DE1809360A1 - INSULATING COMPOUNDS FOR THE PRODUCTION OF AN INSULATING LAYER ON SOLIDS MISSILE DEPLOYMENT AND ITS USE FOR THE PRODUCTION OF THIS INSULATION LAYER - Google Patents

Description

15. KovemlSei • Ke / Ki

Dynamit Nobel Aktiengesellschaft, Troisdorf District Cologne

Isolierrr.asse for the production of an isolation layer on solid rocket propellants and their use for the production of this insulation layer

In the case of solid rockets, there are those used for propulsion Solid fuels from those necessary for combustion Components that decompose exothermically with the formation of propellant gases or react with one another. These solid fuels represent a system in the sense of rocket technology, in which the fuel and the oxidizing agent but are either united in the same molecule separated from each other in a homogeneous or heterogeneous mixture come into use.

The solid propellants used in rocket technology are particularly those produced without the use of solvents zv: one of the polybasic powder, also called FOL-Fulver, significant. Of these, the dibasic powders contain which are mainly used, in addition to nitrocellulose, an energy-rich liquid nitric acid ester, for example nitroglycerin, while the three-base FOL-Fulver as a third base another nitro compound, for example nitroguanidine. In addition to these FOL fulvers, there is another in many cases Class of solid propellants for use, that of the so-called composite solid propellants, which are also from the components necessary for combustion, which are exo-

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therm with the formation of propellants disintegrate or react with each other, are composed. Fuel and oxidizer are mostly used in a heterogeneous mixture, the main oxidizing agents being used inorganic perchlorates, such as ammonium perchlorate or alkali perchlorate, can be used while as fuel primarily organic polymers, for example Polyesters, polyamides, polybutadienes or polyurethanes can be used.

When producing solid propellants from POL powders or composite propellants, mixtures Stabilizers, plasticizers, burn-off regulators and lubricants are added to the starting materials. Afterward the mixtures are formed, either directly or by extrusion, optionally via the stage one Granules. In addition, methods are known in which the solid propellants by pouring sludge-shaped Mixing of the starting components in forms or by sucking the liquid components into a solid Mixing of the other components in a vacuum with subsequent curing, if necessary using Heat.

Due to the strongly exothermic burn-off of solid propellants from cast or extruded two- or polybasic · »; ii FOL powder solid propellants as well as composite solid propellants, especially with solid fuels with high heat of combustion and high density released ^ Heat will reduce the mechanical strength of the rocket combustion chambers in which the solid propellants are housed, and which are mostly made of steel, light metal alloys or made of reinforced plastics, are so badly impaired that the ra-

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ket combustion chambers are destroyed. It is therefore special It is important to protect the combustion chamber walls from the effects of temperature. To this end, Iran can open the surface of the propellant is firmly adhering, not self-burning and apply a thermally stable insulation layer, so that the pre-calculated burn-up of the solid propellant charge can only be done via its non-isolated surfaces can. These solid propellants are provided on the surface with an insulation layer protecting against burn-off The combustion chamber walls are only thermally stressed little, especially when it comes to solid propellants from internal burner type.

It is already known for such insulating layers, die.for example by spraying, pouring, brushing, dipping The winding is applied to the propellant surface be able to use common insulating materials, such as cellulose derivatives or polyvinyl acetate, but especially those insulating compounds based on synthetic resin, which in addition to the usual hardener, accelerator, Stabilizer and plasticizer additives nor feuerhemrr.er.de fillers, such as silicon dioxide or barium sulfate, preferably contained in powder form. Here the "synthetic resin is used as a binder; it is suitable mainly polyepoxides and resins Based on polyesters, polyurethanes, polyamides, polyvinyl chloride and polymers from Plenen, preferably from Eutadiene, and copolymers of these pienes with olefins or compounds of the acrylic acid series, including aalkyl-substituted Derivatives of acrylic acid are to be understood.

However, these binders have to be used when they are used Production of plastic-based insulation layers have a number of disadvantageous properties. For example rrvssen when processing these binders too

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mostly organic solvents are used, for example in order to set a suitable processing state of the insulating compound, whereby the solvents in diffuse in and phlegmatize them in the deeper layers of nr.ehr or keniger, whereby the burning properties of the solid propellants are adversely affected. They are also binders based on plastic despite their often good low-temperature elasticity and adhesion to the propellant surface disadvantageous with regard to their usually relatively low reaching and decomposition temperatures. Follow from this low mechanical and thermal strength of the insulation layers made with these plastics the temperatures, pressures and temperatures occurring during the combustion of the solid propellants in the rocket combustion chamber Qas business. As a result of this become frequent Fragments of the insulation layer ejected from the nozzle of the rocket combustion chamber, which together with the application high-carbon binders based on plastic often do not produce smoke to be avoided Operation, control and monitoring in particular of Guided missiles difficult.

