EP0816307A1 - Clean-gas generating pyrotechnic compositions and use thereof in a gas generator employed in a protection system in motor vehicles - Google Patents
Clean-gas generating pyrotechnic compositions and use thereof in a gas generator employed in a protection system in motor vehicles Download PDFInfo
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- EP0816307A1 EP0816307A1 EP97401483A EP97401483A EP0816307A1 EP 0816307 A1 EP0816307 A1 EP 0816307A1 EP 97401483 A EP97401483 A EP 97401483A EP 97401483 A EP97401483 A EP 97401483A EP 0816307 A1 EP0816307 A1 EP 0816307A1
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- 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
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B33/00—Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide
- C06B33/04—Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide the material being an inorganic nitrogen-oxygen salt
Definitions
- the present invention relates to the field of automotive safety. More specifically the invention relates to new pyrotechnic compositions clean and non-toxic gas generators, essentially consisting of nitrogen and water, and intended to inflate protective cushions for occupants of a motor vehicle.
- compositions based on sodium azide like, for example, those described in the patent US-A-4,929,290.
- the compositions based sodium azide have many disadvantages.
- sodium azide which can lead to explosives primary, by combination with metals to form for example lead azide, these compositions must be subject to precautions when manufacturing and disposal of waste.
- compositions as a propellant for rocket and missile engines are known and described in numerous patents such as, for example, the US-A-3,725,516 which describes propellants for rocket engines constituted by a fluorinated binder, a salt oxidant such as ammonium nitrate or perchlorate potassium and a metal in powder form.
- propellants are not usable in gas generators intended for the automotive safety for at least two reasons. Of a apart from that they contain a very high level of binder, often between 10 and 35%, and therefore produce large quantities of gas by combustion very toxic like carbon monoxide, and other apart they use metallic compounds which generate large amounts of solid residue.
- compositions based on ammonium nitrate and / or potassium perchlorate in combination with tetrazole derivatives and compounds metallic like boron oxide, vanadium oxide or silicates Such compositions which are, for example, described in US-A-5,035,757 give many non-toxic nitrogen-rich gases but still produce many solid residues which make it necessary to have a important filtration.
- compositions expressly excluding the presence of metallic compounds and comprising essentially an oxygenated thermoplastic binder, a energy plasticizer such as polyazide glycidyl and a compound oxidizing charge for at least 85% of its weight by ammonium nitrate.
- the composition contains at least 8% by weight of binder not to mention the energy plasticizer and the skilled person is, at least for some applications, again faced with the problem of gas toxicity.
- the object of the present invention is precisely to propose a family of compositions that meets this need.
- compositions according to the invention are presented therefore as over-oxygenated compositions containing very little binder. Under these conditions these compositions can admit small amounts of boron or which give them the speed of combustion required by automotive safety without production excessive carbon monoxide.
- Another benefit of the invention lies in the fact that the selection of two particular metals, boron and aluminum, avoid the formation of heavy particles capable of build hot spots in the airbag. Indeed, under the combustion conditions of the automotive safety it has been found that these two metals form residue as particles extremely fine, non-toxic solids that do not not require the presence of a filtration system sophisticated in the generator, unlike metals like magnesium, beryllium or zirconium which are commonly used in self propulsion but which absolutely not suitable in the context of this invention.
- the use of boron as a metal is preferred in the scope of the invention.
- the binder rate will advantageously be between 3 and 6% of the total weight of the composition.
- the binder will used without energy plasticizer and will preferably chosen from the group consisting of polymers and copolymers with epoxy units, with units ether, ester motifs, amide motifs or by polyacrylates. Polyepoxy binders are suitable particularly good at implementing the invention.
- the oxidizing charge also includes perchlorate potassium, the content of which is not more than 30% of the total weight of the composition. This content will often between 20% and 30% of the total weight of the composition.
