US1819458A - Propellent explosive - Google Patents

Description

Batented Aug. 18, 193i 1 I I4 D Ho Drawing.

My invention relates to an improvement 7 in propellent explosive compositions and more particularly to propellent explosives of the fiashless-smokeless type. The invention a comprises both a new composition and the process of making same.

Specifically my invention relates to 'a new powder comprismg ammonium' nitrate, colloided starch and colloided nitrocellulose. These are so minutely and intimately blended that desirable combustible properties are obtained when dry. Also, in the process of manufacture, while containing the solvents, it yields plastic masses capable of being molded in sizes and shapes commonly used with propellent powders,

The desirable properties obtainable with such hlended materials are five-fold. First with proper high concentration of am monium nitrate, and also starch, in mixtures with nitrocellulose, comparatively low temperatures oi? combustion are obtained and nozzle flash is eliminated. The efiect of lowering the temperature, by the use of am-.

25 monium nitrate, is well lrnown with many explosive compositions and was disclosed in colloided starch-ammonium nitrate compositions in an application filed January 1.0,

19%, Serial No. 685, l55, but is new with the 'present application for the triple combina tion above reterred to,

Second, both ammonium nitrate and starch contribute to explosion gases an increased concentration of water molecules, because the former contains 45 per cent and the latter, 55 per cent of water. The advantages of such increase of water molecules not only raises the temperature of possible initial luminosity but also yields increased power, because water possesses the highest temperature of initial luminosity and the lowest molecular weight of all explosion gases. More than 10 per cent of increased power was obtained.

Third, ammonium nitrate and starch contribute to the safety qualities of explosive mixtures for the reason that all mixtures of these two components, having the high combined water concentration just referred to,

1:4 PELLME'E PLOSIVE applieation filed October 28, 1923. Serial No. 408,132.

are not onl dificultly combustible but also diflicultl etonating. 1

Fourt the starch in the gelatinous form not only contributes to the plastic condi= tion of its mixtures in the process of manufaoture but also aflords a medium for dissolving, comminuting and holding the am monium nitrate, so as to yield an intimate and compact mass of the three components,

Fifth, ammonium nitrate itseli can (3011- w tribute oxygen to all combustible explosive materials, hence in mixtures with nitrow cellulose and starch, the proportions can be chosen so that the hydrogen will burn to water molecules and the carbon will burn M to form Ct), CU or any intermediate mix tureot the latter two molecules. This ads vantage in various mixtures, therefore, at: lords control of oxidation, sensitiven-ess, power and rate of detonation.

t is well lmown that mixtures of monium nitrate and nitrocellulose t1: m selves afiord proper regulation of the oxidant and combustible requirements, and it is also well known that all properly blended as mixtures of these two must contain more than 36 per cent of nitrocellulose, (compare equations 0 and d below), otherwise in the hot explosion gases an excess of tree oxygen is formed and this contributes to gun ero- 84D sion. However, with starch as a component, not only is the water content advantageously increased, but the nitrocellulose content can be decreased, thereby regulating the oxygen requirements, lowering the cost as of materials, and greatly lowering the explosion temperature below that producing luminosity and consequently yielding a power that is flashless. That is, in these mixtures, by making starch replace a sub- 90' stantial portion of the nitrocellulose, the flash point is favorably changed without loss of desirable explosive roperties. Thus, these mixtures can be ma e to be suficiently sensitive to inflammability, and while yieldas I ing smokeless, flashless and non-erosive gases, the power can be regulated and, indeed, can be increased through control of oxident-combus-tible requirements as indicated by the CO and CO limits of the foluse lowing equations, in which nitrocellulose of 12.75 per cent N is taken as the basis:

sible to select the other components so as to yield explosion gases CO or CO2 or equimolecular mixtures of these two gases, as indicated in the following table:

Nitrocellulose 15.00 15. 15. 00:20.00 20.00 20. 00:25.00 25. 00 25.00 Starch 12. 24 10. 35 8. 46:11. 52 9. 72 7. 92: 10. 80 8. 5. 50 Ammonium nltrate 72.76 74. 65 76. 54:68. 48 70. 28 72. 08:64. 66. 85 69. 50

Ex losion gases 3 C0 CO 00100 CO 00100 CO CO,

C 02 C02 C01 N itroce11u1ose 30. 00 30.00 30. 00 Starch 10. 08 6. 30 2. 52 Ammonium nitrat 59. 92 63. 70 67. 48

e Explosion gases. C0 C0 C 02 A good example of my new product is that comprising twenty-five per cent of nitrocellulose, 8.15% of starch and 66.85% of ammonium nitrate, the 25% of nitrocellulose being sufiicient to sensitize the compositions with the stated contents of starch and ammonium nitrate so that an ordinary rifle cap causes uniform and complete burning of the charge, and the components being proportioned to secure equivalents of CO and CO as oxidation products.

