US1854776A

US1854776A - Nitrocellulose propellent powder

Info

Publication number: US1854776A
Application number: US515642A
Authority: US
Inventors: Woodbridge Richard George
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1931-02-13
Filing date: 1931-02-13
Publication date: 1932-04-19
Anticipated expiration: 1949-04-19

Description

Patented Apr. 19, 1932 are ever Ltdtjlt RICHARD GEORGE WOODBRIDGE, OF WILMINGTON, DELAWARE, ASSIGNOR T0 E. I. DU PONT DE NEMOURS & CQMPANY, OF WILMINGTON, DELAWARE, A. CORPORATION OF DELAWARE IiTITROCELLULOSE PROPELLENT POWDER No Drawing.

This invention relates to nitrocellulose propellent powder having certain advantageous properties, and to a process of making such powder.

This application is a continuation as to common subject matter of my copending application Serial No. 81,086, filed January 13, 1926.

The object of my invention is to produce a smokeless propellent powder from nitrocellulose without the aid of nitroglycerine which will possess greatly reduced hygroscopic qualities as compared with a powder made from nitrocellulose only. A further object of my invention is the elimination of the white luminous flash such as is produced at the muzzle of guns by the present pyro service powder of the United States Government. This white luminous muzzle flash is commonly attributed to the ignition of the combustible gases formed during the combustion of smokeless powder, due to their high temperature when emerging from the muzzle of the gun and coming in contact with the oxygen of the air. The gaseous products formed by the combustion of smokeless powder are nitrogen, carbon dioxide, carbon monoxide, hydrogen, water vapor and small amounts of methane. Of these the combustible gases are carbon monoxide, hydrogen and methane. The white luminous flash at the muzzle of the gun is due to the combustion of these latter gases in the presence of oxygen. This combustion can be prevented in the case of small arms by firing into an atmosphere of carbon dioxide. When the white luminous flash is eliminated in this manner, or is eliminated by the use of a powder containing suitable ingredients, only a small reddish glow appears at the muzzle of the gun upon firing. This glow is not readily visible and can be easily concealed.

A further object of my invention is the production of a nitrocellulose propellent Application filed February 13, 1931. Serial No. 515,642.

powder which, besides being of greatly reduced hygroscopicity and flashless in most guns, contains no water soluble ingredients aside from the volatile solvents, ether and ethyl alcohol, which may be used in the manufacture, and therefore can be dried not only in air but also in hot water to more effectively and expeditiously remove the volatile solvents added for the purpose of assisting in the colloiding of the nitrocellulose.

The hygroscopicity of a nitrocellulose propellent powder is a factor largely of the amount, and nitrogen content, of the nitrocellulose used. For example, nitrocellulose of 12.60% nitrogen content will contain about 2.00% moisture when in equilibrium with 70% relative humidity at 30 C. A nitrocellulose of 13.15% nitrogen will contain about 1.5% moisture under the same conditions. Colloiding the nitrocellulose with ether and alcohol has but little effect on the hygroscopicity of the nitrocellulose in the small rifle powder grains and even in powder grains suitable for the 75 m/m field gun, but there is a gradual reduction in hygroscopicity as the size of the powder grains is increased or, in other words, as the amount of residual solvent ether and alcohol left in the powder is increased.

I have found that certain classes of organic compounds are particularly suitable for the double purpose of reducing the hygroscopicity of the nitrocellulose and eliminating the luminous white muzzle flash at the same time. The compounds which I have found especially suitable are dibutylphthalate, diethylphthalate, dibutyltartrate, ethyl palmitate, acetyllaurins, etc. These compounds possess the desirable properties of being good solvents for nitrocellulose, liquid at ordinary temperature, of relatively low volatility, especially when colloided with nitrocellulose; besides being substantially insoluble in water and substantially non-hygroscopic. These compounds are further characterized by being deterrent materials of a non-explosive character, containing a relatively small percentage of oxygen and a relatively high percentage of carbon and hydrogen.

I have further found that the quantity of the above compounds required to eliminate the muzzle flash of a nitrocellulose propellant is relatively small, so that when used alone with nitrocellulose the quantity required to produce flashlessness, particularly in the smaller guns, would be insuflicient to have much effect on reducing the hygroscopicity of the nitrocellulose.

