Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B25/00—Compositions containing a nitrated organic compound
  • C06B25/34—Compositions containing a nitrated organic compound the compound being a nitrated acyclic, alicyclic or heterocyclic amine
• • 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
  • C06B45/04—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive
  • C06B45/06—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component
  • C06B45/10—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component the organic component containing a resin
  • C06B45/105—The resin being a polymer bearing energetic groups or containing a soluble organic explosive

Definitions

• the present invention relates to a method of using beta-octogen having a multimodal grain size distribution with an average grain diameter of less than 50 ⁇ m in the preparation of propellants and to the resulting propellants.
• octogen as employed in the present invention is understood to mean, as is known, 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane or also cyclotetramethylene-tetranitramine.
• This compound is also known under the name of “HMX” (high melting explosive of His Majesty's explosive).
• HMX high melting explosive of His Majesty's explosive.
• Four crystalline modifications are known of this compound, namely the orthorhombic alpha form, the monoclinic beta form, the monoclinic gamma form, and the hexagonally crystallizing delta form.
• the beta form is a customary modification, the quality control of which is described in Military Specification MIL-H-45444 B (PA), Amendment 1, Jul. 15, 1975.
• PA Military Specification MIL-H-45444 B
• a distinction is made between purity grades A and B.
• the grain sizes are differentiated in accordance with several classes.
• beta-octogen has been utilized in the state of the art as the sole explosive in passivated form, as a booster charge, in mixtures with TNT (octols) and others, and also as an explosive in solid rocket propellants or in barrel-type weapon propellants.
• TNT octols
• the conventional areas of usage thus cover detonative as well as explosive reactions or deflagrations.
• deflagration is understood to mean, as is known, reactions occurring substantially below the speed of sound in the material.
• the reactions are propagated by the thus-released heat of reaction.
• the reaction products flow away in opposition to the propagation direction.
• the detonative reaction of an explosive as is known, is coupled with a shock wave during its reaction.
• the burning of a propellant powder is a deflagration process.
• the determination of the deflagration velocity can here be utilized, inter alia, as a suitable measuring variable.
• the linear burning rate of a propellant is the velocity at which the chemical reaction progresses from the ignition site. This rate is dependent on the composition, the pressure, the temperature, the physical state of the propellant, and the shape of the propellant.
• the physical state of the propellant along these lines includes, in particular, the porosity, compactness, and grain size and grain size distribution of the components.
• beta-octogen as the energy carrier of propellants, such dependencies have been described in the literature.
• Technical Memorandum 33-801 entitled “Nitramine Propellant Research” of the Jet Propulsion Laboratory, Pasadena, Calif., Oct. 15, 1976, the internal ballistics of fine-grained beta-octogen is examined. The following report is rendered on the dependency of the linear burning rate from the muzzle pressure:
• the breaking point of the 20 ⁇ m particles occurs at 280 bar (4,000 psi), the breaking point of the 10 ⁇ m particles at 420 bar (6,000 psi), and that of 5 ⁇ m particles at 1380 bar (20,000 psi).
• the effects of the 10 ⁇ m and 20 ⁇ m particles are greater than could be expected from their low concentration (in total 17%), on account of their deep penetration during combustion on the surface structure of the propellant.
• an actual propellant would exhibit a prolonged transition in place of a stepped transition.
• the pressure exponent can be determined from the thus-measured curves with the aid of an ascending slope.
• an excessively steep pressure rise is undesirable, as set out above.
• a pressure exponent of ⁇ 1 is obtained with hexogen grain sizes of 4-15 ⁇ m.
• the maximal pressures are too high, at more than 6,000 bar.
• DE 3,614,173 C1 discloses a granulated beta-octogen having a grain size of less thai 50 ⁇ m which is encased by synthetic resins.
• U.S. Pat. No. 3,959,042 describes the use of beta-octogen (HMX) in propellant charges, introduced into a solution of an inactive binder.
• HMX beta-octogen
• DE 2,753,555 C1 describes, inter alia, the use of beta-octogen in conjunction with high proportions of active binders, accompanied by high proportions of inactive binders and fillers.
• the disclosure contains no data on the grain size or the grain size distribution of the beta-octogen utilized.
• DE 3,617,408 C1 discloses a process for the production of fine-grained beta-octogen.
• the object of the present invention resides in preparing an octogen having a suitable grain configuration, grain size, and grain size distribution for the prevention of jumps in the curves of linear burning rate versus pressure. Moreover, the pressure exponent of the deflagration rate should be ⁇ 1. Furthermore, the present invention has as its objective a reduction of the pressure rise gradient and of the maximum pressure in the cartridge chamber as compared with the state of the art.
• beta-octogen having a multimodal grain size distribution with an average grain diameter of less than 50 ⁇ m in propellants made up of explosives, inert binders, and active binders.
• a multimodal grain size distribution along the lines of the present invention means a grain size spectrum as can be illustrated, in particular, by a Gaussian distribution curve.
• the production of especially fine-grained beta-octogen has been known from DE 3,617,408 C1. According to this document, a solution of beta-octogen in a gamma-lactone is treated with toluene in a temperature range of between 5° and 15° C.; the desired fine and very fine beta-octogen crystals being precipitated in high purity.