The present invention is based on the object the described tile parts of the previously known insulation layers to eliminate and to develop insulation that is sufficiently mechanical and elastic Properties not only good on the surface of the propellant adheres and is also smoke-free, but also has sufficient thermal stability for d: Le intended uses, which under comparable conditions v.e is generally better than the previous thermal stability known insulation reports.

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The solution to this problem is an insulating compound, which can optionally be cured using heat, for the production of an insulating layer on solid rocket propellants on the basis of two- or multi-base FOL powders or Corapoaite pestle, which according to the invention is characterized in that it is 30 to 90% by weight binder-free binder based on plastic prepolymers and / or condensates, 5 to 65% by weight mineral ^{fillers, optionally pre-shrunk or dehydrated by thermal pretreatment at temperatures up to 1000 °} C., in powder or fiber form and 5 to 50 Weight * contains endothermically reacting substances during propellant combustion, each based on the total weight of the insulating breed.

Liquid precursors of polyepoxy resins, polyester resins, polymers or copolymers from Plenen are preferably suitable as solvent-free binders or polyurethanes, which after application to the optionally with suitable adhesion promoters, such as for example aromatic diisocyanates ^ pretreated Trelbsatzoberflachen either'at room temperature or cure with the application of heat. Amine-cured polyurethanes are preferably used as solvent-free Binders used in the new Isolierifiaaee. These Polyurethane precursors are preferably made from a) 63.1 to 81.1 parts of a viscous, prepolymerized diisocyanate obtained from tolylene diisocyanate and butanediol-1, * »with an average molecular weight of 2000 and an effective isocyanate content of A * and b) a solution of 6.9 to 8.9 parts of methylene-o-chloroaniline in o) 30 to 10 parts of dinrethylgly-

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Colphthalate is produced as a plasticizer, and as a hardener additive such an Anin is rooted, which is related to on the processability; of the binding agent a particularly large processing tent (pot life ^ guaranteed.

As refractory mineral fillers know In der Isclienr.asse according to the invention in addition to powdered! Fillers, such as titanium dioxide, Siliclurr.dicxyd, lithopone or barium sulfate, with particular advantage refractory mineral fibers are used, which give the insulation layer a significantly better mechanical strength than is the case with powdered fillers. For example, fibers made of glass, quartz or magnesium oxide as well as fibers based on boron and silicon are suitable. Carbon or titanium, but especially asbestos fibers. It has surprisingly been shown that the mechanical; Strength and thus. The thermal stability of the insulation layers can also be significantly increased if these fibers are subjected to a thermal treatment at higher temperatures, for example up to ICCO ⁰ C, before they are used, during which they shrink or sinter. Pies is particularly advantageous with naturally occurring mineral fibers, such as asbestos fibers, which are freed from trapped water of crystallization by annealing for two hours at temperatures of up to 800 ° C and shrink in the process the subsequent shrinkage has a detrimental effect on the mechanical and thermal stability of the insulation layers produced with such fibers. _N

According to the invention, substances which react endothermically in the combustion of propellants are to be understood as

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uc ^ -hUmieren, residue which either under heat ^{consumption s} "bll ™ ^ ^r * ' _al , _pro

„/„ _H (- visible spai-profrei endothermic in gaseous, not alcni

products disintegrate or endothermic "it ^elB » ¹ "·""T'"!"der! .oll« »... or the combustion.pr.duK e * sentence. KUhlstofro "called re Meng ^ depends among other things on the viscosity of the processing state.

Al ₃ KUhlstoffe have in the I ^"0? Invention especially ammonium salts and acid amides tlscher, preferably catfish / geradkettlger dicarboxylic acids having _a C-8 M. Ato, en honor, -spielte .c ^ ce O. acid as nlumoxalat On ^ or Oxamld. These νt disintegrate endothermically and residue-free with bilution ven colorless and relatively cooler reaction products, well, I present water, hydrogen, onlak and oxides of carbon, which can thus protect the binding agent of the olation In accordance with the invention, organic polymers can also be used which depolymerize thermally and residue-free with the formation of colorless, relatively minor cleavage products, such as, for example, methylene polymers, in particular polymers of formaldehyde.

