EP0659712B1 - Pyrotechnic compositions for producing clean non-toxic gases containing an elastomeric thermoplastic binder - Google Patents

Pyrotechnic compositions for producing clean non-toxic gases containing an elastomeric thermoplastic binder Download PDF

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Publication number
EP0659712B1
EP0659712B1 EP94402714A EP94402714A EP0659712B1 EP 0659712 B1 EP0659712 B1 EP 0659712B1 EP 94402714 A EP94402714 A EP 94402714A EP 94402714 A EP94402714 A EP 94402714A EP 0659712 B1 EP0659712 B1 EP 0659712B1
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Prior art keywords
binder
composition according
pyrotechnic composition
weight
plasticizer
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EP94402714A
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German (de)
French (fr)
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EP0659712A1 (en
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Bernard Finck
Alain Lefumeux
Christian Perotto
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Societe Nationale des Poudres et Explosifs
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Societe Nationale des Poudres et Explosifs
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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
    • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
    • C06B45/04—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive
    • C06B45/06—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component
    • C06B45/10—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component the organic component containing a resin
    • C06B45/105—The resin being a polymer bearing energetic groups or containing a soluble organic explosive

Definitions

  • the present invention relates to the field of automotive safety and, more specifically, that of the protection, in the event of a collision, of the occupants of a motor vehicle thanks to cushions inflated by combustion gas of a pyrotechnic composition contained in a gas generator.
  • the invention relates to gas-generating pyrotechnic compositions clean and non-toxic, containing a binder thermoplastic.
  • compositions therefore requires gas generators equipped with powerful filtration means gases.
  • compositions described in this application are mainly consisting of the reaction product of a glycidyl polyazide with a polyisocyanate such as binder and with ammonium nitrate as oxidizing charge. These compositions give all satisfaction to the plan of gas non-toxicity, speed of combustion and the absence of solid residue but however, they are delicate to implement, especially in continuous processes involving a extrusion phase, due to the fact that they use crosslinkable binders which harden very quickly.
  • thermoplastic binder in composite compositions of this type would allow a easier to use, especially for processes continuous; but, if the use of compositions pyrotechnics with thermoplastic binder as propellants for rockets or as explosives is known, for example by USP patents 4,806,613, 4,875,949 and 4,925,503, their job in automotive safety is little used to this day. Indeed the pyrotechnic compositions thermoplastic binder composites known to date do not do not meet all of the requirements in field.
  • US-A 4,806,613 describes, for example, pyrotechnic compositions with binders thermoplastics which may contain (i) a plasticizer energy like nitroglycerin, butanetriol trinitrate (BTTN) or the trimethylolethane trinitrate (TMETN), (ii) an oxidizing charge mineral or organic, (iii) aluminum powder and (iv) additives known to those skilled in the art.
  • BTTN nitroglycerin, butanetriol trinitrate
  • TMETN trimethylolethane trinitrate
  • an oxidizing charge mineral or organic iii
  • aluminum powder aluminum powder and additives known to those skilled in the art.
  • the object of the present invention is precisely to propose such compositions.
  • the invention therefore relates to a composition pyrotechnics whose combustion products are mainly non-toxic clean gases, consisting essentially by a binder which is an elastomer thermoplastic, by an energy plasticizer, by a mineral oxidizing charge and by additives intended for regulate combustion, characterized in that said binder is an oxygenated thermoplastic elastomer, in that that the said plasticizer is a product of polymerization of glycidyl azide and in that the said oxidizing charge is constituted for at least 85% of its weight by ammonium nitrate.
  • the said binder is a block copolymer consisting mainly with polyamide patterns and polyether patterns.
  • the said energy plasticizer is a polyazide of glycidyl with hydroxyl endings whose molecular mass number average is between 1,000 and 7,000.
  • the said additives are chosen from the group consisting of potassium nitrate and perchlorate ammonium.
  • the energy binder / plasticizer set represents between 5 and 15% of the total weight of the composition, the weight of the energy plasticizer representing approximately 30% of the binder weight.
  • compositions according to the invention burn quickly in essentially releasing as combustion gases from nitrogen and carbon dioxide with very little carbon monoxide. Furthermore, they do not produce little or no residue, depending on the additives used solid.
  • pyrotechnic gas generators intended for inflate protective cushions for occupants of a motor vehicle.
  • binder of an elastomer gives granules or blocks of pyrotechnic composition of mechanical properties particularly interesting for products intended to be kept for many years in a motor vehicle.
  • the invention therefore relates to pyrotechnic compositions whose combustion products are mainly clean, non-toxic gases. These compositions are essentially made up of a binder, by an energetic plasticizer, by an oxidizing charge mineral and by additives intended to regulate the combustion of the composition.
  • This type of block copolymer is marketed by ATOCHEM company under the PEBAX® brand.