- the oxidizing charge also includes a nitrogen compound chosen from the group consisting of perchlorate ammonium, triaminoguanidine nitrate, hexogen, octogen or hexanitrohexaazaisowurtzitane again known by the acronym "HNIW”.
- a nitrogen compound chosen from the group consisting of perchlorate ammonium, triaminoguanidine nitrate, hexogen, octogen or hexanitrohexaazaisowurtzitane again known by the acronym "HNIW”.
- HNIW hexogen, octogen or hexanitrohexaazaisowurtzitane again known by the acronym "HNIW”.
- HNIW hexogen, octogen or hexanitrohexaazaisowurtzitane again known by the acronym "HNIW”.
- the content of the composition in such a nitrogen compound is at most equal to 15% of its total weight.
- ammonium nitrate will be an ammonium nitrate stabilized by nitrate of potassium in the presence of an organic dye comprising an arylsulfonate group as described for example in French patent application 96.00778 or in the European patent application 97 400 149.7.
- an organic dye comprising an arylsulfonate group as described for example in French patent application 96.00778 or in the European patent application 97 400 149.7.
- the use of this type of ammonium nitrate allows better stability of the mechanical and pyrotechnic properties of material during thermal cycles.
- We will use advantageously a stabilized ammonium nitrate containing 96.5% by weight of ammonium nitrate, 3% of potassium nitrate and 0.5% amaranth.
- the said binder is a flexible binder which has a tensile elongation at 20 ° C equal to or greater than 15% and a coefficient of expansion at least equal to 2x10 -5 % per degree Celsius in the temperature range between -40 ° C and + 110 ° C.
- the binder will advantageously be chosen from the group consisting of polyepoxy binders and polyacrylic binders.
- compositions according to the invention find their preferred use as loads for pyrotechnic gas generators intended for safety automotive, in particular gas generators intended for inflate protective cushions for occupants of a motor vehicle.
- the oxygenated binder is then added in the state liquid, not completely polymerized.
- a thermosetting binder it will be liquid resin mixed with its hardener.
- the hardener will be advantageously a polyamine which is not very reactive so as to have a "pot life" for the binder of about 24 hours.
- compositions according to the invention being to contain only very little binder compared to usual compositions for propellants or low powders "LOVA" type vulnerability, a difficulty not negligible formulation of compositions according to the invention consists in successfully permeating the whole solid constituents, and in particular nitrate ammonium, with this small amount of liquid binder.
- the liquid binder will advantageously be introduced into the mixer in diluted form in a solvent very volatile and inert towards constituents of the composition.
- a polyepoxy binder advantageously use trichloroethane as a diluent.
- the mixer is then started and left on turn, open tank, for about an hour. In these conditions we can permeate all of the solid constituents by the binder and all of the diluent was removed by evaporation during the mixing operation.
- composition which appears at this stage under the appearance of a slightly wet powder is brought to the desired shape by compression. In general it is put in the form of pellets.
- the polymerization of the binder takes place at temperature ambient and after 24 hours, in the case of a binder polyepoxy, the pyrotechnic charges thus obtained have good mechanical strength allowing their use in gas generators intended for the automotive safety.
- compositions according to the invention contain a low level of binder which is not sufficient for fill all the gaps between the nitrate grains ammonium. Therefore putting into the form of pellets by compression leads to objects having a natural porosity corresponding to an increase in the area available for combustion, which is very favorable in terms of the rate of combustion of the composition.
- the gas-generating material must retain all of its properties over time, in particular after a succession of thermal cycles.
- so-called "flexible" oxygenated binders having a tensile elongation at 20 ° C equal to or greater than 15% and a coefficient of expansion, in the temperature range between -40 ° C and +110 ° c, at least equal to 2x10 -5 % per ° C.
- acrylic binders based on methyl acrylate or methacrylate containing a difunctional reactive diluent with long chain (of C 8 and C 15 ) as well as a metallic organic salt as catalyst.
