WO1998006683A1 - Compositions a inflammation spontanee pour generateurs de gaz de dispositifs de gonflage - Google Patents

Compositions a inflammation spontanee pour generateurs de gaz de dispositifs de gonflage Download PDF

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Publication number
WO1998006683A1
WO1998006683A1 PCT/US1997/013070 US9713070W WO9806683A1 WO 1998006683 A1 WO1998006683 A1 WO 1998006683A1 US 9713070 W US9713070 W US 9713070W WO 9806683 A1 WO9806683 A1 WO 9806683A1
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WO
WIPO (PCT)
Prior art keywords
autoignition
weight
oxidizer
composition
mixture
Prior art date
Application number
PCT/US1997/013070
Other languages
English (en)
Inventor
Sean P. Burns
Larry A. Moquin
Original Assignee
Automotive Systems Laboratory, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US08/906,496 external-priority patent/US6007647A/en
Application filed by Automotive Systems Laboratory, Inc. filed Critical Automotive Systems Laboratory, Inc.
Priority to EP97937024A priority Critical patent/EP0944562B1/fr
Priority to JP50975298A priority patent/JP4021491B2/ja
Publication of WO1998006683A1 publication Critical patent/WO1998006683A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
    • C06C9/00—Chemical contact igniters; Chemical lighters
    • 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
    • C06B31/02—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate

