case of complete absence of water in the formulation of the latter) over the entire temperature range. During storage, the ice-forming activity of the patented composition is practically unchanged, as can be seen from the table of changes in the ice-forming activity of the patented composition and the prototype when modeling long-term storage. In the case of the presence of adsorbed water in the prototype composition, the ice-forming activity of the prototype decreases even more rapidly.

The results of comparative climatic tests are reflected in the test report. As can be seen from the photographs of massive samples of the compositions (shown in the test report), externally, the samples of the prototype composition during storage modeling for up to 10 years do not change both with the complete absence of sorbed water and with its content up to 1%, although the ice-forming activity of the formulation at storage simulations are reduced. If the water content is more than one percent, already when modeling two years of storage, the destruction of the pieces of the composition with the release of decomposition components to the surface of the cardboard shell is observed. With long storage times, there is a significant violation of the integrity of the charge, recrystallization of the components, a decrease in the strength of the cardboard shell of the charge and corrosion of the metal parts of the case. The total decrease in the ice-forming activity of the prototype composition can reach three orders of magnitude or more.

Additionally, with an increase in stability and an increase in the warranty period of the pyrotechnic composition while maintaining the threshold of crystallizing action and the yield of active crystallization nuclei at temperatures from minus 2 ° С, the following is achieved:

- the lack of requirements for using absolutely dry ingredients as starting components, which is rather difficult, for example, for lithium iodide or sodium iodide, to obtain anhydrous forms of which is a very serious technological problem;

- lack of requirements to control and maintain low humidity in industrial premises;

- lack of requirements for increased tightness of the packaging of finished products;

- improving the technological properties of the formulation and processing safety, since the dull pressing of the powder compositions is replaced either by injection molding or by continuous pressing of the plastic mass of the composition, which also reduces the risk of fire and explosion during the process;

- improving the stability of products during storage, especially in wet conditions;

- the hazard class of generators equipped with this composition is reduced and the range of their application is expanded. For example, the explosions of generators that periodically occur during technological operations of deaf pressing, as well as when using compositions of this type from an aircraft, are completely eliminated. The composition does not detonate from the KD-8 detonator capsule, the frontal mode of combustion of the generator charge is maintained at elevated pressures to any values possible in the shells used (from 10 to 100 MPa). In this case, the transition of the operating mode of combustion to volumetric combustion and subsequent detonation is completely excluded, which is characteristic of the prototype composition.

The components of the composition have a wide raw material and production base. As can be seen from the above, the proposed formulation will be widely used both in existing and newly developed anti-hail and precipitation products.

Table The change in the ice-forming activity of the patented composition and prototype when modeling long-term storage Years of storage The number of ice-forming particles per gram of composition at the appropriate temperature Temperature - 4 ° С Temperature - 7 ° C Temperature - 10 ° С Prototype Composition Suggested composition Prototype Composition Suggested composition Prototype Composition Suggested composition 0 3.25E + 11 6.32E + 12 6.05E + 12 1.22E + 13 1.20E + 13 2.45E + 13 2 2.63E + 11 6.64E + 12 2.60E + 12 1,14E + 13 9.60E + 12 2,01E + 13 four 2,49Е + 11 7.18E + 12 4.78E + 12 1,03Е + 13 5.65E + 12 1,50Е + 13 6 1.93E + 11 7.24E + 12 2,35Е + 12 1,06Е + 13 4.15E + 12 1,50Е + 13 8 8.17E + 10 6.56E + 12 9.86E + 11 1,14E + 13 1.45E + 12 1.20E + 13 10 5.09E + 10 6.13E + 12 4.93E + 11 1.01E + 13 8.60E + 11 1,60Е + 13

Claims (1)

Pyrotechnic composition for active exposure to supercooled clouds and mists, containing ammonium perchlorate, a fuel-binder, a flame arrester and a combustion rate controller, Ag ₃ CuJ ₄ as an ice-forming reagent, an iodine additive in the form of potassium iodide or ammonium iodide and a technological additive, characterized in in that the fuel-binder it contains a polybutadiene rubber with an isocyanate curing system, as a flame arrester - (NH _{4) 2} c ₂ O _4, and as the combustion rate regulator - CuO next sod rye, wt.%:
Ammonium perchlorate from 40 to 55 Isocyanate Polybutadiene Rubber curing from 15 to 30 (NH ₄ ) ₂ C ₂ O ₄ and CuO from 1 to 10 Ag ₃ CuJ ₄ from 2 to 15 Potassium iodide or ammonium iodide from 10 to 30 Technological Additive from 1 to 4