Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B41/00—Compositions containing a nitrated metallo-organic compound
• • 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
• • 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

Definitions

• the present invention is directed to non-azide gas generant compositions useful, for example, to provide inflation for automobile air bag restraint systems.
• Gas generant compositions for inflating automobile air bag restraint systems presently predominantly use sodium azide as the fuel. Because of toxicity problems with respect to sodium azide and instability problems due to reaction of sodium azide with heavy metal contaminants, gas generants based upon alternative fuels have been proposed, although none, so far, has replaced sodium azide compositions to any appreciable extent.
• One type of alternative fuel comprises tetrazoles, triazoles and their salts, as described, for example in U.S. Patent No. 4,909,549, the teachings of which are incorporated herein by reference.
• the mixture of non-salts and salts of tetrazoles combines advantageous features of each to provide an improved gas generant composition.
• Non-salts have the advantage in that the only combustion products attributed to the non-salt tetrazoles are gases, whereas the tetrazole salts also produce undesirable slag in the form of metal oxides.
• production of toxic oxides is temperature dependent, being produced in greater amounts at the higher combustion temperatures of the non-salt tetrazole compounds. Accordingly, salts, such as tetrazole salts, are used in conjunction with non-salt tetrazole compounds to control combustion temperature and thereby provide high gas output, without generation of high levels of toxic oxides.
• a gas generant composition comprises between about 30 and about 65 wt% of fuel, between about 5 and about 75 wt% of the fuel comprising a non- salt component selected from the group consisting of aminotetrazole, tetrazole, bitetrazole, triazole and mixtures thereof and between about 25 and about 95 wt% of the fuel comprising an alkali or alkaline earth metal salt of 5- nitrobarbituric acid, 5-nitroorotic acid or mixtures thereof; and between about 45 and about 65 wt% of an oxidizer.
• the azole compound i.e., the non-salt form of amino tetrazole, tetrazole, bitetrazole, triazole or mixture thereof provided, upon combustion with the oxidizer, a high volume of generant gas which is high in nitrogen (N2) content.
• This fuel component produces only gases as combustion products.
• the alkali metal or alkaline earth metal salt of 5-nitrobarbituric acid and/or 5-nitroorotic acid is a fuel component which lowers the combustion temperature of the composition (relative to use of the azole component alone).
• These salts are advantageous relative to azole salts in being non-hygroscopic. Thus, even if precautions against moisture fail, the composition of the present invention should continue to function efficiently as a gas generant.
• the mixture is desirably as rich in azole compound relative to the salt of 5-nitrobarbituric acid and/or 5-nitroorotic acid as is consistent with achieving a desirably low combustion temperature.
• the oxidizer includes at least one ammonium, alkali metal or alkaline earth metal nitrate, perchlorate or chlorate or a transition metal oxide.
• the cations of the 5-nitrobarbituric acid salts and 5- nitroorotic acid salts and the cations of the oxidizer component preferably include both alkali metal cations and alkaline earth metal cations.
• the former upon combustion, produce liquid slag components; the latter solid components.
• the combination of liquid and solid slag components promotes formation of clinkers which are easily filterable.
• SiO2 up to about 10 wt%, preferably at least 0.5 wt%, to scavenge K2CO3, KOH, K2O and related products from the combustion products, thereby forming K2SiO3, a liquid slag component.
• the silica may be provided as particulates or as a sole or joint component of fibers.
• Catalysts may include, for example, transition metal oxides, transition metal chromates, transition metal vanadates, transition metal manganates, boron hydrides and mixtures thereof.
• Binders include, but are not limited to molybdenum disulfide, graphite, polytetrafluoroethylene, Viton ® (copolymer of vinylidene fluoride and hexfluoro propylene), nitrocellulose, polysaccharides, polyvinylpyrrolidones, polycarbonates, sodium silicate, calcium stearate, and magnesium stearate.
• Additional components which may be used at levels totalling about 10 wt% include, but are not limited to graphite fibers, alumina fibers, alumina/silica fibers, boron oxide and titanium dioxide.
• compositions formulated as per the table below were prepared by slurry blending the solids with about 25% to 30% water, drying the mixture thoroughly at 80°C under vacuum (25 mmHg) and screening the composition through a 16 mesh screen. Pellets were prepared by compression molding at 40,000 psi. The table also list combustion temperature and gas output.
• Formulations A, B, D, and E in wt% are given as examples.
• Formulations C, F, G, H and I are given for comparison.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Air Bags (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (5)

Cited By (3)

Citations (4)

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• 1994
  • 1994-10-20 AU AU75956/94A patent/AU663659B2/en not_active Ceased
  • 1994-10-24 CA CA002134188A patent/CA2134188A1/en not_active Abandoned
  • 1994-11-11 EP EP94308329A patent/EP0661252A2/en not_active Withdrawn
  • 1994-12-06 KR KR1019940032899A patent/KR950017870A/ko active IP Right Grant
  • 1994-12-09 JP JP6306305A patent/JPH07206569A/ja active Pending

Patent Citations (4)

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