Classifications

• • 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
  • C06B45/24—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 the compound being an organic explosive or an organic thermic component
• • 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
• • 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
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
  • C06C5/00—Fuses, e.g. fuse cords
  • C06C5/04—Detonating fuses
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S149/00—Explosive and thermic compositions or charges
  • Y10S149/11—Particle size of a component

Definitions

• This invention relates to explosive compositions of the kind comprising particulate explosive and binding material therefor and to a process for preparing such compositions.
• the explosive compositions of the invention comprise explosive particles coated and bound together by a binding agent which, initially at least, confers plastic properties on the composition. Explosive compositions of a plastic consistency are advantageous for many uses because they can be readily shaped by pressure deforming operations such as extrusion or moulding.
• the binding agents used to plasticize explosives have been viscous (usually oleaginous) liquids which tend to give a sticky product and to exude under pressure or to migrate from the composition when in contact with absorbent material.
• the liquid binding agent comprises a sensitive explosive liquid such as, for example, nitroglycerine.
• particulate explosive solids can be plasticized by coating the particles with solid polytetrafluoroethylene (PTFE) without markedly impairing the explosive properties.
• PTFE solid polytetrafluoroethylene
• an explosive composition of this invention comprises particulate explosive material coated with solid polytetrafluoroethylene.
• This plastic composition may be prepared by the process of the invention which comprises mixing particulate explosive material with finely divided PTFE to distribute the PTFE over the surface of the particles and compressing the mixture to convert it to a coherent plastic mass.
• plastic explosive compositions wherein the particles are incompletely covered with PTFE
• the quantity of PTFE used and the degree of mixing should be suflicient to effect complete coverage of the surface of the particles.
• the degree of binding of the plastic composition increases with increasing PTFE content up to PTFE contents of about 30% by weight.
• PTFE contents in the range 15% by weight are usually suflicient to give compositions which can be formed in Patented Sept. 9, 1969 coherent plastic state under very light compression and which have a consistency somewhat resembling the confection known as marsh-mallow.
• compositions may be extruded through a nozzle into the form of a cord or column or may be rolled or moulded into the form of a pliable sheet.
• the compositions When highly compressed the compositions substantially lose their plasticity and become hard, rigid solids.
• PTFE plasticising and binding etfect of PTFE is believed to result from the cohesion of the PTFE coating layers which, because of the low coefficient of friction between them, can slip over each other when the mass is subjected to pressure.
• the use of PTFE as binding material in these explosives permits the preparation of plastic explosives of higher strength than those hitherto available because of the relatively low proportions required.
• PTFE being chemically and thermally stable, does not aflect the stability of the explosive composition.
• An especially useful plastic composition of this invention is one in which the particulate solid is pentaerythritol tetranit'rate (PETN) since it may be moulded as the core of detonating fuse-cord to give a fuse-cord which is easier to manufacture than the commonly used fusecord containing a core of dry particulate PETN encased in a thermoplastic sheet.
• PETN pentaerythritol tetranit'rate
• compositions of the invention may be advantageously formed into shaped charges or into plastic sheet explosives, specially suited to the requirements of metal forming operations. They may also be used as detonator, booster and propellent charges.
• plastic compositions of the present invention include cyclotrimethylene trinitramine, blackpowder, TNT, pentolite, tetryl, styphnic acid, and explosive mixtures comprising chlorates, perchlorates, and nitrates of sodium, potassium, calcium or ammonia.
• a powdered TNT/ammonium nitrate explosive may, for example, be admixed with PTFE to form a plastic explosive which may be sheeted and used for metal forming, or cyclotrimethylene trinitramine may be plasticised with PTFE to form a plastic composition which is superior for shaped charges to the wax-plasticised compositions usually employed.
• the velocity of detonation of such plastic explosive compositions may be varied by varying the density or by the inclusion therein of non-explosive particulate solids such as, for example, sodium chloride, or in the case of sheet explosive by varying the sheet thickness.
• the strength of sheet explosives may be improved by incorporating fibrous material such as cellulose.
• the average particles size of the particulate explosive constituent of the composition is not critical; good compositions may be obtained with particles as small as 1 micron or as large as 1000 microns.
• Plastic explosive compositions of the invention may be prepared by admixture of the particulate explosive with finely divided dry PTFE, an especially convenient material being in the form of a coagulated dispersion obtained by coagulating and drying a liquid dispersion of PTFE.
• PTFE coagulated dispersion obtained by coagulating and drying a liquid dispersion of PTFE.
• superior compositions are obtained if the PTFE is used in the form of a fine dispersion in a liquid medium and the liquid is removed after mixing.
• the particle size of the PTFE in the dispersion may conveniently be 0.1-5
• water is generally satisfactory, although with certain very watersoluble explosive materials it may be found more convenient to use an organic liquid.
• Aqueous dispersions may advantageously contain a wetting agent such as, for example, sodium lauryl sulphate or Triton X (registered trademark).
• a wetting agent such as, for example, sodium lauryl sulphate or Triton X (registered trademark).
• the PTFE may be coagulated on the water-wet particulate explosive by adding acetone to the mixture, and the composition may be freed from acetone and wetting agent by filtering and washing with water.
