DE2048583A1 - Pourable white smoke mixture - Google Patents

Description

DR. ING. E. HOFFMANN · DIPL. ING. W. EITLE DR. RER. NAT. K. HOFFMANN

PAXE NTANWl-LTK D-8000 MÖNCHEN 81ARABELLASTRASSE 4 TELEPHONE (0811) 911087

North American Rockwell Corporation, El Segundo, Calif. / UNITED STATES

Pourable white custom mix

The invention relates to a pyrotechnic mixture and in particular on a pourable pyrotechnic white smoke mixture,

Smoke markers or grenades are for both military and civilian use Purposes very useful »For military purposes, the smoke markers can be used to identify the target sites. In addition, such smoke markers are used in both the military and the Im civilian life is used to rescue the lost Identify parties. To have such a smoke marker without To further make it operational, it should be In a closed can or Can be placed in a closed container, the latter in some cases it can actually be a grenade. When dlo

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Smoke mixture on these catfish is in a closed container, then it must develop smoke even in the absence of oxygen or air can. In other words, it means that the mixture itself should be burning. Furthermore, the smoke mixture should be the Smoke can slowly release over a certain period of time in order to facilitate identification to allow the area from which the smoke is coming.

So far, white phosphorus has been the main one in various mixtures smoke-forming ingredient used. However, white phosphorus possesses the disadvantage that it burns spontaneously in the air, making it extremely dangerous to handle. Furthermore, the white phosphorus gives off the smoke very much quickly and thus does not allow a gradual release of the breath,

In the past little attention was paid to the use of rough mixtures containing red phosphorus. When red phosphorus was used it was in the form of a pressed powder rather than a cast granule. This approach is expensive, time consuming, and sometimes even dangerous. Furthermore, pressed powders do not have the structural uniformity of cast grains. The known pressed mixtures based on red phosphorus also require air for combustion and are not self- sustaining. For these reasons, they cannot be used in closed containers where air cannot reach the material.

In contrast, the invention provides a pourable white smoke mixture based on red phosphorus which burns in the absence of atmospheric oxygen. The mixture according to the invention contains red phosphorus as the primary fuel component in order to generate smoke. The mixture also contains an alkali metal nitrate as an oxidizing agent. It also contains a metallic fuel, such as magnesium, which is present in a relatively small amount. Finally , the mixture is held together by a pourable binder, which also acts as a fuel. Practically any polymeric binder that is suitable for solid propellants can be used for this purpose. It is preferred that the binder have a relatively high oxygen content and that it cure to a rubbery state. A typical Uelsple! for such a binder is the class

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the Folysulfld rubbers. In addition, other materials can be used in small amounts such as crosslinking agents, plasticizers, fillers and the like be present in the mixture of the invention, the individual ingredients vverdon mixed together in a suitable mixer, into the Containers or hardware for the smoke mixture poured in and at hardened to suitable temperature and re-hardening conditions. By Variation of the composition and through the use of reactive The separation speed of the smoke mixtures according to the invention can also be adjusted be closely controlled.

The main component of the Rauel mixture according to the invention is red phosphorus, v.le has already been expressed above is redder until now Phosphorus was rarely used in wet mixes, in an earlier one Intended use red phosphorus was mixed with a nitrate and pressed into a mixture that gives a bright flash of light. Against it The preparation of a smoke mix was not considered. In the In cases where red phosphorus has heretofore been used to form a smoke-producing mixture, it has been in a pressed rather than cast form used. He also needed air to burn. Against it was on on the other hand, white phosphorus is often used in chewing mixes, However, this modification of phosphorus burns spontaneously in air, which made a slow, controlled breakdown of the smoke impossible will.

The proportion of red phosphorus can vary from 31 to 47 percent by weight of the smoke mixture. Üer red phosphorus is usually present in the form of fine particles. It is not readily available in various particle sizes. Because of this fact, it is not easy to achieve a high solids loading in a casting mix, so that the upper limit of 47% by weight of this material is determined by the ability of the casting mixes for solids loading.

An alkali metal nitrate is used as the oxidizing agent in the mixture according to the invention. Typical nitrates are sodium and potassium nitrate. One of the major problems in forming a suitable mixture is the undesirable reaction between the oxidizer and the phosphorus. Qa-

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Here are highly reactive materials, such as chlorates and perchlorates, for the mixtures not suitable for the invention. The nitrate becomes particulate in solid Form and used in amounts of 18 to 32 wt .-% of the smoke mixture.

To form a flame hot enough to burn the phosphor To maintain, magnesium is added to the mixture according to the invention. The magnesium reacts with the existing nitrate, creating the necessary heat for the continued combustion of the phosphorus is released without going out. Implementation of the magnesium with the nitrate also helps to achieve reliable burning of the smoke mixture. It has been found to contain 4 to 5 weight percent magnesium in the smoke mixture are sufficient for the aforementioned purposes.

