Gas-generating material for gas-actuated car safety devices

Abstract

The present invention relates to a process for the preparation of gas-releasing pyrotechnical compositions that are intended primarily for use in gas-actuated car safety devices such as air-bag assemblies, safety-belt tighteners, inflatable neck supports, etc. and which can be recovered if they are not actively used. The invention also relates to these compositions themselves. The invention is mainly characterized by the use of guanidine dinitramide, possibly combined with guanyl urea dinitramide, as gas-generating substance(s) in products of the said type.

1 . Process for the preparation of gas-actuated car safety devices of the type of air bags, safety-belt tighteners, inflatable neck supports and similar devices, from which the chemicals used as gas-generating substances can be recovered, if the device has not seen active use, after removing the car safety device from its original position when its normal service life has expired, characterized in that a pyrotechnical material comprising guanidine dinitramide, which can be recrystallized from water, is used as a gas-releasing substance in these car safety devices.  
     
     
         2 . Process according to  claim 1  for making car safety devices whose chemical substances can be recovered after their normal service life is finished, characterized in that the gas-releasing material is guanidine dinitramide, whose rate of burning is adjusted to the required value by admixing a suitable amount of guanyl urea dinitramide to it.  
     
     
         3 . Process according to  claim 1  or  2  for recovering the said chemicals, guanidine dinitramide and guanyl urea dinitramide, characterized in that this is done by low-temperature crystallization from water at various temperatures.  
     
     
         4 . Pyrotechnical gas-generating substances for gas-actuated car safety devices such as air bags, safety-belt tighteners, etc., made according to the process specified in claims  1 - 3 , characterized in that they contain guanidine dinitramide as the gas-forming substance.  
     
     
         5 . Pyrotechnical gas-generating substances according to  claim 4 , characterized in that their main component is guanidine dinitramide, whose rate of burning is regulated to obtain the required value by admixing a suitable amount of guanyl urea dinitramide.  
     
     
         6 . Pyrotechnical gas-generating substances according to claims  4  and  5 , characterized in that they comprise more than 50 wt-% of guanidine dinitramide.  
     
     
         7 . Pyrotechnical gas-generating substances according to claims  4 - 6 , characterized in that they are used in the form of pressed tablets, prepared possibly with a binder whose total amount does not exceed 10 wt-%.