RU2242451C1 - Method of manufacturing charge of blended solid rocket fuel - Google Patents

Abstract

FIELD: rocket fuels.

SUBSTANCE: method according to invention comprises mixing components of blended solid rocket fuel using binder based on nitroester-plasticized polyurethane rubber to produce fuel mass, putting rubber heat-protective coating onto body of rocket engine, putting nylon elastic textile, applying securing composition, drying securing composition, applying thereon dinitrile oxide hardener in ethyl acetate solvent, forming fuel mass in the body, and hardening charge. Securing composition contains low-molecular unsaturated bonds-bearing epoxidated rubber with 2.8 to 4.2% epoxy group content, colophony-modified diphenylolpropane-formaldehyde condensation product, dinitrile oxide hardener, and ethyl acetate.

EFFECT: enabled manufacturing strongly secured, on rocket engine body, fuel charge based on nitroester-plasticized polyurethane rubber binder.

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Description

The invention relates to the field of development of a technology for processing mixed solid rocket propellants (SRTT) into charges.

Among a large number of missile charges from SRTT, an important place is occupied by charges for ballistic missiles and deep thrust control engines, the fuels of which are subject to a number of special requirements, such as the absence of a condensed phase in the combustion products, the high and variable value of the ν index in the law of the rate of combustion, and others.

One of the options for mixed solid rocket fuel for such charges, which most fully meets the specified requirements, is a fuel whose binder is made on the basis of urethane rubber plasticized with nitroesters.

Such a fuel contains an oxidizing agent, plasticizers, including nitroesters, a hardener, additives that control the burning rate, and other components.

The curing of the fuel is carried out, as a rule, at a temperature of 20 ... 40 ° C for 10 ... 40 days.

The manufacture of charges from such fuels is carried out according to the method described in patent No. 2155789 C1, 09/10/2000, IPC 7 C 09 J 175/14.

One of the urgent problems of improving the method of manufacturing charges when using the specified fuel is to increase the strength of fastening the fuel charge with the body, reducing diffusion processes between the fuel, the protective-fixing layer and the heat-shielding coating, which increase the reliability during operation of rocket engines. This task is complex and urgent, since, for example, in deep thrust control engines, fuel combustion occurs at various “ν” values in the law of the burning rate, and this places a high demand on the uniformity of the burning rate along the charge set. Owing to the diffusion of plasticizers from the fuel in the heat-transfer zone of the RD housing, the burning rates in the boundary layers of the fuel are greater than in the deep layers of the charge.

The uniformity of the burning rate is usually achieved using diffusion-resistant fastening compositions and heat-protective coatings.

The technical task of the present invention is the development of an improved technological process for the manufacture of SRTT charges firmly bonded to the casing, which allows to increase the bonding strength of the fuel with the casing and to reduce the spread in burning rate due to the diffusion of plasticizers from the fuel into a protective-fixing layer and a heat-protective coating.

The specified technical problem was solved by using in the manufacture of charges SRTT based on a binder of polyurethane rubber TU 38.303. 04.1-09-94 or TU 2294-009-13175942-2002, containing nitroester plasticizer, hardener, oxidizing agent, combustion rate regulators and other additives due to a set of operations, including preparation and mixing of components, molding the resulting mass into a housing in which a heat-protective coating is used rubber based on a copolymer of ethylene, propylene and a diene compound TU 2512-013-05766882-97, for duplication - nylon elastic fabric art. 56151 TU 17RSFSR2-5969-78 or art. 56383 TU 17-040812-458-94, on which, before molding the fuel mass, a fixing composition is applied, consisting of (wt.%):

- low molecular weight with unsaturated bonds epoxidized rubber with an epoxy content of 2.8 ... 4.2% - 40 ... 60

- product of condensation of diphenylolpropane with formaldehyde modified with rosin - 2.5 ... 5.5

- hardener of the class of dinitrile oxides, in particular di-N-oxide-1,3-dinitrile-2,4,6-triethylbenzene - 1.5 ... 6.0

- ethyl acetate 40 ... 60,

and after drying the fixing composition, a hardener of the dinitrile oxide class is additionally applied, in particular di-N-oxide-1,3-dinitrile-2,4,6 triethylbenzene in an amount of from 5 to 60 g / m ² in the form of 5 ... 20% - a solution in ethyl acetate; wherein charge curing is carried out at a temperature of 20 ... 40 ° C for 10 ... 40 days.

The hardener of the class of dinitrile oxides, for example, di-N-oxide-1,3 dinitrile-2,4,6-triethylbenzene, has the technical name TON-2, is produced by the industry according to TU 2471-307-05121441-98.