A polymeric binder is used to form a pourable smoke mix. Practically any binder that is suitable for solid propellant mixtures can be used. However, it is not advisable to set the rough mixture too rigid or too brittle, since it _; especially when used as a grenade is often exposed to shock loads. It is preferred that the polymer cure to a rubbery state.

It has also been found useful to use a binder with a high oxygen content to use because the amount of solid oxidizing agent required can be reduced if the binder is part of the for the oxidation of phosphorus and the others present in the mixture Can provide fuels required oxygen available. Preferred Binders are therefore e.g. polysulphide rubbers, polysulphide-epoxy mixtures, like Thlokol LP-3, Dow Epoxy DER 321 and DER 736, as well as polyester, the reaction of zwet-Basl acids with dihydric alcohols are formed. A typical polyester binder is a hydroxy compound Polyester R-18 from Mobay Chemical Co., derived from adipic acid and diethylene glycol is formed. Furthermore, hydroxy and Carboxy-terminated butadienes contemplated. In fact, anyone can any of the indicated polymeric binders can be used. Along with The polymer material is generally a suitable plasticizer and a crosslinking agent used,

Various suitable plasticizers are contemplated are known and selected in each individual case according to the binder used can be. Typical plasticizers include, for example, trlacetin, bis-dinitropropyl acrylate formal (BDNPA-F), and trimethylol ethane nitrate (TMETN) a. Other plasticizers can of course also be used.

In addition to the plasticizers, the binder mixture also contains a certain amount of a crosslinking material. A preferred crosslinking agent is HAPI, which is a polymethylene polyphenyl isocyanate. Other suitable crosslinking agents are, for example, trimethylolpropane, Hexanetrlo ^ castor oil, toluene disocyanate, diphenylmethane diisocyanate and MAPO, which is TrIsL ₁ I- (2-methyI) -aziridinylJ-phosphine oxide,

About the binder and plasticizer, if any, generally make 25 to 35 percent by weight of the chew mix. The <3 weight ratio of plasticizer to binder can vary from 0.1 to 1.5s1. The crosslinking agent varies from 10 to 20> 3% by weight of the active binder material, depending on the ones used Materials and the desired hardening state in the end product »

It has also been found that FEAA, which is Elsen (III) acetylacetonate, can be added to the mixture according to the invention in order to achieve accelerated curing. In general for this purpose are added to 0.001 to 0.01 Caew .-% FEAA, may also be used other accelerators to shorten the curing time _e The choice of fuel accelerators depends on the chosen mixture. If, for example, TNiETf i is used as a plasticizer, then trimethylolpropane TMP together with Hlaa is the most suitable accelerator,

ε.-. It should be noted that the above composition area is a Kauchi-r-ilsch'in'j erj'jLMri, ίΙο> interoxyJiert. In other words, dips means that before γ ι Λ ichi'Mmetrl :. 'Λ \ νη -tcindpurikt not seen from that' .jaunr ^ toff before ~ h'-jriii'-n l'.t to r \\ " . full «/ ürbrennunn of the bronze component to © rmöqll- ■; r | f; ri ..>'\ , .r · J.π / tcind i .t juhr important, cia feiJtfjfj ^ tollt v / urdo, ümü bs> l voil-I-oifM -. [. yV.iX "■. ·. {■ '->, ■ / ■■ \ .-; t'JM ι ii -, '., huno ^ n üor i; uuch In a nloM> l

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burns too violently. Nevertheless, the mixture gives a pourable Smoke mass that burns in the absence of atmospheric oxygen. BIshsr became such a pourable smoke mixture based on red Phosphorus, which burns off even in the absence of air, was not thought possible.

., The formulation of the smoke mix is simple. In general, this will be

j Magnesium, phosphorus, plasticizer and binder first in one j Mixer entered and left at a suitable temperature for a long enough time.

ΐ mixes that homogeneity is achieved. Then the nitrate is added and

At the mixing temperature, the mixture is stirred in a vacuum. At this stage will

] Worked in vacuo to give the trapped in <ier mixture to remove air so that denser GuBkörper can be prepared "Finally, the crosslinking agent and the other additives, such as the FEAA _1, after the nitrate has been mixed into the mixture, was added and mixing is continued until all materials are thoroughly blended. It is preferred to pour the mixture into the iron molds made

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pour men in vacuum. Such forms are e.g. rifles, grenades or other suitable container for the smoke mixture. The casting conditions> naturally depend on the binder and the crosslinking agent used, away. A rubber-like mass should be obtained during curing

and not brittle or rigid.

A tinder is required for the initial ignition of the smoke mixture. The smoke mixture according to the invention can be ignited by practically any ignition technique used with solid propellants. These techniques can, for example, use boron / potassium nitrate pellets, electrical primers, electrical detonators and explosive materials such as Detacord, Primacord and Pyrocor. In addition, an initial combustion mixture or an initial mixture can also be applied to the surface. A typical ignition mixture consists of silicon, bioxide and copper (l) oxyte, which is mixed with nitrocellulose in a suitable solvent to form a lacquer that is applied to the surface to be ignited.

