EP0678492A1 - Gas generant compositions with alkali oxide scavengers - Google Patents

Gas generant compositions with alkali oxide scavengers Download PDF

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Publication number
EP0678492A1
EP0678492A1 EP95301693A EP95301693A EP0678492A1 EP 0678492 A1 EP0678492 A1 EP 0678492A1 EP 95301693 A EP95301693 A EP 95301693A EP 95301693 A EP95301693 A EP 95301693A EP 0678492 A1 EP0678492 A1 EP 0678492A1
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EP
European Patent Office
Prior art keywords
gas generant
generant composition
alkaline earth
acid
composition according
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Legal status (The legal status 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 status listed.)
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Application number
EP95301693A
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German (de)
French (fr)
Inventor
Robert D. Taylor
Thomas M. Deppert
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Morton International LLC
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Morton International LLC
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Classifications

    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents

Definitions

  • the present invention is directed to gas generant compositions suitable for automotive air bag restraint systems, particularly restraint systems in which the gas generant is encased in aluminum housing and/or generates gases which come into contact with aluminum components, such as filters.
  • This patent teaches that minimal amounts of non-gas generating components should be added, except up to 1 wt% fibers, such as graphite or iron fibers, which increase the burning rate and transfer heat during combustion.
  • US-A-5, 015,309 teaches that the compositions are useful for inflators as taught in US-A-4,547,342 to Adams et al.
  • the inflators taught in US-A-4,547,342 have aluminum housings and other aluminum components.
  • a disadvantage with compositions such as taught in US-A-5,015,309 is that combustion products include K2O which is highly corrosive to aluminum. Improved formulations are needed to reduce degradation of aluminum components during combustion of the gas generant composition. Also, it is highly desirable that the combustion products include a slag which is filterable.
  • the compositions taught in US-A-5,015,309 are not filterable.
  • a gas generant composition using as the fuel component a compound selected from 5-nitrobarbituric acid, 5-nitroorotic acid, alkali and alkaline earth metal salts thereof; an oxidizer for the fuel selected from ammonium, alkali metal and alkaline earth metal salts of chlorates, perchlorates and nitrates and transition metal oxides; and a binder, also contains alumina (Al2O3) and/or silica (SiO2) as a scavenger of alkali metal oxides.
  • alumina Al2O3
  • silica silica
  • the fuel comprises between 5 and 55 wt%, preferably at least 20 wt.%, of the gas generant composition.
  • Preferred fuels are the potassium salts of 5nitrobarbituric acid (also called dilituric acid) and 5nitroorotic acid.
  • the oxidizer which is used at a level of between 30 and 75 wt%, preferably at least 50 wt.%, is selected from ammonium, alkali metal and alkaline earth metal chlorates, perchlorates, nitrates, transition metal oxides, and mixture thereof.
  • a portion of the oxidizer may be a transition metal oxide, such as cupric oxide.
  • a transition metal oxide preferably comprises between about 5 to about 35 wt% of the composition.
  • these oxides provide hard particles, facilitating compaction of the composition into pellets or other consolidated solid shapes.
  • the cations of the fuel salts and oxidizers are preferably mixture of alkali metal cations, i.e., lithium, sodium and potassium, and alkaline earth metal cations, i.e., magnesium, strontium, barium and cerium.
  • alkali metal cations i.e., lithium, sodium and potassium
  • alkaline earth metal cations i.e., magnesium, strontium, barium and cerium.
  • the alkali cations form liquid combustion products and the alkaline earth metal cations form solid combustion products, the mixture of liquid and solid combustion products forming clinkers which can be readily removed from the gas stream by filtration.
  • the ratio of solid to liquid combustion products may be adjusted by the ratio of alkaline earth metal cations to alkali metal cations.
  • sodium is preferred over potassium as sodium oxide is more readily scavenged by alumina or silica than potassium oxide.
  • alumina, silica or mixtures thereof are added to scavenge corrosive alkali metal oxides, such as sodium oxide and potassium oxide.
  • the composition of the present invention contains alumina and/or silica at a level of between about 0.5 and about 10 wt%, preferably between about 1 and about 8 wt%.
  • the alumina and/or silica may be in the form of particulates or as fibers, such as fibers of various silica/alumina content.
  • Alumina is generally preferred over silica, being a more efficient scavenger.
  • a binder is added at a level of between about 1 and about 5 wt%.
  • Suitable binder materials include but are not limited to molybdenum disulfide, graphite, polytetrafluroethylene, Viton® (a copolymer of vinylidene fluoride and hexafluoropropylene), nitrocellulose, polysaccharides, polyvinylpyrrolidones, polycarbonates, sodium silicate, calcium stearate, magnesium stearate and mixtures thereof.
  • Preferred binder materials are molybdenum disulfide and polycarbonates.
  • Alkali metal and alkaline earth metal carbonates and/or oxalates may optionally be added up to 40 wt%. These act as coolants, lowering the combustion temperature. Lower combustion temperatures minimize production of toxic gases, such as CO and NO x . Generally, if used, these coolants are used at a level of at least 1 wt%.
  • the alumina and/or silica may be in the form of fibers. Fibers help to mechanically reinforce the consolidated unburned material and subsequently consolidate slag material formed by burning the composition.
  • Graphite fibers e.g., at between 1 and 10 wt%, may be also be used, either as the sole fibrous material or in conjunction with alumina-containing fibers to perform this reinforcing function.
  • Gas generant formulations according to the invention and their combustion properties are shown in the table below. Component levels are in weight percent.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Air Bags (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