  • an energy plasticizer is added to the binder which is a product of polymerization of azide glycidyl.
  • a favorite family of plasticizers energy consists of the polyazides of glycidyle with hydroxyl endings whose mass number average molecular is between 1,000 and 7,000 and, preferably between, 1,500 and 2,500.
  • the glycidyl polyazides to hydroxyl endings do not participate in any reaction chemical condensation; they are therefore well used as an energy plasticizer for the thermoplastic elastomer and not as a component of the binder as is usually the case when used in the presence of an isocyanate or other reactive agent with the hydroxyl groups OH.
  • the energy binder / plasticizer set represents preferably between 5% and 15% of the total weight of the composition while the weight of said plasticizer energy preferably represents around 30% of the weight of the binder / plasticizer assembly.
  • the pyrotechnic composition contains a oxidizing charge formed for at least 85% of its weight by ammonium nitrate.
  • an ammonium nitrate will be used stabilized.
  • the stabilizer could for example be consisting of a little nickel oxide NiO.
  • This quality of ammonium nitrate is sold commercially and generally contains 3% by weight of nickel oxide compared to pure ammonium nitrate.
  • the expression "ammonium nitrate” covers the assembly consisting of pure ammonium nitrate and by any stabilizer present.
  • nickel oxide is non-combustible, its presence in small amount is not a problem in the context of present invention.
  • the entire oxidizing charge can be consisting of ammonium nitrate but it is imperative in the context of the present invention that the ammonium nitrate represents, by weight, at least 85% of the oxidizing charge.
  • the oxidizing charge When the oxidizing charge is not formed at 100% with ammonium nitrate, it can be supplemented with triaminoguanidinium nitrate, with nitroguanidine or by a nitramine such as hexogen or octogen.
  • compositions according to the invention also contain additives intended in particular for adjust the rate of combustion of the composition in the pressure range corresponding to the operation of the generator.
  • additives exclude metals or compounds metal likely to constitute residues solids entrainable by combustion gases.
  • These additives could for example be carbon black or m-methyl p-nitroaniline.
  • these additives can also be selected from the group consisting of nitrate of potassium and ammonium perchlorate, additives also playing in the latter case the role of charge oxidizing.
  • compositions as part of the present invention contain as additives a mixture potassium nitrate and ammonium perchlorate, the potassium nitrate representing approximately 7% by weight ammonium nitrate and ammonium perchlorate representing between 4 and 6% of the total weight of the composition.
  • compositions according to the invention can easily be done continuously or batchwise in a mixer-extruder using solvent or solvent-free techniques known from the skilled person.
  • a mixer heated extruder usually at a temperature between 80 ° C and 130 ° C, and preferably at a temperature close to 120 ° C.
  • the binder is introduced and the energy plasticizer then we add the charge oxidizing agent and any additives.
  • the coating load and additives by the binder is complete the paste obtained is extruded to the desired geometry and let cool.
  • the binder using a suitable solvent in a mixer extruder.
  • Binder solvent should not dissolve or chemically attack the oxidative charge and additives.
  • the light alcohols such as ethanol, propanol and preferably butanol, light hydrocarbons such as kerosene or benzene, methyl ethyl ketone, chlorinated or fluorinated hydrocarbons such as chloride methylene, trichlorethylene, perchlorethylene or trichlorofluoromethane.
  • compositions according to the invention burn with speeds compatible with safety requirements automobile by releasing combustion gases essentially consisting of nitrogen and dioxide carbon monoxide content is located within the limits allowed for the automotive safety. Furthermore, these compositions do not produce little or no residue solids, so they can be used in gas generators without a filtration chamber or fitted with very simple filtration devices. Finally the presence of a binder which is an elastomer having elastic properties improves resistance mechanics of the loads arranged inside the gas generators.
  • This block was burned in a gas generator. The combustion was done without solid residues and the carbon monoxide content reduced to a useful volume of 2.7 m 3 which is the standard volume of a passenger compartment of a motor vehicle, was 40 ppm.
  • an 8 g block of double-base powder with nitrocellulose and nitroglycerin gives a similar gas yield but provides a carbon monoxide content of 1000 ppm for a useful volume of 2.7 m 3 .
  • This block was burned in a gas generator. Combustion produced 6% by weight of solid residue based on potassium chloride but the speed of combustion was greater than that of Example 1.
  • the carbon monoxide content reduced to a useful volume of 2.7 m 3 was 40 ppm.

Description

La présente invention se rapporte au domaine de la sécurité automobile et, plus précisément, à celui de la protection, en cas de collision, des occupants d'un véhicule automobile grâce à des coussins gonflés par les gaz de combustion d'une composition pyrotechnique contenue dans un générateur de gaz. L'invention concerne des compositions pyrotechniques génératrices de gaz propres et non toxiques, contenant un liant thermoplastique.The present invention relates to the field of automotive safety and, more specifically, that of the protection, in the event of a collision, of the occupants of a motor vehicle thanks to cushions inflated by combustion gas of a pyrotechnic composition contained in a gas generator. The invention relates to gas-generating pyrotechnic compositions clean and non-toxic, containing a binder thermoplastic.

