Metal complexes for use as gas generants

Abstract

Gas generating compositions and methods for their use are provided. Metal complexes are used as gas generating compositions. These complexes are comprised of a metal cation template, a neutral ligand containing hydrogen and nitrogen, and sufficient oxidizing anion to balance the charge of the complex. The complexes are formulated such that when the complex combusts, nitrogen gas and water vapor is produced. Specific examples of such complexes include metal nitrite ammine, metal nitrate ammine, and metal perchlorate ammine complexes, as well as hydrazine complexes. A binder and co-oxidizer can be combined with the metal complexes to improve crush strength of the gas generating compositions and to permit efficient combustion of the binder. Such gas generating compositions are adaptable for use in gas generating devices, such as automobile air bags.

1 . A gas generating composition, comprising: 
 at least one metal complex comprising a metal cation, a hydrazine ligand, and sufficient oxidizing anion to balance the charge of the metal cation, wherein the gas generating composition comprises about 48.5% to less than about 100% by weight of the at least one metal complex.    
     
     
         2 . The gas generating composition of  claim 1 , wherein the at least one metal complex is selected from the group consisting of metal nitrite hydrazines, metal nitrate hydrazines, metal perchlorate hydrazines, and mixtures thereof.  
     
     
         3 . The gas generating composition of  claim 1 , wherein the metal cation is a transition metal, alkaline earth metal, metalloid, or lanthanide metal cation.  
     
     
         4 . The gas generating composition of  claim 1 , wherein the metal cation is selected from the group consisting of cobalt, magnesium, manganese, nickel, titanium, copper, chromium, zinc, tin, rhodium, iridium, ruthenium, palladium and platinum.  
     
     
         5 . The gas generating composition of  claim 1 , wherein the oxidizing anion is selected from the group consisting of nitrate, nitrite, chlorate, perchlorate, peroxide, and superoxide.  
     
     
         6 . The gas generating composition of  claim 1 , wherein the oxidizing anion is free of carbon.  
     
     
         7 . The gas generating composition of  claim 1 , wherein the at least one metal complex comprises at least one common ligand in addition to the hydrazine ligand, wherein the at least one common ligand is selected from the group consisting of aquo (H 2 O), hydroxo (OH), perhydroxo (O 2 H), peroxo (O 2 ), carbonato (CO 3 ), carbonyl (CO), oxalato (C 2 O 4 ), nitrosyl (NO), cyano (CN), isocyanato (NC), isothiocyanato (NCS), thiocyanato (SCN), amido (NH 2 ), imdo (NH), sulfato (SO 4 ), chloro (Cl), fluoro (F), phosphato (PO 4 ), and ethylenediaminetetraacetic acid (EDTA) ligands.  
     
     
         8 . The gas generating composition of  claim 1 , wherein the at least one metal complex includes a common counter ion in addition to the oxidizing anion, wherein the common counter ion is selected from the group consisting of hydroxide (OH − ), chloride (Cl − ), fluoride (F 31  ), cyanide (CN 31  ), thiocyanate (SCN 31  ), carbonate (CO 3   −2 ), sulfate (SO 4   −2 ), phosphate (PO 4   −3 ), oxalate (C 2 O 4   −2 ), borate (BO 4   −5 ), and ammonium (NH 4   + ) counter ions.  
     
     
         9 . The gas generating composition of  claim 1 , further comprising a co-oxidizer.  
     
     
         10 . The gas generating composition of  claim 9 , wherein the co-oxidizer is selected from the group consisting of alkali perchlorates, alkaline earth perchlorates, lanthanide perchlorates, ammonium perchlorates, alkali chlorates, alkaline earth chlorates, lanthanide chlorates, ammonium chlorates, alkali peroxides, alkaline earth peroxides, lanthanide peroxides, ammonium peroxides, alkali nitrites, alkaline earth nitrites, lanthanide nitrites, ammonium nitrites, alkali nitrates, alkali earth nitrates, lanthanide nitrates, and ammonium nitrates.  
     
