US2337943A - Propellent powder process - Google Patents
Propellent powder process Download PDFInfo
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- US2337943A US2337943A US243767A US24376738A US2337943A US 2337943 A US2337943 A US 2337943A US 243767 A US243767 A US 243767A US 24376738 A US24376738 A US 24376738A US 2337943 A US2337943 A US 2337943A
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- 239000000843 powder Substances 0.000 title description 72
- 238000000034 method Methods 0.000 title description 29
- 230000008569 process Effects 0.000 title description 25
- 239000002904 solvent Substances 0.000 description 67
- 239000003795 chemical substances by application Substances 0.000 description 39
- 239000000243 solution Substances 0.000 description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 33
- 239000000020 Nitrocellulose Substances 0.000 description 24
- 229920001220 nitrocellulos Polymers 0.000 description 24
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Natural products CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 19
- 238000002485 combustion reaction Methods 0.000 description 19
- 239000000839 emulsion Substances 0.000 description 18
- 239000003607 modifier Substances 0.000 description 16
- 238000010521 absorption reaction Methods 0.000 description 13
- 238000013019 agitation Methods 0.000 description 13
- SNIOPGDIGTZGOP-UHFFFAOYSA-N Nitroglycerin Chemical compound [O-][N+](=O)OCC(O[N+]([O-])=O)CO[N+]([O-])=O SNIOPGDIGTZGOP-UHFFFAOYSA-N 0.000 description 12
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 12
- 239000002585 base Substances 0.000 description 12
- 229960003711 glyceryl trinitrate Drugs 0.000 description 12
- 239000000006 Nitroglycerin Substances 0.000 description 11
- 238000011282 treatment Methods 0.000 description 11
- 239000000084 colloidal system Substances 0.000 description 10
- 230000001681 protective effect Effects 0.000 description 10
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 9
- 239000002131 composite material Substances 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 8
- 239000006185 dispersion Substances 0.000 description 7
- 238000004381 surface treatment Methods 0.000 description 7
- 239000000725 suspension Substances 0.000 description 7
- 239000007788 liquid Substances 0.000 description 6
- 239000007900 aqueous suspension Substances 0.000 description 4
- 230000001804 emulsifying effect Effects 0.000 description 4
- 238000004581 coalescence Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000035515 penetration Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- DYSXLQBUUOPLBB-UHFFFAOYSA-N 2,3-dinitrotoluene Chemical compound CC1=CC=CC([N+]([O-])=O)=C1[N+]([O-])=O DYSXLQBUUOPLBB-UHFFFAOYSA-N 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- -1 al yl phthalates Chemical class 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 description 2
- DMBHHRLKUKUOEG-UHFFFAOYSA-N diphenylamine Chemical compound C=1C=CC=CC=1NC1=CC=CC=C1 DMBHHRLKUKUOEG-UHFFFAOYSA-N 0.000 description 2
- 239000003995 emulsifying agent Substances 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000011877 solvent mixture Substances 0.000 description 2
- WSLDOOZREJYCGB-UHFFFAOYSA-N 1,2-Dichloroethane Chemical compound ClCCCl WSLDOOZREJYCGB-UHFFFAOYSA-N 0.000 description 1
- LZDKZFUFMNSQCJ-UHFFFAOYSA-N 1,2-diethoxyethane Chemical compound CCOCCOCC LZDKZFUFMNSQCJ-UHFFFAOYSA-N 0.000 description 1
- ADCBKYIHQQCFHE-UHFFFAOYSA-N 1,3-dimethyl-1,3-diphenylurea Chemical compound C=1C=CC=CC=1N(C)C(=O)N(C)C1=CC=CC=C1 ADCBKYIHQQCFHE-UHFFFAOYSA-N 0.000 description 1
- DURPTKYDGMDSBL-UHFFFAOYSA-N 1-butoxybutane Chemical compound CCCCOCCCC DURPTKYDGMDSBL-UHFFFAOYSA-N 0.000 description 1
- MCIDYUGTJBLEST-UHFFFAOYSA-N 2,3-dinitrobenzaldehyde Chemical compound [O-][N+](=O)C1=CC=CC(C=O)=C1[N+]([O-])=O MCIDYUGTJBLEST-UHFFFAOYSA-N 0.000 description 1
- 241000416162 Astragalus gummifer Species 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920000084 Gum arabic Polymers 0.000 description 1
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N Methyl ethyl ketone Natural products CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 1
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 1
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical class O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 241000978776 Senegalia senegal Species 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 229920001615 Tragacanth Polymers 0.000 description 1
- 239000000205 acacia gum Substances 0.000 description 1
- 235000010489 acacia gum Nutrition 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 150000001447 alkali salts Chemical class 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 235000013877 carbamide Nutrition 0.000 description 1
