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
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B43/00—Compositions characterised by explosive or thermic constituents not provided for in groups C06B25/00 - C06B41/00

Definitions

• the invention relates to a stable, nitrogen-rich organic compound and its use as a pyrotechnic mixture.
• Nitrogen-rich organic compounds are widely used in chemistry and technology, be they as reactants in chemical processes or as gas, especially inert gas-generating substances.
• the problem is that the direct coupling of N atoms to one another is only slightly stable in nitrogen-rich compounds and such compounds are therefore out of the question for many applications.
• tetrazole for example, is known as a very stable compound, but has a relatively low nitrogen content. This in turn could be significantly increased by connecting two tetrazole rings via an azo bridge to form the 5,5 'azotetrazole. This compound is not very stable as a free acid.
• Salts of 5,5'-azotetrazole have also been proposed as substances which generate inert gas.
• a bis (triaminoguanidinium) -5,5'-azotetrazolate is known (US Pat. No. 4,601,344) for use in fire extinguishing agents.
• this compound has such a high sensitivity to friction and impact that it falls into the category of initial explosives is classified.
• the thermal stability is also so low that the connection has only a short life at elevated temperature.
• the still known aminoguanidinium-5,5'-azotetrozolate has the same disadvantage (DE-B-2 004 620 with DE-A-34 22 433).
• the intermediate product sodium 5,5'-azotetrazolate pentahydrate can be prepared by dissolving 5-aminotetrazole monohydrate in NaOH, adding powdery KMnO4 to the solution, filtering off the reaction mixture and sodium 5,5'-azotetrazolate pentahydrate from the filtrate is crystallized out.
• the pentahydrate is then reacted in aqueous solution with guanidinium chloride or nitrate to diguanidinium 5,5'-azotetrazolate. With this conversion, the diguanidinium-5,5'-azotetrazolate is obtained as an easily filterable yellow precipitate with a good yield.
• the pyrotechnic kits used to inflate air cushions for occupant protection devices in motor vehicles also called “airbags", as used in practice (DE-A-22 36 175), contain the highly toxic sodium azide. With the constant increase in motor vehicles with such occupant protection devices, considerable environmental problems arise from this. Because of the good water solubility of sodium azide, there is a risk of soil and groundwater contamination in scrap yards. When exposed to acids, e.g. Battery acid, the highly explosive hydrochloric acid forms. In contact with heavy metals such as lead, copper, brass, highly explosive heavy metal azides can occur.
• the compound according to the invention is outstandingly suitable as a basis for a pyrotechnic mixture for the production of environmentally friendly and non-toxic gases which, despite the required liveliness, is stable even under extreme operating conditions and has a long service life by using diguanidinium-5,5'-azotetrazolate (GZT) a powdery, chemically stable oxidizer is mixed.
• GZT diguanidinium-5,5'-azotetrazolate
• the CCT used according to the invention can be processed as a powdery substance.
• a powdery, chemically stable oxidizer which in particular must not be hygroscopic, a mixture can be produced in which the oxygen balance is largely balanced.
• These mixtures are very stable thermally and are insensitive to impact and friction.
• the invention thus proposes an azide-free, in particular sodium azide-free product which is consequently considerably more environmentally friendly.
• KNO3 is preferably used as an oxidizer.
• a mixture made from this with GZT can also be finely ground in larger batches due to its high handling safety - as can be seen from the characteristic values given further below.
• a particle size spectrum can be produced in which over 50% of the particles in the mixture have a particle diameter of ⁇ 15 ⁇ m.
• the grain size distribution and the grain size itself largely determine the liveliness of such a gas generator mixture, whereby it is naturally necessary to ensure a homogeneous mixture.
• Shaped bodies can be produced from the powder mixture by adding organic or inorganic binders.
• the proportion of binders should not exceed 5% by weight.
• the combustion behavior can be significantly influenced by different geometries of the shaped bodies.
• Findings about the combustion behavior and the gas generation can be gathered from the pressure development (pressure-time curves) during ignition attempts in a ballistic bomb.
• the pressure-time behavior of a GZT-KNO3 formulation without a binder is shown at a loading density of 10 g to 100 cm3.
• Decisive for a specific application can e.g. B. the ignition delay, the edge steepness and the time until the maximum pressure is reached.
• the 30/80 time gives an important cognitive value for the liveliness of gas generation, i.e. the slope of the burn-up curve in the range between 30% and 80% of the maximum pressure.
• the shape of the curve in the pressure-time diagram can also be influenced, among other things, by the geometry of the shaped bodies. Of course, any inorganic or organic binders that are present also exert an influence on the slope.
• catalytic combustion controllers can be used in a proportion of 0.1 to 5% by weight.
• organic or inorganic salts of these metals can also be used as the combustion controller.
• a measure of the thermal stability can be determined by measuring the weight loss at 130 ° C in loosely closed test tubes. In a GZT-KNO3 formulation, it is only 0.3% by weight after 34 days.
• the ignition temperature of this formulation is between 251 and 253 ° C with a weight of 0.2 g and a heating rate of 20 K / min.
• the impact sensitivity determined according to the BAM drop hammer method (Koenen and Ide "Explosivstoffe” 9 (1961) page 4, 30), is over 10 kpm, which means that the 10 kg drop hammer could not react at a drop height of 1 m to be watched.
• the determination of the friction sensitivity did not result in a reaction with a pin load of 36 kp.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Air Bags (AREA)

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Citations (5)

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• 1991
  • 1991-03-14 DE DE4108225A patent/DE4108225C1/de not_active Expired - Fee Related
• 1992
  • 1992-02-22 EP EP92103023A patent/EP0503341B1/fr not_active Expired - Lifetime
  • 1992-02-22 DE DE59202770T patent/DE59202770D1/de not_active Expired - Fee Related
  • 1992-03-10 US US07/848,929 patent/US5198046A/en not_active Expired - Lifetime

Patent Citations (5)

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