Il est connu de gonfler, pour assurer la sécurité des occupants d'un véhicule automobile en cas de collision, des coussins de protection au moyen des gaz de combustion de compositions pyrotechniques contenues dans des générateurs de gaz. Les gaz de combustion ainsi produits doivent être non toxiques pour les occupants du véhicule et doivent pouvoir être produits en des temps très courts, de l'ordre de quelques dizaines de millisecondes. Les premières compositions pyrotechniques satisfaisant à ces exigences retenues par l'homme de métier ont été essentiellement des compositions constituées par un azoture alcalin ou alcalino-terreux et par un oxydant minéral. De telles compositions sont, par exemple, décrites dans le brevet USP 4 547 235. Ces compositions fournissent bien des gaz dans les conditions requises par la sécurité automobile mais produisent également, par combustion, une quantité importante de résidus solides qui constituent des points chauds qui ne doivent pas pénétrer dans le coussin de protection.It is known to inflate, to ensure safety occupants of a motor vehicle in the event of a collision, protective cushions by means of combustion of pyrotechnic compositions contained in gas generators. Combustion gases as well products must be non-toxic to the occupants of the vehicle and must be capable of being produced in time very short, of the order of a few tens of milliseconds. The first pyrotechnic compositions satisfying these requirements retained by the man of craft were essentially compositions consisting of an alkali or alkaline earth azide and by a mineral oxidant. Such compositions are, for example, described in USP 4,547,235. These compositions provide much gas in the automotive safety requirements but also produce, by combustion, a quantity important solid residues which constitute points that should not enter the cushion protection.

L'emploi de ces compositions nécessite donc des générateurs de gaz équipés de puissants moyens de filtration des gaz.The use of these compositions therefore requires gas generators equipped with powerful filtration means gases.

Parallèlement , depuis une vingtaine d'années, dans le but d'alléger le poids des dispositifs de sécurité et d'en diminuer les coûts, les constructeurs de véhicules automobiles souhaitent pouvoir disposer de générateurs simples, sans chambre de filtration, ou muni d'une chambre de filtration très simple et très légère.At the same time, for the past twenty years, in the purpose of reducing the weight of the safety devices and reduce costs, vehicle manufacturers cars want to have generators simple, without a filtration chamber, or fitted with a very simple and very light filtration chamber.

L'homme de métier est donc à la recherche de compositions pyrotechniques fournissant par combustion, dans des conditions de temps et de non toxicité compatibles avec les exigences de la sécurité automobile, des gaz propres sans résidus solides.The skilled person is therefore looking for pyrotechnic compositions providing by combustion, in time and non-toxic conditions compatible with security requirements automotive, clean gases without solid residues.

Après s'être orienté vers les poudres propulsives à base de nitrocellulose et de nitroglycérine qui brûlent vite, sans aucun résidu solide mais qui ne donnent pas toujours entière satisfaction au plan de la non toxicité des gaz, l'homme de métier s'est tourné vers les compositions dites "composites" constituées par un liant organique et par un oxydant minéral ou organique. Néanmoins la difficulté est grande avec ce type de compositions, souvent riches en carbone et en éléments minéraux, de satisfaire simultanément aux trois exigences de :

  • i) non toxicité des gaz,
  • ii) grande vitesse de combustion,
  • iii) absence de résidus solides ou en tout cas très faible quantité de résidus solides.
    • After focusing on propellant powders based on nitrocellulose and nitroglycerin which burn quickly, without any solid residue but which do not always give full satisfaction in terms of the non-toxicity of gases, the skilled person turned towards the so-called "composite" compositions constituted by an organic binder and by an inorganic or organic oxidant. However, the difficulty is great with this type of composition, often rich in carbon and mineral elements, to simultaneously satisfy the three requirements of:
  • i) non-toxicity of gases,
  • ii) high burning speed,
  • iii) absence of solid residues or in any case very small quantity of solid residues.

    • Toutefois le brevet français 2692257 déposée le 12 juin 1992 a proposé un type de compositions qui satisfont à cette triple exigence.However, French patent 2,692,257 filed on June 12, 1992 proposed a type of composition which meet this triple requirement.

    Les compositions décrites dans cette demande sont principalement constitué par le produit de réaction d'un polyazoture de glycidyle avec un polyisocyanate comme liant et par du nitrate d'ammonium comme charge oxydante. Ces compositions donnent toutes satisfactions au plan de la non toxicité des gaz, de la vitesse de combustion et de l'absence de résidus solides, mais elles sont cependant d'une mise en oeuvre délicate, notamment dans des procédés continus impliquant une phase d'extrusion, du fait qu'elle font appel à des liants réticulables qui durcissent très vite.The compositions described in this application are mainly consisting of the reaction product of a glycidyl polyazide with a polyisocyanate such as binder and with ammonium nitrate as oxidizing charge. These compositions give all satisfaction to the plan of gas non-toxicity, speed of combustion and the absence of solid residue but however, they are delicate to implement, especially in continuous processes involving a extrusion phase, due to the fact that they use crosslinkable binders which harden very quickly.