     
         11 . The gas generating composition of  claim 9 , wherein the co-oxidizer is selected from the group consisting of metal oxides, metal hydroxides, metal peroxides, metal oxide hydrates, metal oxide hydroxides, metal hydrous oxides, basic metal carbonates, basic metal nitrates, and mixtures thereof.  
     
     
         12 . The gas generating composition of  claim 9 , wherein the co-oxidizer is selected from the group consisting of oxides of copper, cobalt, manganese, tungsten, bismuth, molybdenum, and iron.  
     
     
         13 . The gas generating composition of  claim 9 , wherein the co-oxidizer is selected from the group consisting of CuO, Co 2 O 3 , Co 3 O 4 , CoFe 2 O 4 , Fe 2 O 3 , MoO 3 , Bi 2 MoO 6 , Bi 2 O 3 , Fe(OH) 3 , Co(OH) 3 , Co(OH) 2 , Ni(OH) 2 , Cu(OH) 2 , Zn(OH) 2 , Fe 2 O 3 .xH 2 O, SnO 2 .xH 2 O, MoO 3 .H 2 O, CoO(OH) 2 , FeO(OH) 2 , MnO(OH) 2 , MnO(OH) 3 , CuCO 3 .Cu(OH) 2  (malachite), 2Co(CO 3 ).3Co(OH) 2 .H 2 O, Co 0.69 Fe 0.34 (CO 3 ) 0.2 (OH) 2 , Na 3 [Co(CO 3 ) 3 ].3H 2 O, Zn 2 (CO 3 )(OH) 2 , Bi 2 Mg(CO 3 ) 2 (OH) 4 , Fe(CO 3 ) 0.12 (OH) 2.76 , Cu 1.54 Zn 0.46 (CO 3 )(OH) 2 , Co 0.49 Cu 0.51 (CO 3 ) 0.43 (OH) 1.1 , Ti 3 Bi 4 (CO 3 ) 2 (OH) 2 O 9 (H 2 O) 2 , (BiO) 2 CO 3 , Cu 2 (OH) 3 NO 3 , Co 2 (OH) 3 NO 3 , CuCo(OH) 3 NO 3 , Zn 2 (OH) 3 NO 3 , Zn 2 (OH) 2 NO 3 , Mn(OH) 2 NO 3 , Fe 4 (OH) 11 NO 3 .2H 2 O), Mo(NO 3 ) 2 O 2 , BiONO 3 .H 2 O, and Ce(OH)(NO 3 ) 3 .3H 2 O.  
     
     
         14 . The gas generating composition of  claim 9 , wherein the co-oxidizer is present in an amount of from 5% to 50% by weight of the gas generating composition.  
     
     
         15 . The gas generating composition of  claim 1 , further comprising a binder.  
     
     
         16 . The gas generating composition of  claim 15 , wherein the binder is selected from the group consisting of naturally occurring gums, polyacrylic acids, and polyacrylamides.  
     
     
         17 . The gas generating composition of  claim 15 , wherein the binder comprises guar gum or acacia gum.  
     
     
         18 . The gas generating composition of  claim 15 , wherein the binder is selected from the group consisting of nitrocellulose, VAAR (vinyl acetate vinyl alcohol resin), and nylon.  
     
     
         19 . The gas generating composition of  claim 15 , wherein the binder has a concentration in the gas generating composition of at least 0. 1% by weight.  
     
     
         20 . The gas generating composition of  claim 15 , wherein the binder has a concentration in the gas generating composition from 0.5% to 10% by weight.  
     
     
         21 . The gas generating composition of  claim 1 , wherein the at least one metal complex is Zn(N 2 H 4 ) 3 (NO 3 ) 2  (tris-hydrazine zinc nitrate), Mg(N 2 H 4 ) 2 (ClO 4 ) 2  (bis-hydrazine magnesium perchlorate), or Pt(NO 2 ) 2 (NH 2 NH 2 ) 2  (bis-hydrazine platinum(II) nitrite).  
     