The use of rubber based on a triple copolymer of synthetic ethylene-propylene rubbers (SKEPT) as a heat-shielding coating can significantly reduce the diffusion of nitro-ester plasticizers from fuel into a heat-shielding coating, since the maximum swelling of rubber and fixing composition is 5 ... 8% at a temperature of 40 ° C.

As a result, the chemical composition and fuel structure of the boundary and deep charge layers will be close, therefore, the burning rate and physico-mechanical properties will be close, that is, they will meet the requirements of the technical specifications.

Duplication of the rubber surface with a nylon elastic fabric ensures uniform distribution of the fastening composition over the surface of the taxiway housing and the continuity of fuel bonding. A vulcanizing additive in the form of a 20% solution of di-N-oxide-1,3-dinitrile-2,4,6-triethylbenzene in ethyl acetate is necessary for interaction with the excess binder based on urethane rubber, which is usually observed in the wall layers of RD due to some redistribution of components in the fuel mass when filled into a rocket engine.

The use of a taxiway housing with a heat-shielding rubber coating based on a copolymer of ethylene, propylene and a diene compound, duplicated by a nylon elastic fabric with a fastening composition based on a low molecular weight polymer containing unsaturated bonds of epoxidized rubber and epoxy groups in an amount of 2.8 ... 4, 2%, and after drying the fixing composition - VD in the form of a 20% solution of TON-2 in ethyl acetate leads to the most complete vulcanization of the urethane rubber of the fuel with the formation of a stable strong adhesive joint dy thermal barrier coating, protective layer and securing the fuel.

The implementation of the method is illustrated by the following example. Example: SRTT is prepared using free casting technology on existing equipment, based on the content of the following components (wt.%):

- urethane rubber SUREL-9 - 5 ... 12

- plasticizers - 9 ... 25

- filler - 50 ... 70

- hardeners - 0.4 ... 1.2

- special additives - 0.1 ... 2.6

At the first stage, SUREL urethane rubber is dissolved in plasticizers, then mineral and metal (metal powders) fillers and other additives are dosed into the resulting mixture. After each download, the mixture is stirred, and the final mixing is carried out under vacuum. The finished fuel mass is molded into the housing of the taxiway with a rubber heat-insulating coating duplicated by a nylon elastic fabric, on which a fixing composition and vulcanizing additives are applied. The case with fuel is thermostated at a temperature of 20 ... 40 ° C for 10 ... 40 days.

The solid fuel charge obtained by the above method has the following level of characteristics of the adhesive strength of the fuel with the body of the taxiway (table. 2).

table 2

Dependence of the strength of bonding the fuel to the RD case, on which a heat-protective coating is made of rubber based on a copolymer of ethylene, propylene and a diene compound, duplicated by a nylon elastic fabric and a fixing composition based on low molecular weight with unsaturated bonds epoxidized rubber with an epoxy content of 2.8 ... 4.2 of the amount and concentration of the solution of the vulcanizing additives of di-N-oxide-1,3-dintril-2,4,6-triethylbenzene in ethyl acetate (VD), applied after drying of the COP. Consumption of fixing composition per 1 m ^{2 of} surface - 400 g.

Db

From this table. 2 it follows that the optimal adhesion strength is the application of a 5 ... 20% solution for di-N-oxide-1,3-dinitrile-2,4,6 triethylbenzene in ethyl acetate, which is equivalent to the amount of 20 ... 60 g / m ² on a dry residue.

Claims (1)

A method of manufacturing a charge of mixed solid rocket fuel, comprising mixing the components of mixed solid rocket fuel using a binder based on polyurethane rubber, plasticized with nitroesters, to obtain a fuel mass, applying a rubber heat-protective coating to the rocket engine body, wearing a nylon elastic fabric, applying a fixing composition, this use the following fixing composition, wt.%: Low molecular weight epoxidized rubber with epoxy content 2.8 ... 4.2% 40 ... 60 The condensation product of diphenylolpropane with rosin-modified formaldehyde 2.5 ... 5.5 Hardener of a class of dinitriloxides 1,5 ... 6,0 Ethyl acetate 40 ... 60 drying the fixing composition, applying a hardener of the dinitrile oxide class in the form of a solution in ethyl acetate, molding the fuel mass into the body and curing the charge at a temperature of 20 ... 40 ° C, characterized in that rubber based on ethylene copolymer is used as a rubber heat-resistant coating, propylene and diene compounds, and as low molecular weight epoxidized rubber - low molecular weight with unsaturated bonds epoxidized rubber, a hardener of the class of dinitriloxides is applied in an amount of from 5 to 60 g / m ² in the form of a 5 ... 20% solution in ethyl acetate, curing of the charge is carried out for 10 ... 40 days.