- 235000014633 carbohydrates Nutrition 0.000 description 1
- 150000001720 carbohydrates Chemical class 0.000 description 1
- 239000005018 casein Substances 0.000 description 1
- BECPQYXYKAMYBN-UHFFFAOYSA-N casein, tech. Chemical compound NCCCCC(C(O)=O)N=C(O)C(CC(O)=O)N=C(O)C(CCC(O)=N)N=C(O)C(CC(C)C)N=C(O)C(CCC(O)=O)N=C(O)C(CC(O)=O)N=C(O)C(CCC(O)=O)N=C(O)C(C(C)O)N=C(O)C(CCC(O)=N)N=C(O)C(CCC(O)=N)N=C(O)C(CCC(O)=N)N=C(O)C(CCC(O)=O)N=C(O)C(CCC(O)=O)N=C(O)C(COP(O)(O)=O)N=C(O)C(CCC(O)=N)N=C(O)C(N)CC1=CC=CC=C1 BECPQYXYKAMYBN-UHFFFAOYSA-N 0.000 description 1
- 235000021240 caseins Nutrition 0.000 description 1
- 229920003086 cellulose ether Polymers 0.000 description 1
- 150000008280 chlorinated hydrocarbons Chemical class 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- UQXKXGWGFRWILX-UHFFFAOYSA-N ethylene glycol dinitrate Chemical compound O=N(=O)OCCON(=O)=O UQXKXGWGFRWILX-UHFFFAOYSA-N 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229940035429 isobutyl alcohol Drugs 0.000 description 1
- JMMWKPVZQRWMSS-UHFFFAOYSA-N isopropanol acetate Natural products CC(C)OC(C)=O JMMWKPVZQRWMSS-UHFFFAOYSA-N 0.000 description 1
- 229940011051 isopropyl acetate Drugs 0.000 description 1
- GWYFCOCPABKNJV-UHFFFAOYSA-N isovaleric acid Chemical compound CC(C)CC(O)=O GWYFCOCPABKNJV-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229920000609 methyl cellulose Polymers 0.000 description 1
- 239000001923 methylcellulose Substances 0.000 description 1
- 235000010981 methylcellulose Nutrition 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 238000006396 nitration reaction Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 125000005498 phthalate group Chemical class 0.000 description 1
- XNGIFLGASWRNHJ-UHFFFAOYSA-L phthalate(2-) Chemical compound [O-]C(=O)C1=CC=CC=C1C([O-])=O XNGIFLGASWRNHJ-UHFFFAOYSA-L 0.000 description 1
- 239000003380 propellant Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 150000005846 sugar alcohols Polymers 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- 150000003672 ureas Chemical class 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
- C06B21/0083—Treatment of solid structures, e.g. for coating or impregnating with a modifier
Definitions
- This invention relates to propelient powder and more particularly to an improved process for surface treating propellent powder grains in order to modify the characteristics thereof.
- the object oi'this invention is to provide a process for the surface treatment of powder grains by means of which the treating agent is uniformly distributed among the grains under treatment.
- the absorption oi treating agent by the grains may be made to occur as rapidly as desired. and the rate and extent of impregnation may be readily controlled.
- Such treating agents have been added to the smokeless powder base either during the manufacturing operation prior to the fabrication of the grains, as exemplified by the process dein British Patent No. 6,448 of 1892, or
- surface treatment of powder grains may be accomplished by means of an emulsion or dispersion of a combustion modifier in water, or by means of an emulsion or dispersion of a combustion modifier solution in water.
- the combustion modifier was extended with a volatile solvent for the same which was .cases there existed a tendency toward coalescence of the line globules of combustion modifier, or combustion modifier solution. to produce larger globules than were desirable, with the result that the application oi the treating agent was not uniform throughout the mass of grains being treated,
- a more specific object of the present invention is to provide a process oi suriace treating pro pellent powder grains wherein absorption of the treating agent is facilitated and the tendency of protective colloids and/or volatile non-solvents for the powder grains to inhibit absorption, overcome.
- absorption of surface treating -agents by propellent powder grains is facilitated and accelerated. and in cases where the surface treatment is carried out in the presence oi a protective colloid, or in the presence of a volatile solvent for the treating agent which is not a solvent for the powder grains.
- the tendency of those materials to inhibit a so ption is overcome by the use of a relatively small quantity of volatile solvent which itself is a solvent for nitrocellulose.
- the present invention contemplates the application of treating agents to smokeless powder grains according to a procedure in which the treating agent is applied to the grains in the form of a dispersion or emulsion of a composite volatile solvent solution.
- one component of the solvent is a water immiscible nonsolvent for the smokeless powder base, while another component is a solvent for the smokeless powder base.