- This last family of binders is particularly interesting because of its anaerobic characteristics that allow it to polymerize at 20 ° C in the absence of oxygen.
- compositions according to the invention were manufactured which have been tested in pyrotechnic operation.
- compositions corresponding to Examples 9 and 10 relate to the use of ammonium nitrate stabilized by 3% by weight of potassium nitrate and 0.5% by weight amaranth as described above. These compositions have have been pelletized and subjected to a standard aging cycle between -35 ° C and + 105 ° C. After this cycle, the pastilles have kept all their mechanical and pyrotechnic properties of operation in a gas generator.
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Abstract
Description
La présente invention se rapporte au domaine de la sécurité automobile. Plus précisément l'invention concerne de nouvelles compositions pyrotechniques génératrices de gaz propres et non toxiques, essentiellement constituées par de l'azote et de l'eau, et destinées à gonfler des coussins de protection pour les occupants d'un véhicule automobile.The present invention relates to the field of automotive safety. More specifically the invention relates to new pyrotechnic compositions clean and non-toxic gas generators, essentially consisting of nitrogen and water, and intended to inflate protective cushions for occupants of a motor vehicle.
Pour produire par voie pyrotechnique des gaz riches en azote on s'intéresse depuis longtemps aux compositions pyrotechniques à base d'azoture de sodium, comme, par exemple, celles décrite dans le brevet US-A-4,929,290. Toutefois les compositions à base d'azoture de sodium présentent de nombreux inconvénients. Tout d'abord, par combustion, ces compositions génèrent de nombreuses poussières solides qui constituent dans les gaz de combustion des points chauds et qui ne doivent donc pas pénétrer dans le coussin gonflable. Il est donc nécessaire, lorsque l'on utilise ce type de compositions, d'équiper le générateur de gaz d'un dispositif sophistiqué de filtration ce qui augmente le poids et le coût du générateur. Par ailleurs les compositions à base d'azoture sont très sensibles à l'humidité et se conservent mal dans le temps. Enfin, l'azoture de sodium pouvant conduire à des explosifs primaires, par combinaison avec des métaux pour former par exemple de l'azoture de plomb, ces compositions doivent faire l'objet de précautions lors de leur fabrication et lors de l'élimination des déchets.To produce rich gases by pyrotechnics in nitrogen we have long been interested in pyrotechnic compositions based on sodium azide, like, for example, those described in the patent US-A-4,929,290. However the compositions based sodium azide have many disadvantages. First, by combustion, these compositions generate a lot of solid dust which constitute points in the combustion gases hot and therefore should not enter the airbag. It is therefore necessary, when one uses this type of composition, to equip the generator gas from a sophisticated filtration device which increases the weight and cost of the generator. otherwise azide-based compositions are very sensitive to humidity and do not keep well over time. Finally, sodium azide which can lead to explosives primary, by combination with metals to form for example lead azide, these compositions must be subject to precautions when manufacturing and disposal of waste.
Pour toutes ces raisons l'homme de métier a cherché à s'affranchir de l'azoture de sodium et s'est orienté vers des compositions solides générant de l'azote et constituées par un liant et une charge oxydante, compositions qui sont très stables dans le temps. For all these reasons the skilled person sought to get rid of sodium azide and oriented towards solid compositions generating nitrogen and consisting of a binder and an oxidizing charge, compositions which are very stable over time.
L'emploi de ce type de compositions comme propergol pour moteurs de fusées et de missiles est connu et décrit dans de nombreux brevets comme, par exemple, le brevet US-A-3,725,516 qui décrit des propergols pour moteurs de fusée constitués par un liant fluoré, un sel oxydant comme le nitrate d'ammonium ou le perchlorate de potassium et un métal sous forme pulvérulente.The use of this type of composition as a propellant for rocket and missile engines is known and described in numerous patents such as, for example, the US-A-3,725,516 which describes propellants for rocket engines constituted by a fluorinated binder, a salt oxidant such as ammonium nitrate or perchlorate potassium and a metal in powder form.