    L'emploi d'un liant thermoplastique dans des compositions composites de ce type permettrait une mise en oeuvre plus aisée, notamment pour des procédés continus ; mais, si l'emploi de compositions pyrotechniques à liant thermoplastique comme propergols pour fusées ou comme explosifs est connu, par exemple par les brevets USP 4 806 613, 4 875 949 et 4 925 503, leur emploi dan la sécurité automobile est peu usité à ce jour. En effet les compositions pyrotechniques composites à liant thermoplastique connues à ce jour ne satisfont pas l'ensemble des exigences requises dans domaine. Le brevet US-A 4 806 613 décrit, par exemple, des compositions pyrotechniques à liants thermoplastiques pouvant contenir (i) un plastifiant énergétique comme la nitroglycérine, le trinitrate de butanetriol (BTTN) ou le trinitrate de triméthyloléthane (TMETN), (ii) une charge oxydante minérale ou organique, (iii) de l'aluminium en poudre et (iv) les additifs connus de l'homme de métier. Une telle composition, en raison de sa forte teneur en composés hydrocarboné et en raison de la présence de particules métalliques libres ne satisfait ni aux exigences de non-toxicité des gaz ni à celles d'absence de résidus solides requises pour la sécurité automobile.The use of a thermoplastic binder in composite compositions of this type would allow a easier to use, especially for processes continuous; but, if the use of compositions pyrotechnics with thermoplastic binder as propellants for rockets or as explosives is known, for example by USP patents 4,806,613, 4,875,949 and 4,925,503, their job in automotive safety is little used to this day. Indeed the pyrotechnic compositions thermoplastic binder composites known to date do not do not meet all of the requirements in field. US-A 4,806,613 describes, for example, pyrotechnic compositions with binders thermoplastics which may contain (i) a plasticizer energy like nitroglycerin, butanetriol trinitrate (BTTN) or the trimethylolethane trinitrate (TMETN), (ii) an oxidizing charge mineral or organic, (iii) aluminum powder and (iv) additives known to those skilled in the art. Such a composition, in because of its high content of hydrocarbon compounds and due to the presence of free metal particles neither meets the requirements for non-toxicity of gases nor to those of absence of solid residues required for the automotive safety.

    L'homme de métier est donc à la recherche de compositions pyrotechniques génératrices de gaz propres et non toxiques, qui brûlent à une vitesse compatible avec les exigences de la sécurité automobile et qui soient d'une mise en oeuvre aisée à l'échelle industrielle.The skilled person is therefore looking for clean gas generating pyrotechnic compositions and non-toxic, which burn at a compatible speed with the requirements of automotive safety and who are easy to scale up industrial.

    L'objet de la présente invention est précisément de proposer de telles compositions.The object of the present invention is precisely to propose such compositions.

    L'invention concerne donc une composition pyrotechnique dont les produits de combustion sont principalement des gaz propres non toxiques, constituée essentiellement par un liant qui est un élastomère thermoplastique, par un plastifiant énergétique, par une charge oxydante minérale et par des additifs destinés à régler la combustion, caractérisée en ce que le dit liant est un élastomère thermoplastique oxygéné, en ce que le dit plastifiant est un produit de polymérisation de l'azoture de glycidyle et en ce que la dite charge oxydante est constituée pour au moins 85 % de son poids par du nitrate d'ammonium.The invention therefore relates to a composition pyrotechnics whose combustion products are mainly non-toxic clean gases, consisting essentially by a binder which is an elastomer thermoplastic, by an energy plasticizer, by a mineral oxidizing charge and by additives intended for regulate combustion, characterized in that said binder is an oxygenated thermoplastic elastomer, in that that the said plasticizer is a product of polymerization of glycidyl azide and in that the said oxidizing charge is constituted for at least 85% of its weight by ammonium nitrate.

    Selon une première variante préférée de l'invention le dit liant est une copolymère bloc constitué principalement par des motifs polyamide et des motifs polyéther.According to a first preferred variant of the invention the said binder is a block copolymer consisting mainly with polyamide patterns and polyether patterns.

    Selon une seconde variante préférée de l'invention le dit plastifiant énergétique est un polyazoture de glycidyle à terminaisons hydroxyles dont la masse moléculaire moyenne en nombre est comprise entre 1 000 et 7 000.According to a second preferred variant of the invention the said energy plasticizer is a polyazide of glycidyl with hydroxyl endings whose molecular mass number average is between 1,000 and 7,000.

    Selon une troisième variante préférée de l'invention les dits additifs sont choisis dans le groupe constitué par le nitrate de potassium et le perchlorate d'ammonium.According to a third preferred variant of the invention the said additives are chosen from the group consisting of potassium nitrate and perchlorate ammonium.

    Selon une dernière variante préférée de l'invention l'ensemble liant/plastifiant énergétique représente entre 5 et 15 % du poids total de la composition, le poids du plastifiant énergétique représentant environ 30 % du poids liant.According to a last preferred variant of the invention the energy binder / plasticizer set represents between 5 and 15% of the total weight of the composition, the weight of the energy plasticizer representing approximately 30% of the binder weight.

    Les compositions selon l'invention brûlent vite en dégageant essentiellement comme gaz de combustion de l'azote et du dioxyde de carbone avec très peu de monoxyde de carbone. Par ailleurs, elles ne produisent pas, ou peu, selon les additifs utilisés, de résidus solides.The compositions according to the invention burn quickly in essentially releasing as combustion gases from nitrogen and carbon dioxide with very little carbon monoxide. Furthermore, they do not produce little or no residue, depending on the additives used solid.