- the powder grains are advantageously maintained in suspension in the treating bath as by vigorous agitation. Uniform distribution oi the treating agent among the powder grains and over the surfaces oi the individual grains is thus insured by the dilution or extension of the treating agent with a solvent and by maintaining such solution dispersed in the tom of fine globules throughout he re ns bath by adequate agitation.
- the use oi a protective colloid may irequently be desirable to decrease the tendency toward coalescence or the dispersed globules of treating agent ture oi two or more such substances.
- Suitable accelerators are nitroglycerin, nitroglycol, and
- nitric acid esters oi polyhydric alcohols
- nitrohydrocarbons such as dinitrotoluene
- non-volatile esters such as al yl phthalates, substituted ureas such as dimethyl-diphenyl-urea, and compounds at similar properties are suitable deterrents.
- the quantity of treating agent to be added to the powder base usually amounts to less than ten per cent by weight of the finished product. although the quantity at an accelerator such as nitroglycerin may be as high as fifty percent.
- the treating agent is extended by solvent which is a non-solvent for .the smokeless powder base.
- the treating agent is dissolved in a composite volatile solvent, one component of which is immiscible with water and is a non-solvent ior the smokeless powder base. while another component is a solvent for the powder base.
- the volatility oi the solvent mixture should be sufficiently high to permit the ready removal of the solvent from the grains following the surface-treatment and in general those with boiling points below about 150 C. have been found useiul.
- aromatic hydrocarbons such as benzene or toluene.
- chlorinated hydrocarbons such as ethylene chloride or trlchloroethylene
- solvent naphthas others such as isopropyi ether or normal butyl ether
- water-immiscible alcohols such as butyl or isobutyl alcohol.
- the quantity of such solvent that may be used with advantage depends on the quantity of treating agent it is desired to add to the grains, and may range from a weight equal to that of the treating agent when the latter amounts to tilt? percent the finished product to about ten to twenty times the weight of treating agent when one percent of the latter is being added.
- a volatile solvent for the smokeless powder base such as ethyl or isopropyl acetate. acetone; ethyl methyl or methyl isobutyl ketone. or ethylene glycol diethylether in the-case oi pyrocollodion type. of nitrocellulose. in an amount equal to 1596 to 100% of the amount of the above described non-solvent which is used.
- the quantity of solvent for the powder base may be varied according to the particular solvent used. the desired rate oi absorption. and the desired extent of penetration of the modtirer in the powder grains. Both the rate of abeorption and the extent of penetration are increased with increasing proportion of such solvent in the mixture. An excao of such solvent should Benerally be avoided since a tendency toward sticking and agglomeration of grains is caused thereby. while a quantity substantially less than the stated minimum has no appreciable eiiect.
- the solution of treating agent in the composite solvent may be emulsified by means oi-suitable agitation in water containing suincient protective colloid to maintain the resulting fine droplets of solution in dispersed form until absorbed during the surface treatment of the powder grains.
- the treatment is preferably carried out by suspending powder grains in water by vigorous agitation and adding the solution of combustion modifier, or a preformed emulsion of combustion modifier solution. to the bath as agitation is continued.
- the treatment may be carried out at ordinary room or higher temperatures as desired. absorption of the droplets of treating agent solution being more rapid the higher the temperature. A temperature of 50 to C. has been found'to give good results.
- nitrocellulose powder grains in the form of spherical droplets 0.010 inch in diameter resulting from the process described in U. 8. Patent No. 2,027,114 to Olsen. Tibbitts, and Kerone, is sued January 6, 1936, may be surface treated as iollows:
- 300 pounds oi powder grains are suspended by thorough agitation in 1200 pounds of water contained in a suitable jacketed vessel and hot water or steam is applied to the Jacket so that the temperature of the powder-water suspension is raised to 65 C.
- an emulsion consisting oi a solu-- tion of 5: pound of gum arable in pounds of water in which there has previously been dis persed. by means of vigorous agitation. fine globnice of a solution containing 83 pounds of nitroglycerine, 33 pounds of toluene. 3.5 pounds of dinitrotoluene and 16 pounds of ethyl acetate.
- the dispersed globules of solution are thus uniformly distributed among the powder grains and their composition is such that they are completely taken up by the powder grains within iliteen minutes after the addition.
- ethyl acetate or other nitrocelluloee sol-- vent which is.highly fluid.
- similarly dispersed droplets of solution remain unabsorbed by the powder grains even after sixty minutes agitation under the same conditions. when the desired extent of impregnation has been attained. as by continuing the agitation at 65 C. for thirty to sixty minutes. the suspension is cooled by passing cold water through the jacket. Less penetration oi the treating agent into the grains may be secured by decreasing the quantity oi nitrocellulose solvent. ethyl acetate in the present example.
- the powder grains are ireed of excess water as by centrifuging. after which they are washed with cold water. and dried by means or air at 50' C. Finishing treatments, such as glazing with graphite, may then be applied according to lmown methods.
