Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D1/00—Fire-extinguishing compositions; Use of chemical substances in extinguishing fires
  • A62D1/06—Fire-extinguishing compositions; Use of chemical substances in extinguishing fires containing gas-producing, chemically-reactive components
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B31/00—Compositions containing an inorganic nitrogen-oxygen salt
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B47/00—Compositions in which the components are separately stored until the moment of burning or explosion, e.g. "Sprengel"-type explosives; Suspensions of solid component in a normally non-explosive liquid phase, including a thickened aqueous phase
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06D—MEANS FOR GENERATING SMOKE OR MIST; GAS-ATTACK COMPOSITIONS; GENERATION OF GAS FOR BLASTING OR PROPULSION (CHEMICAL PART)
  • C06D5/00—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets

Definitions

• the present invention relates to the field of pyrotechnic compositions generating cold gases, non-toxic and free of solid residues. More precisely, the invention relates to the field of composite pyrotechnic compositions with an amorphous structure comprising one or more oxidants and an organic binder in the gel state.
• the compositions according to 1 'invention are well suited to form loads to inflate protective cushions or to ensure the operation of a pyrotechnic extinguisher.
• cold gases means gases which are produced at a temperature below about 1800 ° C.
• liquid propellants consisting of aqueous solutions of compounds such as hydroxylammonium nitrate, triethanolammonium nitrate, aminotetrazole nitrate, nitrate aminotriazole, urea nitrate, biuret nitrate, etc.
• Such liquid propellants are for example described in US Patents 5,060,973 and US 5,684,269.
• liquid propellants require suitable gas generators, whose structure is complex and which are of a high cost price.
• compositions constituted by a binder such as polyvinyl alcohol and by solid eutectics based on ammonium nitrate and guanidine nitrates or aminoguanidine in the presence of potassium nitrate or perchlorate.
• a binder such as polyvinyl alcohol
• solid eutectics based on ammonium nitrate and guanidine nitrates or aminoguanidine in the presence of potassium nitrate or perchlorate.
• the invention therefore relates to solid pyrotechnic compositions producing by combustion gases free of solid residues and constituted by at least one organic binder with gelling effect and by at least one main oxidizing system in liquid phase absorbed by said binder, said compositions being characterized in that:
• the said organic binder with gelling effect is chosen from the group consisting of polyvinyl alcohol, hydroxyethylcellulose, and xantham gum.
• the said main oxidizing system in the liquid phase consists of a mixture of water and hydroxylammonium nitrate (HAN).
• Polyvinyl alcohol is the preferred binder because it improves the chemical stability of the compositions according to the invention.
• the solid compositions according to the invention thus have an amorphous structure in which the binder is in the form of a solid gel impregnated with the aqueous hydroxylammonium phase.
• these compositions release the water included in the gel in the form of water vapor which contributes to very significantly lowering the temperature of the combustion gases.
• the water content by weight of the compositions according to the invention will be between 5 and 20%.
• the invention thus makes it possible to have available compositions which contain water contents much higher than the moisture contents of the previously known compositions.
• the weight of the hydroxylammonium nitrate represents at least 50% of the total weight of the composition, the content of the latter in hydroxylammonium nitrate being preferably between 60% and 70%.
• One of the advantages of the present invention resides in the fact that at the indicated contents the water / hydroxylammonium nitrate mixtures remain liquid as long as the temperature of the latter does not drop below zero degrees Celsius.
• the compositions according to the invention also contain secondary oxidants which are advantageously chosen from the group consisting of ammonium nitrate, hexogen (RDX) and octogen (HMX).
• secondary oxidants which are advantageously chosen from the group consisting of ammonium nitrate, hexogen (RDX) and octogen (HMX).
• compositions when the compositions are intended to constitute pyrotechnic charges for gas generators having to inflate protective cushions for the occupants of a motor vehicle, the use of ammonium nitrate will be avoided or in any case the weight content of the ammonium nitrate composition will be limited to a few percent.
