Azide-free, gas-generating composition

a technology of gas-generating composition and azide, which is applied in the direction of pressure gas generation, explosives, weapons, etc., can solve the problems of increased proportion of toxic gases in the released gas mixture, increased combustion rate, and increased cost of mixture in a wet process. , to achieve the effect of low carbon monoxide- and nox emissions, high burning speed and low cos

Inactive Publication Date: 2005-09-01
TRW AIRBAG SYST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0020] The proportion of basic copper nitrate in the oxidizer mixture should in any case amount to a maximum of 50% by weight in relation to the oxidizer mixture. In addition to a high burning speed and extremely low carbon monoxide- and NOx emissions, a good readiness of the mixture to ignite and also an excellent retaining capability with regard to the solid combustion residues are achieved. A higher proportion of basic copper nitrate is not desired, because hereby in particular the NOx proportions in the gas would rise unduly.

Problems solved by technology

Owing to the toxicity of sodium azide, however, a search for alternatives to the gas-generating mixtures containing azide was already begun early on.
The gas-generating mixture known from the U.S. Pat. No. 5,608,183 has an insufficient readiness to ignite and also a combustion rate which is too low.
Owing to the high proportion of basic copper nitrate, in addition an increased proportion of toxic gases is to be found in the released gas mixture.
The processing of the mixture in a wet process requires additional drying stages and is therefore cost-intensive.
The use of an additional fuel, such as cyanuric acid for example, in a proportion of more than 5%, however, results in a distinctly reduced combustion rate of the composition.
The composition is therefore unsuitable for use in gas generators for the driver's side, in which owing to the shorter distance between the vehicle occupant and the vehicle components, high combustion rates are preferred.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0023] 473 g micronized guanidine nitrate, 20 g ground cyanuric acid, 231 g each copper oxide and basic copper nitrate and 26 g ammonium perchlorate and 19 g sodium nitrate were weighed in together into a ball mill, ground for three hours and mixed with each other. The obtained mixture was directly pressed into tablets without further processing steps. Tests showed a very good readiness to ignite with a combustion rate of 17 mm / s. The solid component in the released gas mixture amounted to 1.7%.

example 2

[0024] 493 g micronized guanidine nitrate, 231 g each copper oxide and basic copper nitrate and 26 g ammonium perchlorate and 19 g sodium nitrate were weighed in together into a ball mill. In addition 5 g calcium stearate were added to the preparation and worked up as in Example 1. On firing of the obtained tablets, a good ignition readiness resulted and a combustion rate of 17 mm / s, with a solid component in the generated gas of 1.8%. The NOx content of the generated gas, measured in a 60 l test canister, amounted to 550 ppm.

example 3

[0027] 1147 g micronized guanidine nitrate, 612 g basic copper nitrate, 316 g copper oxide (CuO), 242 g iron oxide (Fe2O3), 103 g ammonium perchlorate, 75 g sodium nitrate and 5 g calcium stearate were weighed in together into a ball mill and processed as described in Example 1. The test also showed a good readiness to ignit and a combustion rate of about 15 mm / s.

[0028] The analysis of toxic components in the combustion gases showed that the combination of iron oxide and copper oxide as the metal oxide component in the propellant mixture had a highly favourable influence on the emission of carbon monoxide (CO) and ammonia (NH3). The following emission of gases has been determined by igniting gas generators having the typical performance of gas generators for the driver's side (about 2.3 bar in a 146 l canister):

Co concentrationNH3-concentration[ppm][ppm]Gas generator loaded541266with 150 g pro-pellant inaccordance withComparative Example 1Gas generator loaded37433with 136 g pro-p...

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Abstract

The present invention relates to an azide-free gas-generating composition, in particular for use in safety devices for motor vehicles, comprising a fuel in a proportion of 20 to 60% by weight and consisting of one or more components, and an oxidizer mixture in a proportion of 40 to 80% by weight and consisting of at least three components, each in relation to the total composition. In accordance with the invention, the fuel consists of a guanidine compound in a proportion of at least 95% by weight and a further fuel component in a proportion of 0 to less than 5% by weight, each in relation to the fuel, and the oxidizer mixture consists of one or more transition metal oxides in a proportion of 20 to 80% by weight, 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 metal nitrate, alkaline earth metal nitrate or mixtures thereof in a proportion of 1 to 15% by weight, each in relation to the oxidizer mixture.

Description

[0001] The present invention relates to an azide-free, gas-generating composition, in particular for use in safety devices for motor vehicles. BACKGROUND OF THE INVENTION [0002] Gas-generating compositions which are used in safety devices for motor vehicles generally consist of a fuel based on sodium azide and an oxidation agent. Owing to the toxicity of sodium azide, however, a search for alternatives to the gas-generating mixtures containing azide was already begun early on. [0003] The U.S. Pat. No. 5,608,183 describes a gas-generating mixture which contains between approximately 30 and 85% by weight of a fuel and between approximately 15 and approximately 70% by weight of an oxidation agent. At least 60% by weight of the fuel consists of the nitrate salt of an acidic polyamine or of a C2-C3-alkyl diamine, such as for example the nitrate salts of urea, guanidine, aminoguanidine, diaminoguanidine, semicarbazide, ethylene diamine, 1,3-propane diamine or 1,2-propane diamine, or mixtu...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C06D5/06
CPCC06D5/06
Inventor ZEUNER, SIEGFRIEDHOFMANN, ACHIMSCHROPP, ROLANDRODIG, KARL-HEINZ
Owner TRW AIRBAG SYST
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