US647420A - Process of increasing stability of nitrocellulose. - Google Patents

Description

' UNITED STATES PATENT @rrrce.

ALFRED LUCK, or DAit'i'FORD, AND CI-IARL :s F. onoss, OF- LONDON; ENGLAND.

PROCESS O INCREASING STABILITY OF NITROCE-LVLULOSQE;

STECIFIGATION forming part of Letters Patent N 0. 647,420, dated April 10, 1900. Application filed March 27, 1899. Renewed Maroh 9, 1900. Serial No. 8,078. (No speeimensi) To (1.1], whom, it ntrty concern:

Be it known that we, ALFREi) LUCK, chemist, residing at Brencote, Dartford, in the county of Kent, and CHARLES FREDERICK CROSS, chemist, residing at 4 New Court, Carey street, London, England, citizens of England, have invented a certain new and useful Process for Increasing Stability of Nitrocellulose, (for which we have made application for a patent in Great Britain, No..

18,868, dated September 3, 1808,) of which the following is a specification.

Our invention relates to a process for rendering cellulose nitrates stable, this process being based upon observation of the nature and properties of impurities eliminated from nitrocellulose under the action of diluted solvents. The solutions thus obtained, when freed from any dissolved nitrate of cellulose by further. dilution and filtration, are found to contain an acid substance or substances which unite with metallic bases, such as lead oxide, forming insoluble compounds. These precipitates when dried and analyzed are found to contain ahigh proportion of the metallic oxide-for example, three per cent. of PbO-aud they also contain nitric nitrogenfor instance, three per cent. N, which gives them the characteristics of explosive bodies. It appears that when these acid compounds, which are present in the original gnncotton,

-are combined with basic oxides they are rendered relatively inert and incapable of upset ting the stability of the guncotton. This result is brought about by treating the cellulose nitrates with solutions of the metallic salts. These may be dilute aqueous solutions, or the action may be carried out in presence of acetone. guncotton is digested at 80 to 100 centigrade with sufiicient quantity of a one-per-cent. solution of lead acetate or zinc chloride to entirely cover the guncotton. After thirty to sixty minutes digestion the excess of solution is removed and the nitrate is thoroughly washed until it is free from all traces of the soluble metallic salt, or the guncottou maybe covered with acetone diluted by twioeor thrice its weight of alcohol, and containing also the metallic salt in a one-per-cent. solution added to the extent of abontene per cent.

'magnesium\ carbonates,

When no acetone is present, the

by weightof the diluted acetone. The digestion in this case is effected at ordinary tern? perature in about half an hour, and then the solution is drained 0% and the nitreate is washed with water in successive small quantities until the bulk of the acetone is removed, the wash-waters being retained for the recovery or further use of the acetone. The product is then exhaustively washed. '4

The product of the treatment retains about two per cent. of the basic oxide (PbO) in combination with the acid groups before mentioned. We have obtained products showing satisfactory stability by treating cellulose nitrates with salts of lead, zinc, cadmium, calcium, barium, magnesium, and other metals. The most satisfactory results are obtained, by using'zinc, magnesium, and lead salts. NVe prefer to use the salts of these metals with acids of low hydrolizing function, such as acetates. We are aware that certain metallic compounds have been used in association with guncottons with a view to increase their stability. Of these we mayinstance calcium and which are in some cases addedfor the purpose to the explosive nitrate, but more often find their way into the product as the result of the boiling and washing with ordinary water. ride has also been added to guncottons, and the presence of this salt has been assumed to raise the stability of the explosive; but this conclusion has been shown to result from an interference of the mercury salt with the chemical reactions involvedin the/, usual heat test. These facts are fully s 't forth in the recent publications of Simon homas, Zeits-cll-riff, Augeu'a-ndte Ojtemz'c for 1898, pp.

Mercuric chlo- 1003-6 and 1027-31, which contains no sugized, nor of such treatment as we propose with metallic salts for the purpose of bringing them into a relatively inert form by combination with'basic metallic oxides.

Havingthus described the nature of this invention and the best means we know of carrying the-same into practical eifechwe claim- The herein-described process for increasing the stability of nitrocellulose, which con:

'Sists in freeing the nitrocellulose from the ni- I our hands in presence of two subscribing wittmting acid, treating it with a solution of nesses. acetone and metallic salts, and alcohol, and ALFRED LUCK. washing the nitrocellulose, in successive i CHARLES F. CROSS. 5 washes to removethe acetone, substantially Witnesses:

as specified. 4 JOSEPH LAKE,

In testimony whereof we have hereunto set GERALD L. SMITH.