US1923849A - Propellent powder and process of manufacture - Google Patents

Description

Patented Aug. 22, 1933 UNITED STATES PROPELLENT POWDER. AND PROCESS OF MANUFACTURE Oliver Ward Stickland and Edward Whitworth,

Stevenston, Scotland, assignors to Chemical Industries Great Britain Imperial Ltd.', a Corporation of No Drawing. Application January 15, 1931,

Serial No. 509,029, January 25, 1930 10 Claims. This invention relates to the production of non-solvent propellent powders. For the prep aration of the socalled solventless propellent explosives, it has been customary to make use of the chemical substance diethyl diphenyl urea, as a gelatinizing agent In conjunction with nitroglycerine and under the influence of heat and pressure, it is possible to produce agelatinized nitroglycerine nitrocellulose propellent explosive in the form of flakes or cords as desired, without'the use of any volatile solvent such as acetone, the diethyl-diphenyl-urea. acting as combined gelatinizing agent, stabilizing agent and moderant. Such a propellent explosive possesses many well known advantages.

Diethyl-diphenyl-urea in practice sufiers from the disadvantage that on account of its low solubility in nitroglycerine at ordinary or room temperature, it is impossible to dissolve .a sufllcient amount of the diethyl-diphenyl-urea in nitroglycerine to form the usually required composition of-the propellent explosive. Thus, taking proportions commonly employed, it is impossible to dissolve at room temperature 9 "parts of diethyl-diphenyl-urea in 41 parts oi nitroglycerine for mixing with 50 parts of nitrocellulose. It is true that this proportion of diethyl-diphenylurea can be dissolved in nitroglycerine by heating the latter to a temperature of C. to C.,

but such a proceeding is objectionable as a manufacturing operation on account of the increased risk of accident, and further, on lowering the temperature of the nitroglycerine-diethyl-diphenyl-urea solution, the excess of diethyl-diphenyl-urea separates out as crystals.

A general method of introducing the diethyldiphenyl-urea is in the form of powdered crystals added to the nitrocellulose either before, during, or after mixing with the nitroglycerine. This method isobjectionable on account of the difliculty of. ensuring uniform distribution of the three constituents of the mixture, namely, fibrous nitrocellulose, liquid nitroglycerine and solid diethyl-diphenyl-urea. Such imperfect mixing causes irregularities in gelatinization which cannot be completely removed, even by an increased number of operations in the later stages of production, such as prolonged treatment between heated rolls.

Despite this serious objection, the use of di ethyl-diphenyl-urea as a gelatinizing agent in the production of the so-called solventless propellent powders has been well established, chiefly I because of the many advantages which this comand in Great Britain pound possesses for the production ot propellent, explosives. 3

' The object of the present lnventionls 'to provide a process which, while producing solventless propellent explosives that retain thedesirable' properties conferred by diethyl-diphenyl-urea, at the same time aifords a means wherebyi'the gelatinizing agent can be entirely dissolved in v the nitroglycerine, and this solution uniformly.

mixed with the nitrocellulose. y

We have now discovered that phenyl m'ethana' when mixed in the correct proportions, withdiethyl-diphenyl-urea, forms a mixture that --remains liquid at room temperature and is miscible with nitroglycerine at room temperature with no separation of crystals even on long standing. The phenyl urethane has a melting point of 52 0., and in our researches has been found to possess gelatinizing and stabilizing properties to an outstanding and very high degree.

The following summarizes the properties of the mixtures:

hyl-

% Phenyl Setting point or urethane gg state at 16 C.

62. 5 37. 5 24.0 G. 58. 8 41. 2 Liquid at 15 0. 55. 5 44. 5 Liquid at 16 C.

. qui a 52 6 47 4 Li 'd t150 50. 0 50. 0 Liquid at 15 C. 47. 6 5234 26.5 C.

\ presence of a relatively small quantity of phenyl the mixture is cooled to room temperature, at which it remains in the liquid state. Eighteen (18) parts by weight of the mixture, equivalent to 9 parts by weight of diethyl-diphenylurea plus 9 parts by weight of phenyl urethane, are added to 41 parts by weight of nitroglycerine at room temperature. This results in a homo-.

geneous liquid mixture from which no crystals separate, whereas a mixture of 9 parts diethyldiphenyl-urea and 41' parts nitroglycerine at room temperature consists of a saturated solution containing a considerable amount of undissolved diethyl-diphenyl-urea, and is therefore not homogeneous.