Definitions

  • the present invention relates to autoignition compositions used in infiator bags of automobile passenger- restraint devices.
  • the potential rupture of the pressure vessel is a serious safety concern that has been addressed through utilization of an autoignition compound.
  • the autoignition compound is used to ignite the gas generant of the infiator, thereby preventing rupture and scattered fragmentation of the metallic pressure vessel.
  • Steel canisters are commonly used as the infiator pressure vessel in a passenger-restraint system because of the relatively high strength of steel at elevated temperatures. Given the emphasis on vehicle weight reduction, it is desirable that metals such as aluminum, and smaller or lighter steel vessels be utilized in the pressure vessel.
  • nonazide gas generant compositions do not meet the gaseous effluent requirements met by current azide based inflators.
  • the autoignition material a fraction of the total gas generant, has been found to create excessive levels of undesirable gaseous effluents, particularly carbon monoxide and nitrogen oxides. If an autoignition composition can be developed that produces little or no noxious gases, then the nonazide autoignition compositions will conform more closely to the effluent levels currently achieved by azide fuels.
  • a further concern involves the industry drive to reduce the size of the infiator by eliminating or reducing the volume of its components.
  • Most infiator systems are deployed by the combustion of a gas generant composition comprising a booster, an autoigniter, and a main gas generant charge.
  • a gas generant composition comprising a booster, an autoigniter, and a main gas generant charge.
  • electrical initiation of a squib ignites the booster that in turn supplies sufficient energy to ignite the main gas generant charge thereby deploying the gas infiator.
  • a separate autoignition composition is placed in close proximity to the booster so that during a fire the autoigniter will ignite, thereby igniting the booster and deploying the gas infiator.
  • the booster and autoigniter are separate auxiliary components to the main gas generant, and as such, prior compositions have not significantly contributed to the overall gas generated.
  • U.S. Patent No. 5,035,757 and U.S. Patent No. 5,139,588 to Poole describe azide-free gas generant compositions that form solid "clinkers" thereby providing easily filterable combustion gases.
  • the gas generants comprise a fuel such as 5-aminotetrazole, an oxidizer such as strontium nitrate and/or sodium nitrate, and an inert compound such as clay or silica.
  • the gas generants described therein do not autoignite at or below 175°C.
  • the present invention solves the aforementioned problems by providing an autoignition composition that also functions as a combination autoignition-booster-gas generant within a single chemical charge.
  • An autoignition oxidizer consisting of an alkali metal nitrite combined with a booster oxidizer consisting of an alkaline earth metal nitrate or nitrite forms an oxidizer component.
  • the oxidizer component is mixed with a fuel, such as 5-aminotetrazole (5AT) , thereby providing a gas generant with an autoignition temperature less than or equal to 175°C.
  • a fuel such as 5-aminotetrazole (5AT)
  • the alkali metal nitrite with the high nitrogen fuel creates a higher reactivity at lower temperatures, thereby lowering the autoignition temperature and facilitating the use of a lightweight pressure vessel within the passenger restraint system.
  • the composition passes all high temperature aging tests with a thermal stability at temperatures up to 110°C.
  • the selected compositions are safer to handle and produce minimal noxious gases such as carbon monoxide or nitrogen oxides.
  • Figure 1 is a DSC graphical representation illustrating the exothermic decomposition and autoignition of compositions comprising an alkali metal nitrite, in accordance with the present invention.
  • Figure 2 is a DSC graphical representation illustrating the endothermic decomposition of compositions described in the related art.
  • an autoignition composition that includes a fuel, a booster oxidizer, an autoignition oxidizer, and an optional inert component .
  • a fuel is selected from a group consisting of tetrazoles such as lH-tetrazole, 5-aminotetrazole, 5-nitrotetrazole, 5- nitroaminotetrazole, 5 , 5'-bitetrazole, diguanidinium-5, 5'- azotetrazolate, salts of tetrazoles, triazoles such as nitroaminotriazole, 3-nitro-l, 2 , 4-triazole, 3-nitro-l, 2 , 4- triazole-5-one, salts of triazoles, and mixtures thereof.
  • the preferred fuel is 5-aminotetrazole (5AT) because it is readily available in a pure form at a relatively low cost.
  • the fuel generally comprises 28 to 40% by weight of the autoignition compound.
  • a booster oxidizer is selected from the group consisting of alkaline earth metal nitrates, alkaline earth metal nitrites, and mixtures thereof.
  • the preferred booster oxidizer is strontium nitrate because it is also readily available in pure form at a relatively low cost. Furthermore, strontium nitrate forms an easily filterable slag upon combustion.
  • the booster oxidizer generally comprises 18 to 64% by weight of the autoignition compound.
  • An autoignition oxidizer is selected from the group consisting of alkali metal nitrites. Sodium nitrite is preferred due to its low melting point. The most preferred autoignition oxidizer is sodium nitrite because of its high reactivity at low temperatures when combined with the above fuel component or components.
  • the autoignition oxidizer generally comprises 1 to 30% by weight of the autoignition compound .
  • an optional inert component is selected from the group including clay, diatomaceous earth, talc, silica, and alumina.
  • Multifunctional bentonite clay is a preferred inert component because it can desensitize the composition, act as a binder to provide greater strength to the final form of the autoignition material, and aid in slag filterability by forming alkali metal and alkaline earth metal silicates and aluminates.
  • the inert component generally comprises 0 to 20% by weight of the autoignition compound.
  • An autoignition composition used in a vehicle occupant restraint system must be thermally stable up to 110°C and must rapidly autoignite at temperatures sufficiently low to prevent rupture of the pressure vessel and yet provide normal deployment of the infiator.
  • the temperature at which exothermic decomposition begins to occur is dependent upon the choice of fuel and autoignition oxidizer, and is specifically related to the melting or decomposition temperatures of the individual components.
  • the ratios of autoignition oxidizer to booster oxidizer, and of autoignition oxidizer to inert material, are directly related to the temperature at which autoignition occurs in the compositions of the present invention. It should be noted that the sensitivity of a composition of the present invention to both shock and impact increases as the relative amount of autoignition oxidizer increases.