• the PTFE in the form of a dispersion in a liquid medium, may be mixed with vigorous stirring with the molten material and the mixture cooled to solidify to a plastic mass.
• Example 1 95 parts of PETN were mixed with 20 parts of water and 8.3 parts of a 60% aqueous dispersion of PTFE, commercially available as Fluon (registered trademark) Grade GPI, were added and the mixture stirred for a few minutes. The mixture was then dried at 70 C. for 2 hours. The powder obtained (containing 5% by weight of PTFE) was, under light compression or rolling on a board with a rolling pin, converted into a plastic mass. The Abel heat test (170 F.) of the PETN/PTFE plastic explosive product was 40+ minutes.
• PTFE commercially available as Fluon (registered trademark) Grade GPI
• a g. sample of this plastic explosive was converted to a pellet of density 1.7 g./cc. at a pressure of 12 tons per sq. in. in a diameter mould.
• a /s" cord initiated unconfined with a No. 6 ASA detonator, propagated at a velocity of detonation of 3.7 km./sec.
• Example 2 99 parts of PETN, wetted with 20 parts of water, were mixed with 1.7 parts of a 60% aqueous dispersion of PTFE as used in Example 1 and the mixture stirred for a few minutes. 20 parts of acetone were added and the mixture stirred for 5 minutes and then transferred to a filter and washed with warm water at 70 C. The resulting dough-like mixture was dried at 70 C. for two hours after which it was rolled into the form of a sheet /s" thick. A /s" wide x 10" long strip of this sheet propagated detonation at 3.7 krn./sec. when initiated unconfined with a No. 6 ASA detonator.
• Examples 3-7 100 parts of a mixture of PETN and sodium chloride, wetted with 10 parts of water, were mixed with 8.3 parts of a 60% aqueous dispersion of PTFE as used in Example 1 and the mixture was stirred for 5 minutes and then dried at 70 C. for 2 hours. On rolling on a board, a tough, pliable sheet was formed.
• RDX cyclotrimethylene trinitramine
• the product was very easily converted into a plastic mass on light compression.
• a 3.5 oz. shaped charge pressed at 2 tons/sq. in. gave, on detonation, a penetration of 4 /2" in mild steel.
• Example 9 95 parts of molten TNT at C. were vigorously stirred and 8.3 parts of an aqueous dispersion of PTFE as used in Example 1 were added and the stirring continued for a short time until the moisture was evolved. The molten mixture was then cooled to form a plastic material which was sheeted by rolling on a board.
• Example 10 parts of PETN were mixed for 15 minutes with 5 parts of dry PTFE (coagulated dispersion). The powder obtained was then crushed by rolling on a wooden board with a wooden roller to give a reasonably strong plastic sheet.
• the Abel heat test F.) of the product was 40+ minutes and when a portion of this sheet /s thick by A," wide and 10 long was initiated to detonation with a No. 6 ASA detonator, it propagated at a velocity of 4.6 km./sec.
• Example 11 95 parts of blackpowder were mixed with 10 parts of water and 8.3 parts of a 60% aqueous dispersion of PTFE, as used in Example 1, added and the mixture stirred for a few minutes. After drying the mixture was rolled to form a sheet. From this sheet strips were cut and used to form the central core in a safety fuse which burned at a rate of 1.5 feet per minute. A portion of the sheet was diced to give a granular powder of uniform particle size which was glazed by tumbling with graphite to improve its flow properties. The resultant material was a satisfactory blasting powder.
• Example 12 95 parts of finely powdered pentolite (50/50 PETN/ T NT) were wetted with 15 parts of water and 8.3 parts of a 60% aqueous dispersion of PTFE were added. The mixture was stirred for a few minutes and dried to give a mixture which had a heat test of 40+ minutes. The mixture was rolled on a board to give a tough plastic sheet. A strip 10" long by 41 thick by 1" Wide, when initiated to detonation with a No. 6 ASA detonator, propagated at 5.4 km./sec.
• a further plastic explosive of the same composition except that the PTFE content of the mix ture was increased to 10% by Weight, was prepared and similarly sheeted and cut into strips which propagated detonation at 4.5 km./ sec. Strips of the same dimensions and of similar composition, but in which sodium chloride was incorporated, were prepared in the same manner and the velocity of detonation was measured. The following results show the effect of PTFE and sodium chloride on the velocity of detonation.
• Example 13 80 parts of potassium perchlorate were mixed with 33 parts of a 60% aqueous dispersion of PTFE as used in Example 1 for 10 minutes. The mixture was dried and pressed to form a plastic propellent charge which had a burning speed of 0.10 inch/ second at 1000 p.s.i.
• a process for the preparation of a composition comprising particles of explosive composition coated with polytetrafluoroethylene, said process comprising mixing particles of said explosive composition [particulate explosive] with finely divided polytetrafluoroethylene in discrete particles of average size of 0.1 to 5 microns to distribute over the surface of the particles of explosive composition 1 to 5% by weight of said polytetrafluoroethylene particles based on the total weight of explosive composition and deposited polytetrafluoroethylene and compressing the mixture to convert it to a coherent plastic mass.
• polytetrafluoroethylene is in the form of a compressed dispersion obtained by coagulating and drying a liquid dispersion of polytetrafluoroethylene.
• a process for the preparation of an explosive composition as claimed in claim 1 wherein the explosive composition is an easily melted material and it is mixed in its molten state with said polytetrafluoroethylene particles dispersed in a liquid medium and the mixture is cooled to solidify it to a plastic mass.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Dispersion Chemistry (AREA)
• Molecular Biology (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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Cited By (12)

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Citations (3)

• 1965
  • 1965-07-23 GB GB31475/65A patent/GB1089403A/en not_active Expired
• 1966
  • 1966-07-21 DE DE19661571227 patent/DE1571227A1/de active Pending
  • 1966-07-22 FR FR70485A patent/FR1487580A/fr not_active Expired
  • 1966-07-22 BE BE684485D patent/BE684485A/xx unknown
• 1968
  • 1968-02-15 US US726624*A patent/US3466204A/en not_active Expired - Lifetime
  • 1968-06-19 US US742954A patent/US3455749A/en not_active Expired - Lifetime

Patent Citations (3)

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