CZ303225B6 - Pyrotechnical composition for safety systems of passive protection, particularly for use in airbag or safety belt pre-tensioner - Google Patents

Abstract

In the present invention, there is disclosed a pyrotechnical composition for safety systems of passive protection, particularly for use in airbag or safety belt pre-tensioner containing a fuel, an oxidant, a binding agent, and optionally also an process additive, wherein in concrete terms the pyrotechnical composition according to the present invention contains 5 to 45 percent by weight of fuel comprised of bis(1-amidino-O-alkyl urea) copper nitrate (wherein tie alkyl in the formula is represented by a hydrocarbon radical of the general formula CinHi2n+1, in which n = 1 through 10), 50 to 90 percent by weight of the oxidant, 4 to 20 percent by weight of the binding agent and 0 to 5 percent by weight of process additives.

Description

BACKGROUND OF THE INVENTION The present invention relates to a pyrotechnic composition for passive safety systems, in particular for use in an airbag or belt pretensioner, which comprises a fuel, an oxidant, a binder and optionally a technological additive.

BACKGROUND OF THE INVENTION

Particularly in the automotive industry, passive safety systems such as airbags, seat belt pretensioners, bodywork initiators (such as an active bonnet, etc.) are used to mitigate the consequences of accidents and accidents. These passive safety systems are generally based on a rapid and predefined reaction of the security features to the detected hazard. The reaction speed of the passive protection systems is usually achieved by compressed gas from the pressure vessel or by burning the pyrotechnic composition.

This achieves a rapid and timely response of the passive safety systems, such as airbag deployment, seat belt pretensioner movement, active bonnet movement, etc., resulting in mitigation of accidents and accidents.

The disadvantage of using pressurized gas from the pressure vessel is the relatively high weight and the large volume of the pressure vessel required, which adversely affects the weight gain of the entire device, including the vehicle. Another disadvantage is the difficult and dangerous handling of the high pressure gas pressure vessel. Obviously, there is also a considerable risk of explosion of the pressure vessel itself in an accident or accident, which is another significant drawback of this solution.

The disadvantage of existing pyrotechnic compositions is their nitrocellulose basis, which burns existing pyrotechnic compositions to produce toxic gaseous fumes, mainly containing nitrogen oxides and carbon monoxide, which are dangerous to the health of the crew and the environment, especially when the safety system is activated inside the cab. environment. Another disadvantage is the relatively low thermal stability of the pyrotechnic compositions used.

It is an object of the invention to overcome or at least minimize the drawbacks of the prior art.

SUMMARY OF THE INVENTION

The object of the invention is achieved by a pyrotechnic composition for passive protection safety systems, in particular for use in an airbag or seat belt pretensioner, which comprises 5 to 45 wt. copper bis (1-amidino-O-alkyl urea) nitrate fuel (the alkyl in the formula is a hydrocarbon radical of the formula C _n H2 _{n +} i, where n = 1 to 10),

50 to 90 wt. % oxidizing agents, 4 to 20 wt. % binder and 0 to 5 wt. technological additives.

An advantage of the pyrotechnic composition according to the present invention is the low content of toxic fumes in the gaseous combustion products. The content of the most monitored toxic gases such as carbon monoxide and nitrogen oxides is significantly lower than that of currently used nitrocellulose-based pyrotechnic compositions. A great advantage is also the easy preparation of copper (copper-anndino-O-alkylurea nitrates) copper in high yield and good laboratory performance. Last but not least, the advantage is also the low price of the raw materials and their easy availability. Another advantage of the pyrotechnic composition according to the invention is its higher thermal stability compared to the pyro55 technical compositions based on nitrocellulose.

-1 CZ 303225 B6

Advantageous embodiments of the invention are set forth in the dependent claims and in the Examples.

Description of the drawings

The invention is shown schematically in the drawing, wherein FIG. 1 shows the general chemical formula of copper (1-amidino-β-alkylurea) nitrate (the alkyl in the formula is a hydrocarbon and a residue of the formula C _n H 2 _{n +} t where n = 1 to 10 ) wherein "R" denotes alkyl; Fig. 2 shows the course of pressure versus time during the combustion of pyrotechnic composition # 1 of Table 1 (bis (1-amidino-ethylurea) nitrate copper as fuel).

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described by means of several examples of pyrotechnic composition, in particular with regard to the possible variability of the content of the individual components and the possible variability of the chemical composition of the individual components within given groups of chemical substances and compounds.

The pyrotechnic composition according to the invention contains 5 to 45 wt. % of fuel, 50 to 90 wt. % oxidizing agents, 4 to 20 wt. % binder and optionally 0 to 5 wt. technological additives.

The fuel in the pyrotechnic composition of the present invention is a copper (125 amidino-O-alkylurea) nitrate compound or mixture of compounds (the alkyl in the formula is a hydrocarbon radical of the formula wherein n = 1-10), which is specified in Figure 1. the fuel of the group is bis (l-amidino-O-methyl urea) and / or copper (l-amidino-O-ethylurea) nitrate and / or bis (l-amidino-O-propylurea) nitrate copper (II) and / or other copper (1-amidino-O-alkyl urea) copper nitrates or mixtures thereof.