- the stabilized aqueous emulsion oi the solution of treating agent may be prepared with the use of one or more of the known suitable emuisifyander agents as, for example. water-soluble gums such as gum arable and gum tragacanth. dextrln. starch. water-soluble cellulose ether: such as methyl cellulose containing 22-28% methoxyi. casein. bentonite; alkali salts of sulfated higher alcohols. and the like.
- the quantity of emulsifying agent is adjusted so that separation into the component phases will occur in about 15 to 30 minutes after agitation has stoppedr Ii desired. a portion of the emulsifying scent may be added to the suspension oi powder grains prior to the addition oi the emulsion oi the modtirer solution.
- Another example oi a process embodying the principles oi this invention comprise: the macetreatment oi powder grains prepared by ag omeration of fineIy-dlvided particles oi gelatinized nitrocellulose into clusters, which may range irom stitutea ior nitrocellulose such as nitroctarch or other nitrated carbohydrates, is likewise included within the scope oi this invention.
- the vehicle in a which the powder grains are suspended and in which the treating agent. or treating agent solutionisdispersedoremulslfledhasbeendeslgnated as water it is to be understood that the invention 0.006 'to 0.018 inch in average diameter. as deisnct limited to the use oi water as the treating scribed in the copending application oi Olsen. Tibhitts and Korean, Serial No. @0332. filed June 30, 1932. The treatment is carried out in accordance with the procedure of the first example bath. on the contrary.
- any liquid vehicle which is not a solvent ior the treating agent, and consequently a vehicle in which the treating agent, or-treating agent soluabove, except that the added emulsion consists of tion. may be dispersed or emulsified in the term finely di persed globules oi a solution containing 32 pounds oi nitroglycerin, 32 pounds oi toluene, 1'1 pounds oi dibutyl phthalate. and 6 pounds oi ethyl acetate in 120 pounds oi water containing 55 ct globules, may be employed in lieu oi water; provided. oi course. that the chosen vehicle is not itself a solvent ior the smokeless powder base. Consequently in interpreting the ioregoing depound oi gum arabic. The reduction in the scription andinconstruing thenppended claims.
- 300 pounds oi nitrocellulose powder grains as in the previous example may be suspended in 1,200 pounds oi water at 15'-30 C. while this suspension is vigorously agitated, there is added a solution containing '17 pounds of nitroglycerin.
- the P s comprising. treating smokeency to inhibit absorption of the treating agent by the powder grains the addition oi a small quantity, as ior example, ten to fiity per cent on the weight oi the treating agent, oi a solvent which itseli is a solvent ior nitrocellulose may be incorporated with the treating agent with the resuit that absorption of the treating agent is accelerated.
- the solvent for nitrocellulose may advantageously be of the type which is not substantially miscible with water.
- the process oi this invention may advantageously be utilized ior the application, by sur- 'iace-'-treatment, oi treating agents to any wpe. size or shape of smokeless powder base grains.
- Grains of partly or completly gelatlnized nitrocellulose oi any desired state oi nitration which have been iabricated by any suitable process may be treated in accordance with this process and less powder grains in a non-solvent bath with a dispersion oi a solution, immiscible with the bath, composed of non-volatile combustion modifier.
- the surface-treatment oi doublebase powder grains, containing nitrocellulose and nitroglycerin, as well as 01 grains containing sub- 4.
- aqueous dispersion oi a water immiscible solution oi deterrent and accelerator in a composite volatile solvent containing a solvent ior the powder grains and a non-solvent ior the same.
- the process comprising suspending smokeless powder grains in water, and adding to the suspension is stabilized emulsion of a solution of a non-volatile combustion modifier in a composite volatile solvent containing a solvent for nitrocellulose and a non-solvent for the same, which is immiscible with water and heating the mixture.
- the process or surface-treating smokeless powder grains comprising, dissolving a nonvolatile combustion modifier in a mixed volatile solvent composed of a solvent and 0! a nonsolvent for the powder grains to term a water immiscible solution. emuisiiying the said solution in water containing an emulsifying agent, adding the said emulsion to an aqueous suspension of the powder grains and driving on the volatile solvent.
- the process comprising, treating nitrocellulose grains with an emulsion 01 a solution of nitroglycerin in a volatile mixed solvent comprised of a solvent and a non-solvent for nitrocellulose, said solution being immiscible with the other phase of the emulsion and said other phase being a non-solvent for nitrocellulose the said emulsion being stabilized by means of a protective colloid.
- the step of overcoming the tendency of the stabilized emulsion to inhibit absorption of the combustion modifier by the powder grains which comprises, adding a small quantity of a volatile liquid which is a solvent for both the powder grains and the combustion modifier.