I have further discovered that in order to produce a nitrocellulose propellent powder which will have greatly reduced hygroscopicity as compared with, for example, the present pyro powder of the United States Government and at the same time be flashless in many guns, it is desirable to substitute for a portion of the nitrocellulose, in addition to the portion substituted by the flash eliminating compound, a substantially non-hygroscopic and water insoluble nitro-aromatic compound which when liquid has a substantial solvent action on the nitrocellulose.

As an example of a nitro-aromatic compound which answers my purpose I may mention dinitrotoluene. While ordinary 1-2-4 dinitrotoluene is a solid and as such has no water-proofing-a-ctionon the nitrocellulose, I subject the powder composition containing dinitrotoluene, at some stage of its manufacture, to a temperature suflicient in the presence of a flash reducing ingredient such as dibutylphthalate to cause the mixture to melt. As both dinitrotoluene and dibutylphthalate, either alone or in mixture, are excellent solvents for nitrocellulose, there is obtained a thorough colloiding of the nitrocellulose by the mixture, resulting in a substantial reduction in the hygroscopicity of the nitrocellulose. This reduction is greater thanthe reduction due to simply substituting a portion of the nitrocellulose by an equal portion of the above ingredients, and is due to a depression of the hygroscopic qualities of the nitrocellulose by the colloiding action of the mixture of non-volatile solvents.

My invention may therefore be said to comprise, as one important feature, the combination of a nitro-aromatic compound with a flash eliminating compound, both of which are substantially water insoluble and nonhygroscopic and both of which are substantial solvents, alone or inadmixture, for nitrocellulose. The substitution of a substantial portion of nitrocellulose by these two ingredients, in addition to the so-called water-proofing effect of the ingredients themselves on the nitrocellulose, produces a nitrocellulose propellent powder of greatly reduced hygroscopicity and flashless in many guns.

I do not wish to be understood as asserting that propellent powders made in accordance with my invention are non-hygroscopic, as it has been my experience that all powders, whether of the nitrocellulose orof the nitroglycerine type, possess a definite degree of hygroscopicity. Furthermore, the hygroscopicities of propellent powders made in accordance with my invention areyery .much lower than those of the usual type of nitrocellulose powders. As proof of the above I present the following hygroscopic tests made by exposing powders of the compositions as shown to a relative humidity of at a temperature of 30 C. until equilibrium was reached.

Composition, exclusive of stabilizer Nitrocellulose oi Dinitro- Dlbutyl- 13.15% N. toluene phthalate 100% None. None. 95% None. 5% None. 10% 85% None. 15% 30% None. m Y 5% None. 90% i0 None. 85% .15 0 None. 80% 20% None. 12 80% 0% 0% 13 %py1-o of 12.60% N. None None of these ingredients with 85 parts nitrocellulose without the disadvantage of using 15 parts of either ingredient.

The same advantage as regards hygroscopicity and elimination of flash may be obtained by substituting'for the dibutylphthalate many other deterrent non-volatile solvents for nitrocellulose To illustrate" this point I give the results of ballistic test-in the 7 5 m/m field gun model of 1897 usingthe 13 pound projectile of powders of various compositions, together with the results of hygroscopic tests at 70% I relative humidity at 30 C.':

III

Composition 1 I fi i Lumi- Weight p c nous Dinitrotoluene or 1 chiiige $533; vigil) liiiiz iie 1.315% substitute Flash eliminating ingredient lpgnrdty flash V 0 Feet p51- Lbs 1g u'ncea seco'n sq. m 85% 10% DNT 5% dibut lphthalate 28 1956 35950 0.77% None 85% 107 DNT 5% dimet yldiphenyluroa 27% 1945 35810 0.78% None 85% 10 a DNT 5% acetyl laurins 28% 1947 32280 0.76% N 0116 85% 10% DN T 5% ethyl palmitate 30 1949 30600 0. 82% None DN T d et y p t 27% 1949 33510 0. 69% None 85 DNT 5% dibu yltartrate 27 1925 31900 0.70% None 85 a 10% trinitrotoluene 5% dibutylphthalate 27 1952 35770 0.76% None 1 34% added diphenylamine as a stabilizer. a

oisture determined by heatinc 6 hours in vacuum oven at 50-60 C.

In place of dimethyldiphenylurea, diethyldiphenylurea or methylethyl-diphenylurea may be used.

