Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B43/00—Compositions characterised by explosive or thermic constituents not provided for in groups C06B25/00 - C06B41/00
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B35/00—Compositions containing a metal azide
• • 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
  • C06D5/06—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets by reaction of two or more solids

Definitions

• a fuel selected from the group consisting of alkali metal azides and alkaline earth metal azides,
• an alkali metal oxidant selected from the group consisting of alkali metal perchlorates and bichromates,
• a nitrogenous compound selected from the group consisting of aminotetrazole, aminotetrazole hydrate, azodicarbonamide and azotetrazole, and
• silica as an additive for reacting with the solid combustion residues of the composition.
• compositions are particularly intended for the deployment of inflatable safety devices for driver and passenger protection in automobiles and other fast vehicles.
• the present invention is concerned with pyrotechnic compositions which generate combustion gases which are substantially non-toxic and which can be used, in particular, for the deployment of inflatable safety devices designed to protect the drivers and passengers of motor vehicles and other fast vehicles.
• Propellant compositions containing, as an combustion catalyst, are also known. However, these compositions have only a limited yield of gas unless the mixture is so formulated as to provide a substantially stoichiometric quantity of oxygen which, in turn, leads to the production of toxic nitrogen oxides in the combustion gases.
• These propellant compositions are, however; primarily intended for the propulsion of rockets, for which purpose the production of such nitrogen oxides is not disadvantageous.
• Gas-generating compositions have also been proposed which enable a large volume of non-toxic gas to be obtained in a very short period.
• These compositions comprise an inorganic oxidant and a plastics'binder and produce combustion gases containing a relatively high proportion of oxygen.
• the latter characteristic could be a disadvantage when such compositions are used for the deployment of inflatable safety devices in case of accidents in view of the risk of fire.
• a gasgenerating pyrotechnic composition which comprises:
• a fuel consisting of an alkali metal azide or alkaline earth metal azide
• an alkali metal oxidant selected from alkali meta perchlorates and bichromates
• a nitrogenous compound selected from aminotetrazole, aminotetrazole hydrate, azocarbonamide and azotetrazole, and
• silica as an additive for reacting with
• the weight ratio of azide: alkali metal oxidant ' is greater than 1 and the weight ratio nitrogenous compound:
• azide is less than 48%.
• the composition preferably comprises, by weight: a. 50 to parts of sodium azide, 1 b. 50 to 20 parts of potassium perchlorate, for a total of parts of azide and perchlorate,
• the solid combustion residues of the composition according to the invention comprise alkali metal or alkaline earth metal oxides, most of which have an irritating physiological action and can cause burns, particularly when the constituents (a) and (b) are sodium azide and potassium perchlorate, respectively.
• the incorporation of silica in the composition enables these oxides to be suppressed by converting them into silicates which have no physiological action on the organism.
• the total suppression of sodium oxide in the combustion residues is obtained by using 9.3% of silica with respect to the quantity of sodium azide; in practice, an amount of silica greater than 6% enables a partial, but satisfactory, suppression of sodium oxide to be obtained.
• compositions according to the invention have a shorter ignition time, of the order of several milliseconds, while retaining a sufficiently high selfignition temperature for the composition to be completely safe in use;
• combustion gases obtained from the compositions according to the invention contain some carbon monoxide, the proportion of the latter can be kept below the critical toxic value and the combustion gases contain substantially less toxic nitrogen oxides than the gases obtained from known gasgenerating pyrotechnic compositions. Since the combustion gases obtained from the composition according to the invention are particularly intended for the deployment of inflatable safety devices, for which purpose the gases should be at only a moderate temperature, it is of particular importance to obtain:
• compositions comprising sodium azide, potassium perchlorate, and aminotetrazole hydrate
• the ratio NaNn should be 6 less than i.e. less than 8.5%
• composition diagram When a composition diagram is constructed in which the ordinates represent the weight ratio NaN /KCl and the abscissae the weight ratio aminotetrazole/- NaN the curve passing through the three points, a, b and c, defined as follows:
• the region representing the most preferred compositions is that lying between the curve defined by the three points a, b and c, the ordinate axis, and the straight line parallel to the abscissae axis for which the ordinate value 1, corresponding to equal amounts of potassium perchlorate and sodium azide.
• compositions A, B and C were equal to: 1330 cal/g, 1270 cal/g and 1220 cal/g for compositions A, B and C respectively.
• the self-ignition temperature of the three compsitions was 415C.
• the gas yield was from 0.248 l/g and 0.356 l/g (the gases being at normal pressure and temperature) and the combustion gases contained from 96% to 99.5% of nitrogen mass of the combustion gases.
• the elimination of sodium oxide in the solid combustion residues was satisfactory due to the presence of powdered silica in the indicated quantities.
• compositions A. B, C show the importance of using large amounts of azide. since, on the one hand, the combustion temperature, which is related to the potential of the composition, decreases and, on the other hand, the yield of gases increases. but concommitantly the formation of nitrogen oxides also increases and, for example, in the range of proportions comprised between the compositions of the prior art type have a higher toxicity due to the excessive formation of nitrogen oxides.
• the potentials and combustion rates of these compositions were lower than those of compositions A, B and C having the same NaN /KC10 ratio.
• the potentials obtained were about the order of 1000 cal/g and the gaseous yields were about 0.45 l/g (at normal pressure and temperature).
• Combustion rate 350 mm/s at bars.
• Composition K (in the form of pellets) NaN 70 parts KClO, 30 parts aminotetrazole 6.5 parts SiO (average particle size 30y) 6.5 parts
• the combustion characteristics obtained with this composition were as follows:
• the preparation of the pyrotechnic compositions according to the invention is effected in a conventional manner by mixing of the constituents.
• Shaped charges can be formed by incorporating a suitable binder and subjecting the composition to a conventional pelleting or extrusion operation.
• Various shapes can be used according to the firing characteristics required.
• compositions containing from 1 to 2 parts by weight of a metal stearate and in the form of pellets of 9.5 mm diameter and 3 mm thickness are suitable.
• the constituents are preferably physically treated to select a particular particle size fraction and/or to eliminate moisture.
• potassium perchlorate is preferably dried at 80C for 12 hours and sodium azide is preferably crushed by rollers to pass through a 295 p. screen.
• the mixing should be carried out to obtain a mixture which is powdery and apparently homogeneous. Simultaneous introduction of the constituents into a mixer, such as a V mixer (Moritz), and mixing for 1 hour is suitable in most cases.
• pelletising of the powder mixture is preferably effected under the following working conditions in, for example a pelletiser of the Stokes type:
• a gas-generating pyrotechnic composition which comprises:
• a fuel selected from the group consisting of alkali metal azides and alkaline earth metal azides,
• an alkali metal oxidant selected from the group consisting of alkali metal perchlorates and bichromates,
• a nitrogenous compound selected from the group consisting of aminotetrazole, aminotetrazole hydrate, azodicarbonamide and azotetrazole.
• composition according to claim 1 additionally comprising silica.
• a nitrogenous compound selected from the group consisting of aminotetrazole and aminotetrazole hydrate, and
• composition as set forth in claim 6, which comprises, by weight, about 9.3% of silica with respect to the azide.
• composition as set forth in claim 5 in which- NaN;, 50 aminotetrazole 24 ii. the straight line parallel to the abscissae axis for which the ordinate value 1, and

