US 2696430 A
Description (OCR text may contain errors)
United States Patent Ofi 2,696,430 Patented Dec. 7, 1954 ice STABILIZERS FOR NITRO-CELLULOSE MIXTURES John A. Gallaghan, Indian Head, Md., and Irving Pincus, State College, Pa., assignors to the United States of America as represented by the Secretary of the Navy No Drawing. Application May 3, 1950, Serial No. 159,872
7 Claims. (Cl. 525) (Granted under Title 35 U. S. Code (1952), see. 266) 4-nitroaniline, incorporating them into powders, to lower the melting point, and to improve the plasticizing qualities of these compounds.
Other objects of the invention will appear in and be apparent from the specification.
In the preparation of experimental powders for possible stabilizers, several tests are useful to eliminate all but the most promising for addition to the nitrocellulose. The results of these tests for certain of the compounds screened are tabulated for comparison. Samples used in the 134.5 C. heat test are formed by mechanically extruding 12.6 percent pyrocotton with one-half /2) percent stabilizer, using ether and alcohol as a solvent. The product is allowed to stand one day in air and is then placed in a vacuum oven for eight (8) hours at 40 C. A standard 134.5 heat test and a 5 hour test are run on the sample. The nitrogen dioxide absorption and viscosity tests are conventional laboratory procedures for these purposes.
Screening tests for stabilizers N 02 Absorption at 25 0., Pressure in Heat Test Mercury Viscosity at 134.5 5 hour Change 1 Methyl Test, 10 1 10 (poises) Violet hrs. 1mm] seconds min. min. Final (mm') Diphenylamine 72 32 22 20 1. 5 Ethyl-Oentralite 72 63 48 37 34 g0 82 6 7 86 N -Methyl-4-nitro anilme 72 0 0 0 58 103 5 60 105 N-ethyl-4-n1tro aniline 72 7 1 0 5 1 Viscosity change at 0. for five days using an ethyl Cellosolve solution of cellulose nitrate The present method of stabilizing single base powders is by adding diphenylamine, and in double base powders by adding centralite. A disadvantage of using diphenylamine as a stabilizer is that it reacts with oxygen of the air and also with oxides of nitrogen to form black or dark colored dyes of unproved structures. It further reacts with nitrogen dioxide and nitric acid to form nitrogen monoxide gas. Centralite also reacts with nitrogen tetroxide to form nitrogen monoxide. Since it is the function of a stabilizer to remove these undesirable products, these materials are not as eflective in removing oxides of nitrogen as the chemicals herein disclosed.
The N-alkyl-nitroanilines which contain an alkyl group such as methyl, ethyl, isopropyl, etc., and contain a nitro group in the three or four positions on the benzene ring, when mixed in a nitro-cellulose powder, either single or double base, lead to a powder possessing superior stability. N-methyl-4-nitroaniline, N-ethyl-4-nitroaniline, N- is1opropyl-3-nitroaniline, N-butyl-3-nitroaniline are examp es.
An important object of the present invention is the substitution of from one-half to one percent (up to five percent) of N-ethyl-4-nitroaniline or N-methyl-4-nitroaniline or mixtures thereof in place of diphenylamine in single base nitro-cellulose powders and in place of ethyl centralite in double base nitrocellulose powders.
A further object of the invention is to produce a superior powder of improved stability which does not become discolored by oxidation impurities.
A still further object of the invention is to make the aniline nitrogen sufficiently neutral by the nitro group in N-alkyl-4-nitroanilines, so that it would be compatible with nitroesters and still be a strong absorbent of highly oxidized nitrogen atoms, such as nitric acid and nitrogen tetroxide.
Still a further object of the invention is to prepare a eutectic mixture of N-ethyl-4-nitroaniline and N-methyl- The control dropped an average of 30 poises for this period.
The results of the screening tests indicate that the N- alkyl mononitroanilines possess excellent stabilizing prop erties for single base powder. They efiiciently absorb nitrogen dioxide reducing little or none of it. They further do not aifect the viscosity of cellulose nitrate solution as much as diphenylamine. In the heat test which shows the time in minutes to decolorize methyl violet paper, they compare favorably with diphenylamine.
Double base powders were prepared by dissolving 60 percent cellulose nitrate (13.47% N), 39 percent nitroglycerine and 1 percent stabilizer in acetone and evaporating oif the acetone at room temperature. The products were extended through a micro-press and placed in a vacuum oven for 7 days at 45 C. The comparative results are shown as follows:
H120 t 610 C.
- eat es aeuum Stabfluer (Average) Stability Minutes Test Ethyl Centralite (Control).. 65 8. 32
N-Methyl-4-nitroanlline- 90 8. 37
N -Ethyl-4-nitroaniline 8. 45
third more effective than ethyl-centralite in the heat test and-areabout the sameintheNaQuum-tests, "andtheresiqub q ba e; pow ers is. thus Pre en ed .apnar nt y has improved and superior chara lemfliw, roduc ngia e er es lt than the ngredients-n w. cqrnmen y kno and used as stabilizers.
h invention described here nnay he manuia tq a d s b or o the GQ ernmww t e -niteds ate Amerce f r gove nmenta pun s; wi hout he: Paym t of ny w a s the eon arft erefq st b iz e mn isin an I l a ky troan line .Q n re han' pe ent b b l in com nati n withon qf the g o 9 96 919. ni re e'a d qellules nitrat tm ce in 1 h co hinat enz fi trocellul s .n wde am a k l- -nirroaml ae con itut a t b i er the or- 3. The combination of a nitrocellulose powder and a s a ilize ther i 9 materiah leqt d t am er up consisting of N-ethyl-4-nitroan i1ine and H l\I -methyL-4 nitroaniline of not more than 5 percent by bulk.
4. The combination of cellulose nitrate nitroglycerine powder and not more than five percent by. bulkpf N1 methyl-4-nitroaniline constituting a stabilizer'therefor;
5. A stabilizer for nitrocellulose powders comprising a mixture of"N'-ethyl-4-nitroaniline and N-methyl-4-nitroanilineof-not more than 5 percentfiby bulhiucorporate'd into a nitrocellulose powder with improved plasticizing qualities.
References Cited in the file or this patent .SIATESPATEN S Number. Name I Date 875.922 mes. a 7. 9 8 875,923 Holmes Jan. 7, 1908 1,329,212 Spelling et a1. Ian. 27, 1920 2,261,630 Regestein Nov. 4, 1941 2,323,948 Von-'Bramenet a1 July 13, 1943 2,378,594 Swan et a1. June 19, 1945 2,381,015 Von Bramenet a1 Aug. 7,1945 2,383,361 Basset a1. Aug..'21, 1945 F R N PATEN S.
Number Country Date 12,746 Great Britain of 1912 'DavisJohn' Wiley and Sons, 1943, N. Y., vol. II, pp. 269