Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06D—MEANS FOR GENERATING SMOKE OR MIST; GAS-ATTACK COMPOSITIONS; GENERATION OF GAS FOR BLASTING OR PROPULSION (CHEMICAL PART)
  • C06D5/00—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets
  • C06D5/06—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets by reaction of two or more solids

Definitions

• Gas generating compositions used in safety devices used for motor vehicles mostly consist of a fuel based on sodium azide and an oxidizing agent. However, due to the toxicity of sodium azide, it was premature started looking for alternatives to the azide-containing gas generators To look for mixtures.
• US-A-5 608 183 describes a gas generating mixture containing between about 30 and 85 percent by weight of a fuel and between about 15 and about 70 percent by weight of an oxidizing agent.
• At least 60% by weight of the fuel consists of the nitrate of an acidic polyamine or a C 2 -C 3 -alkyldiamine, such as, for example, the nitrates of urea, guanidine, aminoguanidine, diaminoguanidine, semicarbazide, ethylenediamine, 1,3-propanediamine or 1, 2-propanediamine, or mixtures thereof.
• the oxidizing agent comprises at least 60% by weight of basic copper nitrate and / or cobalt triamine trinitrate. The mixture is processed in a wet process.
• the gas generating mixture known from US-A-5 608 183 has however, an insufficient willingness to ignite and a too low Burn-up speed. Due to the high proportion of basic Copper nitrate is also an increased proportion of toxic gases in the released Detectable gas mixture. Processing the mixture in A wet process requires additional drying stages and is therefore expensive.
• the German utility model No. 298 06 504 represents a gas-generating Composition ready, the one of at least two components existing fuel mixture in a proportion of 20 to 60 wt .-% and an oxidizer mixture consisting of at least three components in a proportion of 40 to 80% by weight, based in each case on the total composition, includes.
• the fuel mixture of the known composition is from 5 to 95% by weight of a guanidine compound, 5 to 95 % By weight of a heterocyclic organic acid, for example Cyanuric acid, as well as 0 to 20% by weight of other fuels.
• the oxidizer mixture of the known composition consists of one or more transition metal oxides in a proportion of 20 to 70% by weight and 10 to 50% by weight of basic copper nitrate and 2 to 30 % By weight metal chlorate, metal perchlorate, ammonium perchlorate, alkali nitrate, Alkaline earth nitrate or mixtures thereof.
• an additional fuel such as However, cyanuric acid
• the Composition is therefore for use in gas generators for the Driver's side unsuitable because of the shorter distance between high burn-up speeds for the vehicle occupant and the vehicle internals to be favoured.
• the additional fuels used must have a lower oxygen balance than guanidine nitrate also a higher proportion of oxidizer to balance the mixture and to achieve an optimally reduced harmful gas emission be used.
• the higher proportion of oxidizer leads to a increased solids content in the gas mixture and thus to an increased Particle emission.
• gas generating compositions for use in security devices for motor vehicles with a high burning rate can be achieved with low particle emissions at the same time.
• the oxidizer mixture consists of one or more transition metal oxides in a proportion of 20 to 80 wt .-%, basic copper nitrate in a proportion of 0 to 50% by weight, metal chlorate, metal perchlorate, Ammonium perchlorate or mixtures thereof in a proportion of 1 to 15 % By weight and alkali nitrate, alkaline earth nitrate or mixtures thereof a proportion of 1 to 15 wt .-%, each based on the oxidizer mixture.
• Preferred guanidine compounds are guanidine carbonate, guanidine nitrate, Guanidine perchlorate, aminoguanidine nitrate, diaminoguanidine nitrate, Triaminoguanidine nitrate, nitroguanidine or mixtures thereof used.
• the further fuel component is preferably an organic one Compound that has an oxygen balance of more than -90%.
• Cyanuric acid is particularly preferred as a further fuel component, Urea, oxamide, urazole, alloxan, alloxantin and parabanic acid or mixtures thereof.
• oxygen balance is to be understood as the amount of oxygen in percent by weight which is released when a compound or a mixture is completely converted to CO 2 , H 2 O, Al 2 O 3 , B 2 O 3 , etc. (O 2 overbalancing) . If the available oxygen is not sufficient for this, the shortfall necessary for complete conversion is given with a negative sign (O 2 under-balancing).
• the oxidizer mixture preferably contains a mixture of Fe 2 O 3 and CuO, in addition to the other components of the oxidizer mixture.
• the Fe 2 O 3 is preferably present in a proportion of at least 4% by weight, particularly preferably in a proportion of at least 9%, based on the overall composition.
• the simultaneous use of Fe 2 O 3 and CuO enables a further reduction in the proportion of toxic gases in the combustion products.
• the composition may also include conventional processing aids a proportion of up to 5% by weight, based on the total composition, included, the processing aids preferably from the consisting of the flow aids, pressing aids and / or lubricants Group are selected.
• compositions according to the invention stand out the previously known mixtures due to improved combustion behavior, and in particular through an extremely low particle emission in combination with a high burning rate. they are therefore particularly suitable for use in driver airbag systems.
• the improved burning behavior of the compositions according to the invention is achieved through the use of at least one organic compound favored as a fuel from the group of guanidine compounds.
• the use of guanidine nitrate is particularly preferred because of its favorable oxygen balance of - 26.2%. Compared to others organic compounds or their mixtures with guanidine nitrate less oxidizer is thus required to balance the mixture. This measure therefore already results in lower particle emissions reached.
• the proportion of basic copper nitrate in the oxidizer mixture should in any case be at most 50% by weight, based on the oxidizer mixture.
• the mixture In addition to a high combustion rate and extremely low carbon monoxide and NO x emissions, the mixture is easy to ignite and has excellent retention properties with regard to solid combustion residues. A higher proportion of basic copper nitrate is undesirable since this would in particular increase the NO x proportions in the gas inadmissibly.
• a mixture of 47.1 parts guanidine nitrate and 52.9 parts basic copper nitrate was prepared according to the procedure described in Example 1 of US-A-5,608,183. The mixture showed poor ignitability and only a slow burning rate. The NO x portion of the gas generated measured in the test jug was 1300 ppm.
• the analysis of the toxic component of the combustion gases showed that the combination of iron oxide (Fe 2 O 3 ) and copper oxide (CuO) as a metal oxide component in the blowing agent mixture has a particularly favorable influence on the emissions of carbon monoxide (CO) and ammonia (NH 3 ) .

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Organic Chemistry (AREA)
• Air Bags (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1998
  • 1998-12-02 DE DE29821541U patent/DE29821541U1/de not_active Expired - Lifetime
• 1999
  • 1999-12-01 DE DE59902827T patent/DE59902827D1/de not_active Expired - Lifetime
  • 1999-12-01 EP EP99123906A patent/EP1006096B1/fr not_active Expired - Lifetime
• 2005
  • 2005-03-14 US US11/079,718 patent/US20050189052A1/en not_active Abandoned

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