  • the pressure generated during deployment is correspondingly kept to a minimum thereby permitting the use of a lightweight pressure vessel. Maintaining the autoignition temperature below the melting point of the primary gas generant prevents detonation or rapid deflagration of the primary gas generant .
  • compositions of the present invention when ignited, produce little or no toxic gases such as carbon monoxide or nitrogen oxides.
  • the compositions of the present invention can be formulated to be oxygen deficient (higher CO and lower N0 X ) or oxygen rich (lower CO and higher NO . This is measured by the oxygen balance of the composition, which is the percent by weight of molecular oxygen in the composition which is needed (negative oxygen balance) or liberated (positive oxygen balance) , to result in a stoichiometric reaction of the composition ingredients thereby forming nitrogen, carbon dioxide, water, and the most common oxides of other elements present.
  • an autoignition composition be utilized in which the oxygen balance can be easily tailored to meet individual customer requirements, and yet still retain a lower autoignition temperature.
  • the preferred oxygen balance of the compositions of the present invention is between -3.0% and 1.0% by weight.
  • the most preferred oxygen balance is between -2.0% and 0.0% by weight.
  • the mechanism that leads to autoignition in the present invention occurs with as little as 1.0% by weight of an alkali metal nitrite autoignition oxidizer.
  • an alkali metal nitrite is the only oxidizer, an excessively high burn rate will result leading to possible detonation or rapid deflagration if a minimum mass is autoignited under confinement in an infiator.
  • Example 6 given below, is illustrative. It is equally well known that the bulk of undesirable water-soluble particulate produced by both azide and nonazide inflators are alkali metal solids that come from the combustion of compounds containing alkali metals.
  • an alkaline earth nitrate or nitrite can be used in combination as a more stable booster oxidizer.
  • the burn rate of the compositions can be decreased to a safe level while still retaining autoignition at a significantly reduced temperature.
  • alkaline earth nitrates and nitrites as a major constituent of the oxidizer, water soluble particulate is minimized.
  • the preferred embodiment is utilized as an autoignition-booster in conjunction with a primary gas generant, thereby alleviating the need for a separate booster charge.
  • the compositions of the present invention generate gas at levels similar to common nonazide gas generants or approximately 2.4 moles of gas per 100 grams of generant.
  • the autoignition composition can actually function as a combination autoignition-booster-primary gas generant in an infiator system.
  • the autoignition composition may also be utilized as a separate autoignition component in conjunction with separate booster and separate primary gas generant components.
  • compositions of the present invention contain no individually explosive components and are therefore relatively insensitive to shock and impact thereby simplifying processing methods and raw material handling procedures.
  • Figures 1 and 2 were generated using a differential scanning calorimeter (DSC) .
  • a downward peak indicates an endothermic process (melting or endothermic decomposition) while an upward peak indicates an exothermic process (ignition or exothermic decomposition) .
  • Table 1 correlates the curves of Figures 1 and 2 with the respective compositions found in the related art and with those described in the examples given below.
  • an alkali metal nitrite such as sodium nitrite reduces the autoignition temperature within a given gas generant composition.
  • compositions not incorporating an alkali metal nitrite do not exhibit exothermic reactions culminating in an autoignition temperature below 175 °C.
  • the Tammann temperature is used to describe the temperature at which there is enough vibrational freedom in the lattice of an inorganic oxidizer to allow for intimate mixing with a mobile, reactive fuel. This is considered to be the temperature at which a self-sustaining reaction is likely to occur with minimal energy input, and is quite low for most alkali metal nitrites, chlorates, and perchlorates. Of particular interest are common oxidizers such as sodium nitrite and potassium chlorate, which have Tammann temperatures of -1°C and 42 °C respectively. Although certain alkali metal nitrites have a lower Tammann temperature than common alkali metal chlorates and perchlorates, the decomposition of the disclosed oxidizers are not exothermic as with chlorates.
  • a small amount of energy such as that provided from an impact or electrostatic discharge may activate a reaction, but is less likely to cause a self-propagating reaction due to the nature of the individual components, specifically the oxidizers that decompose endothermically rather than exothermically, in accordance with the present invention.
  • a mixture of 51.9% strontium nitrate Sr(N0 3 ) 2 , 36.4% 5- aminotetrazole (5AT) , and 11.7% sodium nitrite (NaN0 2 ) was prepared. Each component was dried and ground separately and then mixed by dry-blending. The composition was tested on a differential scanning calorimeter (DSC) at a heating rate of 10°C per minute. Endothermic decomposition occurred with an onset at 137°C and a peak at 142°C. Exothermic decomposition followed immediately, with an initial onset at 154 °C and a peak at 183 °C.
  • DSC differential scanning calorimeter
  • EXAMPLE 2 A mixture of 42.7% Sr(N0 3 ) 2 , 36.9% 5AT, and 20.4% NaN0 2 was prepared and tested as described in example 1. Endothermic decomposition occurred with an onset at 136 °C and a peak of 142°C. Exothermic decomposition followed immediately, with an initial onset at 154°C and a peak at 180°C. This example demonstrates that the amount of NaN0 2 present does not significantly effect the mechanism which causes autoignition in the present invention. EXAMPLE 3
  • a mixture of 53.0% Sr(N0 3 ) 2 , 37.0% 5AT, and 10.0% NaN0 2 was prepared and tested as described in example 1. Exothermic decomposition occurred with an onset at 156 °C and a peak at 183 °C. Impact sensitivity was tested using a standard Bureau of Explosives Impact Machine consisting of an eight pound weight dropped from a given height. The impact sensitivity of a composition as defined here is the minimum drop height at which initiation occurs in two of two tests. The impact sensitivity of this composition was found to be 3 inches, with complete combustion of the sample. Autoignition was tested using an aluminum fixture containing a small amount of composition (70-100mg) and a temperature probe.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Air Bags (AREA)