     
         22 . The gas generating composition of  claim 1 , further comprising carbon powder present in an amount from 0.1% to 6% by weight of the gas generating composition.  
     
     
         23 . The gas generating composition of  claim 1 , wherein the gas generating composition is in the form of pellets or granules.  
     
     
         24 . The gas generating composition of  claim 1 , wherein the gas generating composition comprises at least about 60% by weight of the at least one metal complex.  
     
     
         25 . The gas generating composition of  claim 1 , wherein the gas generating composition comprises at least about 65% by weight of the at least one metal complex.  
     
     
         26 . The gas generating composition of  claim 1 , wherein the gas generating composition comprises about 50% to about 80% by weight of the at least one metal complex.  
     
     
         27 . The gas generating composition of  claim 1 , further comprising at least one additive selected from the group consisting of bum rate modifiers, slag formers, release agents, coolants and NO x  reducing agents.  
     
     
         28 . A gas generating device, comprising: 
 a gas generating composition comprising at least one metal complex of a transition metal cation or alkaline earth metal cation, a hydrazine ligand, and sufficient oxidizing anion to balance the charge of the metal cation, such that when the at least one metal complex combusts, a mixture of gases containing nitrogen gas and water vapor is produced; and    an igniter to ignite the gas generating composition.    
     
     
         29 . The gas generating device of  claim 28 , wherein the igniter comprises an igniter composition that includes a mixture of Mg/Sr(NO 3 ) 2 /nylon and B/KNO 3 .  
     
     
         30 . An air bag system for a vehicle comprising: 
 a collapsed, inflatable air bag;    a gas generating device connected to the collapsed, inflatable air bag for inflating the collapsed, inflatable air bag, wherein the gas generating device includes a gas generating composition comprising at least one metal complex of a transition metal cation, a hydrazine ligand, and sufficient oxidizing anion to balance the charge of the transition metal cation; and    an igniter to ignite the gas generating composition.    
     
     
         31 . The air bag system of  claim 30 , wherein the gas generating composition comprises from 48.5% to less than about 100% by weight of the at least one metal complex.  
     
     
         32 . The air bag system of  claim 30 , wherein the gas generating composition comprises the at least one metal complex, at least one member selected from the group consisting of a water-soluble binder and carbon powder in an amount of 0. 1% to 6% of the gas generating composition, and less than 50% by weight of an inorganic co-oxidizer.  
     
     
         33 . A vehicle equipped with a supplemental restraint system, the supplemental restraint system including an air bag system which comprises: 
 a collapsed, inflatable air bag;    a gas generating device connected to the collapsed, inflatable air bag for inflating the collapsed, inflatable air bag, wherein the gas generating device contains a gas generating composition comprising at least one metal complex of a transition metal cation, a hydrazine ligand, and sufficient oxidizing anion to balance the charge of the transition metal cation; and    an igniter to ignite the gas generating composition.    
     
     
         34 . The vehicle of  claim 33 , wherein the gas generating composition further comprises at least one of a binder and carbon powder, wherein the crush strength of the gas generating composition is increased compared to the gas generating composition without the carbon powder.  
     
     
         35 . The vehicle of  claim 33 , wherein the gas generating composition comprises about 48.5% by weight to less than 100% by weight of the at least one metal complex.  
     
     
         36 . The vehicle of  claim 33 , wherein the gas generating composition further comprises at least one of a binder and carbon powder in an amount of 0. 1% to 6% by weight of the gas generating composition.  
     
     
         37 . The vehicle of  claim 33 , wherein the gas generating composition comprises the at least one metal complex, at least one member selected from the group consisting of a binder and carbon powder in an amount of 0.1 to 6% by weight, a secondary fuel, less than 50% by weight of an inorganic co-oxidizer, and at least one additive selected from the group consisting of bum rate modifiers, slag formers, release agents, coolants, and NO x  reducing agents.  
     