In addition to or instead of the previously mentioned coolants, such coolants can also be used with particular advantage which do not gasify residue-free, but instead run through intermediate stages during their operation the endothermic decay form refractory residues such as oxides and thus form further refractory residues Plastic-based fillers in the binder act, Surprisingly, it has been shown that a particularly good mechanical and thermal stability of the The insulation layer was present when the intermediate

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between stages occurring endothermic decay of the just The mentioned class of coolants, their refractory residues from the combustion of the solid propellant occurring temperatures on their own or together with other components of the Insulation layer, for example with the contained therein other refractory mineral fillers, but especially together with asbestos fibers. Sintered body formed, for example in the form of mixed oxides. Particularly. In this context, ammonium all of iso- and / or heteropolyacids have proven suitable, which contain silicon, phosphorus or titanium as central atoms Eorv, especially the tetrahydrate des Ammonlumpentaborate

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Suitably, the particle size of the cooling materials is chosen so 'that all particles passed through a sieve with a ~ Maschenv: AGE - pass \ of 0.1 mm. 5

The advantages of a corresponds for example by means of a poly \ urethane, asbestos, lithopone and ammonium pentaborate I

holding insulating compound built-up insulation layer I

consist in that after the burning of the insulating damifc \ th solid propellant in the Raketenbrennk & mmer a \ sleeve having a hard and smooth inner surface:

remains without visible abrasion by the fire gases,

while its outer |

The surface is still as elastic as it was before it was burned off. Due to its mechanical, thermal and dimensional stability, this sleeve is capable of the rocket combustion chamber effectively to protect against the effects of temperature and gives even during the burn-up of the solid propellant no cause for smoke development. ·:

Insulation layers for solid rocket propellants ⁷ .

that in

j 'v / earth is expediently produced according to the invention in such a way that ir.an

the individual components of the insulating compound in the usual

> Mixing devices, preferably in a vacuum, to a bla-

i sen-free mass mixes. Before applying this mass

^f j on the solid propellant to be isolated, the Ofcer-

{ flat of shaped propellant first of adhesive

, Dust, grease or solvents freed and given-

I if coated with an adhesion promoter. Thereupon

I trates and fixes rr. To the solid propellant as a form

\ core in an inside preferential prices with Teflon

\ ' layered cylindrical metallic mold., in particular

/ special made of steel, in such a way that one goes to the cylinder

\ areas a distance from the precalculated pick of the

: Complies with the insulation layer. The insulating compound is then applied, ^see

^: , 'for example by means of a hydraulic feeding device

? tion, pressed into the mold until it starts

• the outflow openings provided and at tempe-

ί temperatures in the range between 20 ° and 8O ⁰ C, preferably

4 hardens between 45 ° and 6O ^{0 C.}

.]. 2,4- or 2,6-Toluylenedi-

; isocyanate, or a mixture of these two substances

! use.

1 It can also be advantageous to use the

; Production of the insulation layers used Iso ~

ί can be made of foils, mats or Tefelmaterial

, make by putting these insulating compounds in bubble-free

; State of the example of zv / ischen polyethylene cover films

■ embedded and then on a roller mill to foil,

\ Rolls out mats or sheets of a predetermined thickness,

which are then placed between the polyethylene cover films,

: if necessary with the application of heat, cured

will. The insulating foils, mats or insulation produced in this way

; -tafein know later with the propellant to be isolated-

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- ίο - 180S360

surface, for example by gluing, the plastic-based binder used in the insulating compound is expediently used as the adhesive; . '' - / - -

25 * 24 parts of a viscous, prepolymerized diisocyanate from toluylene diisocyanate and butanedio1-1.4 with an average molecular weight of 2000 and an effective isocyanate content of 4 % v / earth with a solution of 2.76 parts of methylene-bis-o-chloroaniline in 7 Parts of dimethyl glycol phthalate mixed and mixed with 10 parts of ammonium oxalate (grain size <100 yu) and 55 parts of annealed asbestos fibers with a fiber length of about 3 mm. After thorough mixing in a vacuum, a spreadable and sprayable paste is obtained, which is composed as follows:

35 wt.% Polyurethane

10% ammonium by weight.

55 wt. $ Asbestos.

The paste has a processing time (pot life) of approx. 40 minutes. It hardens bei'20 ⁰ C within 3 days, at 8o ° C within. 1.6 hours off.

