Prodn. of gas-generating granules useful for inflating vehicle airbag

摘要

The process concerns the prodn. of a gas generating compsn. (I), esp. for inflating airbags for vehicle passenger compartments, by mixing and moulding alkali(ne earth) metal azide(s), oxidising salt(s) and metal oxide(s) as oxidant in the stoichiometric amt. for oxidn. of the alkaline earth azide and a slag former. The novelty is that the mixt. is made into a paste with water and the paste is moulded and dried. The amt. of water used is 5-50 wt.% w.r.t. total paste, while the moisture content of the dried moulding is less than 2 wt.%. The salt is KNO3 or NaNO3, and the oxide is Fe2O3. The slag former is untreated SiO2, and caustic alkali is added to the water after adding SiO2 to maintain a pH of over 7. Mixing is carried out above 30 deg C by consecutive addn. of slag former, oxidising salt, metal oxide and azide to the water in a mixer. The paste is converted to a granulate or roller foil or extruded and opt. chopped. It is cooled during granulation, which is carried out in a mixer with at least 2 stirred spindles, each with several sets of stirring bars intermeshing with similar bars on the other spindle. The granulate is classified before drying and the over- and under-sized material is made into a paste by adding water.