US2031659A - Process for making smokeless powder - Google Patents

Description

letill FIPYQUQ UNITED STATES as Reierelice PATENT OFFICE PROCESS FOR MAKING SMOKELESS POWDER,

Delaware N Drawing. Application November 24, 1933,

Serial No. 699,639

5 Claims.

This invention relates to a process of producing smokeless powder of a type adapted for use in small arms ammunition and more specifically for shotgun shell. Smokeless powder may be nitrocellulose, nitrocellulose colloided with nitroglycerine, or either of these two products treated with stabilizing compounds and materials adapted to influence the speed of burning and hence the ballistic properties of the powder. In most cases the propellant powderused in the ammunition comprises a blend of two or more powders of the type specified.

The present invention relates primarily to a process of producing grains of nitrocellulose suitable for use as a bulk powder and characterized by the property of being readily ignited. These nitrocellulose grains are however adapted for fur ther treatment such as colloiding with nitroglycerine, so the secondary aspect of the invention resides in the process of colloiding these grains with nitroglycerine. The nitrocellulose grains colloided with nitroglycerine may then be treated for stabilization or for the purpose of further modifying the speed of burning or ballistic properties.

The primary and secondary aspects of the invention as described are inter-related in that the first step or process of forming the nitrocellulose grains provides a product peculiarly adaptable for the second step of colloiding the grains with nitroglycerine.

The starting material is nitrocellulose which has been reduced to a physical fineness of such degree that most of it passes a fifty mesh sieve and all of it passes a forty mesh sieve. This nitrocellulose is placed in water and the entire remainder of the process takes place in closed vessels under water. This handling of the nitrocellulose provides the greatest margin of safety.

The finely divided nitrocellulose under water is pumped into a container in which it may be heated and agitated to controllable degrees. The agitation provides a suspension of the nitrocellulose in the water. Into this container or cooker is pumped a mixed solvent for the nitrocellulose comprising one solvent which is miscible with the water and one which is not. A mixture of acetone and amyl acetate constitutes an appropriate mixed solvent.

The mixed solvent is then agitated in the cooker with the suspended nitrocellulose. The acetone, being miscible with both the water and the amyl acetate, divides between them, some being in aqueous solution and some in solution in the amyl pended nitrocellulose particles which are dissolved by the globules. The solvents are then distilled. off by the application of heat.

The function of the acetone is to control the density of the nitrocellulose grains formed by the agglomeration of the nitrocellulose particles.

Acetone, methyl acetone and similar solvents have the property of leaving nitrocellulose in porous condition when expelled from the nitrocellulose by heat. .The process therefore produces grained nitrocellulose which may then be screened and used as finished bulk powder after supplemental finishing processes. If it is desired, however, that the grained nitrocellulose be colloided with nitroglycerine, it is again suspended in Water by agitation in the cooker and nitroglycerine pumped very slowly into the cooker.

Preferably the nitroglycerine has incorporated in'it a substance to reduce the hazard of explosion, such as benzol. When the benzol strikes the water in the cooker, most of it floats off on the surface so it is to be observed that the benzol is used for the purpose of reducing danger of explosi'on solely and plays not part in the colloiding action. I

The suspended nitrocellulose grains are agifated until the desired quantity of nitroglycerine has been pumped slowly into the cooker. Then the benzol is distilled oil and the heating continued for a period of from eight to twenty-four hours at a controlled temperature such as 185 F. The purpose of this continued heating is to cause the solvent to penetrate and completely colloid with the entire nitrocellulose grain so that a hard, homogeneous product is produced. The quantity of nitroglycerine is chosen in relation to the quantity of nitrocellulose so that the entire grain may be colloided and still a hard, stable grain be produced. The porousness of the nitrocellulose grain facilitates the complete colloiding thereof. If the colloiding were less than complete, the nitrocellulose grains would tend to be jell-like or sticky on their surfaces.

While still in aqueous suspension, the grain may be treated further with an explosive deterrent such as dinitrotoluene, with other materials adapted to impart specific ballistic properties, and with stabilizers.