Beispi el 2

25/24 parts of a viscous, prepolymerized diisocyanate of tolylene diisocyanate and 1,4-butanediol with an average molecular weight of 2000 and an effective isocyanate content of 4 % are mixed with a solution of 2.76 parts of methylene-bis-o-chloroaniline in 7 parts of diir .ethyl glycol phthalate and mixed with 10 parts of oxamide (grain size <100 n) and 55 parts of annealed asbestos fibers with a fiber length of approx. 3 jnn? ver

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puts. After thorough mixing in vacuo, one obtains a spreadable and sprayable paste, which is composed as follows:

35 wt. $ Polyurethane

10% oxamide wt.

55 wt. # Asbestos.

The paste has a processing time (pot life) of approx. 40 minutes. It hardens within l6 hours at 20 ⁰ C within 3 days, at 8o ° C.

Example el_3

50.54 parts of a viscous, prepolymerized diisocyanate from TaluylendJULsocyanat and 1,4-butanediol with an average molecular weight of 2000 and an effective isocyanate content of 4 % are mixed with a solution of 5.55 parts of methylene-bis-o-chloroaniline in 14 parts of dimethyl glycol phthalate mixed and mixed with 25 parts of oxamide (grain size <100 u) and 5 parts of MgO fibers. After thorough mixing in a vacuum, a spreadable and sprayable paste is obtained, which is composed as follows:

70 Geu _e # Polyurethane
25 wt. # Oxamide
5 wt. $ Magnesium oxide fibers o

The paste has a processing time (pot life) of approx. 50 minutes. It cures at 20 ° C within 3 days, at 8D ⁰ C within 16 hours.

32, ^ 0 parts of a viscous, prepolymerized di-. isocyanates from tolylene diisocyanate and 1,4-butanediol with an average molecular weight of 2000 and an effective

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12 ~ ■ :. "" '■ - ■ - ■. "■■ - ■■■ -

seed isocyanate content of $ 4 is mixed with a solution of 3.50 parts of methylene-bis-o-chloroaniline in 9 parts of dimethyl glycol phthalate. 3 parts of Lithopone (trade mark "Silver Seal ¹¹ , grain size <50 μ), 7 parts of ammonium pentaborate tetrahydrate (grain size <100 / l) and 45.10 parts of annealed asbestos fibers with a fiber length of approx. 3 ram are added to this mixture" after thorough mixing in a vacuum you get a spreadable and sprayable paste / which is composed as follows : "■■■■■" ■■ ■ '

44.9% by weight of polyurethane

45.1 wt. Asbestos
5 * 0 wt. % Lithopone
""'^"7.0. Öew.-Ji (NH ^) B ₅ Og \ 4HgO The paste has a Yerarbeitungszeit (pot life) about 40 minutes cure at 20 ⁰ C within 3 days, at 80 ^0. C within 16 hours,

The following examples illustrate the production of the insulation layers using those previously described Insulating compounds. .

Example 5;

A zKeibasiger POL solid rocket propellant of known composition of the forehead burner type with a. A diameter of fB.-tnm and a length of 138 mm is freed from adhering dust * ■ fat and solvents and coated with a thin film of a liquid mixture of 2,4- and 2,6-toluene diisocyanate up to a surface of about 30 mm _{...; r;}

After this diisocyanate film has dried completely in the air, the propellant is in a cylindrical steel mold with Teflon-coated inner walls and an interior

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ner. diameter of 80 mm fixed with a distance of 2 mm to the cylinder surfaces. By means of a hydraulic pressing device, an insulating compound of the composition given in Examples 1 to 4 is now pressed into the cylindrical steel mold under a pressure of 100 kg / cm until the solid propellant is completely pressed around and the excess material emerges from the outflow openings of the mold. The mold is then heated to a temperature of 60 ^° C. for 24 hours, then the propellant is removed from the steel mold and an end face is exposed by turning on the lathe, via which the propellant is later ignited in the rocket combustion chamber.

Example_6

A two-base POL solid rocket propellant of known composition of the forehead burner type with a diameter of 100 mm and a length of 150 mm is freed from adhering dust, grease and solvents and coated with a thin film of a liquid mixture of 2A and 2.6 -Toluylene diisocyanate coated. After complete drying, this Diisocyanatfilmes in the air of the propellant charge is plane-parallel to the lathe between the two., Adjacent end plates clamped the end faces of the cylindrical solid-fuel propellant charge of light metal with a diameter corresponding to the planned outer diameter of the finished insulated propellant and centered so that by the Propellant charge evenly protruding end disks on all sides, the thickness of the insulation layer is adjusted. Then, while slowly rotating the propellant charge on the lathe, an insulating compound of the composition given in Examples 1 to 4 is applied to the surface of the propellant charge using a ruler

£ ß

and let it dry completely. The insulation layer is cured ^{at 60 ° C. within 24 hours.}

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Eei a Eeschußversuch in a Raketenbrennkamiter, wherein the burned according to Example 5 with a 2 mm thick insulation layer, using the procedure described in Example 4 equipped insulating solid propellant as long 1β seconds was obtained, the entire insulation. She pointed to the Eeschuß only a 'Shuah charred, hard and smooth inner surface with no visible removal by the fire _gases} so that it is considered more likely, and thermal stability at gutter ir.echanis as a reliable temperature protection for the rocket engine chamber.

