Explosive and thermic compositions or charges – Containing inorganic nitrogen-oxygen salt – Ammonium nitrate
Reexamination Certificate
1999-04-12
2002-10-22
Poon, Peter M. (Department: 3641)
Explosive and thermic compositions or charges
Containing inorganic nitrogen-oxygen salt
Ammonium nitrate
C149S061000
Reexamination Certificate
active
06468369
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to gas generating compositions of which combustion gases act as the operation gas for inflating air bags to be mounted in automobiles, aircraft or the like for the protection of the human body.
DESCRIPTION OF THE PRIOR ART
Recently, development has been carried out of non-azide gas generating compositions in place of sodium azide based compositions which have toxic problems, as gas generating compositions for air bag systems mounted in transportation means (vehicles) such as automobiles and the like. As the non-azide gas generating compositions, U.S. Pat. No. 4,909,549 discloses a composition comprising a tetrazole or triazole compound containing hydrogen, and an oxygen-containing oxidant, U.S. Pat. No. 4,369,079 discloses a composition comprising a metal salt of bitetrazole containing no hydrogen, and an oxygen-containing oxidant, and Japanese Patent Application Laid-Open (JP-A) No. 6-239683 discloses a composition comprising carbohydrazide, and an oxygen-containing oxidant.
However, when these non-azide fuels are used, essential are a large amount of metal compounds such as metal salts, metal oxides and the like as oxidants or catalysts. Even though such compositions are improved as compared with azide compositions in a view of toxic properties, they have still problems that combustion products contain mist formed of solid and liquid of metal compounds, and gas generating efficiency decreases due to formation of residues in an inflator, and therefore a large amount of gas generating compositions must be used. Further, when solid mist and liquid mist having high temperature immediately after combustion are allowed to contact directly with a bag, the bag tends to be damaged. To cut off such mist, additional parts such as a metal net-like filter and the like are consequently required. Accordingly, weight reduction and downsizing of a gas generator itself is difficult to be achieved with a gas generating composition which forms a large amount of mist and consequently exhibits low gas generating efficiency.
Use of a non-metal compound as an oxidant such as ammonium perchlorate or ammonium nitrate is advantageous for reduction of mist and improvement of gas generating efficiency because these compounds turn into gases on combustion. However, when a composition containing a large amount of ammonium perchlorate burns, a hydrochloric acid gas is generated in amount in significantly excess of allowable value for human bodies and environments. Ammonium nitrate, whose one of phase transition temperatures is in normal temperature range (about 32° C.), changes largely in volume when passing the transition temperature. Large change in volume of a molded article leads to unstability in abilities of the composition, therefore, a composition containing ammonium nitrate showing large change in volume is not suitable to be used in environment wherein an automobile air bag is exposed to various temperature changes.
For solving such problems when ammonium nitrate is used, there is a method such that a phase stabilized agent which can suppress shift of phase transition temperature and change in volume is added to ammonium nitrate. For example, WO095/04710 discloses a gas generating composition comprising a phase stabilized ammonium nitrate, a nitrogen-containing compound such as triaminoguanidine nitrate to be used as a fuel, and an organic binder. Moreover, U.S. Pat. No. 5,545,272 and WO096/27574 disclose a gas generating composition which obtains a melting point of 100° C. or more by using, as essential components, 35 to 55% by weight of nitroguanidine and 45 to 65% by weight of a phase stabilized ammonium nitrate.
However, such a composition has high initiation sensitivity and causes a problem that there exists constantly crisis accompanying production, transportation and other handling in large amount. Further, there are other problems of such a composition that the composition is burnt successfully in relatively high pressure range, while at lower pressure range, a pressure exponent which indicates the sensitivity of burning rate against combustion pressure is high, and in some cases, combustion is interrupted or ignition is impossible.
It is desirable for a gas generating composition for an air bag that it is safe against human bodies and environments, the gas output is high, the amount produced of solid and liquid particles (residues), namely the amount produced of metal compounds is small, and safety regarding handling such as production, transportation and the like is high, and further, it is stable against change in pressure and the like. Therefore, the known gas generating compositions as described above can not be satisfactory regarding application to air bag systems.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a gas generating composition for an air bag which can enhance safety of producers and users when applied to air bag system by improving combustion behavior and handling safety, and can downsize and reduce weight of air bag system.
The present inventors have found that the above described object can be attained by the following way and completed the present invention; By combining a phase stabilized ammonium nitrate with a compound having pressure exponent adjustment effect or detonation inhibition effect as well as utilizing synergistic action with other components, the problems caused when a phase stabilized ammonium nitrate is used as an oxidant can be solved and only advantages thereof can be provided.
Namely, the present invention provide a gas generating composition for an air bag comprising (a) a guanidine derivative compound, (b) a phase stabilized ammonium nitrate and (c) a silicon compound having an activity as a pressure exponent adjuster or a detonation inhibitor.
The invention provides a gas generating apparatus which comprises the composition as defined above, an airbag system for automobiles or vehicles including the same apparatus and use of the composition as defined above in an airbag system.
In the gas generating composition for an air bag of the present invention, only advantages of the component (b), a phase stabilized ammonium nitrate can be provided by the action of the component (c), silicon compound. Consequently, a large amount of gas can be generated by combustion, and safety in handling such as production, transportation and the like can be enhanced due to low initiation sensitivity, and moreover, it can be burned successfully at lower pressure range as compared with a conventional gas generating composition containing a phase stabilized ammonium nitrate.
The gas generating composition for an air bag of the present invention can significantly downsize and reduce weight of a gas generator since generation of mist is suppressed and gas generation efficiency is enhanced on combustion by such outcome of only advantages of the component (b), a phase stabilized ammonium nitrate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The guanidine derivative compound, i.e. the component (a) of the present invention, acts as a fuel in the composition. Such compound has high nitrogen content and low carbon content with chemically stable structure and can accomplish high speed burning in addition to reducing the amount of a poisonous gas (carbon monooxide) produced on combustion.
As the component (a), guanidine derivative compound, there are listed one or more compounds selected from the group consisting of nitroguanidine (NQ), guanidine nitrate (GN), guanidine carbonate, guanidine perchlorate, aminonitroguanidine, aminoguanidine nitrate, aminoguanidine carbonate, aminoguanidine perchlorate, diaminoguanidine nitrate, diaminoguanidine carbonate, diaminoguanidine perchlorate, triaminoguanidine nitrate and triaminoguanidine perchlorate. Among these compounds as the component (a), preferable are nitroguanidine, guanidine nitrate, aminonitroguanidine, aminoguanidine nitrate, diaminoguanidine nitrate and triaminoguanidine nitrate.
The content of the component (a) in the composi
Baker Aileen J.
Daicel Chemical Industries Ltd.
Poon Peter M.
LandOfFree
Gas generating composition for air bag does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas generating composition for air bag, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas generating composition for air bag will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2936154