A gas generant composition adapted for use with airbag restraint systems containing aluminum components includes a fuel which is 5-nitrobarbituric acid (or salts thereof), 5-nitroorotic acid (or salts thereof); an oxidizer which is an ammonium, alkali metal and/or alkaline earth metal salt of a chlorate, perchlorate or nitrate and/or is a transition metal oxide, such as cupric oxide; alumina and/or silica; and a binder.

Description

  • The present invention is directed to gas generant compositions suitable for automotive air bag restraint systems, particularly restraint systems in which the gas generant is encased in aluminum housing and/or generates gases which come into contact with aluminum components, such as filters.
  • Most automotive air bag restraint systems, presently in use, use gas generant compositions in which sodium azide is the principal fuel. Because of disadvantages with sodium azide, particularly instability in the presence of metallic impurities and toxicity, which presents a disposal problem for unfired gas generators, there is a desire to develop non-azide gas generant systems and a number of non-azide formulations have been proposed. However, to date, non-azide gas generants have not made significant commercial inroads.
  • US-A-5,015,309 to Wardle et al., teaches gas generant compositions in which fuels are salts of 5-nitrobarbituric acid, salts of 5-nitroorotic acid and nitrouracil (which doesn't form a salt), oxidizers include alkali (except sodium) and alkaline earth metal salts of nitrates, nitrites and hexanitrocobaltate, and binders, when needed for pelletization.
  • This patent teaches that minimal amounts of non-gas generating components should be added, except up to 1 wt% fibers, such as graphite or iron fibers, which increase the burning rate and transfer heat during combustion.
  • US-A-5, 015,309 teaches that the compositions are useful for inflators as taught in US-A-4,547,342 to Adams et al. The inflators taught in US-A-4,547,342 have aluminum housings and other aluminum components. A disadvantage with compositions such as taught in US-A-5,015,309 is that combustion products include K₂O which is highly corrosive to aluminum. Improved formulations are needed to reduce degradation of aluminum components during combustion of the gas generant composition. Also, it is highly desirable that the combustion products include a slag which is filterable. The compositions taught in US-A-5,015,309 are not filterable.
  • According to the present invention a gas generant composition using as the fuel component a compound selected from 5-nitrobarbituric acid, 5-nitroorotic acid, alkali and alkaline earth metal salts thereof; an oxidizer for the fuel selected from ammonium, alkali metal and alkaline earth metal salts of chlorates, perchlorates and nitrates and transition metal oxides; and a binder, also contains alumina (Al₂O₃) and/or silica (SiO₂) as a scavenger of alkali metal oxides.
  • The fuel comprises between 5 and 55 wt%, preferably at least 20 wt.%, of the gas generant composition. Preferred fuels are the potassium salts of 5nitrobarbituric acid (also called dilituric acid) and 5nitroorotic acid.
  • The oxidizer, which is used at a level of between 30 and 75 wt%, preferably at least 50 wt.%, is selected from ammonium, alkali metal and alkaline earth metal chlorates, perchlorates, nitrates, transition metal oxides, and mixture thereof.
  • Optionally, a portion of the oxidizer may be a transition metal oxide, such as cupric oxide. Such a transition metal oxide preferably comprises between about 5 to about 35 wt% of the composition. In addition to their oxidizing function, these oxides provide hard particles, facilitating compaction of the composition into pellets or other consolidated solid shapes.
  • As is taught in US-A-5,139,588, the teachings of which are incorporated herein by reference, the cations of the fuel salts and oxidizers are preferably mixture of alkali metal cations, i.e., lithium, sodium and potassium, and alkaline earth metal cations, i.e., magnesium, strontium, barium and cerium. Upon combustion, the alkali cations form liquid combustion products and the alkaline earth metal cations form solid combustion products, the mixture of liquid and solid combustion products forming clinkers which can be readily removed from the gas stream by filtration. The ratio of solid to liquid combustion products may be adjusted by the ratio of alkaline earth metal cations to alkali metal cations. Of alkali metal cations, sodium is preferred over potassium as sodium oxide is more readily scavenged by alumina or silica than potassium oxide.
  • In accordance with the present invention, alumina, silica or mixtures thereof are added to scavenge corrosive alkali metal oxides, such as sodium oxide and potassium oxide. Accordingly, the composition of the present invention contains alumina and/or silica at a level of between about 0.5 and about 10 wt%, preferably between about 1 and about 8 wt%. The alumina and/or silica may be in the form of particulates or as fibers, such as fibers of various silica/alumina content. Alumina is generally preferred over silica, being a more efficient scavenger.
  • A binder is added at a level of between about 1 and about 5 wt%. Suitable binder materials include but are not limited to molybdenum disulfide, graphite, polytetrafluroethylene, Viton® (a copolymer of vinylidene fluoride and hexafluoropropylene), nitrocellulose, polysaccharides, polyvinylpyrrolidones, polycarbonates, sodium silicate, calcium stearate, magnesium stearate and mixtures thereof. Preferred binder materials are molybdenum disulfide and polycarbonates.
  • Alkali metal and alkaline earth metal carbonates and/or oxalates may optionally be added up to 40 wt%. These act as coolants, lowering the combustion temperature. Lower combustion temperatures minimize production of toxic gases, such as CO and NOx. Generally, if used, these coolants are used at a level of at least 1 wt%.
  • As noted above, the alumina and/or silica may be in the form of fibers. Fibers help to mechanically reinforce the consolidated unburned material and subsequently consolidate slag material formed by burning the composition. Graphite fibers, e.g., at between 1 and 10 wt%, may be also be used, either as the sole fibrous material or in conjunction with alumina-containing fibers to perform this reinforcing function.
  • The invention will now be described in greater detail by way of specific example.
    • Examples 1-8
  • Gas generant formulations according to the invention and their combustion properties are shown in the table below. Component levels are in weight percent.
    Figure imgb0001
    Figure imgb0002