• the compositions will most often contain stabilizing additives which will be chosen from bipyridine, ammonium hydrogen phosphate and ammonium acetate. The weight content of these stabilizers in the composition will be close to 2%. Bipyridine and ammonium hydrogen phosphate are preferred stabilizers.
• compositions will contain thickening additives which will be chosen from the group consisting of water-soluble isocyanates, melamine-formaldehyde resins and borax which is a sodium tetraborate of formula: Na 2 B 4 O 7 , 10H 2 O.
• the invention also relates to a process for the continuous production of solid pyrotechnic charges with an amorphous structure, the composition of which corresponds to the compositions described above and which is characterized in that:
• a mixing and extrusion apparatus is fed continuously on the one hand with a liquid phase containing at least water and hydroxylammonium nitrate and on the other hand with solid granules comprising at least one binder gelling effect,
• a profiled rod is extruded which is hardened in an oven and cut to the desired length, for example in the form of tubes or crowns.
• the kneading and extrusion apparatus is a twin-screw extruder.
• the binder with gelling effect is polyvinyl alcohol and the twin-screw extruder is heated to a temperature between 50 ° C. and 60 ° C., the temperature inside the oven being close to 80 ° C.
• all the constituents other than the binder and which are soluble in water will be mixed with the liquid phase containing the water and the hydroxylammonium nitrate before introduction of the latter into the twin-screw extruder.
• the pyrotechnic charges thus obtained can in particular be used either in pyrotechnic extinguishers to constitute the source of engine gas in these extinguishers, or in pyrotechnic gas generators intended to inflate protective cushions for the occupants of a motor vehicle.
• FIG. 1 represents the diagram of an installation for continuously manufacturing loads according to the invention.
• the installation shown in FIG. 1 basically comprises a twin-screw extruder 1 extended by an extrusion head 2, a conveyor belt 3 passing inside an oven 4 and a cutting system 5. At the start of 1 'extruder are provided two feed devices.
• the first device consists of a pipe 6 connected via a tap 7 to a tank 8 provided with an agitator 9. Downstream in the operating direction of the extruder 1 is a second feed device constituted by a hopper 10 and a conveyor belt 11.
• the tank 8 contains a liquid mixture A consisting of water, hydroxylammonium nitrate and, where appropriate, the constituents other than the binder and soluble in water such as ammonium nitrate.
• the reactive constituents with respect to water are not incorporated into this aqueous liquid phase.
• the conveyor belt 11 feeds the hopper 10 with a mixture of granules B comprising granules of binder and, where appropriate, granules of additives which are not soluble in water and in particular granules of oxidizers which are not soluble in water such hexogen or octogen.
• the extruder 1 is temperature controlled to have an internal temperature between 50 ° C and 60 ° C when the binder is polyvinyl alcohol.
• the liquid phase A and the granules B are mixed in the extruder 1 to form, by gelation of the binder, a composite paste with an amorphous structure which is extruded through the extrusion head 2 in the form of a profiled rod 12.
• This rod may be a simple cylindrical strand, possibly provided with internal channels, to give, after cutting, loose grains or be a rod of larger dimensions, with, if necessary, a worked external profile, to give after cutting. solid or annular blocks.
• This rod 12 is led via the conveyor belt 3 through a heated oven to cause hardening of the gelled binder.
• the binder is polyvinyl alcohol the temperature of the oven will be close to 80 ° C and the residence time of the rod in the oven will be a few minutes.
• the rod 12 is cut using the cutting system 5 into elementary loads 13 which are stored in a container 14.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Inorganic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Air Bags (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
• Treatment Of Sludge (AREA)
• Glanulating (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (1)

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Citations (6)

• 1998
  • 1998-06-05 FR FR9807090A patent/FR2779426B1/fr not_active Expired - Fee Related
• 1999
  • 1999-05-21 JP JP2000553386A patent/JP2002517376A/ja active Pending
  • 1999-05-21 AT AT99920902T patent/ATE228984T1/de not_active IP Right Cessation
  • 1999-05-21 EP EP99920902A patent/EP1087919B1/de not_active Expired - Lifetime
  • 1999-05-21 DE DE69904326T patent/DE69904326T2/de not_active Expired - Lifetime
  • 1999-05-21 WO PCT/FR1999/001206 patent/WO1999064375A1/fr active IP Right Grant

Patent Citations (6)

Non-Patent Citations (2)

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