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Claims (11)

Claims 1,} If necessary, curable with the use of heat Isolierrcasse for the production of an isolation layer on solid rocket propellants on the basis of zv: single or multi-base FOL powders or composite fes fuels, characterized in that they are 30 Up to 90 wt. # solvent-free binder on the Easis of plastic prepolymers and / or condensates, 5 to 65 wt. $> mineral, if necessary by a thermal pretreatment at temperatures up to 1000% pre-shrunk or drained fillers ^ in powder or fiber form and 5 to 50 wt. # for the ™ Propellant combustion endothermic reacting substances, each based on the total weight of the insulating gases, contains. 2.} _ Insulating compound according to claim 1, characterized in that that it is an amine-hardened binder as a solvent-free binder Contains polyurethane, which from a) 63.1 ti3 8l, 1 Divide a viscous, varpolymerized from Toluylene diisocyanate and 1,4-butane diisocyanate with an average molecular weight of 2C00 and one effective isocyanate content of 4 #, b) 6.9 to 8.9 parts Methylene-bis-o-chlcraniline and c) 30 to 10 parts .Di- | methyl glycol phthalate has been produced. 3.) insulating compound according to claim 1 or 2 _y, characterized in that it contains as mineral fillers glass or quartz fibers cder fibers on the Easis vcn Ecr, silicon, carbon, titanium cder Magnesiuiroxyd. 309818/0341 BAD ORiGiNAt 4.) Isclierrr.asse according to claim 1 to 3> characterized in that it is at temperatures up to 1000 ⁰ G within. 1 to 4 hours · contains thermally pretreated asbestos fibers with an average fiber length "of 5 ^m m . 5) Insulating compound according to claim 1 to 4, characterized in that that it contains lithopone in combination with asbestos fibers as a refractory filler.- ". '■■' .: 6.) insulating material according to claim 1 to 5, -dadurch gekennzeich- W net, that it contains as endothermic reacting substances ammonium salts or amides of aliphatic dicarboxylic acids and / or endothermic depolymerizing plastics, 7.) insulating compound according to claim 6 ₃ -. characterized,. ■ that it contains ammonium oxa- .. lat or oxamide as endothermic substances. - ■.-'..- · _: 8.) insulating compound according to claim 6, characterized in that it contains oxymethylene polymers, in particular polymers, of formaldehyde as endothermic depolymerizing plastics. ■ - - 9.) Isolierir.asse according to claim 1 to 5, dadurch.gekennzeich » netj that they are ammonium- as endothermic substances. salts of iso- and / or heteropoly acids des-boron> Contains silicon, phosphorus or titanium. '\ 10.) insulating compound according to claim 9 *, characterized in that it contains ammonium pentaborate (NH ₄ ) B ₅ Og.4H ₂ O as an endothermic substance. 309818 / 03A1 " BATH 11.) insulating compound according to claim 1 to 10, characterized in that that it contains the endothermic reacting substances in a grain size of less than 0.1 mm in diameter. 12,) Use of an insulating compound according to claim 1 to 11 for the production of an insulation layer on two- or multi-base FOL powders or composite propellants, characterized in that the freed from dust, grease and solvents and optionally with a mixture of 2.4 - and 2,6-toluene diisocyanate pretreated as an adhesion promoter, as a mold core in a cylindrical metallic compression mold, preferably coated with Teflon on the inside, with a uniform, spacing corresponding to the thickness of the insulation layer, centered solid propellant with the insulation and then layered at temperatures in the range. ■; between 20 ° and 8Q ⁰ C, preferably between-45 ° to ⁰ C 6Q, Removing; .; cured, ■ ■ "■■.. . · .-. '■' - '.. . ^ 1) Insulation layer for solid rocket propellant charges sawn ■ standing out from the cured Igoliermasse according to claim i to ii;: ^':::' ■ '■■ * ■■ - ■;.'. : ■ - -t ' ^: . ■■ .. · ■ · ": ■■■. ■■ ·. ■ /. ■■ - ■ .- · - ■ 309818/0341 8AD ORiGlMAi.