The oxidant in the pyrotechnic composition of the present invention is potassium perchlorate and / or ammonium perchlorate and / or sodium perchlorate and / or potassium nitrate and / or strontium nitrate and / or sodium nitrate and / or zinc peroxide.

The binder in the pyrotechnic composition according to the invention is nitrocellulose and / or carboxymethylcellulose and / or hydroxypropylmethylcellulose and / or cellulose ethers and / or polyvinyl isobutyl ether and / or fluoroelastomer and / or dextrin and / or guar gum and / or copolymer of polyvinyl isobutyl ether polyvinyl chloride.

The composition of the six specific pyrotechnic compositions of the present invention is shown in Table 1 below.

-2GB 303225 B6

Folders Content in% wt. sklad no. 1 sklad No.2 sklad č.3 sklad č.4 sklad No.5 sklad No.6 KCIO ₄ 53 41 NH4CIO4 36 33 36 Sr _{(NO3) 2} 36 33 41 KNO ₃ 36 ΖΓ1Ο2 84 bis (1-amidino-O- copper urea) 18.5 35.5 5.5 bis (1-amidino-O-) nitrate ethyl urea) 15 Dec 7 bis (1-amidino-O- propylurea) of copper 11.5 binder 10.5 14 10 15 Dec 9 9.5 dibutyl phthalate 1 1 1 Fe ₂ O ₃ 1 1 1 1 graphite 0.5 0.5 0.5 0.5 0.5 0.5

Table 1

The composition of these pyrotechnic compositions corresponds to an almost balanced oxygen balance, which ensures a minimum volume of toxic gases in the combustion products.

The pyrotechnic compositions were prepared by mixing the oxidant (or mixture of oxidants) with the fuel consisting of bis (1-amidino-O-alkyl urea) nitrate copper. The binder was added as an aqueous solution. Finally, the physical properties modifier, vinyl acetate-ethylene copolymer, was incorporated into the mixture. After homogenization by kneading, pressing and cutting, the final pyrotechnic composition was obtained, which upon ignition and combustion produces gaseous products of low toxicity.

The advantage of the pyrotechnic composition according to the invention is the low content of toxic fumes in the combustion gases of said composition, which is significantly lower in the most monitored gases such as carbon monoxide and nitrogen oxides than in currently used nitrocellulose-based pyrotechnical compositions.

The content of the presumed toxic combustion products of pyrotechnic composition No. 1 from Table I is stated in Table 3.

toxic combustion products gas content in ppmv WHAT 1150 NO 94 no ₂ 2 NO _X 96 Cl ₂ 0

Table 2

The minimum content of toxic combustion products is achieved in a pyrotechnic composition with a balanced oxygen balance or with an oxygen balance close to the balanced oxygen balance.

Progression of pressure versus time during burning of pyrotechnic composition No. 1 from table no. 1 (bis (1-amidino-O-ethylurea) copper (II) nitrate as fuel) in a ballistic bomb is shown in Figure 2.

The calorific and calculated aggregation heats of copper (I-amidino-O-alkylurea) nitrate io (the alkyl in the formula is a hydrocarbon radical of the formula C _n H _2n + b where n = 1 to 4) determined in the calorific calorimeter are given in the following table 3.

bad heat (kJ.jnol · ¹ ) combining heat (kJ.mol · ¹ ) copper (1-amidino-O-methylurea) nitrate -3 840 -960 copper (1-amidino-O-ethylurea) nitrate -4 770 -32 copper (1-amidino-O-propylurea) nitrate -6 190 + 1 390 copper (1-amidino-O-butylurea) nitrate -7 540 + 2 740

Table 3

Industrial applicability

The pyrotechnic composition according to the invention is useful as an active part of gas generators in passive protection systems in cars and other vehicles, in particular for belt pretensioners, airbags and the like.

Claims (3)

25 PATENT CLAIMS Pyrotechnic composition for passive protection safety systems, in particular for use in an airbag or belt pretensioner, comprising a fuel, an oxidant, a binder and a technological and / or additive comprising 5 to 45 wt. Copper bis (1-amidino-O-alkyl urea) nitrate fuel (alkyl in the formula is % Of hydrocarbon radical of the formula C _n H 2 _{n + 1} , wherein n-1 to 10), 50 to 90 wt. % oxidizing agents, 4 to 20 wt. % binder and 0 to 5 wt. technological additives. Pyrotechnic composition according to claim 1, characterized in that the oxidant consists of sodium perchlorate and / or potassium perchlorate and / or ammonium perchlorate and / or potassium nitrate and / or strontium nitrate and / or sodium nitrate and / or zinc peroxide, and / or an ammonium salt of dinitramine acid (ADN). Pyrotechnic composition according to claim 1, characterized in that the binder is also composed of nitrocellulose and / or carboxamethylcellulose and / or hydroxypropylmethylcellulose and / or cellulose ethers and / or polyvinyl isobutyl ether and / or fluoroelastomer and / or dextrin and / or guar gum and / or guar gum and / or or a polyvinylisobutyl ether-polyvinyl chloride copolymer.