    Elles peuvent donc avantageusement être utilisées dans les générateurs pyrotechniques de gaz destinés à gonfler des coussins de protection pour occupants d'un véhicule automobile. Par ailleurs la présence comme liant d'un élastomère confère aux granulés ou aux blocs de composition pyrotechnique des propriétés mécaniques particulièrement intéressantes pour des produits destinés à être conservés pendant de nombreuses années dans un véhicule automobile.They can therefore advantageously be used in pyrotechnic gas generators intended for inflate protective cushions for occupants of a motor vehicle. Furthermore, the presence as binder of an elastomer gives granules or blocks of pyrotechnic composition of mechanical properties particularly interesting for products intended to be kept for many years in a motor vehicle.

    On donne ci-après une description détaillée de l'invention.A detailed description is given below the invention.

    L'invention concerne donc des compositions pyrotechniques dont les produits de combustion sont principalement des gaz propres et non toxiques. Ces compositions sont essentiellement constituées par un liant, par un plastifiant énergétique, par une charge oxydante minérale et par des additifs destinés à régler la combustion de la composition.The invention therefore relates to pyrotechnic compositions whose combustion products are mainly clean, non-toxic gases. These compositions are essentially made up of a binder, by an energetic plasticizer, by an oxidizing charge mineral and by additives intended to regulate the combustion of the composition.

    Selon une première caractéristique essentielle de l'invention le liant utilisé est un élastomère thermoplastique oxygéné, les élastomères thermoplastiques non oxygénés n'entrant pas dans le cadre de la présente invention car ils conduisent à des gaz de combustion trop riches en monoxyde de carbone et donc trop toxiques pour les exigences de la sécurité automobile. Comme liant on préférera les copolymères aliphatiques blocs constitués principalement par des blocs à motifs polyamide et par des blocs à motifs polyéther et dont la masse moléculaire est inférieur à 20000. Un liant particulièrement préféré dans le cadre de la présente invention est constitué par un copolymère aliphatique bloc de formule :

    Figure 00060001
       dans laquelle :

    • C, H, O représentent respectivement le carbone, l'hydrogène et l'oxygène,
    • PA représente un bloc polyamide obtenu par condensation de l'acide dodecanedioïque avec la 1, 12 dodecanediamine,
    • PE représente un bloc polyéther obtenu par condensation du tétraméthylène glycol,
    • n représente un nombre entier compris entre 2 et 10.
    According to a first essential characteristic of the invention, the binder used is an oxygenated thermoplastic elastomer, the non-oxygenated thermoplastic elastomers not falling within the scope of the present invention because they lead to combustion gases too rich in carbon monoxide and therefore too toxic for automotive safety requirements. As a binder, the aliphatic block copolymers are preferably constituted mainly by blocks with polyamide units and by blocks with polyether units and whose molecular weight is less than 20,000. A binder which is particularly preferred in the context of the present invention consists of an aliphatic copolymer formula block:
    Figure 00060001
    in which :
    • C, H, O represent carbon, hydrogen and oxygen respectively,
    • PA represents a polyamide block obtained by condensation of dodecanedioic acid with 1.12 dodecanediamine,
    • PE represents a polyether block obtained by condensation of tetramethylene glycol,
    • n represents an integer between 2 and 10.

    Ce type de copolymère bloc est commercialisé par la société ATOCHEM sous la marque PEBAX® .This type of block copolymer is marketed by ATOCHEM company under the PEBAX® brand.

    Selon une seconde caractéristique essentielle de l'invention on rajoute au liant un plastifiant énergétique qui est un produit de polymérisation de l'azoture de glycidyle. Une famille préférée de plastifiants énergétiques est constituée par les polyazotures de glycidyle à terminaisons hydroxyles dont la masse moléculaire moyenne en nombre est comprise entre 1 000 et 7 000 et, préférentiellement entre, 1 500 et 2 500.According to a second essential characteristic of the invention an energy plasticizer is added to the binder which is a product of polymerization of azide glycidyl. A favorite family of plasticizers energy consists of the polyazides of glycidyle with hydroxyl endings whose mass number average molecular is between 1,000 and 7,000 and, preferably between, 1,500 and 2,500.

    Ces polyazotures de glycidyle répondent à la formule suivante :

    Figure 00070001
    dans laquelle :

    • C, H, O, N représentent respectivement le carbone, l'hydrogène, l'oxygène, et l'azote,
    • m représente un nombre entier en général compris entre 5 et 100.
    These glycidyl polyazides correspond to the following formula:
    Figure 00070001
    in which :
    • C, H, O, N respectively represent carbon, hydrogen, oxygen, and nitrogen,
    • m represents an integer generally between 5 and 100.

    Il convient de souligner que, dans le cadre de la présente invention, les polyazotures de glycidyle à terminaisons hydroxyles ne participent à aucune réaction chimique de condensation ; ils sont donc bien utilisés comme plastifiant énergétique de l'élastomère thermoplastique et non comme élément constitutif du liant comme c'est généralement le cas lorsqu'ils sont utilisés en présence d'un isocyanate ou d'un autre agent réagissant avec les groupes hydroxyles OH.It should be noted that, as part of the present invention, the glycidyl polyazides to hydroxyl endings do not participate in any reaction chemical condensation; they are therefore well used as an energy plasticizer for the thermoplastic elastomer and not as a component of the binder as is usually the case when used in the presence of an isocyanate or other reactive agent with the hydroxyl groups OH.