     
         38 . A method of inflating an inflatable air bag or balloon comprising: 
 generating substantially non-toxic gases by combusting an at least essentially azide-free gas generating composition comprising at least one metal complex having a transition metal cation or alkaline earth metal cation and at least one neutral ligand comprised of ammonia, and sufficient oxidizing anion to balance the charge of the metal cation, wherein when the at least essentially azide-free gas generating composition combusts, a substantially non-toxic mixture of gases comprising nitrogen gas and water vapor is produced; and    inflating the inflatable air bag or balloon with the substantially non-toxic mixture of gases.    
     
     
         39 . The method of  claim 38 , wherein the metal cation is selected from the group consisting of manganese, magnesium, cobalt, and zinc.  
     
     
         40 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition further comprises an oxidizing agent and wherein the oxidizing agent is other than a metal ammonia complex and is at least one member selected from the group consisting of nitrates, nitrites, chlorates, perchlorates, peroxides, and metal oxides.  
     
     
         41 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition further comprises a fuel.  
     
     
         42 . The method according to  claim 38 , wherein the at least essentially azide-free gas generating composition is in the form of pellets or granules.  
     
     
         43 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition further comprises a binder in an amount of 0.5 to 12% by weight of the at least essentially azide-free gas generating formulation.  
     
     
         44 . The method of  claim 43 , wherein the binder is selected from the group consisting of naturally occurring gums, polyacrylic acids, and polyacrylamides.  
     
     
         45 . The method of  claim 43 , wherein the binder is selected from the group consisting of nitrocellulose, VAAR, and nylon.  
     
     
         46 . The method of  claim 43 , wherein the binder comprises guar gum or acacia gum.  
     
     
         47 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition further comprises carbon powder in an amount of 0.1 % to 6% by weight of the at least essentially azide-free gas generating composition.  
     
     
         48 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition further comprises at least one additive selected from the group consisting of burn rate modifiers, slag formers, release agents, coolants, and NO x  reducing agents.  
     
     
         49 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition comprises at least about 60% by weight of the at least one metal complex.  
     
     
         50 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition comprises at least about 65% by weight of the at least one metal complex.  
     
     
         51 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition comprises at least about 50% by weight but less than 100% by weight of the at least one metal complex.  
     
     
         52 . The method of  claim 38 , wherein the at least essentially azide-free gas generating composition comprises at least about 50% to about 80% by weight of the at least one metal complex.  
     
     
         53 . The method of  claim 38 , wherein combustion of the at least one metal complex is initiated by heat.  
     
     
         54 . The method of  claim 38 , wherein the at least one metal complex is selected from the group consisting of a metal nitrite ammine, a metal nitrate hydrazine, and a metal perchlorate ammine.  
     
     
         55 . The method of  claim 38 , wherein the transition metal cation or the alkaline earth metal cation is selected from the group consisting of magnesium, manganese, nickel, titanium, copper, chromium, zinc, rhodium, iridium, ruthenium, palladium, and platinum.  
     
     
         56 . The method of  claim 38 , wherein the oxidizing anion is selected from the group consisting of nitrate, nitrite, chlorate, perchlorate, peroxide, superoxide, and mixtures thereof.  
     
     
         57 . The method of  claim 38 , wherein the oxidizing anion and the at least one neutral ligand are free of carbon.  
     
     
         58 . The method of  claim 38 , wherein the at least one metal complex includes at least one other common ligand in addition to the at least one neutral ligand and wherein the at least one common ligand is selected from the group consisting of aquo (H 2 O), hydroxo (OH), perhydroxo (O 2 H), peroxo (O 2 ), carbonato (CO 3 ), carbonyl (CO), oxalato (C 2 O 4 ), nitrosyl (NO), cyano (CN), isocyanato (NC), isothiocyanato (NCS), thiocyanato (SCN), amido (NH 2 ), imdo (NH), sulfato (SO 4 ), chloro (Cl), fluoro (F), phosphato (PO 4 ), and ethylenediaminetetraacetic acid (EDTA) ligands.  
     