With the exception of the dimet-hyldiphenylurea, diethyldiphenylurea and methylethyld'iphenylurea, all of the above flash eliminating ingredients are liquid. They are also excellent solvents for nitrocellulose. While tetra substituted urea compounds are solid, when mixed with the dinitrotoluene mixtures can be obtained melting below 80 C. that is, at a temperature Well within suitable limits for safe manufacture, especially when the powder is subjected towater drying treatment after the removal of volatile solvents. It should, therefore, be understood that either or both the nitro-aromatic compound and the flash eliminating 'ingredient may be solid provided that a mixture of the two will melt below a temperature of about 80 C. and thus colloid the nitrocellulose by reason of their combined solvent action on the same.

I have found that no single composition will give fiashless results in all types of guns. In some guns, due to relatively short barrel and relatively severe ballistic requirements, it is often impossible to obtain flashless results with a powder which may give fiashless results in some other gun. Furthermore, that the manner in which the powder is ignited, the quantity and arrangement of the supplementary black powder ignition charge are all of great importance in some guns in connection with obtaining fiashless results. I have further found that in some guns the type of powder grain is of importance, and that the strip type of powder grain appears to give better results in some guns than the multior single perforated.

I have further found that the chemical stability of powder made in accordance with my invention, for example from nitrocellulose, dinitrotoluene, dibutylphthalate and diphenylamine, is far greater than that of powder made from nitrocellulose and diphenylamine only; this I attribute as being due to the thorough colloiding of the nitrocellulose by the mixture of dinitrotoluene and dibutylphthalate used and the solution of the diphenylamine in the latter mixture.

Nitrocellulose of relatively high nitrogen is preferred in order to obtain the advantage of the lower hygroscopicity possessed by nitrocellulose of high nitrogen content. I no not limit myself to the use of nitrocellulose with a nitrogen content of 13.15% which has been previously set. forth in certain examples as purely illustrative. It will be apparent from the foregoing that I can use nitrocellulose of much higher nitrogen content, for example as high as 13.50, or even higher, and in conjunction therewith increased or decreased amounts of dinitrotolucne and dibutylphthalate depending on the ballistic and chemical qualities desired and whether or not flashless results are desired. I, therefore, do not limit myself as regards the maximum nitrogen content of the nitrocellulose. It will also be apparent that I can use nitrocellulose of lower nitrogen content than 13.15% with various amounts of dinitrotoluene and dibutylphthalate, but as nitrocellulose of lower nitrogen content is more hygroscopic and of less potential than nitrocellulose of higher nitrogen content, I prefer to use nitrocellulose with nitrogen content in excess of 12.85%. As indicated in the foregoing, I can use nitrocellulose having a nitrogen content-greater than 13.50, but heretofore nitrations other than by laboratory methods have not produced a product having satisfactory stability. While I may use more than 10% of the nitro-aromatic compound, such as dinitrotoluene, in the composition, I have found that this amount is very satisfactory to give with nitrocellulose of about 13.15% nitrogen content and 215% of dibutylphthalate, a propellent powder possessing requisite potential for present type of ordnance. When as much as 5% of dibutylphthalate is used, no muzzle flash is obtained in many of the smaller guns. For example, flashless results are obtained with a powder of the composition85 parts nitrocellulose of about 13.15% nitrogen, 10 parts dinitrotoluol, 5 parts dibutylphthalate and 1% diphenylamine when fired in the 7 5 mm. French field gun model 1897, with the 13% pound projectile at the usual muzzle new velocity of 1955 feet per second. For this articular gun and projectile the amount of ibutylphthalate may be reduced to i parts, the nitrocellulose content being increased to 86 parts and flashless results still be obtained. However, it is preferable to use 5 parts of dibutylphthalate when flashless results are desired in this gun because of providing greater margin of safety as regards fiashlessness.

In some guns fiashless results may be obtained by increasing the amount of dibutylphthalate as illustrated by the following com-' positions:

Nitrocellulose of t 1 mm Di he 1 high nitrogen Dinitrotoluene l u y p a p content late amine parts 10 parts 7 parts lpart .82 parts 10 parts 8 parts 1 part 80 parts "I 10 parts 10 parts 1 part However, the use of too much. dibutyl late and 1 part diphenylamine and are preferred for use in a number of guns where flashless results are either not desired or where fiashlessness is a secondary conideration to other properties. For example, a powder of the composition 87 parts of nitrocellulose of 13.15% nitrogen, 10 parts dinitrotoluene, 3 parts of dibutylphthalate and 1 part of diphenylamine gives very satisfactory ballistic results in the larger guns, particularly on account of slightly increased potential and is also entirely suitable for use in smaller guns where fiashlessness is not desired, although in some of the smaller guns this composition gives flashless results.