De tels propergols ne sont cependant pas utilisables dans des générateurs de gaz destinés à la sécurité automobile pour au moins deux raisons. D'une part ils contiennent un taux de liant très élevé, souvent compris entre 10 et 35%, et de ce fait produisent par combustion de grandes quantités de gaz très toxiques comme le monoxyde de carbone, et d'autre part ils font appel à des composés métalliques qui génèrent de grandes quantités de résidus solides.However, such propellants are not usable in gas generators intended for the automotive safety for at least two reasons. Of a apart from that they contain a very high level of binder, often between 10 and 35%, and therefore produce large quantities of gas by combustion very toxic like carbon monoxide, and other apart they use metallic compounds which generate large amounts of solid residue.
Pour tenter de remédier à ces difficultés, l'homme de métier a alors proposé des compositions à base de nitrate d'ammonium et/ou de perchlorate de potassium en association avec des dérivés du tétrazole et de composés métalliques comme l'oxyde de bore, l'oxyde de vanadium ou des silicates. De telles compositions qui sont, par exemple, décrites dans le brevet US-A-5,035,757 donnent bien des gaz non toxiques riches en azote mais produisent toujours de nombreux résidus solides qui rendent nécessaire la présence d'un système de filtration important.To try to remedy these difficulties, man by trade then proposed compositions based on ammonium nitrate and / or potassium perchlorate in combination with tetrazole derivatives and compounds metallic like boron oxide, vanadium oxide or silicates. Such compositions which are, for example, described in US-A-5,035,757 give many non-toxic nitrogen-rich gases but still produce many solid residues which make it necessary to have a important filtration.
Il a également été proposé, par exemple par le brevet US-A-5,482,579, des compositions à base d'acétate de cellulose, de nitrate d'ammonium et de perchlorate de potassium. De telles compositions conduisent bien à des gaz riches en azote mais, compte-tenu de leur teneur en liant, ces gaz sont souvent toxiques car trop riches en monoxyde de carbone. Par ailleurs pour atteindre les vitesses de combustion requises par les exigences de la sécurité automobile, l'homme de métier est, dans la pratique, obligé de rajouter des oxydes métalliques ou des poudres métalliques, comme indiqué dans ce brevet, et de ce fait se trouve de nouveau confronté à la nécessité de filtrer les gaz de combustion.It has also been proposed, for example by the US-A-5,482,579, acetate-based compositions cellulose, ammonium nitrate and perchlorate potassium. Such compositions do lead to nitrogen-rich gases but, given their content binder, these gases are often toxic because they are too rich in carbon monoxide. Furthermore, to reach combustion rates required by the requirements of the automotive safety, the skilled person is, in the practical, forced to add metal oxides or metallic powders, as indicated in this patent, and therefore again finds itself confronted with the need to filter the combustion gases.
Il a alors été proposé par la demande de brevet FR-A-2 713 632 des compositions excluant expressément la présence de composés métalliques et comprenant essentiellement un liant thermoplastique oxygéné, un plastifiant énergétique comme le polyazoture de glycidyle et une charge oxydante composée pour au moins 85% de son poids par du nitrate d'ammonium.It was then proposed by the patent application FR-A-2 713 632 of compositions expressly excluding the presence of metallic compounds and comprising essentially an oxygenated thermoplastic binder, a energy plasticizer such as polyazide glycidyl and a compound oxidizing charge for at least 85% of its weight by ammonium nitrate.
Pour que les chargements ainsi constitués présentent une tenue mécanique satisfaisante, aussi bien immédiatement après la fabrication qu'après un long vieillissement, il est cependant nécessaire, en pratique, que la composition contienne au moins 8% en poids de liant sans parler du plastifiant énergétique et l'homme de métier se trouve, au moins pour certaines applications, à nouveau confronté au problème de la toxicité des gaz.So that the loads thus constituted have satisfactory mechanical strength, as well immediately after manufacture only after a long aging, however, it is necessary practical, that the composition contains at least 8% by weight of binder not to mention the energy plasticizer and the skilled person is, at least for some applications, again faced with the problem of gas toxicity.
