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
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
  • C06B45/18—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component
  • C06B45/20—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component the component base containing an organic explosive or an organic thermic component
  • C06B45/22—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component the component base containing an organic explosive or an organic thermic component the coating containing an organic compound

Definitions

• ABSTRACT Manufacture of burning rate deterrent coated propellants by contacting a nitrocellulose smokeless powder, at an elevated temperature, with a defined linear polyester of a new class of burning rate deterrents, which.
• nitrocellulose smokeless powder propellants having as a burning rate deterrent, the defined polyester coating diffused by its own plasticizing action into the propellant to form a resulting burning rate gradient therefor.
• the deterrent coating materials utilized have been of two types, based on their solubility in the propellant material, viz. the soluble, or plasticizer type, and the insoluble, or barrier type.
• the soluble, or plasticizer type, deterrent coating due to its ability to plasticize the propellant material penetrates the propellant grain so that as the powder burns, the successively exposed surfaces contain gradually less and less of the deterrent material thus causing the combustion of the grain to proceed with increased speed along a substantially uniform burning rate gradient.
• the plasticizer type deterrent coating initially produces the desired burning rate gradient for requisite progressive burning, those materials, during propellant storage, continue to migrate throughout the propellant grain and, after a period of time, they reach equilibrium concentration throughout the grain and hence fail to provide for the requisite burning rate gradient.
• the barrier, or non-plasticizer type does not penetrate the propellant material and, although it does not migrate into the propellant during storage, it neveretheless fails to provide the progressivity of burning required for many applications.
• Various means have been proposed for dilution of the barrier type deterrents with materials soluble in the propellant material to afford some degree of penetration and hence burning grade gradient, but they have been disadvantageous in numerous applications, particularly when applied to the manufacture of small arms powders.
• My invention is based on my discovery of a class of materials which function as burning rate deterrents for smokeless powder propellants, to provide broad uniform burning rate gradients without appreciable migration of the deterrent material into the propellant particles during storage; and hence provide propellants having improved burning rate gradient, and ballistics, stability.
• a process for the manufacture of burning rate deterrent coated propellants having improved burning rate gradient and ballistics properties which comprises contacting a nitrocellulose smokeless powder, at an elevated temperature, with a linear polyester which is compatible with said nitrocellulose, has a weight average molecular weight of from about 1,500 to 30,000 and a melting point not exceeding about lF., which wets and diffuses into said smokeless powder at said elevated temperature as a plasticizer therefor but is substantially non-migrating within said smokeless powder at lower temperatures; effecting said contacting under conditions causing said polyester to coat, and penetrate, said smokeless powder to form said coated propellant; and reducing the temperature of the resulting coated propellant to a lower temperature above described.
• the invention further provides nitrocellulose smokeless powder propellants having a linear polyester as a burning rate deterrent coating and diffused by its own plasticizing action into said propellant to form a resulting burning rate gradient therefor; said polyester being compatible with said nitrocellulose, having a weight average molecular weight of from 1,500 to 30,000, a melting point not exceeding l90F., and being substantially non-migrating within said smokeless powder at temperatures not exceeding about F.
• the invention in preferred practice, is directed to smokeless powder propellants, and their manufacture, for small arms, and cannon, and to the deterrent treatment of smokeless powders for caseless ammunition charges and other applications, including cartridge actuated, and numerous other, industrial and military propellant devices.
• Exemplary linear polyester burning rate deterrent materials utilized in practice in the invention are those formed from dihydric alcohol components such as ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol and neopentyl glycol, and dibasic acid components such as adipic acid, azelaic acid, phthalic acid, and sebacic acid.
• dihydric alcohol components such as ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol and neopentyl glycol
• dibasic acid components such as adipic acid, azelaic acid, phthalic acid, and sebacic acid.
• polyester deterrent materials having a weight average molecular weight within the range of 1,500 20,000 as further illustrated herein.
• the polyester deterrent plasticizes the smokeless powder particle surfaces and remains in the substantially non-migrating state of diffusion, without rendering the propellant surfaces sticky or otherwise separating from the powder particles.
• nitrocellulose smokeless powders it is meant single, double, and triple based smokeless powders well known in the -such as illustrated in U.S. Pat. No. 3,235,425.