- the step of overcoming the tendency of the stabilized emulsion to inhibit absorption of the combustion modifier by the powder grains which comprises, adding a small quantity of a volatile liquid which is a solvent for boththe powder grains and the combustion modifier, said volatile liquid bein immiscible with the water phase of the emulson.
Description
Patented Dec. 28, 1943 PROPELLENT POWDER PROCESS Charles Earnest Silk. Alton. m, mi ito Western Cartridge Company, East Alton, 11L, a corporation of Delaware No Drawing. Application December 3. 1938, Serial No. 243.767
14 Claims.
This invention relates to propelient powder and more particularly to an improved process for surface treating propellent powder grains in order to modify the characteristics thereof.
The object oi'this invention is to provide a process for the surface treatment of powder grains by means of which the treating agent is uniformly distributed among the grains under treatment. the absorption oi treating agent by the grains may be made to occur as rapidly as desired. and the rate and extent of impregnation may be readily controlled.
In the course of the development of smokeless powders. a number of substances for improving the ballistic properties and/or storage characteristics have become known. These are generally substantially non-volatile compounds which are usually solvents for the smokeless powder base.
.Those agents which afiect the burning rate of the resistance to moisture absorption of powders may likewise be improved by the addition of an acc'elerator or deterrent, although substances are known which may be added to accomplish these results specifically. for example, diphenylamine for enhanced stability.
Such treating agents have been added to the smokeless powder base either during the manufacturing operation prior to the fabrication of the grains, as exemplified by the process dein British Patent No. 6,448 of 1892, or
they have been added to the fabricated grains by a process of surface-treatment, for example, as
taught in United States Patents No. 1,862,914 and In accordance with the process as described in the above mentioned United States Patent No. 1,955,927. surface treatment of powder grains may be accomplished by means of an emulsion or dispersion of a combustion modifier in water, or by means of an emulsion or dispersion of a combustion modifier solution in water. In the latter instance the combustion modifier was extended with a volatile solvent for the same which was .cases there existed a tendency toward coalescence of the line globules of combustion modifier, or combustion modifier solution. to produce larger globules than were desirable, with the result that the application oi the treating agent was not uniform throughout the mass of grains being treated,
and, in the case of large grains. was not uniform over the suriace oi the individual grains. While this tendency toward coalescence could be overcome by stabilizing the dispersion or emulsion as by use of a protective colloid, the presence of the protective colloid appeared to further increase the resistance toward absorption.
A more specific object of the present invention is to provide a process oi suriace treating pro pellent powder grains wherein absorption of the treating agent is facilitated and the tendency of protective colloids and/or volatile non-solvents for the powder grains to inhibit absorption, overcome.
Other objects will become apparent to those skilled in the art when the following description is read:
In accordance with the present invention absorption of surface treating -agents by propellent powder grains is facilitated and accelerated. and in cases where the surface treatment is carried out in the presence oi a protective colloid, or in the presence of a volatile solvent for the treating agent which is not a solvent for the powder grains. the tendency of those materials to inhibit a so ption is overcome by the use of a relatively small quantity of volatile solvent which itself is a solvent for nitrocellulose. More specifically one phase oi the present invention contemplates the application of treating agents to smokeless powder grains according to a procedure in which the treating agent is applied to the grains in the form of a dispersion or emulsion of a composite volatile solvent solution. In such case one component of the solvent is a water immiscible nonsolvent for the smokeless powder base, while another component is a solvent for the smokeless powder base. During the treatment, the powder grains are advantageously maintained in suspension in the treating bath as by vigorous agitation. Uniform distribution oi the treating agent among the powder grains and over the surfaces oi the individual grains is thus insured by the dilution or extension of the treating agent with a solvent and by maintaining such solution dispersed in the tom of fine globules throughout he re ns bath by adequate agitation. The use oi a protective colloid may irequently be desirable to decrease the tendency toward coalescence or the dispersed globules of treating agent ture oi two or more such substances. Suitable accelerators are nitroglycerin, nitroglycol, and
other nitric acid esters oi polyhydric alcohols while nitrohydrocarbons such as dinitrotoluene.
non-volatile esters such as al yl phthalates, substituted ureas such as dimethyl-diphenyl-urea, and compounds at similar properties are suitable deterrents. The quantity of treating agent to be added to the powder base usually amounts to less than ten per cent by weight of the finished product. although the quantity at an accelerator such as nitroglycerin may be as high as fifty percent.