It will, of course, be understood that the components of the mixed solvent used in forming examine:

The agitation produces a multitude of I the nitrocellulose grains may be other than acetone and amyl acetate. For instance, in place of the acetone, one may use methyl acetone, ethyl ketone, ethyl ketol, propyl ketol and similar low boiling point solvents of the ketone type. In place of the amyl acetate, one may use butyl acetate, ethyl acetate, and similar water immiscible nitrocellulose solvents. The water cible solvent may comprise 10 to 50% and the water immiscible solvent 90 to 50% of the mixed solvent employed.

However. in accordance ,with this invention,

one component of the mixed solvent must be highly volatile and miscible both withthe other solvent and with water. The other solvent must be immiscible with water so that it iorms mlnute globules in the water upon agitation. 4 Likewise, materials other than benzol, such as gasoline and similar low boiling dlstillates may be used for ering the nitroglycerine less dangerous to handle. For the purpjos'el of assisting the skilled in the art inp'racticingthis process, the following detailed; description of the process is provideclz I I v 800 pounds of finely divided nitrocellulose is agitated with I H 200 gallons of watertin'afclosed cooker. U 30 gallmis a j e l a e iq ll'oeso ace o e and 100 gallons of water are agitated together in an open tank.

The n s f th qn l, at ramp d into the cooker. Agitation in both containers'is continued during this period and is also r cone tinued in the cooker during the rdmainder of the process --U.-. 7

As soon the finely divided nitrocellulose is formed into proper sized particles'heatis applied causing the volatile solvents to be stiiled of; into a condenser, which discliarg' into tlieiopen agij tated tank, completing the graining cycle; A30 pounds of nitroglycerine (20%" mtr glyc containing 240' pounds of benz ol issl owtlyadded to the suspended powder grains whicharaagain; placed in the cooker. The temperature during this period is held at approximately 15 Heat'- is applied driving oif the bnz'ol', which is can: densed, and collected. I I, I

Agitation is continued and the temperatures held between 75 and 80 C. until the powder grains are quite hard. This takes from eight to twenty-four hours.

The grained powder is chilled and then is discharged into suitable containers. Having described my invention', I desire to be limited only by the ensuing claims:

1. A process of forming grains of nitrocellulose suitable for bulk powder from finely divided nitrocellulose, said process, comprising, the step of suspending the finely divided nitrocellulose in water and agitating said suspension in the presence of a mixed solvent comprising one component which is a solvent for a nitrocellulose and which is miscible with water, and another component which is a solvent for the nitrocellulose but is not miscible with water, and then driving ofi said solvents.

2. A process of forming grains of nitrocellulose suitable for bulk powder from finely divided nitrocellulose powder said process comprising the step of suspending the finely divided nitroce1lulose powderin water and agitating said suspension in the presence of a mixed solvent comprising acetone and amyl acetate, and then driving offsaid solvents. V

I 3. A process of forming grains of nitrocellulose suitable for bulk powder from finely divided nitrocellulose, said process, comprising, the step of suspending the finely divided nitrocellulose in water and agitating said suspension in the presence ofa mixed solvent comprising 40% acetone and 60% amyl acetate by volume, and then driving on said solvents.

4. A process of forming grains of nitrocellulose from finely divided nitrocellulose, said process, comprising, thestep of suspending the finely divided nitrocellulose in water and agitating said suspension in the presence of a mixed solvent comprising one component which is a solvent for a nitrocellulose and which is miscible with water, and another component which is a solvent for the nitrocellulose but is not miscible with water, then driving off said solvents, and then agitating the nitrocellulose grains so formed in aqueous suspension in the presence of nitroglycerine in quantity sufiicient to colloid each grain in entirety. I, H v 5. A process of forming grains of nitrocellulose from finely divided nitrocellulose, said process, comprising, the step of suspending the finely divided nitrocellulose in water and agitating said suspension in the presence of a mixed solvent comprising one component which is a solvent for a nitrocellulose and which is miscible with water, and another component which is a solvent for the nitrocellulose but is not miscible with water, then driving of: said solvents, then agitating the nitrocellulose grains so formed in aqueous suspension in the presence of nitroglycerine in quantity suflicient to colloid each grain in entirety, and then subjecting the nitrocellulose grains so treated with nitroglycerine to a controlled temperature for a period of from eight to twentyfour hours to' efi'ect the complete colloiding of the nitrocellulose grains with the nitroglycerine.

MILTON F, LINDSLEY, JR.