• the smokeless powder-polyester deterrent contacting, or coating, step is carried out at a temperature within the range of 150 212F. for a period of from 1 to 200 minutes, utilizing from 0.5 to 10 weight percent of the polyester deterrent material, based on the weight of the uncoated smokeless powder.
• the smokeless powder-polyester coating step is advantageously carried out in the presence of water, the proportions of water being variable over a broad range.
• the weight ratio of water to smokeless powder in the aqueous slurry can be in the range of from 1:1 to 20:1, more often at least as high as about 4:1.
• a lesser proportion of water can be advantageously utilized, generally without formation of an aqueous slurry as illustrated with reference to Example 1.
• a weight ratio of water to the smokeless powder in the coating system within the range of from about 0.05:1 to about 1:1, but more often not exceeding about 0.2: 1 is utilized.
• the amount of water utilized in these embodiments is generally within the range of from about 0.05:1 to 20:1, the higher proportions within that range are applicable to aqueous slurry coating systems.
• the polyester deterrent material when dissolved in a solvent-diluent therefor, which is not a solvent for the nitrocellulose, to lower viscosity and thereby facilitate uniform distribution of the polyester material throughout the mass of smokeless powder.
• a solvent-diluent for the deterrent is also characterized by low water solubility i.e., it is substantially water insoluble.
• Methylene chloride is a now preferred solvent diluent; and other solvent diluents advantageously utilized include benzene, diethyl ether and nbutanol.
• the solvent-diluent generally has a boiling point not exceeding about 125C.
• the deterrent is introduced into the system as an aqueous emulsion, as an aqueous homogenized suspension, or in the case of a non-aqueous system is dissolved in a suitable volatile non-aqueous solvent for the polyester, which is a non-solvent for nitrocellulose.
• a burning rate deterrent coated propellant of the invention is prepared by placing dry granular smokeless powder, to be coated, in a mixing vessel equipped with agitation means, followed, optionally, by addition of water in an amount up to about 40 weight percent of the dry smokeless powder. From 0.5 to weight percent of the polyester deterrent coating material, based on the uncoated smokeless powder, is then introduced into admixture with the smokeless powder and water if present, and is often advantageously dissolved in a suitable diluent-solvent, which is not a solvent for the nitrocellulose in the smokeless powder, such as in methylene chloride in about equal weight proportions. The mixture vessel is then closed and the powder-polyester admixture is heated under constant agitation, generally by tumbling action, to 150 212F. and maintained at that temperature for a period of from about l to 200 minutes.
• the vessel At the end of the coating period, and with continued heating, the vessel, when methylene chloride or other volatile solvent-diluent for the deterrent material, and- /or water is present, is opened and agitation is resumed to permit evaporation of the water and/or diluent, and drying of the resulting coated product until it becomes free flowing, at which time heating is terminated for recovery of the resulting dried coated propellant product at ambient temperature for storage.
• granular smokeless powder, to be coated is slurried in a mix tank with water in a water: smokeless powder weight ratio above described, more often from about 4:1 to :1, and the resulting slurry is maintained under agitation conditions while adding the deterrent coating material thereto in an amount of from about 0.5 to 10 weight percent based on the uncoated smokeless powder, the latter optionally dissolved in a suitable diluent, such as methylene chloride as above described.
• a suitable diluent such as methylene chloride as above described.
• the resulting water slurry of deterrent coating material and propellant powder is then heated during continued agitation to 150 212F. and maintained at that temperature level for a period of from 1 to 200 minutes to accomplish the required penetration.
• the temperature of the water slurry of coated propellant product is reduced to below the storage temperature level, generally below 150F., and the coated propellant product is removed from the slurry and air dried to form free flowing coated propellant.
• the dry coated propellant product can be glazed, cleaned, and blended, when necessary, to provide the requisite ballistics.
• EXAMPLE 1 A granular double base smokeless powder having an average grain size of 0.65 inch (diameter) X 0.01 1 inch (length) was coated with a linear polyester having a weight average molecular weight of about 6,600, as a burning rate deterrent material of the invention.
• the barrel of the tumbler vessel was then closed, tumbling action was initiated, and heating fluid was circulated through the barrel jacket to increase the temperature of the smokeless powder/water/polyester admixture to 2001F.