L'homme de métier est donc toujours à la recherche, à l'heure actuelle, d'une composition pyrotechnique solide sans azoture, possédant une grande vitesse de combustion pour être compatible avec les temps de combustion très courts requis pour le gonflage d'un sac et fournissant des gaz riches en azote, non toxiques, c'est-à-dire très pauvres en monoxyde de carbone, et propres, c'est-à-dire sans ou en tout cas avec seulement très peu de résidus solides de manière à ne pas avoir besoin d'un important système de filtration.The skilled person is therefore always on the lookout, at present, of a pyrotechnic composition solid without azide, having a high speed of combustion to be compatible with the times of very short combustion required to inflate a bag and providing nitrogen-rich, non-toxic gases, that is to say very low in carbon monoxide, and clean, that is to say without or in any case with only very few solid residues so as not to have need a large filtration system.
L'objet de la présente invention est précisément de proposer une famille de compositions qui réponde à ce besoin.The object of the present invention is precisely to propose a family of compositions that meets this need.
L'invention concerne donc une composition
pyrotechnique génératrice de gaz propres comprenant un
liant organique oxygéné et une charge oxydante contenant
au moins du nitrate d'ammonium, caractérisée en ce que :
Les compositions selon l'invention se présentent donc comme des compositions suroxygénées contenant très peu de liant. Dans ces conditions ces compositions peuvent admettre de faibles quantités de bore ou d'aluminium qui leur confèrent la vitesse de combustion requise par la sécurité automobile sans production excessive de monoxyde de carbone. Un autre avantage de l'invention réside dans le fait que la sélection des deux métaux particuliers, le bore et l'aluminium, évite la formation de particules lourdes susceptibles de constituer des points chauds dans le coussin gonflable. En effet, dans les conditions de combustion de la sécurité automobile, il a été constaté que ces deux métaux forment des résidus à l'état de particules solides extrêmement fines et non toxiques qui ne nécessitent pas la présence d'un système de filtration sophistiqué dans le générateur, contrairement aux métaux comme le magnésium, le béryllium ou le zirconium qui sont couramment utilisés en autopropulsion mais qui ne conviennent absolument pas dans le cadre de la présente invention. L'emploi du bore comme métal est préféré dans le cadre de l'invention.The compositions according to the invention are presented therefore as over-oxygenated compositions containing very little binder. Under these conditions these compositions can admit small amounts of boron or which give them the speed of combustion required by automotive safety without production excessive carbon monoxide. Another benefit of the invention lies in the fact that the selection of two particular metals, boron and aluminum, avoid the formation of heavy particles capable of build hot spots in the airbag. Indeed, under the combustion conditions of the automotive safety it has been found that these two metals form residue as particles extremely fine, non-toxic solids that do not not require the presence of a filtration system sophisticated in the generator, unlike metals like magnesium, beryllium or zirconium which are commonly used in self propulsion but which absolutely not suitable in the context of this invention. The use of boron as a metal is preferred in the scope of the invention.
Le taux de liant sera avantageusement compris entre 3 et 6% du poids total de la composition. Le liant sera utilisé sans plastifiant énergétique et sera préférentiellement choisi dans le groupe constitué par les polymères et copolymères à motifs époxy, à motifs éther, à motifs ester, à motifs amide ou encore par les polyacrylates. Les liants polyépoxy conviennent particulièrement bien à la mise en oeuvre de l'invention.The binder rate will advantageously be between 3 and 6% of the total weight of the composition. The binder will used without energy plasticizer and will preferably chosen from the group consisting of polymers and copolymers with epoxy units, with units ether, ester motifs, amide motifs or by polyacrylates. Polyepoxy binders are suitable particularly good at implementing the invention.