• the very fine beta-octogen after separation from the toluene, can be made into a slurry with water and combined, at temperatures of between 30° and 60° C., with a solution, suspension or emulsion of a polymer under agitation. During this step, the product is encased by the polymer.
• Another process for producing the very fine beta-octogen grain resides in comminuting a commercially available product, as classified according to MIL-H-45444 B.
• the grain sizes range from about 45 ⁇ m up to several hundred ⁇ m.
• comminution of the crystals by grinding poses great difficulties since beta-octogen is extremely sensitive to friction and shock. Therefore, this procedure can only be performed under special safety precautions in appropriate devices.
• Another process for the production of an especially fine-grained beta-octogen resides in the separation of the desired grain fractions.
• the starting material can be derived in this method from normal production or from the previously described comminution procedure.
• the separating methods are known per se.
• the use of hydrocyclones is of advantage in the production of grains according to the present invention. It is self-evident that an especially fine grain constitutes merely a fraction of the bulk employed, whereby the process Per se becomes more expensive.
• the special advantage of the direct production of fine grains resides in that the crystals from the crystallization are intact, as contrasted to those from the comminution process.
• a preferred active binder along the lines of the present invention is polynitrophenylene. In case less temperature-sensitive propellants are not disadvantageous it is, however, also possible to employ nitrocellulose as the active binder.
• beta-octogen resides in using same in propellants which contain e-octogen, polynitrophenylene, hexogen (cyclonite, RDX), guanidine nitrate, hexanitrodiphenylamine, dipicrylsulfone, hexanitrostilbene and/or tetranitrodibenzo-1,3a-4,6a-tetraazapentalene as additional explosives.
• Propellants according to this invention contain, besides active binders, also inactive binders.
• active binders also inactive binders.
• these are understood to be, in particular, also those based on a synthetic resin. Since the use of binders results, besides in a reduction of detonation sensitivity, also in a strengthening of crystalline powder, good tackifying properties as well as a good dimensional stability within a temperature range from ⁇ 40° C. to +70° C. are desirable.
• the binders should moreover be free of halogen and should yield a low quantity of solid combustion products.
• Preferred binders are those based on polyurethanes, polymethyl acrylates, polyvinyl acetates, silicone, and polyvinyl alcohols, especially partially or completely acetalized polyvinyl alcohols with C 1 - to C 5 -aldehydes, obtainable per se in commerce.
• polyvinyl butyral resin is of special significance; this compound is commercially obtainable.
• the type and amount of binders depend on the desired usage, especially for regulating the internal ballistics after shaping.
• the amount of active and inert binders amounts, in each case independently of each other, to 5-15% by weight, based on the propellant.
• the propellants obtainable with of this invention can also contain conventional plasticizers, lubricants and/or stabilizers known in the art.
• propellants can be utilized in loose or press-molded form. According to this invention, propellants in pressed form are utilized with preference.
• the quantity of the multimodal beta-octogen in propellants of explosives, inert binders and active hinders is not critical.
• the multi-modal beta-octogen can be used without additional after-treatment in the above-cited propellants.
• a special embodiment of the present invention resides in encasing the crystals of this beta-octogen with thermoplastic polymers prior to use in the aforementioned propellants.
• beta-octogen having an average grain size of less than 50 ⁇ m
• at least 95% by weight of the beta-octogen grains also exhibit a grain size of less than 100 ⁇ m.
• Table II indicates the grain size spectrum or distribution of beta-octogen having an average grain size of 23 ⁇ m. TABLE II Grain Size Distribution, beta-Octogen having Average Grain Size 23 ⁇ m ⁇ 10 6.5% by weight 10-20 ⁇ m 46.5% by weight 20-30 ⁇ m 27.0% by weight 30-40 ⁇ m 10.0% by weight 40-50 ⁇ m 4.0% by weight 50-60 ⁇ m 2.5% by weight 60-80 ⁇ m 3.5% by weight 100% by weight
• the composition of the propellants from Examples 5 and 6 was identical except for the difference of the octogen having average grain sizes of 23 and 9 ⁇ m, respectively.
• the 9 ⁇ m average grain size has an analogous grain size distribution as the octogen with an average grain size of 23 ⁇ m.
• the production of the cartridges, their mass of propellants, dimensions, and ignition systems were identical.
• a propellant was mixed with the same proportion of energy carrier, but in this case of beta-octogen having an average grain size of 6 ⁇ m, inert binders, and active binders in the same composition, and cartridges having an identical ignition system were produced from this mixture in accordance with the same method.
• the propellant of this invention comprises 70 to 95 wt. % explosive and 5 to 30 wt. % binder.
• the explosive is composed of 5 to 100 wt. % of beta-octogen and 0 to 95 wt. % of the other additional explosives heretofore described.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
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• Life Sciences & Earth Sciences (AREA)
• Dispersion Chemistry (AREA)
• Molecular Biology (AREA)
• Crystallography & Structural Chemistry (AREA)
• Agricultural Chemicals And Associated Chemicals (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 1991
  • 1991-08-15 DE DE4126981A patent/DE4126981C1/de not_active Expired - Fee Related
• 1992
  • 1992-08-17 EP EP92113959A patent/EP0528392B1/fr not_active Expired - Lifetime
  • 1992-08-17 DE DE59204051T patent/DE59204051D1/de not_active Expired - Lifetime
• 2000
  • 2000-12-12 US US09/733,963 patent/US20010023727A1/en not_active Abandoned

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