The manufacture of the powder requires no special skill. The nitrocellulose is dehydrated with denatured ethyl alcohol of suitable grade and then colloided. in a suitable mixer with the addition of ether. There is added in the ether or directly to the mixer, the dinitrotoluene and the dibutylphthalate. Due to the solvent action of the latter two ingredients, the amount of ether and alcohol required is somewhat less than usually used for nitrocellulose powders not containing these ingredients. Acetone may be used to replace all or part of the ether. DiphenyL amine is usually added as a stabilizer and is usually dissolved in the ether. The colloid may be pressed either in cylindrical grains with one or more perforations or without perforations, or in the ribbon or strip form of grain or any other kind.

The grains of powder aregiven thorough perature maybe used without injury to thechemical sta lity of the powder.

As many. apparetnly widely different embodiments of this invention may be made without departing from the spirit thereof, it is to be understood that I do not limit myself.

to the foregoing examples'or descriptions except as indicated in the following patent claims:

I claim:

1. A ropellent powder, capable of being water 'ried, comprising nitrocellulose incorporated with a deterrent explosive'and aflash-eliminant ingredient, each of which when in liquid form has a substantial solvent action on the nitrocellulose the deterrent explosive being present in greater amount than the flash-eliminant ingredient.

2. A propellent powder, capable of being Water dried, comprislng nitrocellulose incorporated with a nitro-aromatic compound'and a flash-eliminant ingredient, each of which when in liquid form has a substantial solvent action on the nitrocellulose the deterrent explosive being present in greater amountthan the flash-eliminant ingredient.

3. A propellent powder, capable of being water dried, comprising nitrocellulose incorporated with a nitro-aromatic compound and a flash-eliminant ingredient, each of which when in liquid form has a substantial solvent action on the nitrocellulose, and each of which is substantially insoluble in water, the-deterrent explosive being present in greater amount than the fiash-eliminant ingredient.

4. A propellent powder, capable of being.

water dried, containing nitrocellulose, a polynitrotoluene, and a dialkyl phthalate.

5. A propellent powder, capable of being water dried, comprising nitrocellulose, an organic nitro-compound other than nitrocellu-v lose which is substantially non-hygroscopic and water-insoluble and which when in liquid form has a substantial solvent action on nitrocellulose, and an alkyl ester of an organic acid, said ester having flash-eliminating properties and being further characterized by havingin liquid form a substantial solvent action on nitrocellulose, a low volatility when colloided with nitrocellulose, and

by being substantially insoluble in water, and

substantially non-hygroscopic;

6. A propellent powder, capable of being water dried, comprising nitrocellulose having incorporated therein a nitro-aromatic compound, and a flash-eliminant in .;.l30

cut, the nitroaromatic compound and the water dried, containing nitrocellulose, dini- 10. A nitrocellulose trotoluene and dibutyl phthalate.

9. A propellent powder, capable of being water dried, containing nitrocellulose, dinitrotoluene, dibutyl phthalate and diphenylamine.

propellent powder,

I the hygroscopicity of which is depressed below that of the nitrocellulose itself by a mixture incorporated therein of a nitro-aromatic compound and a flash-eliminant ingredient, both of which when liquid have substantial solvent action on the nitrocellulose, the nitroaromatic compound being present in greater amount than the flash-eliminant ingredient.

11. A propellent powder as defined in claim 1 in which at least a substantial part of the nitrocellulose has a nitrogen content of 12.85 per cent to 13.50 per cent.

12. A propellent powder as defined in claim 2 in which at least a substantial part of the nitrocellulose has a nitrogen content of 12.85 per cent to 13.50 per cent.

13. A propellent powder as defined in claim 3 in which at least a substantial part of the nitrocellulose has a nitrogen content of 12.85 per cent to 13.50 per cent.

14. A propellent powder as defined in claim 4 in which at least a substantial part of the nitrocellulose has a nitrogen content of 12.85 per cent to 13.50 per cent.

15. A propellent powder as defined in claim 5 in which at least a substantial part of the nitrocellulose has a nitrogen content of 12.85 per cent to 13.50 per cent.

16. A propellent powder as defined in claim 6 in which at least a substantial part of the nitrocellulose has a nitrogen content of 12.85 per cent to 13.50 per cent.