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Air Bags (AREA)
• Emergency Lowering Means (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=9105769

Family Applications (1)

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Cited By (43)

Families Citing this family (4)

Citations (2)

• 1972
  • 1972-10-17 FR FR7236738A patent/FR2228043B1/fr not_active Expired
• 1973
  • 1973-09-25 IE IE1714/73A patent/IE38282B1/xx unknown
  • 1973-09-26 GB GB4516573A patent/GB1406002A/en not_active Expired
  • 1973-09-26 ZA ZA737600*A patent/ZA737600B/xx unknown
  • 1973-09-26 CH CH1379973A patent/CH584669A5/xx not_active IP Right Cessation
  • 1973-10-09 US US404762A patent/US3912561A/en not_active Expired - Lifetime
  • 1973-10-11 AU AU61304/73A patent/AU476753B2/en not_active Expired
  • 1973-10-11 AR AR250495A patent/AR200284A1/es active
  • 1973-10-15 LU LU68613A patent/LU68613A1/xx unknown
  • 1973-10-15 NL NL7314143.A patent/NL161424C/xx active
  • 1973-10-15 ES ES419629A patent/ES419629A1/es not_active Expired
  • 1973-10-16 SU SU1976301A patent/SU559638A3/ru active
  • 1973-10-16 JP JP11536973A patent/JPS572677B2/ja not_active Expired
  • 1973-10-16 SE SE7314045A patent/SE399063B/xx unknown
  • 1973-10-16 BR BR8071/73A patent/BR7308071D0/pt unknown
  • 1973-10-16 IT IT70060/73A patent/IT999653B/it active
  • 1973-10-17 CS CS737154A patent/CS190412B2/cs unknown
  • 1973-10-17 CA CA183,564A patent/CA1020357A/en not_active Expired
  • 1973-10-17 BE BE136804A patent/BE806209A/xx unknown

Patent Citations (2)

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