These three materials, being solids, could be ground to minute powders and then intimately mixed, but it is evident that if they could be minutely blended in compact masses the advantages of increased density and molded forms could be obtained.

In my process through the use of two solvents, the three materials are blended and consolidated by means of two miscible solvents, preferably water and acetone. Water is used to dissolve a substantial portion of the ammonium nitrate and to gelatinize the starch. Acetone is used to colloidize the nitrocellulose. Since acetone is soluble in water, mixtures of such two solutions, 'or concentrated gelatinous forms of the same, can be mingled and blended without flocculation or clotting, when conditions are properly controlled. And I have found that the resulting mass possesses plastic properties suitable for die pressing, or for molding into sizes and shapes commonly used for propellent explosives.

As an example of my method of manufacture, I first make a very concentrated solution of 25 parts of nitrocellulose in acetone. l[ make an intimate mixture of 66.85 parts of finely ground ammonium nitrate and 8.15 parts of sifted starch. To this mixture, I add substantially 10 parts of water and heat at 55100 C. until the mass is uniformly gelatinized. To this I add the nitrocellulose solution, with as complete avoidance of inclusion of air bubbles as practicable, and then mix mechanically, while maintaining the temperature of 55100 C. The warm smooth resulting plastic is pressed and cut in the customary manner for various propellent explosive purposes and dried. The dr ing can be effected at ordinary or elevate temperatures or by a combination of the two, or partial drying can be made before the pressed forms are cut.

Owing to hydrolysis and solution of the starch if the mixture is heated too long or at too high temperature, the composition may become too thin for die-pressing. This adverse condition is avoided by employing a suitably lower temperature or cooling to such lower temperature. The pressed forms can either be out immediately or after such time, cooling and drying as will be necessary with the particular proportion of components used, to yield a mass that can be cut smoothly and show no tendency to distort or stick together.

The example of percentages given herewith is for illustration and affording an understanding of the invention, and can be varied to give powders of varied explosive properties, and yet fall within the scope of my claims.

Having now described my process and new composition of matter, what I claim is:

1. As an improvement in the manufacture of propellent powders, the process comprising the plasticizing of mixtures of starch, an alkali nitrate and nitrocellulose through the use of two miscible solvents, substantially as described.

2. As an improvement in the manufacture of propellent powders, the process comprising plasticizing mixtures of starch, am-

moniu'm nitrate and nitrocellulose, whose percentages are within the calculated oxidant-combustible explosive limits, through the use of two miscible solvents, substantially as described.

3. As an improvement'in the manufacture of propellent powders, the process comprising blending by mechanical means an acetone solution of nitrocellulose with a heated mixture of water, starch and ammonium nitrate.

4:. As an improvement in the manufacture of propellent explosives, the process compris ing mixing by mechanical means a concentrated acetone solution of nitrocellulose with a thick, gelatinized mixture of water, ammonium nitrate and starch.

5.-As an improvement in the manufacture of propellent explosives, the process comprising gelatinizing a mixture of acetone, nitrocellulose, water, ammonium nitrate and starch, pressing and cutting the same into monium nitrate.

eas es shapes and sizes commonly used with propellent powders, and subsequently drying the same.

6. As an improvement in the manufacture of propellent' explosives, the process of heating to 100 C. a mixture of starch, ammonium nitrate and Water and then mechanically mingling with this a concentratedsolution of nitrocellulose dissolved in acetone, subsequently shaping this mass into propellent grains and drying the same.

7. A propellent explosive comprising a greatly preponderating proportion of ammonium nitrate in 'an intimate state and molded form with starch and colloidized nitrocellulose, the quantity of nitrocellulose exceeding that of the starch, substantially as described. a

8. A propellent explosive comprising approximately 15-30 parts of nitrocellulose, 12-3 parts of starch, and 70 parts of am- 9. A propellent explosive comprising approximately 25 parts of nitrocellulose, 8 parts of starch and 67 parts of ammonium nitrate.

10. A propellent explosive Which Will burn Without material production of free oxygen, comprising a preponderance of ammonium nitrate, nitrocellulose over 10% and under 36% and approximately as much starch as nitrocellulose.

In testimony whereof, I have signed my name hereto.

' WILLIAM M. DEHN.

enemas. 1,819,458. Grant'ed August is, ioei, to

WlLLlAM llii. DEHN.

it is hereby certilied that error appears in the printed specification of the above numbered patent requiringacorrection as follows: Page 1, line 213, for the word 'i'nozzle" read muzzle; and that the said Letters Patent should be read with this correction therein that the some may conform to the record of the case in the Patent @fiiice.

Signed and sealed this 22nd day oi September, A. D. 1931'.

p M. J. Moore,

(Seal) Acting Commissioner of Patents.