It is therefore merely necessary to add, after cooling, the requisite amount of the phenyl urethane and diethyl-diphenyl-urea (melted toegther in the correct proportions) to the nitroglycerine at room temperature, and to mix this solution with nitrocellulose suspended in water'by any of the well known methods, such as spraying or air agitation. There is thus obtained a uniform mixture of all 'the constituents, which is in the most favourable condition for the subsequent operation of gelatinization. .By this method the gelatinization is then more thorough, and is carried more easily to completion than when diethyl-diphenyl-urea alone is used, thus leading to an increase of output and reduction in cost in conjunction with a considerablyimproved product. The risk of fire at the rolling stage is also greatlyreduced.

As far as the above material is concerned, it may be said briefly therefore that we employ in non-solvent propellent explosives mixtures of diethyl-diphenyl-urea and phenyl urethanethat are liquid at normal temperatures.

Wehave continued our research in this work and have found that we can with safety also use liquid mixtures of diethyl-diphenyl-urea, phenyl urethane and nitroglycerine, whether themixtures of diethyl-diphenyl-urea and phenyl urethane themselves are liquid or not, provided that when admixed 'with the nitrog1ycerine,'the mixture is liquid.

All mixtures of phenyl urethane and diethyldlphenyI-urea containing more than 63 per cent phenyl urethane are solid at room temperature but 9 parts of any of those mixtures will dissolve in 41 parts of nitroglycerine to 'give'a liquid from which no crystals separate at 0 0., even if it is seeded with crystalsof phenyl urethane or diethyl-diphenyl-urea or both and allowed to stand with occasional stirring for four hours.

Again, a 48:52 mixture of phenyl urethane and diethyl-diphenyl-urea is solid at room temperature and behaves with nitroglycerine exactly as do the mixtures described above; at 35:65 mixture behaves in the same way.

From mixtures such as the above, but, containing appreciably more than 65% of diethyldiphenyl-urea, crystals separate when the liquid formed by dissolving-9 parts of this gelatinizing mixture in 41 parts nitroglycerine, is cooled to 0 C. or cooled and kept -at 0 0. Thus a 30:70 mixture dissolves very readily in nitroglycerine at room temperature, but if the liquid is cooled to 0 C. and seeded as described above with small crystals, within two hours it becomes cloudy; a 20:80 mixture still dissolves at room tempera- -ture, but on cooling to 0 (2., crystals separate in half an hour. a

We can therefore avoid the absence of a solid' am, the good gelatinizing action of diethyl-dimixture of phenyl urethane diethyl-diphenylurea and nitroglycerine, whether the mixture of diethyl-diphenyl-urea and phenyl urethane be liquid or solid, provided, as we have said above, that the mixture of the three materials is liquid.

Mixtures of phenyl urethane and diethyldiphenyl-urea, containing a proportion of diethyl-diphenyl-urea greater than that which would form a liquid mixture with phenyl urethane, are preferable, from the point of view of manufacture to mixtures of phenyl urethane and diethyl-diphenyl-urea containing a proportion of phenyl urethane greater than that which would form with diethyl-diphenyl-urea a liquid mixture, and to the liquid mixtures of phenyl urethane and diethyl-diphenyl-urea themselves. A suitable mixture consists of two parts of diethyl-diphenyl-urea and one part of phenyl urethane. This mixture, since it contains more than 50% of diethyl-diphenyl-urea, is solid at 15 C.-, but, since it contains little more than 65% of diethyl-diphenyl-urea,. crystals do not separate from the mixture with nitroglycerine at 0 C.

By mixing phenyl urethane and diethyl-diphenyl-urea in proportions substantially similar to'those given above, we can also utilize the ear-'- tremely good stabilizing action of phenyl urethphenyl-urea and the liquidity of the gelatinizer-, stabilizer nitroglycerine mixture. It might also be added that if the phenyl urethane be dissolved first, this appears to facilitate the solution of the diethyl-diphenyl-urea in the mixture.