In accordance with this invention where the treating agent is extended by solvent which is a non-solvent for .the smokeless powder base. the treating agent is dissolved in a composite volatile solvent, one component of which is immiscible with water and is a non-solvent ior the smokeless powder base. while another component is a solvent for the powder base. The volatility oi the solvent mixture should be sufficiently high to permit the ready removal of the solvent from the grains following the surface-treatment and in general those with boiling points below about 150 C. have been found useiul. As illustrating some of the suitable water-immiscible non-solvents may be mentioned aromatic hydrocarbons such as benzene or toluene. chlorinated hydrocarbons such as ethylene chloride or trlchloroethylene, solvent naphthas, others such as isopropyi ether or normal butyl ether, and water-immiscible alcohols such as butyl or isobutyl alcohol. The quantity of such solvent that may be used with advantage depends on the quantity of treating agent it is desired to add to the grains, and may range from a weight equal to that of the treating agent when the latter amounts to tilt? percent the finished product to about ten to twenty times the weight of treating agent when one percent of the latter is being added. I
To complete the formation of the treating agent solution. there is added a volatile solvent for the smokeless powder base such as ethyl or isopropyl acetate. acetone; ethyl methyl or methyl isobutyl ketone. or ethylene glycol diethylether in the-case oi pyrocollodion type. of nitrocellulose. in an amount equal to 1596 to 100% of the amount of the above described non-solvent which is used. The quantity of solvent for the powder base may be varied according to the particular solvent used. the desired rate oi absorption. and the desired extent of penetration of the modiiler in the powder grains. Both the rate of abeorption and the extent of penetration are increased with increasing proportion of such solvent in the mixture. An excao of such solvent should Benerally be avoided since a tendency toward sticking and agglomeration of grains is caused thereby. while a quantity substantially less than the stated minimum has no appreciable eiiect.
The solution of treating agent in the composite solvent may be emulsified by means oi-suitable agitation in water containing suincient protective colloid to maintain the resulting fine droplets of solution in dispersed form until absorbed during the surface treatment of the powder grains. The treatment is preferably carried out by suspending powder grains in water by vigorous agitation and adding the solution of combustion modifier, or a preformed emulsion of combustion modifier solution. to the bath as agitation is continued. The treatment may be carried out at ordinary room or higher temperatures as desired. absorption of the droplets of treating agent solution being more rapid the higher the temperature. A temperature of 50 to C. has been found'to give good results. v
As an illustrative embodiment of this invention. nitrocellulose powder grains in the form of spherical droplets 0.010 inch in diameter, resulting from the process described in U. 8. Patent No. 2,027,114 to Olsen. Tibbitts, and Kerone, is sued January 6, 1936, may be surface treated as iollows:
300 pounds oi powder grains are suspended by thorough agitation in 1200 pounds of water contained in a suitable jacketed vessel and hot water or steam is applied to the Jacket so that the temperature of the powder-water suspension is raised to 65 C. To this suspension there is rapidly added an emulsion consisting oi a solu-- tion of 5: pound of gum arable in pounds of water in which there has previously been dis persed. by means of vigorous agitation. fine globnice of a solution containing 83 pounds of nitroglycerine, 33 pounds of toluene. 3.5 pounds of dinitrotoluene and 16 pounds of ethyl acetate. The dispersed globules of solution are thus uniformly distributed among the powder grains and their composition is such that they are completely taken up by the powder grains within iliteen minutes after the addition. In the absence of ethyl acetate or other nitrocelluloee sol-- vent which is.highly fluid. similarly dispersed droplets of solution remain unabsorbed by the powder grains even after sixty minutes agitation under the same conditions. when the desired extent of impregnation has been attained. as by continuing the agitation at 65 C. for thirty to sixty minutes. the suspension is cooled by passing cold water through the jacket. Less penetration oi the treating agent into the grains may be secured by decreasing the quantity oi nitrocellulose solvent. ethyl acetate in the present example. which is used. Aiter being cooled. the powder grains are ireed of excess water as by centrifuging. after which they are washed with cold water. and dried by means or air at 50' C. Finishing treatments, such as glazing with graphite, may then be applied according to lmown methods.
The stabilized aqueous emulsion oi the solution of treating agent may be prepared with the use of one or more of the known suitable emuisifyiile agents as, for example. water-soluble gums such as gum arable and gum tragacanth. dextrln. starch. water-soluble cellulose ether: such as methyl cellulose containing 22-28% methoxyi. casein. bentonite; alkali salts of sulfated higher alcohols. and the like. For best results, the quantity of emulsifying agent is adjusted so that separation into the component phases will occur in about 15 to 30 minutes after agitation has stoppedr Ii desired. a portion of the emulsifying scent may be added to the suspension oi powder grains prior to the addition oi the emulsion oi the modiiler solution.
Another example oi a process embodying the principles oi this invention comprise: the macetreatment oi powder grains prepared by ag omeration of fineIy-dlvided particles oi gelatinized nitrocellulose into clusters, which may range irom stitutea ior nitrocellulose such as nitroctarch or other nitrated carbohydrates, is likewise included within the scope oi this invention.