    L'ensemble liant/plastifiant énergétique représente de préférence entre 5 % et 15 % du poids total de la composition tandis que le poids du dit plastifiant énergétique représente de préférence environ 30 % du poids de l'ensemble liant/plastifiant. On observe ainsi que l'invention permet d'utiliser grâce à l'emploi d'un liant thermoplastique approprié, des compositions composites présentant un taux de liant relativement faible, ce qui est très avantageux au plan de la non toxicité des gaz.The energy binder / plasticizer set represents preferably between 5% and 15% of the total weight of the composition while the weight of said plasticizer energy preferably represents around 30% of the weight of the binder / plasticizer assembly. We thus observe that the invention allows to use through the use of a suitable thermoplastic binder, compositions composites with a relatively high binder content low, which is very advantageous in terms of not gas toxicity.

    Selon une troisième caractéristique essentielle de l'invention, la composition pyrotechnique contient une charge oxydante constituée pour au moins 85 % de son poids par du nitrate d'ammonium.According to a third essential characteristic of the invention, the pyrotechnic composition contains a oxidizing charge formed for at least 85% of its weight by ammonium nitrate.

    On utilisera avantageusement un nitrate d'ammonium stabilisé. Le stabilisant pourra par exemple être constitué par un peu d'oxyde de nickel NiO. Cette qualité de nitrate d'ammonium est vendue dans le commerce et contient en général 3 % en poids d'oxyde de nickel par rapport au nitrate d'ammonium pur. Dans la présente description l'expression "nitrate d'ammonium" recouvre l'ensemble constitué par le nitrate d'ammonium pur et par le stabilisant éventuellement présent. Bien que l'oxyde de nickel soit non combustible, sa présence en faible quantité s'avère non gênante dans le cadre de la présente invention.Advantageously, an ammonium nitrate will be used stabilized. The stabilizer could for example be consisting of a little nickel oxide NiO. This quality of ammonium nitrate is sold commercially and generally contains 3% by weight of nickel oxide compared to pure ammonium nitrate. In this description the expression "ammonium nitrate" covers the assembly consisting of pure ammonium nitrate and by any stabilizer present. Although nickel oxide is non-combustible, its presence in small amount is not a problem in the context of present invention.

    La totalité de la charge oxydante peut être constituée par du nitrate d'ammonium mais il est impératif dans le cadre de la présente invention que le nitrate d'ammonium représente, en poids, au moins 85 % de la charge oxydante. The entire oxidizing charge can be consisting of ammonium nitrate but it is imperative in the context of the present invention that the ammonium nitrate represents, by weight, at least 85% of the oxidizing charge.

    Lorsque la charge oxydante n'est pas constituée à 100 % par du nitrate d'ammonium, elle peut être complétée par du nitrate de triaminoguanidinium, par de la nitroguanidine ou encore par une nitramine comme l'hexogène ou l'octogène.When the oxidizing charge is not formed at 100% with ammonium nitrate, it can be supplemented with triaminoguanidinium nitrate, with nitroguanidine or by a nitramine such as hexogen or octogen.

    Avantageusement, les compositions selon l'invention contiennent également des additifs destinés notamment à régler la vitesse de combustion de la composition dans la gamme de pression correspondant au fonctionnement du générateur. Ces additifs excluent les métaux ou composés métalliques susceptibles de constituer des résidus solides entrainables par les gaz de combustion. Ces additifs pourront être par exemple du noir de carbone ou de la m-méthyl p-nitroaniline. Selon une réalisation préférée de l'invention ces additifs peuvent également être choisis dans le groupe constitué par le nitrate de potassium et le perchlorate d'ammonium, les additifs jouant également dans ce dernier cas, le rôle de charge oxydante. Des compositions préférées dans le cadre de la présente invention contiennent comme additifs un mélange de nitrate de potassium et de perchlorate d'ammonium, le nitrate de potassium représentant environ 7 % du poids de nitrate d'ammonium et le perchlorate d'ammonium représentant entre 4 et 6 % du poids total de la composition.Advantageously, the compositions according to the invention also contain additives intended in particular for adjust the rate of combustion of the composition in the pressure range corresponding to the operation of the generator. These additives exclude metals or compounds metal likely to constitute residues solids entrainable by combustion gases. These additives could for example be carbon black or m-methyl p-nitroaniline. According to an achievement preferred of the invention these additives can also be selected from the group consisting of nitrate of potassium and ammonium perchlorate, additives also playing in the latter case the role of charge oxidizing. Preferred compositions as part of the present invention contain as additives a mixture potassium nitrate and ammonium perchlorate, the potassium nitrate representing approximately 7% by weight ammonium nitrate and ammonium perchlorate representing between 4 and 6% of the total weight of the composition.

    La formulation et la mise en forme des compositions selon l'invention peut aisément être faite en continu ou en discontinu dans un malaxeur-extrudeur en utilisant les techniques avec solvant ou sans solvant connues de l'homme de métier.The formulation and formatting of the compositions according to the invention can easily be done continuously or batchwise in a mixer-extruder using solvent or solvent-free techniques known from the skilled person.

