US2396074A - Propellant powders containing pelargonic esters - Google Patents

Description

Patented Mar. 5, 1946 UNITED STATE PROPELLANT POWDERS CONTAINING PELARGONIC ESTERS :George Barsky, New York, N. Y., assignor to E. F. Drew & 00., Inc., New York, N. Y., a corporation of Delaware No Drawing. Application May 13, 1942, Serial No. 442,857

9 Claims.

The present invention is directed to propellant powders having nitrocellulose of explosive grade as a principal ingredient. More particularly, the invention relates to a composition containing an esterifled material as a plasticizer or modifying agent for the propellant.

In converting nitrocellulose into powder grains it is customary to add certain substances, usually organic in nature, and sometimes having explosive properties in order to plasticize the nitro-' cellulose and render it more easily extruded or molded to the desired size and shape. It is also highly desirable in propellant powders to avoid a flash which normally occurs in a gun barrel when the gun is fired.

Various substances have been added to the powder in an attempt to overcome these defects. However, various disadvantages are inherent in the substances previously used. Generally, a substance which reduces the flash of the powder is likely to produce a considerable amount of smoke. Among such substances are the dialkylphthalates which, while having the property or reducing the flash, give an excessive amount of black smoke when used in sufficient quantities to eliminate the flash. Also, other substances previously proposed for the purpose hav the disadvantage that they are more or less water soluble and therefore increase the tendency of the powder to absorb moisture from the air.

The present invention is intended and adapted to provide a composition which will obviate the disadvantages of previous plasticizers, it being among the objects thereof to provide a propellant powder of reduced flash during the firing thereof.

It is also among the objects of the present invention to provide a composition containing a plasticizer having a substantial solvent power for the nitrocellulose in order to render the extrusion of the composition to form powder grains, rapidly andreadily accomplished.

In practicing the present invention I provide a nitrated cellulose as the principal explosive material and add thereto esters of certain acids which have the desired modifying characteristics. The present invention is based upon the discovery that an open-chain monobasic carboxylic acid having 9 carbon atoms, when esterifled with a p'olyalkylene glycol to form a substantially neutral ester, provides a substance which when added to nitrocellulose materials, reduces the flash of the composition, gives plasticity thereto and allows the detonation of the composition without producing any substantial amount of smoke. The addition 01' the ester has the further advantage of reducing the tendency of the nitrocellulose to absorb water. and thereby renders the composition substantially nonhygroscopic.

Other acids closely related to the acid having 9 carbon atoms maybe used, and it has been found that the open-chain acid having '7 carbon atoms is also suitable for the purpose. Not only are the normal pelargonic and the normal heptoic acids suitable for the purpose, but various isomers thereof are equally adaptable.

The polyalkylene glycol used for esterification is a lower glycol, namely, the ethylene and propylene glycols, and particularly the diand triethylene glycols. Said glycols may be used either singly or in-admixture of each other and the esterification may be with a single acid or a mix ture of acids.

The following is an example of a composition embodying the present invention:

Parts by weight Nitrocellulose 86 Dinitrotoluol 10 Triethylene glycol dipelargonate 4 A mixture is first made of the nitrocellulose and nitrotoluol and the plasticizer, dissolved in a suitable solvent, is incorporated therein by ordinary working methods. This composition is then extruded through suitable die and the olvent al lowed to evaporate. The extrusion process is quite simple and the lubricating effect of the plasticizer enables a quick and complete operation to be conducted thereon without the expenditure of any undue amount of power in the operation.

Another composition embodying the present invention is the following:

Parts by weight Nitrocellulose 82 Trinitrotoluol 15 Diethylene glycol diheptoate 3 Still another composition coming within the scope of the present invention is the following:

' Parts by weight Nitrnrellulnqe 96 Mixed dland triethylene glycol pelargonate and caprylate 4 All these compositions have the advantage that they have excellent plasticity to render the extrusion process readily accomplished. None of the compositions gives off any substantial amount of smoke when burnt and therefore the smokeless characteristic of the explosive is retained. The

is incorporated with a mixture of 'diethylene plasticizer also makes the composition fiashless.