Lrflnduny is explained in more detail in the examples «

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example 1

A batch of 5000 g with the following composition was produced. In this and in the following examples, is the percentage of the accelerator based on the total composition of the smoke mixture.

Components% by weight

Stabilized red phosphorus 38.10

Sodium nitrate 28.30

Magnesium. 4.90

Mobay R-18 polyester binder 12.70

Triacetin 14.70

PAPI 1.30

FEAA (added) 0.02

For mixing the individual components has a vertical Baker-Perkins mixer with a capacity of 3.79 I ₁ which is usually used for the mixing of solid propellants used. The polyester binder, triacetin, magnesium and phosphorus were initially added to the mixer and mixed together at 43.3 ° C. for 15 minutes. Mixing was stopped and the sodium nitrate added. The mixture was then stirred in vacuo at 71.1 ° C. for a further 10 minutes. After this period of time had elapsed, the PAPI and the FEAA were finally added and the mixture was mixed for a further 10 minutes at 71.1 ° C. in vacuo. At this point in time, the mixing of the smoke mixture was complete. The mixture was ready to be poured. The mixture was vacuum poured into polyethylene tubing 7.30 cm long and 1.90 cm in diameter. The filled tubes were placed in an oven
cured state.

the put in an oven and 16 hours at 71.1 C to a rubber type

These filled tubes were ignited by an electric igniter. The burn times were determined by visual observation with the stopwatch averages. There was also a burn rate facility (Atlantic Research Corp.) is used for standard fixed propellant strands that automatically record burn times. For obvious reasons, however, external tests are used better.

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The mixture described above was found to have a burning rate of 1.78 cm per minute. The auto-ignition temperature was determined to be above 260 ° C. The crowd was performing one Impact test with a weight of 2.27 kg from a height of at least 127 cm insensitive. The earth burned with a bright yellow flame and produced voluminous amounts of a white smoke,

Example 2

A slow-burning mass was produced which had the following composition exhibited:

"Components% by weight

Red phosphorus 46.90

Sodium nitrate 18.30

Magnesium 4.60

MobayR-18 polyester binder 14.00

Trlacetin 15.80

PAPI 1.40

FEAA (added) 0.02

The procedure was as in Example 1 to formulate the granules. as The casting vessel and container for the hardened material were made from the same polyethylene tube This approach had a burn rate of 9.14 cm per minute, which is about half the burn rate the mixture of example 1. This slowdown can change the The ratio of oxidant to fuel can be attributed. Even here the mass gave a light yellow flame with large amounts of white. Smoke.

Example 3

Following the procedure of Example 1, a snow-burning mass was obtained manufactured. The same polyethylene pipes were used. The crowd had the following composition:

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Components

Red Phosphorus Sodium Nitrate Magnesium Mobay K-18 polyester binder PAPI

TMETN

TMP (added) FEAA (added)

Due to the presence of TMETN instead of Triacetln together with TMP, burning rates of 4.0 to 5.5 cm / min obtained. The burning rate of this mass is therefore two to three times as large as that of the mass of Example 1. This mass, too, burned with a light yellow flame and gave off large quantities of a white smoke.

20th A 8 583 30th Weight % 30th 31, 50 31, 60 4, 90 11 30th G, 10 20, 02 O, O,

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Claims (10)

^'10 "204 ^ 83 Claims / ΐ .Λ QieSable white smoke mixture, consisting of red phosphorus in one , an amount sufficient to generate the smoke, an alkali metal nitrate in an amount sufficient to oxidize the mixture, magnesium in a sufficient amount to generate heat to prevent the phosphor from burning to maintain, and a polymeric binder to bind the components into a castable mass. 2. Mixture according to claim 1, characterized in that Ψ it contains 31 to 47 wt .-% red phosphorus. 3. Mixture according to claim T _1, characterized in that the alkali metal nitrate is potassium nitrate or sodium nitrate » 4. Mixture according to one of claims 1 to 3, characterized in that g e k e η η, that it contains 18 to 32% by weight of the alkali metal nitrate. 5. Mixture according to one of claims 1 to 4, characterized in that it contains 4 to 5 wt .-% magnesium. 6. Mixture according to one of claims 1 to 5, characterized in that g e k e η η k ■] indicates that the binder with a suitable plasticizer and a suitable crosslinking agent is added. 7. Mixture according to claim 6, characterized in that that it contains 25 to 35 wt .-% binder and plasticizer. 8. Mixture according to claim 6 or 7, characterized by lehnet, j that the plasticizer TrlmethylolÜthantrlnltrat, triacetin or bis-Dinltropropylacrylqt-Forrnal Is. 9. Mixture according to one of Claims 6 to 8, characterized in that, based on the binder, it contains 10 to 20 Q & vj * -% of the crosslinking agent. ORIGINAL INSPECTED -11 - 204P58-3 10. Mixture according to one of the preceding claims, characterized in g e mark It seems that the binder is a hydroxy-terminated polyester resin Is formed from adipic acid and diethylene glycol, 9816 / Pb84 ORlSiNAL WSPECTED