The mixture, in brief, consists in a process for no the production of non-solvent-propellent explosives in which the so-called gelatinizing agent is amixture of phenyl urethane and diethyl-diof the process according to the preceding paragraph, in which the mixture of phenyl urethane and diethyl-diphenyl-urea is not of itself liquid at normal temperatures, but when admixed with the nitroglycerine the mixture is such that no separation of crystals occurs, even on long standing, and the mixture is liquid at normal temperatures.

The invention also consists in methods for the production of non-solvent propellent explosives substantially as herein described, and in nonsolvent propellent explosives such as may be made by methods substantially as herein described.

The following example illustrates how the in-' vention may be carried into effect, references to parts being to parts by weight.

diphenyl-urea are melted together and cooled to room temperature. Nine (9) parts of this liquid are added to 41 parts of nitroglycerine at room temperature, and thoroughly mixed and the homogeneous mixture thus obtained is mixed by air agitation with 50 parts of nitrocellulose suspended in water. The mixture containing all the constituents of the epropellentexplosive is separated from the bulk of the water by settling and is then squeezed to effect a further separation of water. The wet lumps are broken down form, the material is then rolled down to the required thicknesa'and out to the required size. If the non-solvent propellant explosive is desired in cords, the sheets are cut into discs, extruded from a hydraulic press heated by a hot water jacket to 75 C., at a pressure of 5000 lbs. per

square inch through a die having holes of the appropriate size. The extruded cords are then cut to the desired length.

The resultant propellant explosive is then ready for use.

General plosives prepared as described above are substantially of the same level as those of a propellent explosive containing the same proportions of nitroglycerine and nitrocellulose with 9 parts of diethyl-diphenyl-urea.

The replacements of a portion of the diethyl-' diphenyl-urea by an equivalent amount of phenyl rating the water, gelatinizing, rolling or pressing the material may be employed, and the liquid mixture of diethyl-diphenyl-urea, phenyl ureth ane and nitroglycerine, may be prepared in any desired way, and in any appropriate proportions. As many apparently widely difierent embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the foregoing examples or descriptions except as indicated in the following patent claims.

The ballistic properties of the propellent ex- We claim:

1. A composition of matter comprises nitrocellulose, nitroglycerin, diethyldiphenylurea and phenyl urethane.

2. A composition of mattercomprising nitrocellulose, nitroglycerin, and approximately two parts of diethyldiphenylurea and one part of phenyl urethane.

3. A composition of matter comprising nitrocellulose, nitroglycerin, diethyldiphenylurea and phenyl urethane in liquid form.

4. A composition of matter comprising nitroglycerine, diethyldiphenylurea and phenyl urethane.

5. A composition of matter comprising nitroglycerine, diethyldiphenylurea and phenyl urethane in liquid form.

6. A propellent explosive comprising nitroglycerine, nitrocellulose, diethyldiphenylurea,

and phenyl urethane.

7. A propellent explosive comprising approximately nine parts of a homogeneous mixture of phenyl urethane and diethyldiphenylurea, approximately 41 parts of nitroglycerine, and approximately 50 parts of introcellulose.

8. The process of manufacturing propellent explosives which comprises incorporating in nitroglycerine a composition comprising diethyldiphenylurea and phenyl urethane.

9. The process of manufacturing solventless 1 propellent explosives which comprises melting together phenyl urethane and diethyldiphenylurea, adding the liquid components to nitroglycerine at approximately room temperature, and incorporating the resulting product with nitro- 1 cellulose.

10. The process of manufacturing propellent explosives which comprises forming a liquid mixture of phenyl urethane and diethyldiphenylurea, cooling the liquid to room temperature, adding the resulting constituents to nitroglycerine, uniformly mixing the nitroglycerine composition to a suspension of nitrocellulose in water, separating the explosive components from the water, and gelatinizing the product. 1

OLIVER WARD STECKLAND; EDWARD WHITWORTH.

m No. 1,923,849.

August 2:, 193a.

omen WARD snort-AND. m1.

It is hereby certifiedthat error appears in the printed specification otthe above numbered patent requiring correction as' follows: Page 1, line 99, for "'centralite" read jgiigthyl-diphenyl-urea"; page 2, liue' 58, for "at" read "a":

and line 147, for "epropellent" read "propellent"; and that the said Letters Patent should be read with these corrections therein that to the-record of the case inv the Patent Office.

Signed and sealed this 24th day of October, A 1).-

the same my content newsma r m,