     
         59 . The method of  claim 38 , wherein the at least one metal complex includes a common counter ion in addition to the oxidizing anion and wherein the common counter ion is selected from the group consisting of hydroxide (OH − ), chloride (Cl − ), fluoride (F − ), cyanide (CN − ), thiocyanate (SCN − ), carbonate (CO 3   −2 ), sulfate (SO 4   −2 ), phosphate (PO 4    −3 ), oxalate (C 2 O 4   −2 ), borate (BO 4   −5 ), and ammonium (NH 4   + ) counter ions.  
     
     
         60 . The method of  claim 38 , wherein the gas generating composition further comprises a co-oxidizer.  
     
     
         61 . The method of  claim 60 , wherein the co-oxidizer is selected from the group consisting of alkali perchlorates, alkaline earth perchlorates, lanthanide perchlorates, ammonium perchlorates, alkali chlorates, alkaline earth chlorates, lanthanide chlorates, ammonium chlorates, alkali peroxides, alkaline earth peroxides, lanthanide peroxides, ammonium peroxides, alkali nitrites, alkaline earth nitrites, lanthanide nitrites, ammonium nitrites, alkali nitrates, alkali earth nitrates, lanthanide nitrates, and ammonium nitrates.  
     
     
         62 . The method of  claim 60 , wherein the co-oxidizer is selected from the group consisting of metal oxides, metal hydroxides, metal peroxides, metal oxide hydrates, metal oxide hydroxides, metal hydrous oxides, basic metal carbonates, basic metal nitrates, and mixtures thereof.  
     
     
         63 . The method of  claim 60 , wherein the co-oxidizer is selected from the group consisting of oxides of copper, cobalt, manganese, tungsten, bismuth, molybdenum, and iron.  
     
     
         64 . The method of  claim 60 , wherein the co-oxidizer is selected from CuO, Co 2 O 3 , Co 3 O 4 , CoFe 2 O 4 , Fe 2 O 3 , MoO 3 , Bi 2 MoO 6 , Bi 2 O 3 , Fe(OH) 3 , Co(OH) 3 , Co(OH) 2 , Ni(OH) 2 , Cu(OH) 2 , Zn(OH) 2 , Fe 2 O 3 .xH 2 O, SnO 2 .xH 2 O, MoO 3 .H 2 O, CoO(OH) 2 , FeO(OH) 2 , MnO(OH) 2 , MnO(OH) 3 , CuCO 3 .Cu(OH) 2  (malachite), 2Co(CO 3 )3.Co(OH) 2 .H 2 ), Co 0.69 Fe 0.34 (CO 3 ) 0.2 (OH) 2 , Na 3 [Co(CO 3 ) 3 ].3H 2 O, Zn 2 (CO 3 )(OH) 2 , Bi 2 Mg(CO 3 ) 2 (OH) 4 , Fe(CO 3 ) 0.12 (OH) 2.76 , Cu 1.54 Zn 0.46 (CO 3 )(OH) 2 , Co 0.49 Cu 0.51 (CO 3 ) 0.43 (OH) 1.1 , Ti 3 Bi 4 (CO 3 ) 2 (OH) 2 O 9 (H 2 O) 2 , (BiO) 2 CO 3 , Cu 2 (OH) 3 NO 3 , Co 2 (OH) 3 NO 3 , CuCo(OH) 3 NO 3 , Zn 2 (OH) 3 NO 3 , Zn 2 (OH) 2 NO 3 , Mn(OH) 2 NO 3 , Fe 4 (OH) 11 NO 3   −2 H 2 O), Mo(NO 3 ) 2 O 2 , BiONO 3 .H 2 O, and Ce(OH)(NO 3 ) 3 .3H 2 O.  
     
     
         65 . The method of  claim 38 , wherein the at least one metal complex is hexaamminecobalt(III) nitrate, ([(NH 3 ) 6 Co](NO 3 ) 3 ) and the co-oxidizer is copper(II) trihydroxy nitrate (Cu 2 (OH) 3 NO 3 ).