Selon une première variante de l'invention, la charge oxydante comprend également du perchlorate de potassium dont la teneur est au plus égale à 30% du poids total de la composition. Cette teneur sera souvent comprise entre 20% et 30% du poids total de la composition.According to a first variant of the invention, the oxidizing charge also includes perchlorate potassium, the content of which is not more than 30% of the total weight of the composition. This content will often between 20% and 30% of the total weight of the composition.
Selon une seconde variante de l'invention, la charge oxydante comprend également un composé azoté choisi dans le groupe constitué par le perchlorate d'ammonium, le nitrate de triaminoguanidine, l'hexogène, l'octogène ou l'hexanitrohexaazaisowurtzitane encore connu sous le sigle "HNIW". La teneur de la composition en un tel composé azoté est au plus égale à 15% de son poids total. According to a second variant of the invention, the oxidizing charge also includes a nitrogen compound chosen from the group consisting of perchlorate ammonium, triaminoguanidine nitrate, hexogen, octogen or hexanitrohexaazaisowurtzitane again known by the acronym "HNIW". The content of the composition in such a nitrogen compound is at most equal to 15% of its total weight.
Les compositions préférées selon la présente invention contiennent donc :
- entre 3 et 6% en poids de liant polyépoxy,
- entre 50 et 95% en poids de nitrate d'ammonium,
- entre 0 et 30% en poids de perchlorate de potassium,
- entre 0 et 15% en poids de perchlorate d'ammonium,
- entre 2 et 3% de bore.
- between 3 and 6% by weight of polyepoxy binder,
- between 50 and 95% by weight of ammonium nitrate,
- between 0 and 30% by weight of potassium perchlorate,
- between 0 and 15% by weight of ammonium perchlorate,
- between 2 and 3% boron.
Avantageusement encore le nitrate d'ammonium sera un nitrate d'ammonium stabilisé par du nitrate de potassium en présence d'un colorant organique comportant un groupement arylsulfonate comme décrit par exemple dans la demande de brevet français 96.00778 ou dans la demande de brevet européen 97 400 149.7. L'emploi de ce type de nitrate d'ammonium permet une meilleure stabilité des propriétés mécaniques et pyrotechniques du matériau lors des cycles thermiques. On utilisera avantageusement un nitrate d'ammonium stabilisé contenant 96,5% en poids de nitrate d'ammonium, 3% de nitrate de potassium et 0,5% d'amarante.Advantageously also the ammonium nitrate will be an ammonium nitrate stabilized by nitrate of potassium in the presence of an organic dye comprising an arylsulfonate group as described for example in French patent application 96.00778 or in the European patent application 97 400 149.7. The use of this type of ammonium nitrate allows better stability of the mechanical and pyrotechnic properties of material during thermal cycles. We will use advantageously a stabilized ammonium nitrate containing 96.5% by weight of ammonium nitrate, 3% of potassium nitrate and 0.5% amaranth.
Selon une dernière variante préférée de l'invention le dit liant est un liant souple qui présente un allongement en traction à 20°C égal ou supérieur à 15% et un coefficient de dilatation au moins égal à 2x10-5% par degré Celsius dans la plage de température comprise entre -40°C et +110°C. Dans ce cas le liant sera avantageusement choisi dans le groupe constitué par les liants polyépoxy et les liants polyacryliques.According to a last preferred variant of the invention, the said binder is a flexible binder which has a tensile elongation at 20 ° C equal to or greater than 15% and a coefficient of expansion at least equal to 2x10 -5 % per degree Celsius in the temperature range between -40 ° C and + 110 ° C. In this case, the binder will advantageously be chosen from the group consisting of polyepoxy binders and polyacrylic binders.