    Dans une mise en oeuvre sans solvant on profite du ramollissement à chaud du liant pour assurer l'enrobage de la charge oxydante par ce dernier. Dans un malaxeur extrudeur chauffé, en général à une température comprise entre 80°C et 130°C, et préférentiellement à une température voisine de 120°C, on introduit le liant et le plastifiant énergétique puis on rajoute la charge oxydante et les additifs éventuels. Lorsque l'enrobage de la charge et des additifs par le liant est terminée on extrude la pâte obtenue à la géométrie souhaitée et on laisse refroidir.In a solvent-free implementation, we take advantage of the hot softening of the binder to ensure the coating of the oxidizing charge by the latter. In a mixer heated extruder, usually at a temperature between 80 ° C and 130 ° C, and preferably at a temperature close to 120 ° C., the binder is introduced and the energy plasticizer then we add the charge oxidizing agent and any additives. When the coating load and additives by the binder is complete the paste obtained is extruded to the desired geometry and let cool.

    On obtient ainsi des grains, des brins ou même des petits blocs de composition selon l'invention.We thus obtain grains, strands or even small composition blocks according to the invention.

    Dans une mise en oeuvre avec solvant, on dissout le liant à l'aide d'un solvant approprié dans un malaxeur extrudeur. Le solvant du liant ne doit pas dissoudre ni attaquer chimiquement la charge oxydante et les additifs. Comme solvant on utilisera avantageusement les alcools légers comme l'éthanol, le propanol et préférentiellement le butanol, les hydrocarbures légers comme le kérosène ou le benzène, la méthyléthylcétone, les hydrocarbures chlorés ou fluorés comme le chlorure de méthylène, le trichloréthylène, le perchloréthylène ou le trichlorofluorométhane. On rajoute ensuite le plastifiant énergétique, la charge oxydante et les additifs éventuels. Après obtention d'une pâte homogène on extrude cette dernière à la géométrie souhaitée et on chasse le solvant par évaporation éventuellement accompagnée d'un léger chauffage.In an implementation with solvent, the binder using a suitable solvent in a mixer extruder. Binder solvent should not dissolve or chemically attack the oxidative charge and additives. As solvent, the light alcohols such as ethanol, propanol and preferably butanol, light hydrocarbons such as kerosene or benzene, methyl ethyl ketone, chlorinated or fluorinated hydrocarbons such as chloride methylene, trichlorethylene, perchlorethylene or trichlorofluoromethane. We then add the energy plasticizer, oxidizing charge and any additives. After obtaining a homogeneous paste we extrude it to the desired geometry and we removes solvent by evaporation if necessary accompanied by a slight heating.

    L'emploi d'une technique avec solvant est particulièrement recommandée lorsque le liant a un température de ramollissement trop élevée pour le plastifiant énergétique ou pour la charge oxydante.The use of a solvent technique is particularly recommended when the binder has a temperature softening too high for the energy plasticizer or for the oxidizing charge.

    Avec les produits ainsi obtenus on constitue aisément le chargement pyrotechnique d'un générateur de gaz, soit comme chargement de grains en vrac, soit comme fagot de brins allongés, soit encore comme bloc possédant une géométrie adaptée à celle de la chambre de combustion du générateur. With the products thus obtained, it is easy to constitute the pyrotechnic charge of a gas generator, either as bulk grain loading or as bundle of elongated strands, either as a block having a geometry adapted to that of the combustion of the generator.

    Les compositions selon l'invention brûlent avec des vitesses compatibles avec les exigences de la sécurité automobile en dégageant des gaz de combustion essentiellement constitués par de l'azote et du dioxyde de carbone, leur teneur en monoxyde de carbone se situant à l'intérieur des limites admises pour la sécurité automobile. Par ailleurs ces compositions ne produisent pas, ou ne produisent que peu de résidus solides, de sorte qu'elles peuvent être utilisées dans des générateurs de gaz sans chambre de filtration ou munis de dispositifs de filtration très simples. Enfin la présence d'un liant qui est un élastomère possédant des propriétés élastiques améliore la résistance mécanique des chargements disposés à l'intérieur des générateurs de gaz.The compositions according to the invention burn with speeds compatible with safety requirements automobile by releasing combustion gases essentially consisting of nitrogen and dioxide carbon monoxide content is located within the limits allowed for the automotive safety. Furthermore, these compositions do not produce little or no residue solids, so they can be used in gas generators without a filtration chamber or fitted with very simple filtration devices. Finally the presence of a binder which is an elastomer having elastic properties improves resistance mechanics of the loads arranged inside the gas generators.

    Les exemples qui suivent, donnés à titre non limitatif, illustrent certaines possibilités de mise en oeuvre de l'invention.The following examples, given without limitation, illustrate some possibilities of implementation work of the invention.

