RU2276162C2 - Method for decreasing volatility of carboxylate rubber-base solid-propellant compositions of liquid ferrocene compounds and high-modulus carboxylate rubber-base solid-propellant composition and liquid ferrocene-containing catalytically active plasticizer - Google Patents

Abstract

FIELD: fuel materials.

SUBSTANCE: invention relates to using ferrocene-containing catalytically active plasticizers in high-modulus solid-propellant composition for different designations possessing the enhanced exploitation stability and broadly regulated range of the combustion rate. The composition comprises the following components: 60-80 wt.-% of oxidizing agent, for example, ammonium and potassium nitrate or FPCh; 2-20% of aluminum; 5-15% of liquid carboxylate rubber; 1.5-3.5% of epoxy resin, for example, epoxydiane resin ED-20 or resin EC-N; 0.01-4% of liquid ferrocene compound; 0.5-3.5% of co-plasticizer, transformer oil and/or DBS; 0.05-0.5% of hardening accelerating agents, and 0.01-0.2% of surface-active substances. Method for preparing high-modulus solid-propellant composition of reduced volatility of liquid ferrocene compound involves preliminary dissolving the ferrocene compound in co-plasticizer in the mass ratio = (20-80):(1-99) followed by plasticizing a polymeric binding agent and its mixing with surface-active substance, aluminum, oxidizing agent and hardening accelerating agents. Invention provides enhancing the strength properties of the composition.

EFFECT: improved properties of compositions.

3 ex

Description

The invention relates to the field of application of carboxylate rubber (e.g. divinyl nitrile) plasticized with liquid ferrocene compounds (e.g., dialkylferrocene) in solid fuel compositions for various purposes based on an oxidizing agent (e.g., ammonium perchlorate, or potassium (sodium) perchlorate (nitrate) and metallic fuel (e.g. , aluminum powder). At the same time, fuel compositions, regardless of their intended purpose, have a high modulus, strength, operational stability and a widely adjustable range of burning rates.

A number of solid fuel compositions are known that contain ammonium perchlorate, aluminum powders and liquid butadiene, as well as divinyl nitrile rubbers with functional carboxyl or hydroxyl groups (SKD-KTR, SKN-KTR, SKN-18-1, NTRV, PBAN) [L .M. Paushkin. Liquid and solid chemical rocket fuels. M., "Science", 1978; L.A. Smirnov, G.V. Kalabukhov. The creation of mixed solid fuels. M., MGAHM, 1997]. The physicomechanical characteristics of such fuel compositions generally correspond only to the requirements of firmly bonded charges, and depending on the type of rubbers used, their curing systems and component ratios are in the following range: tensile strength 0.7-1.0 MPa, elongation 30 -40% and a modulus (10%) of 3.5-6.0 MPa [AIAA Paper, No. 1417, 1981]. The regulation of the burning rate of these fuels in the range from 5.5 to 12 mm / s at P = 4 MPa is achieved through the use of ammonium perchlorate (PCA) of various dispersion and combustion catalysts. The most effective catalysts include ferrocene compounds and, above all, their liquid alkyl derivatives [Aerospace America, v.22, No. 12, 1984, C.U. Pittman. Polimer Letters, 6, 19, 1968].

To obtain higher CTT combustion rates, the use of higher catalyst concentrations is required, which in the case of alkylferrocenes is difficult to realize because of their high volatility. Therefore, to ensure the stability of fuel properties during storage and operation, the content of liquid ferrocene compounds in the composition, as a rule, does not exceed 1.0%, thereby limiting the possibility of increasing the burning rate of fuel compositions.

In this regard, there are proposals on the use of solid ferrocene catalysts as quick fillers in fast burning CTTs. And this necessitates an increase in the total binder content in the fuel compositions, leading to a noticeable decrease in energy-mass characteristics, or a decrease in their effectiveness, for example, when used as aerosolegenerating fire extinguishing charges.

