CZ2005381A3 - Pyrotechnical compositions for belt tensioning devices - Google Patents

Abstract

The belt pretensioner pyrotechnic compositions, the initiation of which results in a low toxic content of pollutants, consist of 20.0 wt. % to 50.0 wt. high molecular weight, low carbon-containing fuel, e.g., guanidine nitrate, nitroguanidine, guanidine azotetrazolate and the like, alone or in combination, 40.0 wt. % to 78.0 wt. oxidants such as ammonium perchlorate, potassium nitrate, potassium nitrate, strontium nitrate and the like, alone or in combination, 2.0 wt. % to 10.0 wt. binders such as carboxymethylcellulose, carboxypropylmethylcellulose and other substances with binding properties, such as dextrin, guar gum and the like, individually or in combination with each other, and physical property modifiers in an amount of 0.1% by weight. up to 5.0% by weight, such as polyvinylacetate, vinyl acetate copolymers, polyacrylates, polyalkylamides and the like, singly or in combination with each other.

Description

Pyrotechnic compounds for belt pretensioners

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a composition of a pyrotechnic composition generating reduced amounts of toxic fumes useful in passive safety systems, particularly in the automotive industry, such as seat belt pretensioners, airbag inflators, and the like.

BACKGROUND OF THE INVENTION

Presently, belt tensioners with nitrocellulose-based propellants are used. Burning of nitrocellulose produces very quickly fumes that increase the pressure in the pretensioner, which is used to move the moving parts of the system. This will tighten the seat belt. Nitrocellulose-based propellants are mainly used for their high gasification capacity and also for available production technology proven over several decades.

Their disadvantage, especially in common civil applications, is that they generate a high content of toxic fumes during combustion - in particular nitrogen oxides and carbon monoxide - thus burdening the environment and harming human health.

SUMMARY OF THE INVENTION

These disadvantages and drawbacks of the known and used propellants for seat belt pretensioners have largely eliminated the pyrotechnic compositions of the present invention consisting of a 20 wt% blend. % to 5 wt. fuel with a high nitrogen content and a low carbon content in the molecule, 40.0 wt. % to 7b, 0 wt. % oxidizing agents, 0.1 wt. up to 10.0 wt. physical property modifiers and 2, G # mass. % to 10 wt. binders.

The fuel in the pyrotechnic composition of the present invention comprises quanidinonitrate and / or nitroquanidine and / or triaminoquanidinonitrate and / or 5-aminotetrazole and / or quanidinazotetrazolate and / or bis (dicyandiamide) / copper (II) nitrate.

The oxidizing agent in the pyrotechnic composition of the present invention is sodium perchlorate and / or ammonium perchlorate and / or perchlorate.

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and / or potassium nitrate and / or sodium nitrate and / or strontium nitrate.

The physical property modifiers in the pyrotechnic compositions of the present invention are vinyl acetate-ethylene and / or polyvinyl acetate and / or polyacrylate and / or polyalkylamide and / or polytetrafluoroethylene copolymers.

The binder in the pyrotechnic compositions of the present invention is nitrocellulose and / or carboxymethylcellulose and / or hydroxypropyl methylcellulose and / or cellulose ethers and / or a polyvinyl isobutyl ether and / or a fluoroelastomer and / or a dextrin and / or guar gum and / or a polyvinyl isobutyl-polyvinyl chloride copolymer.

The individual components of the pyrotechnic mixture are treated and homogenized by conventional physico-mechanical processes so that, in the final phase, they comprise particles in the size range of 20 m to 100 m, preferably 60 m to 60 m.

By optimally selecting a combination of the individual fuel-forming substances and the oxidant, the content of the physical property modifier may be reduced to a content of 0.3 > % to 1.0 wt.

An advantage of the pyrotechnic compositions of the present invention is that after initiation, toxic fumes such as carbon monoxide and nitrogen oxides are generated at a far greater rate than the present nitrocellulose-based compounds. The difference in the amount of released toxic fumes is in the order of magnitude, which guarantees a considerably lower burden on the environment and human health.

A further distinct advantage is the higher stability of the pyrotechnic compositions of the present invention under high-temperature loading compared to the nitrocellulose-based propellants hitherto used.

In view of these advantageous properties, the main field of application of the pyrotechnic compositions of the present invention is envisaged in passive protection systems for cars and other vehicles, in particular as part of a belt pretensioner, seat belt restrictor and the like.

Examples

1. Pyrotechnic mixture was prepared by mixing 25 _t .0g of ammonium perchlorate and 17, Og of sodium nitrate with a mixture of 5.0 g and 10 quanidinazotetrazolátu Og nitrate bis / dicyandiamide / měčtnatého. Sodium carboxymethycellulose was used as binder. The mixture was

It was subsequently incorporated into the physical properties modifier, which was 0.5g vinyl acetate. After homogenization by kneading, pressing and cutting, the pyrotechnic mixture obtained after initiation guarantees a low OD content of toxic substances in the afterburst gases.

