US1924465A

US1924465A - Process of producing propellent powder

Info

Publication number: US1924465A
Application number: US639838A
Authority: US
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1932-10-27
Filing date: 1932-10-27
Publication date: 1933-08-29
Anticipated expiration: 1950-08-29

Description

Patented Aug. 29, 1933 UNITED STAT- s "1,924,465 w v .raocrs's or PRODUCING PROPELLENT POWD Oliver J. Teeple,.Jr., deceased, late 01' Cragmere, Del., by Ella E. Teeple, administratrix, Cragmere, DeL,

assignor to E.

I. du Pont de Nemours &Company, Wilmington, Del., a corporation of Delaware No Drawing. Application October 27, 1932 Serial No. 639,838

21 Claims;

ders containing nitroglycerin have been made by a variety of processes, of which the following brief descriptions will be illustrative.

For example, in the manufacture of nitroglycerin powders of the Cordite type, the previously dried or dehydrated nitrocellulose is gelatinized in a mixer with nitroglycerin dissolved in acetone, at which time petroleum jelly and other ingredients may be added. vAfter mixing, the colloid is extruded from a press in the forms of length and dried.

In the manufacture of powder of the Ballistite type it is customary to suspend the nitrocellulose in water, and then add nitroglycerin with or without otheringredients, and to continue the agitation-until the nitroglycerin is absorbed by the nitrocellulose according to the well known process of Lundholm and Sayers, U. S. Patent 438,816. The resulting wet paste, as it is commonly termed, is then freed of water, and aged for a period of about seven days to permit further gelatinization of the nitrocellulose by the nitroglycerin. Final gelatinization is accomplished by passing the material through a series of rolls which may or may not be heated. Prior to passing through the final or finishing rolls the gelatinized material may or may not be colloided with acetone in a mixer in order to make the composition softer and to facilitate subsequent rolling into thin sheets of more or less definite thickness. The sheets are cut into grains of the desired size which are dried to remove volatile solvent, if present, glazed and sieved.

Another process which has been used for the manufacture of nitroglycerine powders without volatile solvent is that of Claessen, in which about '70 parts of low viscosity nitrocellulose, 23 parts of nitroglycerin, and '7 parts of methylethyldiphenylurea are colloided in a mixer and then pressed through dies into cords, both mixer and press being heated in order to increase the plasticity of the colloided mass.

Abel, in British Patent 3,652.01 1867, states that he impregnates either partially or completely with what is well known as nitroglycerin cords or ribbons which are cut to the desired granulated or molded masses of guncotton either such as are produced according to the specification of Abels former British Patent 1,102 of 1865, or combined with other materials by either of the processes before described. In British Patent 1,102 of 1865 Abel disclosed re ducing guncotton to a pulp, and consolidating such pulp with or without the aid of pressure into the form of sheets, discs, granules, cylinders, or other solid forms, either with or without the admixture of binding materials.

In British Patent 19,068 of 1891, Curtis and Andre surface treatnitrocellulose powder grains with a solvent for the same in which nitroglycerin may be dissolved.

Maxim in British Patent 15,499 of 1897 applies a size consisting of soluble pyroxylin and nitro-. glycerin, preferably in about equal proportions by-weight, dissolved in wood alcohol or other suitable solven to nitrocellulose in paper or paper board form and to powder grains of the Cordite or other type.

In the manufacture of powders of the nitroglycerin type according to any or all of the foregoing methods, the operations of mixing, rolling, pressing and granulation of nitroglycerin-nitrocellulose compositions, or the treatment of sheets of nitrocellulose or nitrocellulose powder grains with nitroglycerin have involved certain risks and hazards.

One of the objects of my present invention is to reduce the hazard of manufacture of powders containing liquid explosives such, for example, as nitroglycerin. A further object of my invention is the manufacture of propellent powders having improved ballistic properties. Other objects will appear as the description proceeds.