Thus, the CTT formulation is known, containing 5% solid ferrocene compound (1-pyrrolidinyl-methylferrocene), 17.81% butadiene rubber with terminal carboxyl groups, 0.56% tris- [1- (2-methyl) aziridinyl] phosphine oxide, 0.18% epoxy resin ERLA 0510, 66.45% PHA (15 μm), 10% aluminum and 0.20% (in excess of 100%) lecithin [US patent 3765965, NCI 149-7, 1973]. This composition, selected as the closest prototype of the proposed invention, has a burning rate of 25 mm / s at a pressure of 14 MPa (20 mm / s at a pressure of 4 MPa), with a relatively low level of specific impulse (232 s at Pk / Ra = 4/0 , 1), density (about 1.62 g / cm ³ ) and strength properties (tensile strength σ _P not more than 1 MPa).

The aim of the invention is the development of high-performance solid fuel compositions for various purposes with a high level of strength properties that meet the requirements of plug-in type charges (σ _P > 1.4 MPa, module E ₁₀ > 15 MPa), a wide range of regulation of the burning rate of which (from 5 to 30 mm / s at P = 4 MPa) is achieved through the use of liquid ferrocene compounds while providing conditions for reducing their volatility from the compositions.

This goal was achieved due to the use in fuel compositions along with aluminum, curing accelerators and technological additives:

- as a polymer binder liquid carboxylate rubber with optimal molecular structural parameters (SKN-10KTR brand divinyl nitrile rubber with terminal carboxyl groups containing carboxyl groups (3 ± 0.3)% and acrylonitrile (10 ± 3)%; or brand butadiene methacrylate rubber SKD-1A with a mass fraction of carboxyl groups from 3.6 to 4.1%, viscosity at a temperature of 50 ° C from 80 to 150 PaC in combination with ED-20 epoxy resin or EC-N nitrogen-containing epoxy cyanurate resin with a mass ratio of 85 / 15 to 75/25;

- as a plasticizer, a thermodynamically stable catalytically active mixture of liquid ferrocene compounds with additional plasticizers (co-plasticizers) - with transformer oil, and / or dibutyl sebacinate (DBS), and / or dibutyl phthalate (DBP) with a ratio of 80:20 to 1:99 . Moreover, the amount of mixed plasticizer experimentally in most cases is in the range from 15 to 40% by weight of the polymer binder;

- polyfraction oxidizing agent such as ammonium perchlorate (PHA) or ammonium nitrate mixed with potassium nitrate with a total specific surface area of 1000-2800 cm ² / g

Developed and presented in the present invention, a method for producing a solid fuel composition with reduced volatility of a liquid ferrocene compound is that the liquid ferrocene compound is pre-dissolved in a co-plasticizer to obtain a thermodynamically stable catalytically active mixed plasticizer, which plasticizes the binder polymer base and then introduces technological additives with stirring (SAS), aluminum, oxidizing agent and curing accelerators. Our studies have established that the volatility of liquid ferrocene compounds from fuel compositions is determined by the level of their thermodynamic compatibility with the polymer base of the binder. It was found that a sharp increase in their volatility from the composition is associated with the achievement of the compatibility limit, caused only by a change in enthalpy (heat content) in the well-known thermodynamic equation that determines the solubility conditions of two liquids [V.A. Kargin, G.L. Slonimsky. Brief essays on the physical chemistry of polymers. M., IMU, 1960]:

dG = dH-TdS <0

(where dG, dH, and dS are the changes in the thermodynamic potential, enthalpy, and entropy, respectively, and T is the temperature), from which it follows that the dissolution process is favored by positive thermal effects corresponding to dH <0, and an increase in entropy. It is known that a plasticizer energetically bound to the polymer within enthalpy compatibility is more firmly held in the mixture than due to the entropy factor, thereby reducing its volatility from the composition.

When conducting research on the development of a method for reducing the volatility of liquid ferrocene compounds from fuel compositions, we used a thermographic method for estimating the amount of enthalpy bound plasticizer [G.A. Sorokin. Thermodynamic determination of the amount of polymer bound solvent. ZhVS, No. 13, 1971]. The volatility of ferrocene compounds from fuel samples was determined at a temperature of 80 ° C for 10 hours.

The effect of the thermodynamic compatibility of liquid ferrocene compounds with a polymer binder on their volatility from fuel samples can be illustrated by the example of n-butylferrocene. When the composition of this compound was within the enthalpy compatibility with the polymer binder, its volatility under experimental conditions did not exceed 0.003 g per 1 cm ^{2 of} the sample surface. With a further increase in the concentration of the ferrocene compound, a sharp increase in its volatility was observed (almost an order of magnitude with a twofold increase in its concentration).