The new esters may be obtained by a simple esterification process. In order to produce the triethylene glycol pelargonate there is'provided 320 parts by weight of pelargonic acid with 100 several hours. to complete the esterification and to distill on any excess fatty acid which may be present. 4

The crude product may then bepurifled as isv common in the art, by first washingwith caustic soda solution and with water. The ester is then heated in a vacuum to about 90 C. to distill oil any water which may be present. It is then sub- Jected to a bleaching operation with activated carbon'and bleaching earth at about 110 C. and filtered. 7 7

As an example, of a composition which may be used to prepare a plasticizer, theiollowingmixture of fatty acids,

' Parts by weight acid 80 Caprylic aci .15 Heptoic a 5 glycol and triethylene glycol in equalproportions.

The mixture is then esterified as set'torth above and the product purified in the usual manner.

The above compositions are intended to illusly small proportion of a polyethylene glycol ester of an open-chain mcnobasic carboxylic acid taken from the class of acids having 7 and 9 carbon atoms, the amount of said ester being suflicient to plasticize said powder torender it capable of extrusion and to reduce the flash upon firing of said This temperature is maintained for a sufllcient length of time, up to a carboxylic acid taken from the class of acids have trate the nature 01' the invention and not to limit the same. For instance, the pelargonicacidmay various mixtures of explosives may be 7 used in the compositions, as is well known. In the above description it has been stated that the .plasticized powder.- r

3. A composition of matter comprising a nitrocellulose propellant powder containing a relatively small proportion of a polypropylene glycol ester of an open-chain monobasic carboxylic'acid taken from the class of acids, having 'I and 9 carbon atoms," the amount of said ester being sufiicient to plasticize said'powder to render it capable of reduce the flash upon firing of cellulose propellant powder containing a reLatively small proportion of a mixed diand triethylene glycol ester 01' an open-chain monobasic ing' 7 ands carbon atoms, the amount of said ester being sufiicient to plasticizesaid powder to render it capable of extrusion and to reducethe flash upon firing of said powder.

'5. A composition of matter comprising a nitrocellulose propellant powder containing a relatively small proportion of-the triethylene glycol ester or pelargonic acid, the amount of saidester being sumcient to plasticize said powder to render it capable of extrusionand to reduce the flash upon flringot said powder.

6. Acomposition of matter comprising a nitrocellulose propellant powder containing a relatively small proportion of the triethylene glycol ester of a mixtureoi pelargonic acid with an open-chain monocarboxylic acid taken from the class having 7, 8 and 10 carbon atoms, the amount of said ester 'beingsuflicient-to plasticize said powder tocrenderit capable oivextrusion and to reduce the flash upon firing of said powder.

7. Acompositionoi'rmatter comprising a nitrocellulose propellant powder containing a relatively. small proportion of the triethylene glycol ester of heptoic acid, the amount of said ester composition is extruded to form grains. It is not necessary, inail cases, that the nitrocellulose be plasticized with the ester, but the ester may be used as a coating or'water-proo'fing film on the surface of. the propellant powder. To accom-' push this, one may, if desired, omitfentirely' or in part from the" body or the composition, the usual amount! plasticizer and, by spraying or otherwise, form the powder.

These and other changes in the: details of the procedure and compositions may bemade within the spirit of the invention, the scope of which is not to be limited except by the claims appended hereto.

What is claimed is:

1. A composition of matter comprising a nitrocellulose propellant powder containing a relatively small proportion of a polyalkylene glycol ester plasticize said powder to render it capable of extrusion and to reduce the flash upon of said powder;

2. .A composition ot'matter comprising "a cellulose propellant powder containing a relativea film thereof on the mace oi! being sufilcient to plasticize said powder to render it capable of extrusion and to reduce the flash upon firing of said powder. Z"

" 8. A composition or matter comprising a nitrocellulose propellant powder containing a relatively small proportion of the triethylene glycol ester of a mixture or pelargonic acid with an open-chain monocarboxylic acid taken from the class having 7, 8 and 10 carbon atoms, said ester containing a major proportion of pelargonic acid and a minor proportion of the other acids, the

. amount of said ester being sufiicient to plasticize said powder to render'it capable of I V I extrusion and to reduce the flash upon firing of said powder.

9. A composition or matter comprising a nitrocellulose propellant powder having a small amount of a nitroaromatic compound sufilcient to many said powder incorporated therein'and containing a relatively small proportion of a polyalkyle ne glycol ester or an open-chain monobasic v carboxylic acid taken from the class of acids havmg and 9 carbon. atoms, the amount 01' said ester being suilicient to plasticize said powder to render it capable of extrusion and to reduce the flash upon firing o1 saidpowder.

GEORGE BARsKY.