These objects are accomplished by the following invention: In the process, according to my invention, I start with fabricated nitrocellulose 95 powder grains, which may or may not contain a substantial amount of the volatile solvent used in their manufacture. These nitrocellulose powder grains may be made by any of the well known processes. Thus, for example, they may be pow- 100 der grains formed by colloiding nitrocellulose in the presence of water or solution of barium and potassium nitrates with a water insoluble solvent such as butyl acetate, which may or may not be diluted with benzol, and boiling ofi the 105 solvent during the formation of the powder grains. or the powder grains may be formed by the extrusion of colloided or partially colloided nitrocellulose from a press in the form of rods, tubes, ribbons, etc, or by means of rolls formed 110 methylethyldiphenylurea,

into sheets. after which the powder is cut into grains of such dimensions that after subsequent treatment the resulting powder'grains will be suitable for the ammunition and guns in which the powder is to be used.

The nitrocellulose powder grains which I use may or may not contain deterrents such as dinitrotoluol or other nitrohydrocarbons, tetra substituted ureas such as diethyl, dimethyl, or dibutylphthalate or other phthalic acid esters. In general, I may use any substantially non-volatile deterrent having solvent action for a portion or all of the nitrocellulose present. The powder composition will preferably contain diphenylamine or other stabilizer.

It iswell known (from Lundholm British Patent 10,376 of 1889, lines 8 to 11) that it is a property possessed by cellulose nitro-derivatives, of combining with or absorbing nitroglycerin in a uniform vmannervlhen agitated therewith in the presence of water. I have found that when nitrocellulose powder grains are used instead of V nitrocellulose the absorption of nitroglycerin by the powder grains takes place at a relatively slow rate. Furtherrnore, that the rate at which the nitroglycerin is absorbed is materially affected by the nature of the powder grains used and is materially increased by raising the temperature of the water medium-in which the powder grains are agitated. I have further found that the complete absorption of nitroglycerin by nitrocellulose powder grains takes from several hours to several days to go to completion depending on the size of the powder grains and character of the colloid. The object of my invention is, therefore, to cause the absorption of the nitroglycerin by the powder grains to go to completion so that any aging treatment, to which the powder may be subsequently subjected while stored in bulk or in loaded ammunition, will be without effect on the ballistics of the powder.

One process of manufacture by which these objects are accomplished may be substantially as follows: v

The nitrocellulose powder grains which I will hereinafter refer to as the base'powder grains are vigorously agitated in water. A ratio of water to powder grains of about 4 to 1 by weight gives satisfactory results but I do not limit myself to any particular ratio of water to powder. While the base powder grains are being agitated by mechanical means or byair or by a combination of b oth, nitroglycerin is added slowly at such a rate that it is absorbed by the base powder grains without causing them to become stuck or massed together. I have found that the addition of nitroglycerin to give 10 to 40 per cent. by. weight in the finished powder requires from one to eight hours depending on the size and character of the powder grains, the rate of absorption, and the temperature of the water medium, the larger powder grains absorbing the nitroglycerin much more slowly than the smaller grains. However, at the end of this period while the nitroglycerin has been absorbed by the base powder grains, it has not thoroughly penetrated the same. If the agitation in water is stopped at this point the individual powder grains will tend to stick together in more or less irregular masses. Therefore, the

agitation of the powder grains containing nitroglycerin is continued for a number of hours in the water medium in order to cause the penetration of the powder grains by the nitroglycerin to go to completion. In the case of relatively small powder grains intended'for shotguns, revolvers, pistols and small caliber sporting rifles, I have found that at least threehours of treatment in warm water at 70 to Fahrenheit is required, after the addition during one to two hours of 30 parts of nitroglycerin per 70 parts by Weightof base powder grains, in order to obtain complete absorption of the nitroglycerin not only to the point where the grains do not stick together, but also to the point at which the penetration of the powder grains by the nitroglycerin has been caused to go to completion. In the case of larger powder grains intended for high velocity rifles, I have found that eight hours of treatment in hot water at 140 Fahrenheit with agitation is required for the absorption of about 30 parts of nitroglycerin by the '70 parts by weight of'base rifle powder grains and that in addition it is desirable to supplement this treatment by at least two days additional treatment in hot water at about 130 Fahrenheit with or without agitation. The following results of analysis shows the substantially uniform penetration of the nitroglycerin in powder grains which were given the aforementioned treatment:

Percentage of nitroglycerin Outer portion of powder grain 31.13

Middle portion of powder grain 31. 36 Inside portion of powder grain 26. 43

illustrative, may be regarded as the minimum treatments required by powder grains suitable for shotguns and high velocity rifles, respectively.

After the absorption process has been completed, the powder grains are'subjected to an air drying treatment to remove excess moisture',-and the resulting powder grains are preferably glazed with graphite and sieved.

The nitrocellulose of which the base powder grains are made may be of the so-called "soluble type, that is, soluble in a mixture of two parts of ethyl ether and one of ethyl alcohol, or a blend of soluble nitrocellulose with nitrocellulose substantially insoluble in this mixture.

Inorganic nitrates such as barium and potassium nitrates may be incorporated in the base powder grain, but as some of the nitrates may be extracted from the powder during the agitation of the same in water while absorbing the nitroglycerin, I prefer to spray the water soluble salts on to the final powder before glazing with graphite.

While I prefer to incorporate any deterrent material used with the nitrocellulose in the base powder grain, it should be understood that in certain cases, provided the melting points of the deterrents are suitable, it may be advantageous to add them with the nitroglycerin during the absorption process. Furthermore I may apply all or part of the deterrent material to the final powder containing nitroglycerin by one of the well known surface impregnating processes to produce a more progressive burning powder.

In place of using nitroglycerin I may use other liquid explosives of relatively high potential. For example, I may use the nitric esters of glycol or mixtures of these with the nitric esters of glycerol, or with the nitric esters mentioned subsequently. However, I do not limit myself to the nitric esters of glycol and glycerol, or the nitrated esters of an organic acid and glycol or glycerol,

-trate, sorbitol hexanitrate and others.

as I have found very suitable the nitrated lactic esters of glycol or the nitrated lactic esters of glycerol as described in U. S. Patent 1,792,515 to Stine and Burke. I have also found that the nitric esters of other polyhydric alcohols such as sorbitoi, xylitol, arabitol, mannitol, dulcitol ormixtures of these are suitable provided that they are either liquid at ordinary temperatures or may be liquefied without hazard in the presence of hot water at a temperature of less than 212 F. Particularly, I have found suitable the nitric esters of polyhydric alcohols such as xylitol pentanitrate, dulcitol hexanitr'ate, sorbitol pentani- Substances of this type may be used alone or may be dissolved in glycol dinitrate, glycerol trinitrate or ethylene diglycol dinitrate.

In the manufacture of propellent powders according to this invention the amount of liquid explosive which I may use may vary within wide limits depending on the ballistic results desired. For example, I may cause the powder grains to absorb as little as 5% or as much as 50% of the liquid high explosive depending on the potential, density, grain size, web thickness, etc., of the nitrocellulose base powder grains on the one hand and the potential of the liquid high explosive on the other hand, besides the ballistic results desired. In general I have found that the addition of quantities less than 5% of the liquid high explosive has so little effect that it is not worth considering, and that the addition of more than 50% produces a product which is not entirely satisfactory for use as a propellent powder. I preferably use more than 15% of the liquid high explosive.

Since the absorption of nitroglycerin by the nitrocellulose base powder grains takes place in the presence of water the hazard of manufacture of a nitroglycerin containing powder is very much reduced. Furthermore, the actual time of manufacture and handling of a smokeless powder containing nitroglycerin is materially reduced by the above described process.

I do not limit myself to the manufacture of a nitroglycerin containing powder for small arms as it is obvious that the process of manufacture is applicable to powders for ordnance, especially for the smaller guns where the grain sizes are relatively small.