As a result of the studies, it was found that the possibility of using increased amounts of liquid ferrocene compounds in compositions (to obtain high burning rates) is ensured by the use of rubbers containing polar fragments (in particular, nitrile and / or carboxyl groups), as well as epoxy resins of the type ED-20 or EC-N.

A favorable effect on the level of enthalpy compatibility is exerted by the use of additional plasticizer along with liquid ferrocene. If the limit of enthalpy compatibility of diethylferrocene with a polymer binder, including SKD-1A rubber and ED-20 epoxy resin, does not exceed 3.0% (in terms of a fuel composition containing 15% binder), then in the presence of 0.5% transformer oil this the limit increases to 4%. It was experimentally established that the positive effect of the co-plasticizer on the level of enthalpy compatibility of liquid ferrocene compounds with a polymer binder is maintained when their content in the mixture with co-plasticizer is up to 80%. At the same time, conditions are provided for achieving high burning rates of solid fuel compositions. To obtain a reduced burning rate, the amount of ferrocene compounds in the mixed plasticizer should be minimal (up to 1%).

The choice of SKN-10KTR and SKD-1A liquid carboxylate rubbers in combination with epoxy resins as a polymer binder is due not only to their increased thermodynamic compatibility with ferrocene compounds, but also to the possibility of producing highly filled solid fuel compositions with an increased level of strength characteristics and good processability with their use, which cannot be achieved using similar in structure high molecular weight rubbers or hydroxyl-containing prepolymers, for example ep NTRV curable diisocyanates, as well as replacing epoksidianovoy resin ED-20, EC-H or other epoxy resins, such as aliphatic or aziridinily.

According to the obtained experimental data, a change in the molecular structural parameters of these rubbers or the degree of their plasticization, as well as the ratio of rubber and epoxy in comparison with the above, does not seem advisable from the point of view of ensuring the fulfillment of the goals set in the invention. Thus, a decrease in the content of carboxyl groups and epoxy resins in rubber or an increase in the degree of plasticization compared with the stated limits leads to a decrease in the strength of the samples. Conversely, an increase in the content of COOH groups and epoxies, a decrease in the concentration of plasticizer leads to samples having increased fragility, especially at low temperatures.

It was also established that a satisfactory complex of technological and physico-mechanical characteristics of the samples can be ensured with a total polymer binder and a ferrocene-containing catalytically active plasticizer in the composition ranging from 12 to 20 wt.%. The specific composition and content of the binder, as well as the type of oxidizing agent of the curing catalysts and processing aids (subject to changes in their concentration in the recommended range), should be selected depending on the purpose and characteristics of the operation of solid fuel compositions.

It has been experimentally shown that the chemical nature of the oxidizing agents used (ammonium perchlorate, ammonium nitrate and potassium) with an equal particle size distribution and specific surface area of the powders does not significantly affect the formation of the level of technological and strength characteristics of the compositions.

The liquid ferrocene compounds we studied (n-butylferrocene, diethylferrocene, di-n-butylferrocene, bis (ethylferrocene) propane), as well as the co-plasticizers used with them (transformer oil, DBS, DBP) are similar in their effect on the main properties of solid fuel compositions, as well as the level of enthalpy compatibility with a polymer binder.

As curing catalysts, we used standard accelerators of reactions of the interaction of carboxyl and epoxy groups, for example, containing thiuram tertiary amine groups or 2-mercaptobenzothiazole (captax) individually or mixed with zinc oxide (stearate), and surfactants, for example, as technological additives lecithin or diamine dioleate.

Below, as practically implemented examples of the present invention, only 4 variants of the developed formulations of fuel compositions (for various purposes) with technical characteristics obtained from samples of products made under experimental production conditions are given.

Example 1

PHA (specific surface 1080 g / cm ³ ) 64.0 wt.% Aluminum powder 20,0 Rubber SKD-1 A 11.09 Epoxy resin ED-20 2.00 Transformer oil 1,08 Dibutylsebacinate 1.3 2,2-bis- (ethylferrocene) propane 0.02 Zinc stearate 0.3 Tiuram 0.05 Captax 0.15 Lecithin 0.01

Products from such a fuel composition have the following characteristics: a burning rate of 5.2 mm / s at a pressure of 4 MPa, physical and mechanical characteristics (at a temperature of 20 ° C): tensile strength 1.45 MPa, 2% modulus 16 MPa, elongation of 12.3%.