    Exemple 1Example 1

    On a fabriqué, par une technique sans solvant, un bloc annulaire de 8 g ayant la composition suivante : - liant : résine "PEBAX" 2533 (comportant, en poids, 20% de motifs PA et 80% de motifs PE tels que définis plus haut) 8,6 parties en poids - plastifiant énergétique polyazoture de glycidyle de masse 2 000 3,4 parties en poids - nitrate d'ammonium 88,0 parties en poids An 8 g annular block having the following composition was produced, by a solvent-free technique. - binder: resin "PEBAX" 2533 (comprising, by weight, 20% of PA units and 80% of PE units as defined above) 8.6 parts by weight - energy plasticizer polyazid glycidyl mass 2000 3.4 parts by weight - ammonium nitrate 88.0 parts by weight

    Ce bloc a été brûlé dans un générateur de gaz. La combustion s'est faite sans résidus solides et la teneur en monoxyde de carbone ramenée à un volume utile de 2,7 m3 qui est le volume standard d'un habitacle de véhicule automobile, était de 40 ppm.This block was burned in a gas generator. The combustion was done without solid residues and the carbon monoxide content reduced to a useful volume of 2.7 m 3 which is the standard volume of a passenger compartment of a motor vehicle, was 40 ppm.

    A titre de comparaison, un bloc de 8 g en poudre à double base à la nitrocellulose et à la nitroglycérine donne un rendement gazeux analogue mais fournit une teneur en monoxyde de carbone de 1 000 ppm pour un volume utile de 2,7 m3.By way of comparison, an 8 g block of double-base powder with nitrocellulose and nitroglycerin gives a similar gas yield but provides a carbon monoxide content of 1000 ppm for a useful volume of 2.7 m 3 .

    Exemple 2Example 2

    On a fabriqué, par une technique sans solvant, un bloc annulaire de 8 g ayant la composition suivante : -liant : résine "PEBAX" 2533 8,6 parties en poids -plastifiant énergétique polyazoture de glycidyle de masse 2 000 3,4 parties en poids -nitrate d'ammonium 75,6 parties en poids -nitrate de potassium 8,4 parties en poids -perchlorate d'ammonium 4,0 parties en poids An 8 g annular block having the following composition was produced, by a solvent-free technique. - binder: resin "PEBAX" 2533 8.6 parts by weight -energetic plasticizer polyazide glycidyl mass 2000 3.4 parts by weight - ammonium nitrate 75.6 parts by weight - potassium nitrate 8.4 parts by weight - ammonium perchlorate 4.0 parts by weight

    Ce bloc a été brûlé dans un générateur de gaz. La combustion a produit 6 % en poids de résidus solides à base de chlorure de potassium mais la vitesse de combustion a été supérieure à celle de l'exemple 1.This block was burned in a gas generator. Combustion produced 6% by weight of solid residue based on potassium chloride but the speed of combustion was greater than that of Example 1.

    La teneur en monoxyde de carbone ramenée à un volume utile de 2,7 m3 a été de 40 ppm.The carbon monoxide content reduced to a useful volume of 2.7 m 3 was 40 ppm.

    Claims (8)

    1. Gas-generating pyrotechnic composition designed to inflate protective cushions for the occupants of a motor vehicle, consisting essentially of a binder which is a thermoplastic elastomer, an energetic plasticizer, an oxidizing charge and additives designed to regulate combustion, characterized in that the said binder is an oxygenated thermoplastic elastomer, in that the said plasticizer is a product of the polymerization of glycidyl azide and in that at least 85 % of the weight of the oxidizing charge consists of ammonium nitrate.
    2. Pyrotechnic composition according to claim 1, characterized in that the said binder is an aliphatic block copolymer mainly consisting of polyamide units and polyether units.
    3. Pyrotechnic composition according to claim 2, characterized in that the said binder is an aliphatic block copolymer having the formula :
      Figure 00160001
      in which :
      C, H, O represent carbon, hydrogen and oxygen respectively,
      PA represents the polyamide block obtained by condensation of dodecanedioic acid with 1,12-dodecanediamine,
      PE represents a polyether block obtained by condensation of tetramethylene glycol,
      n represents a whole number between 2 and 10.
    4. Pyrotechnic composition according to claim 2, characterized in that the said energetic plasticizer is a glycidyl polyazide with hydroxylated end groups of which the mean molecular mass is between 1000 and 7000.
    5. Pyrotechnic composition according to claim 4, characterized in that the mean molecular mass of the said glycidyl polyazide with hydroxylated end groups is between 1500 and 2500.
    6. Pyrotechnic composition according to claim 2, characterized in that the said additives are selected from the group consisting of potassium nitrate and ammonium perchlorate.
    7. Pyrotechnic composition according to claim 2, characterized in that the binder/energetic plasticizer combination represents between 5 and 15 % of the total weight of the composition.
    8. Pyrotechnic composition according to claim 7, characterized in that the weight of the energetic plasticizer represents approximately 30 % of the weight of the binder/plasticizer combination.
    EP94402714A 1993-12-07 1994-11-29 Pyrotechnic compositions for producing clean non-toxic gases containing an elastomeric thermoplastic binder Expired - Lifetime EP0659712B1 (en)

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    FR9314642 1993-12-07
    FR9314642A FR2713632B1 (en) 1993-12-07 1993-12-07 Pyrotechnic compositions generating clean and non-toxic gases, containing a thermoplastic elastomer binder.

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    DE69411691D1 (en) 1998-08-20
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    JPH07215790A (en) 1995-08-15
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