Gas generating compositions and airbag inflators

Abstract

Airbag inflators employ gas generating compositions formed from a mixture of fuels and a mixture of oxidizers and preferably mica at levels of 1 to 5% by weight. The gas generant composition contains a primary and secondary fuel. The primary fuel is a guanidine compound, preferably guanidine nitrate. The secondary fuel is selected from tetrazoles, triazoles and mixtures thereof at levels of 5% by weight or less of the total gas generant composition. The oxidizer system is a mixture of at least two components selected from the group consisting of transition metal oxides, alkali metal nitrates and alkaline earth metal nitrates. The novel gas generants yield inflating gases having a reduced content of undesirable gases such as nitrous oxides and carbon monoxide.

1 . An airbag inflator comprising:
 (a) a metal housing; and   (b) a gas generant inside the metal housing, the gas generant comprising:
 (i) greater than 1 and less than 5 wt. % mica; 
 (ii) a primary fuel selected from the group consisting of guanidine compounds; 
 (iii) a secondary fuel at levels of less than 5% by weight selected from the group consisting of tetrazoles, triazoles and mixtures thereof; and 
 (iv) an oxidizer system comprising at least two compounds selected from the group consisting of transition metal oxides, alkali metal nitrates and alkaline earth metal nitrates. 
   
   
   
       2 . The airbag inflator of  claim 1  wherein said gas generant comprises guanidine nitrate as the primary fuel and at least one compound selected from the group consisting of 5-amino tetrazole, bitetrazole, 3-nitro-1,2,4-thiazol-5-one and mixtures thereof as the secondary fuel. 
   
   
       3 . The airbag inflator of  claim 1  wherein said gas generant comprises:
 (a) 30-70 wt. % of said primary and secondary fuels; and   (b) 30-70 wt. % of said oxidizer system.   
   
   
       4 . The airbag inflator of  claim 1  wherein said primary fuel is selected from the group consisting of guanidine nitrate, nitroguanidine, aminoguanidine nitrate, diaminoguanidine nitrate, triaminoguanidine nitrate and mixtures thereof. 
   
   
       5 . The airbag inflator of  claim 4  wherein said primary fuel is guanidine nitrate and said secondary fuel is 5-amino tetrazole. 
   
   
       6 . The airbag inflator of  claim 2  wherein said secondary fuel is 5-aminotetrazole and said oxidizer system comprises potassium nitrate, copper oxide and strontium nitrate. 
   
   
       7 . The airbag inflator of  claim 6  wherein said fuel is 30-35 wt. % of said generant, said potassium nitrate is 5-10 wt. % of said generant and said strontium nitrate is 40-50 wt. % of said generant. 
   
   
       8 . The airbag inflator of  claim 1  wherein said generant additionally comprises boron nitride. 
   
   
       9 . A gas generant composition comprising:
 (a) a primary and secondary fuel ranging from about 30 to 70% by weight of the gas generant composition, said primary fuel is a guanidine compound ranging from about 30 to 70% by weight of the gas generant composition and said secondary fuel is a tetrazole or triazole or mixtures thereof ranging from about 1 to 5% by weight of the gas generant composition;   (b) an oxidizer system comprising at least two components, said oxidizer system ranging from about 30 to 70% by weight of said gas generant composition, wherein said oxidizer system consists of (i) a transition-metal oxide ranging from about 5 to 15% by weight of the gas generant composition; and (ii) an alkali metal nitrate, an alkaline-earth metal nitrate, or mixtures thereof, wherein said alkali metal nitrate, alkaline-earth metal nitrate or mixtures thereof range from about 30 to 70% by weight of the gas generant composition; and   (c) from 1 to less than 5% by weight of the gas generant composition of mica.   
   
   
       10 . The gas generant composition in accordance with  claim 9  additionally containing an additive that consists of boron nitride. 
   
   
       11 . The gas generant composition in accordance with  claim 9  wherein said transition-metal oxide is cupric oxide. 
   
   
       12 . The gas generant composition in accordance with  claim 9  which consists of 5-aminotetrazole at a level of about 3% of the total gas generant composition. 
   
   
       13 . The gas generant composition in accordance with  claim 12  wherein said alkali metal nitrate is potassium nitrate. 
   
   
       14 . The gas generant composition in accordance with  claim 12  wherein said alkaline-earth metal nitrate is strontium nitrate. 
   
   
       15 . The gas generant composition in accordance with  claim 9  wherein said secondary fuel is selected from the group consisting of 5-amino tetrazole, bitetrazole, 3-nitro-1,2,4-triazol-5-one, and mixtures thereof. 
   
   
       16 . The gas generant composition in accordance with  claim 15  wherein said secondary fuel is 5-amino tetrazole. 
   
   
       17 . The gas generant composition in accordance with  claim 9  wherein said primary fuel is selected from the group consisting of guanidine nitrate, nitroguanidine, aminoguanidine nitrate, diaminoguanidine nitrate, triaminoguanidine nitrate, and mixtures thereof. 
   
   
       18 . An airbag inflator comprising:
 (a) a metal housing; and   (b) a gas generant located in the metal housing, the gas generant comprising:
 (i) greater than 1 and less than 5 wt. % mica; 
 (ii) a primary fuel selected from the group consisting of guanidine compounds; 
 (iii) a secondary fuel selected from the group consisting of 5-amino tetrazole, bitetrazole, 3-nitro-1,2,4-thiazol-5-one and mixtures thereof. 
   
   
   
       19 . A gas generant composition consisting of:
 (a) 35 to 45 weight % guanidine nitrate;   (b) 25 to 35 weight % strontium nitrate;   (c) 2 to 10 weight % cupric oxide;   (d) 2 to 10 weight % potassium nitrate;   (e) 1 to 5 weight % 5-amino tetrazole;   (f) 1 to 5 weight % boron nitride;   (g) 1 to 5 weight % mica; and   (h) processing aids.