• the tumbling was then continued at 200F. for minutes during which time coating action was complete to provide resulting coated propellant product.
• the tumbling was terminated, the barrel was opened, and tumbling was resumed at the coating temperature level to 6 permit evaporation of the water and methylene chlo- The PolyeslercBumins Rate eterr nt omponent Weight Percent ride to provide dry freeflowmg coated propellant prod Ethylene Glycol 29B uct.
• each coated propellant product was loaded after prepabased on the weight of the uncoated smokeless powder, ration as shotgun cartridge components, and each sewas then added to the smokeless powder/water suspenries of cartridges was fired, one series of each coated sion as a 50 weight percent solution in methylene chlopropellant being fired promptly after loading and the ride, under agitation conditions. After addition of the other after an extended storage period.
• Each coated deterrent material to the smokeless powder/water suspropellant (product and control) contained 1.96 pension, the suspension was heated to 85 90C. weight percent of the deterrent material.
• the above data demonstrate substantially no penetration of the polyester deterrent material into the smokeless powder grains during storage, as evidenced by an actual decrease of 300 psi in average maximum chamber pressure, after storage.
• the data demonstrate ethyl centralite, a well known plasticizer type burning rate deterrent for propellants, to have penetrated the smokeless powder grains during preparation, comparable to that of the polyester deterrent, but to have seriously migrated into the smokeless powder grains, during storage, to impair the original burning rate gradient with a resulting increase in average maximum chamber pressure of 3,500 psi.
• the data demonstrate diffusion of the polyester deterrent into the smokeless powder grains under coating temperature conditions, but substantially no migration at storage temperature levels, generally 150F. or less, to be thereby substantially non-migrating during storage and provide for stable burning rate gradient and ballistics over prolonged periods.
• Example 3 The procedure of Example 1 was repeated except that preparation of the ethyl centralite formulation was omitted, the proportion of the polyester deterrent coating material utilized was 4.5 percent (based on the weight of the uncoated granular smokeless powder) the coated propellant product was fired in each instance as a component of a rifle cartridge, and the formulation of the smokeless powder to be coated was as follows:
• the coated propellant product contained 4.3 weight percent of the polyester deterrent.
• Example 4 The procedure of Example 1 was repeated utilizing the same double base granular smokeless powder, except that the deterrent coating material was a polyester deterrent of the invention having a weight average molecular weight of about 1,600, and preparation of the ethyl centralite formulation was omitted. The following summarizes the tests:
• Example 5 The procedure of Example 1 was repeated utilizing the same double base granular smokeless powder, except that the deterrent coating material of the invention was a polyester having a weight average molecular weight of about 4,400, and preparation of an ethyl centralite formulation was omitted.
• the summarizing data are as follow:
• EXAMPLE 6 The data demonstrate the improved stability of burn- Th f ll i d t ill t Smokeless powder mg rate gradient accomplished in practice of the invenellants having well known burning rate deterrent maas shown y an Increase In average Chamber P terials of the soluble, or plasticizer type, and for com- Sure after g of y 600 P 3 53 Percent parative purposes, a burning rate deterrent coated procrease.
• the process embodiment of the invention utilizing an aqueous slurry type coating step is advantageously applied to water cut smokeless powder, inasmush as it eliminates the need for removal of the water and residual solvent from the smokeless powder, and air drying, prior to the coating step.
• the residual solvent-wet smokeless powder still containing from to 20 parts solvent per 100 parts of smokeless powder, generally a mixture of ethyl alcohol and acetone in about equal volume proportions, is directly slurried with the water for the coating step, under which conditions the warm water due particularly to its large volume, promptly extracts the residual solvent from the smokeless powder to eliminate the presence of that solvent during the coating step.
• the invention provides for the active control of the penetration of the burning rate deterrent to accomplish a stable burning rate gradient.
• the diffusion of the burning rate deterrent into the propellant, and hence its plasticizing action provides for a degree of plasticization which increases with increase in each of time, temperature, and amount of coating material in the coating system; and the penetration accomplished is preserved under storage conditions, and until use, due to the non-migration of the burning rate deterrent within the grains.
• a combination of coating conditions can be readily determined for accomplishing any predetermined degree of penetration, and for then locking in the deterrent to secure the resulting burning rate gradient for subsequent use.
