Explosive and thermic compositions or charges – Containing inorganic nitrogen-oxygen salt
Patent
1997-05-29
1998-10-27
Anthony, Joseph D.
Explosive and thermic compositions or charges
Containing inorganic nitrogen-oxygen salt
149 37, 149 61, 149 83, 1491092, C06B 2900, C06B 3100
Patent
active
058279962
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/JP96/02760 filed on Sep. 24, 1996.
TECHNICAL FIELD
The present invention relates to an air bag gas generating composition.
The air bag gas generating composition according to the present invention possesses advantageous characteristics of suitable burning performance, low burning temperature, low concentration of toxic components such as CO and NOx in the gas generated by the combustion (hereinafter referred to as "after gas"), and remarkably higher safety than conventional azide-based gas generating compositions.
BACKGROUND ART
As the requirements concerning driving safety become more rigorous, the demand for air bag systems is greatly increasing. When a car travelling at high speed is in a crash, the air bag system inflates a nylon bag (air bag) stowed in the steering wheel assembly, the dashboard or the like to thereby protect the occupants from being injured or killed by the impact against the interior of the car. The bag is inflated with a gas generated by the combustion or decomposition of a gas generating composition held in the system.
The air bag gas generating composition is required to have a number of performance characteristics, among which the following four are important requirements. First, the gas generating composition should have appropriate burning velocity. For reducing the impact on the occupants smashing into the air bag, the bag deflates to some extent immediately after the inflation, releasing part of the gas inside the car. If the burning velocity is too high, the occupants smash into the bag before deflation, whereas if the burning velocity is low, the bag is not inflated immediately after the crash. In both cases, the bag can not protect the occupants. The second requirement is low burning temperature, i.e., low after gas temperature. High after gas temperature may impair the bag and cause the occupants to sustain burns, and moreover, may burn the bag and cause fire. The third requirement is low concentration of toxic components such as CO and NOx in the after gas. If the after gas is high in the concentration of toxic components, the occupants are likely to be poisoned by the after gas released inside the car from the deflating bag. The fourth requirement is that the shock ignitability (sensitivity to shock ignition) is low. High shock ignitability involves a high possibility of explosion or detonation in the course of production, e.g., in the mixing or molding process, and thus entails a high risk in handling.
Azide-based gas generating compositions comprising sodium azide as the gas generating base, which are generally used at present, show adequate burning velocity and gas temperature, and the gas generated therefrom mainly comprises nontoxic nitrogen gas. However, said composition has a drawback of high shock ignitability. Further, since sodium azide used as the gas generating base causes a fire or toxic fume on decomposition, or forms toxic substances such as sodium oxide and sodium hydroxide on reaction with an oxidizing agent, handling thereof requires constant and close care, and protection equipment is essential for assuring safety. Moreover, since the absorption of moisture leads to a decrease in the burning performance of sodium azide, there must be a provision for the prevention of moisture absorption. In addition, sodium azide is highly toxic, and thus it is possible that serious environmental pollution will be caused by the spread of sodium azide when an air bag-equipped car is fallen into a river or the sea or experiences floods, or when an air bag-equipped car is scrapped with a cutter.
Recently, people have acknowledged the great importance of environmental protection and safety of operators and users. The azide-based gas generating compositions are not preferred due to the above drawbacks. Accordingly, an azide-free gas generating base substituting for sodium azide is earnestly demanded to be developed.
Azide-free gas generating bases heretofore proposed include nitrogen-containing organic compounds having an amide group,
REFERENCES:
patent: 5035757 (1991-07-01), Poole
patent: 5531941 (1996-07-01), Poole
Chijiwa Shiro
Hara Kazuo
Onishi Junichi
Shimizu Yasuo
Yoshida Tadao
Anthony Joseph D.
Otsuka Kagaku Kabushiki Kaish
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