Claims (7)

  1. A gas generant composition comprising
       between 5 and 55 wt% of a fuel which is selected from 5-nitrobarbituric acid, 5-nitroorotic acid, alkali and/or alkaline earth metal salts of the 5-nitrobarbituric acid or 5-nitroorotic acid, and mixtures thereof,
       between 30 and 75 wt% of an oxidizer selected from ammonium, alkali metal and alkaline earth metal chlorates, perchlorates, nitrates, transition metal ocides, and mixtures thereof,
       between 0.5 and 10 wt% alumina and/or silica, and
       between 1 and 5 wt% of a binder.
  2. A generant composition according to claim 1 wherein said binder is selected from molybdenum disulfide, graphite, polytetrafluoroethylene, vinyl fluoride/hexafluoropropylene copolymer, nitrocellulose, polysaccharides, polyvinylpyrrolidones, polycarbonates, sodium silicate, calcium stearate, magnesium stearate and mixtures thereof.
  3. A gas generant according to claim 1 wherein said binder is selected from molybdenum disulfide and polycarbonates.
  4. A gas generant composition according to any preceding claim comprising between 5 and 35 wt% of a transition metal oxide.
  5. A gas generant composition according to claim 4 wherein said transition metal oxide is cupric oxide.
  6. A gas generant composition according to any preceding claim further containing between 1 and 40 wt% of a coolant selected from alkali metal and alkaline earth metal carbonates, oxalates and mixtures thereof.
  7. A gas generant composition according to any preceding claim further containing between 1 and 10 wt% of graphite fibers.
EP95301693A 1994-04-18 1995-03-14 Gas generant compositions with alkali oxide scavengers Withdrawn EP0678492A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US22898394A 1994-04-18 1994-04-18
US228983 1994-04-18

Publications (1)

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EP0678492A1 true EP0678492A1 (en) 1995-10-25

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EP (1) EP0678492A1 (en)
JP (1) JPH0834693A (en)
KR (1) KR950029072A (en)
AU (1) AU1342695A (en)
CA (1) CA2143360A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19541924A1 (en) * 1995-11-10 1997-05-15 Diehl Gmbh & Co Two stage gas generator for vehicle occupant safety airbag
CN100417631C (en) * 2005-07-29 2008-09-10 比亚迪股份有限公司 Safety gas pocket gas production medicine and its preparation method
WO2016097826A1 (en) * 2014-12-19 2016-06-23 Tubitak O -chlorobenzylidene malononitrile (cs) based self-combustible pyrotechnic compositions which have low ignition temperatures