• a nitrocellulose smokeless powder propellant having a linear polyester as a burning rate deterrent coating diffused by its own plasticizing action into said pro pellant to form a resulting burning rate gradient therefor; said polyester being compatible with said nitrocellulose, having a weight average molecular weight of from 1,500 to 30,000, a melting point not exceeding 190F., and being substantially non-migrating within said smokeless powder at temperatures not exceeding about 150F.
• a smokeless powder propellant of claim 1, wherein said burning rate deterrent coating is a linear polyester formed from a dihydric alcohol and a dibasic acid.
• a smokeless powder propellant of claim 2 wherein said dihydric alcohol is selected from the group consisting of ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol and neopentyl glycol, and said dibasic acid is selected from the group consisting of adipic acid, azelaic acid, phthalic acid, and sebacic acid.
• a smokeless powder propellant product of claim 2 containing said polyester in an amount of from 0.5 to
• a nitrocellulose smokeless powder propellant having an ethylene glycol-sebasic acid resin as a linear polyester burning rate deterrent coating diffused by its own plasticizing action into said propellant to form a resulting burning rate gradient therefor, and said smokeless powder propellant containing said polyester in an amount of from 0.5 to 10 weight percent based on the weight of said smokeless powder when uncoated; said polyester being compatible with said nitrocellulose, having a weight average molecular weight of from 1,500 to 20,000, a melting point not exceeding 190F., and being substantially non-migrating within said smokeless powder at temperatures not exceeding about 150F.
• a nitrocellulose smokeless powder propellant having an ethylene glycol-adipic acid resin as a linear polyester burning rate deterrent coating diffused by its own plasticizing action into said propellant to form a resulting burning rate gradient therefor, and said smokeless powder propellant containing said polyester in an amount of from 0.5 to 10 weight percent based on the weight of said smokeless powder when uncoated; said polyester being compatible with said nitrocellulose, having a weight average molecular weight of from 1,500 to 20,000, a melting point not exceeding lF., and being substantially non-migrating within said smokeless powder at temperatures not exceeding about F.
• a nitrocellulose smokeless powder propellant having an ethylene glycol-phthalic acid resin as a linear polyester burning rate deterrent coating diffused by its own plasticizing action into said propellant to form a resulting burning rate gradient therefor, and said smokeless powder propellant containing said polyester in an amount of from 0.5 to 10 weight percent based on the weight of said smokeless powder when uncoated; said polyester being compatible with said nitrocellulose, having a weight average molecular weight of from 1,500 to 20,000, a melting point not exceeding F., and being substantially non-migrating within said smokeless powder at temperatures not exceeding about 150F.
• a nitrocellulose smokeless powder propellant having a neopentyl glycol-adipic acid resin as a linear polyester burning rate deterrent coating diffused by its own plasticizing action into said propellant to form a resulting burning rate gradient therefor, and said smokeless powder propellant containing said polyester in an amount of from 0.5 to 10 weight percent based on the weight of said smokeless powder when uncoated; said polyester being compatible with said nitrocellulose, having a weight average molecular weight of from 1,500 to 20,000, a melting point not exceeding 190F., and being substantially non-migrating within said smokeless powder at temperatures not exceeding about 150F.
• a single base nitrocellulose smokeless powder propellant having a linear polyester as a burning rate deterrent coating diffused by its own plasticizing action into said propellant to form a resulting burning rate gradient therefor, and said smokeless powder propellant containing said polyester in an amount of from 0.5
• said smokeless powder propellant containing said polyester in an amount of from 0.5 to 10 weight percent based on the weight of said smokeless powder when uncoated; said polyester being compatible with said nitrocellulose, having a weight average molecular weight of from 1,500 to 20,000, a melting point not exceeding 190F., and being substantially non-migrating within said smokeless powder within temperatures not exceeding about F.

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• 1971
  • 1971-09-03 US US00177813A patent/US3743554A/en not_active Expired - Lifetime
• 1972
  • 1972-05-25 CA CA142,956A patent/CA977972A/en not_active Expired
  • 1972-08-25 GB GB3986472A patent/GB1379137A/en not_active Expired
  • 1972-08-31 IT IT28713/72A patent/IT964431B/it active
  • 1972-09-01 JP JP47087205A patent/JPS5115088B2/ja not_active Expired

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