US2511669A - Ignition composition - Google Patents

Description

June 13, 1956 w. FlLBERT 2,51Lfi59 IGNITION COMPOSITION Filed Oct. 20, 1945 INVENVTOR. WILLIAM WEDERICK FILBE'RT A T TORNE Y Patented June 13, 1950 This invention relates to, an improved ignition composition and assembly characterized by speed and uniformity of action and other desirable properties. 4

.It is customary, for thelinitiationof explosive -charges,.,to rnal-:e use ,O'Lpreliminary, readily, ig-

nitalole nompositionsrthatcan be fired by a spark or slight flame, or by the .heat from an, incan- ...descent ,wire. Blastingicapsiand sguibs aretypes -of-. initiators employed with detonating and deflagrating explosives respectively, depending in the first case. foriunetion on the detonatingimpulseyand .inithe second case on the .flame'from the main initiating charge, While the explosion of charges by so-called instantaneous commercial initiators takes ,place With, relatively great rapidity, a significant time flag (invariably clcursbetween thefirst application of flame or' heat and the full development, of the .power .of, the initiator.

vEur certainpurposes whereigniters are used, it is desirable that there 'bea yery shortlag and that uniformity of action should invariably result. ,Priorrartigniters of extremely rapid ,acrtion have tended to :be ,characterizedby aconsid- 'erable degree of .sensitiveness toelectrostatic discharges. This has been particularly undesirable when igniters were usedhavin a relatively'lalfge amount of the flame-producing charge, in order I tion comprising a .black powder type com osition including a minor proportion of .an added ex- .rplosive ignitionaccelerant. While various types ofblackpowder are applicable, desirably affinelydivided unglazed dust ,isused. The above composition alone is not entirely satisfactory and an initial ignition charge is desirably used with the above main charge. A complex salt of lead nitrate with a lead salt of a nitrophenol is a satisfactory ingredient of this initial :Charge, and

Claims.

Illead 'iPotassium INitroiCalciumlSalt Ghlorate .statch .Silicide with "a ibis basi'cjleadsalt o'f "4,6-dinitro-orthocresol-with a binding agent and, if desired, an oxidizin agent. This preferred double salt "I "shall diesignateyas lead salt Thereafter in ,this specification for purposes of simplification.

"Theifollowingexample of compositions and asseniblies williserve to show specific embodiments offtheinvention. "It will he understoodthat these are illustrative only "and are notrlimiting in any ,way.

Accelerated.:black powder charges of the above description were prepared, the black, powder itself having'the composition: potassium nitrate, 74%; charcoal, 15.6%; sulfur, 10.4%. The I01- flowing blends ,Were used:

$25 It was found that mixtures oftheabove-descrip- .tion ,showed. definite decrease in .time ,of ignition, thoughthe ruse ofaninitial ignition charge ahead ..0.f ,the .blaokpowder composition ,wa .dessirable ,ior satisfactory execution. The ,use of the ,veryfine dust. wasadvantageousin avoiding segregation of ,the \difierent components.

:Fnr the primary ignition charge, compositions werens ed .asiollows The *n'itros'tarch in the above com-positions was used as abinding agent, gelatinization being eif ected' by butyl acetate or other suitable volatile solvent; this tsolvent being removed by, evaporaftion prior to use. The -72l810 composition 'was particularly attractive, being readily and "very rapidly ignited by an incandescent Wire and being "capable of extremely-rapid propagation of the "-initia'1' 'firin impulse -to the mainblac'k powder ignition charge. 'Desirably this initial "charge is contain'ed in-the cavity'of -a bridge plug, *surroundingithe-bridge:Wire.

'"'llhez'aceompanyingrdrawingshowssthe assembly preferably I use the double salt of lead nitrate #55 of the two ignition charges. 'ilhei'cylindricalaconthis wire on passage of an electric current there through. This small initial charge comprises the v following composition: 72% of lead salt, 18% of potassium chlorate, and 10%. of nitrostarch.

When this initial charge is fired, the flame instantly ignites the main charge 2, with a very small lag between the breaking of the bridge wire and the exertion of the full igniting power of the main charge.

The main charge in the foregoing igniter is, as has been brought out, an accelerated black powder composition comprising black powder containing desirably between 1 and 25% of an explosive ignition accelerant. While various types of black powder in fine granulation may be used, it is advantageous to employ an unglazed powder of a considerable degree of fineness. Desirably the powder will be comprised of particles suificiently fine to pass a 24-mesh screen. Even finer powder is preferable, and very satisfactory results were obtained when a powder dust was used where substantially all passed an 80-mesh screen and over 50% passed a150-mesh screen. The use of very fine powder not-only gave certain, rapid ignition but was particularly advantageous in facilitating the blending with the accelerant and preventing subsequent segregation. As such high explosive accelerant we may use various complex salts of lead nitrate with lead salts of nitrophenol, for example salts of dinitrocresols, dinitrophenols, trinitrophenols, etc. Preferably I employ the lead salt previously described and designated. Other explosive compounds may be used, however, such as mercury fulminate, diazodinitrophenol, and the like.