Abstract

L'invention concerne une composition à inflammation spontanée pour le générateur de gaz d'un système de retenue des occupants d'un véhicule à moteur. Cette composition est thermiquement stable à des températures pouvant atteindre 110 °C, et s'enflamme entre 150 et 175 °C. Elle produit un minimum de gaz toxiques lors de sa combustion, assure une réduction de la taille du dispositif de gonflage à gaz, et peut être produite en toute sécurité à l'aide de simples procédés de traitement. En mélangeant un nitrite de métal alcalin à l'aide d'un combustible à base d'azote, les générateurs de gaz obtenus s'enflamment spontanément à une température inférieure ou égale à 175 °C. L'addition d'un nitrite ou d'un nitrate de métal terreux alcalin assure la stabilité requise pour servir en outre de propulseur et/ou de générateur de gaz.
PCT/US1997/013070 1996-08-16 1997-08-06 Compositions a inflammation spontanee pour generateurs de gaz de dispositifs de gonflage WO1998006683A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP97937024A EP0944562B1 (fr) 1996-08-16 1997-08-06 Compositions a inflammation spontanee pour generateurs de gaz de dispositifs de gonflage
JP50975298A JP4021491B2 (ja) 1996-08-16 1997-08-06 インフレータのガス発生体用自動点火組成物

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US70068196A 1996-08-16 1996-08-16
US08/906,496 1997-08-05
US08/700,681 1997-08-05
US08/906,496 US6007647A (en) 1996-08-16 1997-08-05 Autoignition compositions for inflator gas generators

Publications (1)

Publication Number Publication Date
WO1998006683A1 true WO1998006683A1 (fr) 1998-02-19

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PCT/US1997/013070 WO1998006683A1 (fr) 1996-08-16 1997-08-06 Compositions a inflammation spontanee pour generateurs de gaz de dispositifs de gonflage

Country Status (3)

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EP (1) EP0944562B1 (fr)
JP (1) JP4021491B2 (fr)
WO (1) WO1998006683A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1000916A1 (fr) * 1998-04-30 2000-05-17 Daicel Chemical Industries, Ltd. Composition ameliorante pour gonfleur
EP1003696A1 (fr) * 1997-08-18 2000-05-31 Breed Automotive Technology, Inc. Composition favorisant l'amor age pour gonfleur d'airbag
WO2003000624A3 (fr) * 2001-05-10 2003-12-11 Dynamit Nobel Ag Agents d'allumage
EP1785409A1 (fr) * 2004-06-17 2007-05-16 Nof Corporation Agent d"allumage pour dispositif générateur de gaz