While in the ioresoing description oi the various embodiments oi the invention. the vehicle in a which the powder grains are suspended and in which the treating agent. or treating agent solutionisdispersedoremulslfledhasbeendeslgnated as water, it is to be understood that the invention 0.006 'to 0.018 inch in average diameter. as deisnct limited to the use oi water as the treating scribed in the copending application oi Olsen. Tibhitts and Korean, Serial No. @0332. filed June 30, 1932. The treatment is carried out in accordance with the procedure of the first example bath. on the contrary. it will be understood that any liquid vehicle which is not a solvent ior the treating agent, and consequently a vehicle in which the treating agent, or-treating agent soluabove, except that the added emulsion consists of tion. may be dispersed or emulsified in the term finely di persed globules oi a solution containing 32 pounds oi nitroglycerin, 32 pounds oi toluene, 1'1 pounds oi dibutyl phthalate. and 6 pounds oi ethyl acetate in 120 pounds oi water containing 55 ct globules, may be employed in lieu oi water; provided. oi course. that the chosen vehicle is not itself a solvent ior the smokeless powder base. Consequently in interpreting the ioregoing depound oi gum arabic. The reduction in the scription andinconstruing thenppended claims.
amount oi ethyl acetate as compared with the first example is made in view oi the presence in the solution oi the phthalate. which is a good solvent ior nitrocellulose.
In a third specific embodiment oi this invention, 300 pounds oi nitrocellulose powder grains as in the previous example may be suspended in 1,200 pounds oi water at 15'-30 C. while this suspension is vigorously agitated, there is added a solution containing '17 pounds of nitroglycerin.
17 pounds of benzene, 7.7 pounds oi dinitrotoluone. and pounds of acetone. Aiter 30 minutes agitation, the temperature oi the suspension is raised to 65 0., for example, by means of a suitable heating jacket. complet aiter 90 minutes agitation at 65 C. The acetone whichis used in this treatment not only cuts down the time ior eomplet absorption oi the globules 0i modifier solution by the powder grains The coating treatment is 5 the term "water" is intended as comprehensive oi such other vehicles.
It will be understood, therefore, that the present invention is not limited to the specific details oi the ioregoing description, but on the contrary, that various modifications in the procedure and changes in the proportion oi the ingredients and other details may be made by those skilled in the are without departing irom the spirit of this invention. It is to be distinctly understood, thereiore, that such modifications and the use oi such individual features and combination oi features as do not depart from the spirit at this invention are. although not specifically described herein,
from ninety minutes at 65 C. to thirty minutes, to W the P s comprising. treating smokeency to inhibit absorption of the treating agent by the powder grains the addition oi a small quantity, as ior example, ten to fiity per cent on the weight oi the treating agent, oi a solvent which itseli is a solvent ior nitrocellulose may be incorporated with the treating agent with the resuit that absorption of the treating agent is accelerated. In such cases where no solvent which is not a solvent for nitrocellulose is employed, the solvent for nitrocellulose may advantageously be of the type which is not substantially miscible with water.
The process oi this invention may advantageously be utilized ior the application, by sur- 'iace-'-treatment, oi treating agents to any wpe. size or shape of smokeless powder base grains. Grains of partly or completly gelatlnized nitrocellulose oi any desired state oi nitration which have been iabricated by any suitable process may be treated in accordance with this process and less powder grains in a non-solvent bath with a dispersion oi a solution, immiscible with the bath, composed of non-volatile combustion modifier. in a composite volatile solvent containing a solvent ior the powder grains and a non-solvent ior the J component oi the solution being immiscibm with the non-solvent oi the bath and continuing the treatment until the treating agent is deposited upon the grains.
3. In the art oi manuiacturlng propellent powder, the process comprising, treating smokeless powder grains with an aqueous dispersion oi a water immiscible solution of combustion modifier in a composite volatile solvent containin a solvent ior the powder grains and a non-solvent ior the same.
converted to a smokeless propellent powder havmg improved stability, resistance to moisture. enhanced progresslvity of combustion, and/or higher potential. The surface-treatment oi doublebase powder grains, containing nitrocellulose and nitroglycerin, as well as 01 grains containing sub- 4. In the art oi manuiacturing propellent p w der. the process comprising, treating smokeless powder-grains with an aqueous dispersion oi a water immiscible solution oi deterrent and accelerator in a composite volatile solvent containing a solvent ior the powder grains and a non-solvent ior the same.
5. In the art oi manufacturing propellent powders, the process comprising heating nitrocellulose grains with a stabilised emsemulsion oi a solution of a non-volatile treating agent in a composite volatile solvent containing a solvent for nitrocellulose and a non-solventfor the same. which is immiscible with water and continuing the treatment until the treating agent is deposited upon the grains.
6. In the art of manufactiu'ing propellant powders, the process comprising suspending smokeless powder grains in water, and adding to the suspension is stabilized emulsion of a solution of a non-volatile combustion modifier in a composite volatile solvent containing a solvent for nitrocellulose and a non-solvent for the same, which is immiscible with water and heating the mixture.