As initial ignition charge, a suitable composition comprises the doublesalt of lead nitrate with a lead salt of a nitrophenol, and again I find the same lead salt specifically designated very satisfactory, preferably with a binding agent and, if desired, an oxidizing ingredient. As binding agent nitrostarch may be used, a gelatinization agent such as butyl acetate or other. suitable volatile solvent being employed to obtain agglomeration, the solvent being subsequently removed by evaporation. My preferred composition includes a blend of the double lead salt, potassium chlorate and nitrostarch, a satisfactory ratio being 72l8-10 for the respective ingredients.

The igniter assembly described in the foregoing possesses high utility for certain applications where unusually rapid and uniform ignition is desired. It may be used, for example, in the ignition of propellants, incendiary compositions, etc. Whereas igniters of safe characteristics previously available showed a total lag from the time the current was applied to the development of the greater part of the pressure of the main ignition charge amounting to around 30 milliseconds, the lag was reduced to around 10- milliseconds, when the igniter assembly of the present invention was used. At the same time, no hazardous condition was present with respect to'accidental ignition by electrostatic discharges accumulated by operators.

The invention has been described adequately in the foregoing, but it will be understood that many variations may be introduced in the details of compositions and assemblies without departure from the scope of the invention. I intend to be limited only by the following claims.

I claim:

1. An ignition composition comprising at least of a black powder composition and from 1 to 25% of an added explosive ignition accelerant consisting essentially of a primary detonating compound.

2. The ignition composition of claim 1, in which the explosive ignition accelerant is mercury fulminate. I v

3. An ignition composition comprising at least 75% of a black powder composition and from 1 to 25% of a complex salt of lead nitrate with a lead salt of a nitrophenol as ignition accelerant,

4. An ignition composition comprising at least 75% '01 a black powder composition and as ignition accelerant from 1 to 25% of a double salt of lead nitrate with a his basic lead salt of 4,6- dinitro-ortho-cresol.

5. An ignition composition comprising at least 7.5% ofunglazed black powder and between 1 and 25% of a doublesalt of lead nitrate with a bis basic lead salt of 4,6-dinitro-ortho-cresol.

6. .An ignition assembly comprising (1) a main ignition charge of at least 75% of a black powder composition and from 1% to 25% of an added explosive ignition accelerant consisting essentially of a primary detonating compound and (2) an initial ignition charge comprising a complex salt of lead nitrate with a lead salt of a nitrophenol.

'7. An ignition assembly comprising (1) a main ignition charge of at least 75% of a black powder composition and from 1% to 25% of an added explosive ignition accelerant consisting essential ly of a primary, detonating compound and (2) an initial ignition charge comprising a double salt of lead nitrate with a bis basic lead salt of 4,6-dinitro-ortho-cresol.

, 8. An ignition assembly comprising (1) a main ignition charge of at least 75% of a black powder composition and from 1% to 25% of an added explosive ignition accelerantconsisting essentially of a primary detonating compound and (2) an initial ignition charge comprising a double salt of lead nitrate with a bis basic lead salt of 4,6- dinitro-ortho-cresol and a binding agent.

9. An ignition assembly comprising 1) a main ignition charge of at least 75% of a black powder composition and from 1% to 25% of an added explosive ignition accelerant consisting essentiallyloi' a primary detonating compound and (2) an initial ignition charge comprising a double salt of lead nitrate with a bis basic lead salt of 4,6-dinitro-ortho-cresol and nitrostarch.

10. An ignition assembly comprising 1) a main ignition charge comprising at least 75% of unglazed black powder and from 1% to 25% ofan added ignition accelerant consisting essentially of a primary detonating compound, and (2) an initial ignition charge located in the cavity of a bridge plug of an electric initiating assembly, said initial charge comprising a blend of a double salt of lead nitrate with a his basic lead salt of 4;,6'-d initro-ortho-cresol, nitrostarch, and an oxidizing agent. I

WILLIAM F. FILBERT.

(References on following page) REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Gentieu Nov. 19, 1907 Sparre Nov. 10, 1914 McNutt May 17, 1932 Brun Jan. 16, 1934 Hill Jan. 8, 1935 Nash Apr. 30, 1935 Brun Mar. 15, 1938 Filbert Apr. 26, 1938 Number Number OTHER REFERENCES Tech. Paper 162, Initial Priming Substances for High Explosives (G. P. 0., Washington,

Hale July 26 1938 15 D. 0.), page 6, last complete paragraph.

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