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007176202A (ja) * 2005-12-27 2007-07-12 Daicel Chem Ind Ltd エアバッグモジュール

Citations (5)

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Publication number Priority date Publication date Assignee Title
US5035757A (en) * 1990-10-25 1991-07-30 Automotive Systems Laboratory, Inc. Azide-free gas generant composition with easily filterable combustion products
US5139588A (en) * 1990-10-23 1992-08-18 Automotive Systems Laboratory, Inc. Composition for controlling oxides of nitrogen
US5386775A (en) * 1993-06-22 1995-02-07 Automotive Systems Laboratory, Inc. Azide-free gas generant compositions and processes
US5472647A (en) * 1993-08-02 1995-12-05 Thiokol Corporation Method for preparing anhydrous tetrazole gas generant compositions
US5501823A (en) * 1993-08-02 1996-03-26 Thiokol Corporation Preparation of anhydrous tetrazole gas generant compositions

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US3653994A (en) * 1954-05-24 1972-04-04 Aerojet General Co Propellant compositions containing a metal nitrite burning rate catalyst
US4369079A (en) * 1980-12-31 1983-01-18 Thiokol Corporation Solid non-azide nitrogen gas generant compositions
CA2167386C (fr) * 1993-08-02 1999-10-05 Alliant Techsystems Inc. Methode de preparation de compositions generatrices de tetrazole gazeux anhydre
US5431103A (en) * 1993-12-10 1995-07-11 Morton International, Inc. Gas generant compositions
US5380380A (en) * 1994-02-09 1995-01-10 Automotive Systems Laboratory, Inc. Ignition compositions for inflator gas generators

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Publication number Priority date Publication date Assignee Title
US5139588A (en) * 1990-10-23 1992-08-18 Automotive Systems Laboratory, Inc. Composition for controlling oxides of nitrogen
US5035757A (en) * 1990-10-25 1991-07-30 Automotive Systems Laboratory, Inc. Azide-free gas generant composition with easily filterable combustion products
US5386775A (en) * 1993-06-22 1995-02-07 Automotive Systems Laboratory, Inc. Azide-free gas generant compositions and processes
US5472647A (en) * 1993-08-02 1995-12-05 Thiokol Corporation Method for preparing anhydrous tetrazole gas generant compositions
US5501823A (en) * 1993-08-02 1996-03-26 Thiokol Corporation Preparation of anhydrous tetrazole gas generant compositions

Non-Patent Citations (1)

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Title
See also references of EP0944562A4 *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1003696A1 (fr) * 1997-08-18 2000-05-31 Breed Automotive Technology, Inc. Composition favorisant l'amor age pour gonfleur d'airbag
EP1003696A4 (fr) * 1997-08-18 2000-09-13 Breed Automotive Tech Composition favorisant l'amor age pour gonfleur d'airbag
US6487974B1 (en) 1997-08-18 2002-12-03 Breed Automotive Technology, Inc. Inflator
EP1000916A1 (fr) * 1998-04-30 2000-05-17 Daicel Chemical Industries, Ltd. Composition ameliorante pour gonfleur
EP1000916A4 (fr) * 1998-04-30 2000-12-27 Daicel Chem Composition ameliorante pour gonfleur
WO2003000624A3 (fr) * 2001-05-10 2003-12-11 Dynamit Nobel Ag Agents d'allumage
EP1785409A1 (fr) * 2004-06-17 2007-05-16 Nof Corporation Agent d"allumage pour dispositif générateur de gaz
EP1785409A4 (fr) * 2004-06-17 2010-04-07 Nof Corp Agent d"allumage pour dispositif générateur de gaz
US7993475B2 (en) 2004-06-17 2011-08-09 Nof Corporation Firing agent for gas generating device

Also Published As

Publication number Publication date
EP0944562A4 (fr) 2000-02-23
EP0944562B1 (fr) 2005-11-23
JP2001507325A (ja) 2001-06-05
JP4021491B2 (ja) 2007-12-12
EP0944562A1 (fr) 1999-09-29

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