7. In the art of manufacturing propellent powders. the process of surface treating comprising, agitating smokeless powder grains in water containing dispersed globules 0! a non-volatile combustion modiiler dissolved in a composite volatile solvent composed of a solvent for the powder grains and a water-immiscible non-solvent for the same, in the presence of a protective colloid and continuing the agitation until the treating agent is deposited upon the grains.
8. In the art of manufacturing propelient powders, the process or surface-treating smokeless powder grains comprising, dissolving a nonvolatile combustion modifier in a mixed volatile solvent composed of a solvent and 0! a nonsolvent for the powder grains to term a water immiscible solution. emuisiiying the said solution in water containing an emulsifying agent, adding the said emulsion to an aqueous suspension of the powder grains and driving on the volatile solvent.
9. In the art of manufacturing propeilent powders, the process comprising, treating nitrocellulose grains with an emulsion 01 a solution of nitroglycerin in a volatile mixed solvent comprised of a solvent and a non-solvent for nitrocellulose, said solution being immiscible with the other phase of the emulsion and said other phase being a non-solvent for nitrocellulose the said emulsion being stabilized by means of a protective colloid.
10. In the art oi manufacturing propellent powders. the process comprising preparing a solution of nitroglycerin; toluene and ethyl acetate. emulsifying the said solution in water containing a protective colloid, and treating nitrocellulose rains therewith in aqueous s ll. In the art oi manufacturing propelient powder the process comprising. preparing a solution of nitroglycerin, benzene, and acetone, emulsifying the said solution in we and treating nitrocellulose grains therewith in aqueous suspension.
12. In the art of manufacturing propellent powder the process comprising. preparing a solution of nitroglycerin in a solvent mixture containing a component, which is a solvent for nitroglycerin but a non-solvent for nitrocellulose, and which is immiscible in water, and another component which is a solvent for both nitroglycerin and nitrocellulose, emulsifying the said solution in water containing a protective colloid, and treating nitrocellulose grains therewith in aqueous suspension.
18. In the process of surface treating smokeless powder grains wherein the powder grains are suspended in a water bath containing a stabilized emulsion of non-volatile liquid combustion modiiler, the step of overcoming the tendency of the stabilized emulsion to inhibit absorption of the combustion modifier by the powder grains which comprises, adding a small quantity of a volatile liquid which is a solvent for both the powder grains and the combustion modifier.
14. In the process of surface treating smokeless powder gralns wherein the powder grains are suspended in a water bath containing a stabilized emulsion of non-volatile liquid combustion modiiler, the step of overcoming the tendency of the stabilized emulsion to inhibit absorption of the combustion modifier by the powder grains which comprises, adding a small quantity of a volatile liquid which is a solvent for boththe powder grains and the combustion modifier, said volatile liquid bein immiscible with the water phase of the emulson.
CHARLES EARNEST SILK.
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US243767A US2337943A (en) | 1938-12-03 | 1938-12-03 | Propellent powder process |
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US243767A US2337943A (en) | 1938-12-03 | 1938-12-03 | Propellent powder process |
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US2337943A true US2337943A (en) | 1943-12-28 |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2771352A (en) * | 1953-09-30 | 1956-11-20 | Olin Mathieson | Process of preparing propellants |
FR2481265A1 (en) * | 1980-04-28 | 1981-10-30 | Hercules Inc | |
EP1164116A1 (en) * | 2000-06-15 | 2001-12-19 | Nitrochemie Wimmis AG | Process for producing a functional high-energy material |
US20090208647A1 (en) * | 2000-06-15 | 2009-08-20 | Nitrochemie Wimmis Ag | Method for producing a funtional, high-energy material |
-
1938
- 1938-12-03 US US243767A patent/US2337943A/en not_active Expired - Lifetime
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2771352A (en) * | 1953-09-30 | 1956-11-20 | Olin Mathieson | Process of preparing propellants |
FR2481265A1 (en) * | 1980-04-28 | 1981-10-30 | Hercules Inc | |
US4354884A (en) * | 1980-04-28 | 1982-10-19 | Hercules Incorporated | Process for preparing progressive burning propellant granules |
EP1164116A1 (en) * | 2000-06-15 | 2001-12-19 | Nitrochemie Wimmis AG | Process for producing a functional high-energy material |
US20020043316A1 (en) * | 2000-06-15 | 2002-04-18 | Kurt Ryf | Method for producing a functional, high-energy material |
US7473330B2 (en) | 2000-06-15 | 2009-01-06 | Nitrochemie Wimmis Ag | Method for producing a functional, high-energetic material |
US20090208647A1 (en) * | 2000-06-15 | 2009-08-20 | Nitrochemie Wimmis Ag | Method for producing a funtional, high-energy material |
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