Example 2

PHA (specific surface area 2800 g / cm ³ ) 68.00 wt.% Aluminum (average particle diameter of 5 microns) 18.00 Rubber SKN-10-KTR 7.50 Epoxy resin ED-20 2.40 Transformer oil 0.8 Diethylferrocene 3.2 Tiuram 0.05 Diamine dioleate 0.05

Products from such a fuel composition have the following characteristics: a burning rate of 28.8 mm / s at a pressure of 4 MPa, physical and mechanical characteristics (at a temperature of 20 ° C): tensile strength 1.68 MPa, 2% modulus 19.4 MPa, elongation of 9.4%.

Example 3

Ammonium nitrate (specific surface 1200 g / cm ³ ) 40.0 wt.% Potassium Perchlorate (with specific surface 2300 g / cm ³ ) 40.0 wt.% Aluminum (average particle diameter 15 μm) 2.0 Rubber SKD-1 A 12.45 Epoxy resin ETs-N 2.80 Dibutylsebacinate 1,5 Di-n-butylferrocene 1,0 Captax 0.10 Zinc stearate 0.10 Lecithin 0.05

Fire extinguishing aerosol-generating products from such a fuel composition have the following characteristics: extinguishing efficiency - 15-22 g / m ³ , burning rate 12.2 mm / s, at a pressure of 0.2 MPa, physical and mechanical characteristics (at a temperature of 20 ° C): tensile strength 1.40 MPa, modulus 2% 17.0 MPa, elongation 12.3%.

Volatility of ferrocene compounds at Т = 80 ° С for 10 hours. Of the above options for solid fuel compositions did not exceed 0.003 g with 1 cm ^{2 the} surface of the samples, which is at the level of volatility of plasticizer type transformer oil.

Thus, the goals set in the present invention to develop conditions for reducing the volatility of liquid ferracene compounds from solid fuel compositions, as well as to develop using them high-modulus solid fuel compositions for various purposes, with increased operational stability and a widely controlled range of burning speeds, are fulfilled.

Claims (2)

1. High-modulus solid fuel composition with reduced volatility of a liquid ferrocene compound, including an oxidizing agent - ammonium perchlorate or ammonium and potassium nitrates; metal fuel - aluminum; a polymer binder is a liquid carboxylate rubber selected from the group: divinyl nitrile rubber with terminal carboxyl groups with a content of acrylonitrile of 10 ± 3% grade SKN-IOKTP and butadiene methacrylate rubber with a content of carboxyl groups of 3.6-4.1% and viscosity at T = 50 ° С 80-150 PaС of grade SKD-1A - in combination with an epoxy resin - epoxy resin of the ED-20 brand or a nitrogen-containing resin of the ETs-N brand - in the mass ratio of rubber and resin ranging from 85:15 to 75:25; plasticizer — a ferrocene-containing catalytically active plasticizer consisting of a mixture of a liquid ferrocene compound and a co-plasticizer — transformer oil, and / or dibutyl sebacinate, and / or dibutyl phthalate, the amount of the specified plasticizer being in the range from 15 to 35% by weight of the polymer binder the total content of plasticized polymer binder in the composition is 12-20 wt.%; curing accelerators and processing aids - surfactants; in the following ratio of components, wt.%: Oxidizer 60.0-80.0 Aluminum 2.0-20.0 Liquid Carboxylate Rubber 5.0-15.0 Epoxy resin 1.5-3.0 Liquid Ferrocene Compound 0.01-4.0 Plasticizer 0.5-3.5 Curing accelerators 0.05-0.5 Surfactant 0.01-0.2 2. A method of obtaining a high-modulus solid fuel composition with reduced volatility of a liquid ferrocene compound according to claim 1, which means that the liquid ferrocene compound is pre-dissolved in a plasticizer in a weight ratio of 80:20 to 01:99 to obtain a thermodynamically stable catalytically active plasticizer, which plasticize the polymeric binder, and then mix with it a surfactant, aluminum, an oxidizing agent, and curing accelerators.