17. A propellent powder capable of being water dried, containing nitrocellulose, in combination with a flash eliminant taken from a group consisting of dibutyl phthalate. diethyl phthalate, dibutyl tartrate, ethyl palmitate, and acetyl-laurin, in which at least a substantial part of the nitrocellulose has a nitrogen content of 12.85 per cent to 13.50 per cent. I

18. A propellent powder as defined in claim 1 in which at least a substantial part of the nitrocellulose .has a nitrogen content of from 13.05 per cent to 13.25 per cent.

A propellent powder as defined in claim 2 in which at least a substantial part of the nitrocellulose has a nitrogen content of from 13.05 per cent to 13.25 per cent.

20. A propellent powder as defined in claim 3 in which at least a substantial part of the nitrocellulose has a nitrogen content of from 13.05 to 13.25 per cent.

21. A propellent powder as defined in claim 4 in which at lease-a substantial part of the nitrocellulose has a nitrogen content of from 13.05 to 13.25 per cent.

22. A propellent powder as defined in claim .5 in which at least a substantial part of the nitrocellulose has a nitrogen content of from. 13.05 to 13.25 per cent.

23. A propellent powder as defined in claim 6 in which at least a substantial part of the nitrocellulose has a nitrogen content of from- 13.05 to 13.25 per cent.

24. A propellent powder as defined in claim 1 in which at-least a substantial part of the nitrocellulose hasa nitrogen content greater than 12.85 percent.

25. A propellent powder as defined in claim 2 in which'at least a substantial part of the nitrocellulose has a nitrogen content greater than 12.85 per cent.

26. A propellent powder as defined in claim 3 in which at least a substantial part of the nitrocellulose has a nitrogen content greater than 12.85per cent. 7

27. A propellent powder as defined in claim 4 in which as least a substantial part of the nitrocellulose has a nitrogen content greater than 12.85 per cent.

28. A propellent powder as defined in claim 5 in which at least a substantial part of the nitrocellulose has a nitrogen content greater than 12.85 per cent.

29. A propellent powder as defined in claim 6 in which at least a substantial part of the nitrocellulose has a nitrogen content greater than 12.85 per cent.

30. A propellent powder capable of being water dried, containing nitrocellulose, in combination with a flash eliminant taken from a group consisting of dibutyl phthalate, diethyl phtllalate, dibutyl tartrate, ethyl palmitate, and acetyl-laurin, in which at least a substantial part of the nitrocellulose has a nitrogen content of from 12.85 per cent to 13.35 per cent.

31. A propellent powder capable of being water dried. containing nitrocellulose, incorporated with a flash eliminant taken from a group consisting of dimethyldiphenylurea, diethyldiphenylurea, phenylurea.

32. A propellent powder, capable of being water dried, containing nitrocellulose, having incorporated therein dinitrotoluene, and a member of a group consisting of dimethyland methylethyldidiphenylurea, diethyldiphenylurea and methylethyldiphenylurea, as a flash ehmlnant, the dinitrotoluene being present in greater quantity than the flash-eliminant ingredient.

33. A propellent powder caplable of being water dried, contaimng nitroce ulose, having incorporated therein dinitrotoluene, and a flash-eliminant taken from a group consisting of dimethyldiphenylurea, diethyldiphenylnrea and methylethyldiphenylurea, in least a substantial part of the nitrowhich at cellulose has a nitrogen content of 12.85 per cent to 13.50 per cent, the dinitrotoluene being present in greater qauntity than the flasheliminant ingredient.

34. A propellent powder capable of being water dried, containing nitrocellulose, having incorporated therein dinitrotoluene, and a flash-eliminant taken from a group consisting of dimethyldiphenylurea, diethyldiphenylurea and methylethyldiphenylurea, in which at least a substantial part of the nitrocellulose has a nitrogen content of 13.05 per centto 13.25 per cent, the dinitrotoluene being present in greater quantity than the flasheliminant ingredient.

35. A propellent powder capable of being water dried, containing nitrocellulose, having incoporated therein dinitrotoluene, and a fiash-eliminant taken from a group consisting of dimethyldiphenylurea, diethyldiphenylurea and methylethyldiphenylurea, in which at least a substantial part of the nitrocellulose has a nitrogen content greater than 12.85 per cent, the dinitrotoluene being present in greater quantity than the flash-eliminant ingredient.

36. A nitrocellulose propellent powder containing nitrocellulose, dinitrotoluene and dibutylphalate, and having a hygroscopicity at a relative humidity of 7 0 per cent and. at a temperature of 30 C. below 1 per cent.

In testimony whereof, I afiix my signature.

. RlCHARD GEORGE WOODBRIDGE.