As many apparently 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.

Iclaim:

1. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with a liquid explosive material of relatively high potential that is substantially insoluble in water and is a solvent for a portion of the powder, until the nitrocellulose is substantially impregnated with the material.

2. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with a liquid explosive material of relatively high potential that is substantially insoluble in water and is a solvent for a portion of the powder, and continuing the treatment in the water medium until the penetration of the nitrocellulose base grain powder by the liquid explosive material goes to completion.

3. The process of producing a propellent powder which comprises treating awater-suspension of a nitrocellulose base grain powder with 5 to50 per cent. of a liquid explosive material of relatively high potential that is substantially insol-' uble in water and is a solvent for a portion of the powder, until the nitrocellulose is substantially impregnated with the material.

4. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with more than 15 per cent. of a liquid explosive material of,relatively high potential that is substantially insoluble in water and is a solvent for a portion of the powder, until the nitrocellulose is substantially impregnated with the material.

5. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with an organic nitrate of relatively high potential which is at least liquid in water at a temperature of less than 100 C. and which is substantially insoluble in water.

6. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with 5 to 50 per cent. of an organic nitrate of relatively high potential which is at least liquid in water at a temperature oi less than C. and'which is substantially insoluble in water. 7

7. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with more than 15 percent. of an organic nitrate of relatively high potential which is at least liquid in water at a temperature of less than 100 9. and which is substantially insoluble in .water.

8. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with a liquid nitric ester of a polyhydric alcohol until the nitric ester is substantially all absorbed by the powder grains.

9. The process of producing a propellent powder which comprises treating a. water-suspension of a nitrocellulose base grain powder with a liquid nitric ester of polyhydric alcohol until the nitric ester which has been absorbed by the powder grain has completely, penetrated the same.

10. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with 5 to 50 per cent. of a liquid nitric ester of a polyhydrlc alcohol until the nitric ester is substantially all absorbed by the powder grains.

11. The process of producing a propellent powder which comprises treating a water-suspenpension of a nitrocellulose base grain powder with more than 15 per cent. of a liquid nitric ester of a polyhydric alcohol until the nitric ester is substantially all absorbed by the powder grains.

12. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with the nitric ester of a straight-chain polyhydric alcohol, and agitating the mixture until the polyhydrlc ester has been substantially absorbed by the powder grains.

18. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with a nitrated glycerol, and agitating the mixture until the glycerol ester has been substantially absorbed by the powder grains.

14. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with a nitrated glycol, and agitating the mixture until the glycol ester has been substantially absorbed by the powder grains.

15. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with a nitrated polyhydric alcohol having from 4 to 6 carbon atoms, and agitating the mixture until the polyhydric ester has been substantially absorbed by the powder grains.

16. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with a nitric ester of an ester of lactic acid and a polyhydric alcohol, and agitating the mixture until the nitrated polyhydric ester has been completely absorbed by the powder grains.

17. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with a glycol, and agitating the mixture until the nitrated ester of lactic acid and ethyleneglycol has been completely absorbed by the powder grains.

19. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with glycerylmonolactate trinitrate and agitating the mixture until the glycerylmonolactate trinitrate has been completely absorbed by the powder grains.

20. The process of producing a propellent powder which comprises treating a water-suspension of a nitrocellulose base grain powder with glycolmonolactate dinitrate, and agitating the mixture until the glycolmonolactate dinitrate has been completely absorbed by the powder grains.

21. The process of producing a propellent powder which comprises treating a water-suspension' of a nitrocellulose base grain powder with a compound comprising a nitrated ester of lactic acid and a polyhydric alcohol having from two to four hydroxyl groups which is capable of colloiding nitrocellulose, and agitating the mixture until the nitrated ester has been completely absorbed by the powder grains.

EILAE. TEEPLE, Administratria: of the Estate 01 Oliver J. Teeple,

J12, Deceased.