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2366457B1 (en) * 2010-03-19 2013-03-06 Alfa Laval Corporate AB Device and method for monitoring and adjusting the radial position of an interface layer in a centrifugal separator
CN112570025B (en) * 2020-10-30 2023-04-21 中北大学 Barbituric acid modified polyoxometalate hybrid and preparation method thereof

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2351379A1 (en) * 1972-10-17 1974-05-09 Poudres & Explosifs Ste Nale PROCESS FOR QUICKLY RECOVERING A LARGE VOLUME OF NON-TOXIC GASES AT MODERATE TEMPERATURES BY COMBUSTION OF A FUEL
US3862866A (en) * 1971-08-02 1975-01-28 Specialty Products Dev Corp Gas generator composition and method
US4547342A (en) * 1984-04-02 1985-10-15 Morton Thiokol, Inc. Light weight welded aluminum inflator
EP0400809A2 (en) * 1989-05-04 1990-12-05 Morton International, Inc. Gas generant compositions containing salts of 5-nitrobarbituric acid, salts of nitroorotic acid, or 5-nitrouracil
EP0438851A2 (en) * 1990-01-09 1991-07-31 Automotive Systems Laboratory Inc. Composition and process for inflating a safety crash bag
US5139588A (en) * 1990-10-23 1992-08-18 Automotive Systems Laboratory, Inc. Composition for controlling oxides of nitrogen
US5160386A (en) * 1991-11-04 1992-11-03 Morton International, Inc. Gas generant formulations containing poly(nitrito) metal complexes as oxidants and method

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4321924A (en) * 1980-05-12 1982-03-30 The Procter & Gamble Company Bordered disposable absorbent article
JPH0680491A (en) * 1992-04-01 1994-03-22 Asahi Chem Ind Co Ltd Gas generator for airbag

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3862866A (en) * 1971-08-02 1975-01-28 Specialty Products Dev Corp Gas generator composition and method
DE2351379A1 (en) * 1972-10-17 1974-05-09 Poudres & Explosifs Ste Nale PROCESS FOR QUICKLY RECOVERING A LARGE VOLUME OF NON-TOXIC GASES AT MODERATE TEMPERATURES BY COMBUSTION OF A FUEL
US4547342A (en) * 1984-04-02 1985-10-15 Morton Thiokol, Inc. Light weight welded aluminum inflator
EP0400809A2 (en) * 1989-05-04 1990-12-05 Morton International, Inc. Gas generant compositions containing salts of 5-nitrobarbituric acid, salts of nitroorotic acid, or 5-nitrouracil
EP0438851A2 (en) * 1990-01-09 1991-07-31 Automotive Systems Laboratory Inc. Composition and process for inflating a safety crash bag
US5139588A (en) * 1990-10-23 1992-08-18 Automotive Systems Laboratory, Inc. Composition for controlling oxides of nitrogen
US5160386A (en) * 1991-11-04 1992-11-03 Morton International, Inc. Gas generant formulations containing poly(nitrito) metal complexes as oxidants and method

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19541924A1 (en) * 1995-11-10 1997-05-15 Diehl Gmbh & Co Two stage gas generator for vehicle occupant safety airbag
CN100417631C (en) * 2005-07-29 2008-09-10 比亚迪股份有限公司 Safety gas pocket gas production medicine and its preparation method
WO2016097826A1 (en) * 2014-12-19 2016-06-23 Tubitak O -chlorobenzylidene malononitrile (cs) based self-combustible pyrotechnic compositions which have low ignition temperatures
CN107108389A (en) * 2014-12-19 2017-08-29 土耳其科学技术研究理事会 O-chlorobenzylidene malononitrile (CS) class self-burning type pyrotechnic composition with low ignition temperature
US10155701B2 (en) 2014-12-19 2018-12-18 Tubitak O-chlorobenzylidene malononitrile (CS) based self-combustible pyrotechnic compositions which have low ignition temperatures
CN107108389B (en) * 2014-12-19 2019-12-24 土耳其科学技术研究理事会 O-chlorobenzylidene malononitrile (CS) type self-igniting pyrotechnic composition with low ignition temperature

Also Published As

Publication number Publication date
AU1342695A (en) 1995-11-16
JPH0834693A (en) 1996-02-06
CA2143360A1 (en) 1995-10-19
KR950029072A (en) 1995-11-22

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