2. A pyrotechnic mixture was prepared by mixing 45.0 g of ammonium perchlorate having a particle size of 60-300 microns and a mixture of fuels of 15.0 g of quanidine azotetrazolate and 5.0 g of quanidine nitrate. 5.0 g of sodium carboxymethycellulose in the form of an aqueous solution was used as binder. The physical properties modifier, 0.5 g vinyl acetate-ethylene copolymer, was then incorporated into the mixture.

After homogenization by kneading, pressing and cutting, a pyrotechnic mixture was obtained from which the initiation of the afterburst fumes contained low amounts of toxic substances.

2. A pyrotechnic mixture was prepared by mixing 21.0 g of ammonium perchlorate, 21.0 g of strontium nitrate having a particle size of 60-300 microns, and 15.0 quanidine azotetrazolate as a fuel. 3.0 g of sodium carboxymethylcellulose were present as an aqueous solution. Subsequently, 0.3g of vinyl acetate-ethylene copolymer and 0.2g of polytetrafluoroethylene were modified to modify the physical properties. After homogenization by kneading, pressing and cutting, a pyrotechnic mixture producing a low-toxic, low-explosive post-explosion product usable for belt pretensioners with the possibility of gravimetric or volumetric lab loading was obtained.

4. The pyrotechnic mixture was prepared by mixing 21.0 g of ammonium perchlorate, 21.0 g of strontium nitrate having a particle size of 60 to 200 microns and 15.0 g of quanidine azotetrazolate. 3.0 g of polyvinylbutylethylene = polyvinyl chloride copolymer in the form of an acetone solution were used as binders. The resulting mixture was then further worked to modify the physical properties of 0.3 g vinyl acetate-ethylene copolymer and 0.5 g polytetrafluoroethylene. After homogenization by kneading, pressing and cutting, a pyrotechnic mixture was obtained which, after initiation, had a low content of toxic substances in the explosion products applicable to belt pretensioners with the possibility of gravimetric and volumetric filling.

5. The pyrotechnic mixture was prepared by mixing 21.0 g of ammonium perchlorate, 21.0 g of strontium nitrate having a particle size of 80-300 microns and 15.0 g of quanidine azotetrazolate as a fuel. The binder in this case was 3.0 g of hydroxypropylmethylcellulose in the form of an aqueous solution. The vinyl acetate ethylene copolymer in an amount of 0.3g and 0.5g of polytetrafluoroethylene was then incorporated into the mixture as a physical modifier. After homogenization by kneading, pressing and cutting, a pyrotechnic mixture was obtained from which the initiation of the afterburst fumes has a low content of toxic substances usable for belt pretensioners with the possibility of gravimetric or volumetric backfilling.

Industries Applicability

The pyrotechnic compositions of the present invention are useful as an active part of gas generators in passive safety systems in the automotive industry, particularly for automotive seat belt pretensioners.

Claims (3)

PATENT CLAIMS 1. Pyrotechnic compounds for belt pretensioners. characterized in that they consist of 2 20.0% by weight of water; % to 50 wt. % of fuel consisting of quanidine nitrate and / or nitroquanidine or / atriaminoquanidinium nitrate and / or 5-aminotetrazole and / or cuanidinazotetrazolate and / or bis (dicyandiamide) copper nitrate, 4%, 0% by weight; 0 to 7B, 0 wt.% sodium perchlorate and / or ammonium perchlorate and / or potassium perchlorate and / or potassium nitrate and / or sodium nitrate and / or strontium nitrate; % to 5 wt. a physical property modifier consisting of a vinyl acetate-ethylene copolymer and / or a polyvinyl acetate and / or a polyacrylate and / or a polyalkylamide and / or a polytetrafluoroethylene and a binder amount of 2.0% by weight. % to 10.0 wt. consisting of nirrocellulose and / or carboxymethylcellulose and / or hydroxypropylmethylcellulose and / or polyacrylate and / or polyvinyl isobutyl ether and / or a copolymer of polyisobutyl ether and polyvinyl chloride and / or cellulose ethers and / or a fluoroelastomer and / or a dextrin and / or a The physical properties comprise particles in the size range of 20 to 400 microns. 2. Pyrotechnic compositions according to claim 1, characterized in that, after homogenizing and adjusting the physical properties, the composition comprises particles in the size range of 80 to 300 microns. 3. Pyrotechnic compositions according to claim 1, characterized in that the content of the physical property modifier is in the range of 0.1% by weight. % to 1.0 wt.