Les compositions selon l'invention trouvent leur utilisation préférée comme chargements pour les générateurs pyrotechniques de gaz destinés à la sécurité automobile, notamment les générateurs de gaz destinés à gonfler des coussins de protection pour occupants d'un véhicule automobile.The compositions according to the invention find their preferred use as loads for pyrotechnic gas generators intended for safety automotive, in particular gas generators intended for inflate protective cushions for occupants of a motor vehicle.
On décrit ci-après une réalisation préférée de l'invention.A preferred embodiment of the invention.
Dans un malaxeur ouvert on introduit les charges solides pulvérulentes constituées par le nitrate d'ammonium, le bore ou l'aluminium et éventuellement par le perchlorate de potassium et les composés azotés cités plus haut.In an open mixer we introduce the charges powdery solids consisting of nitrate ammonium, boron or aluminum and optionally by potassium perchlorate and the nitrogen compounds mentioned upper.
On ajoute ensuite le liant oxygéné à l'état liquide, non complètement polymérisé. Dans le cas d'un liant thermodurcissable il s'agira de la résine liquide mélangée à son durcisseur. Lorsque la résine employée est une résine polyépoxy, le durcisseur sera avantageusement une polyamine peu réactive de manière à disposer d'une "vie de pot" pour le liant d'environ 24 heures.The oxygenated binder is then added in the state liquid, not completely polymerized. In the case of a thermosetting binder it will be liquid resin mixed with its hardener. When the resin used is a polyepoxy resin, the hardener will be advantageously a polyamine which is not very reactive so as to have a "pot life" for the binder of about 24 hours.
Une des caractéristiques fondamentales des compositions selon l'invention étant de ne contenir que très peu de liant par rapport aux compositions usuelles destinées aux propergols ou aux poudres à faible vulnérabilité du type "LOVA", une difficulté non négligeable de formulation des compositions selon l'invention consiste à réussir à imprégner l'ensemble des constituants solides, et notamment le nitrate d'ammonium, avec cette faible quantité de liant liquide.One of the fundamental characteristics of compositions according to the invention being to contain only very little binder compared to usual compositions for propellants or low powders "LOVA" type vulnerability, a difficulty not negligible formulation of compositions according to the invention consists in successfully permeating the whole solid constituents, and in particular nitrate ammonium, with this small amount of liquid binder.
A cette fin le liant liquide sera avantageusement introduit dans le malaxeur sous forme diluée dans un solvant très volatil et inerte vis à vis des constituants de la composition. Par exemple avec un liant polyépoxy on utilisera avantageusement du trichloréthane comme diluant.To this end, the liquid binder will advantageously be introduced into the mixer in diluted form in a solvent very volatile and inert towards constituents of the composition. For example with a polyepoxy binder advantageously use trichloroethane as a diluent.
Le malaxeur est alors mis en route et on le laisse tourner, cuve ouverte, pendant environ une heure. Dans ces conditions on peut imprégner l'ensemble des constituants solides par le liant et la totalité du diluant a été éliminée par évaporation au cours de l'opération de malaxage.The mixer is then started and left on turn, open tank, for about an hour. In these conditions we can permeate all of the solid constituents by the binder and all of the diluent was removed by evaporation during the mixing operation.
La composition qui se présente à ce stade sous l'aspect d'une poudre légèrement humide, est mise à la forme voulue par compression. En général elle est mise sous forme de pastilles.The composition which appears at this stage under the appearance of a slightly wet powder, is brought to the desired shape by compression. In general it is put in the form of pellets.
La polymérisation du liant se fait à température ambiante et au bout de 24 heures, dans le cas d'un liant polyépoxy, les chargements pyrotechniques ainsi obtenus présentent une bonne tenue mécanique permettant leur emploi dans les générateurs de gaz destinés à la sécurité automobile.The polymerization of the binder takes place at temperature ambient and after 24 hours, in the case of a binder polyepoxy, the pyrotechnic charges thus obtained have good mechanical strength allowing their use in gas generators intended for the automotive safety.
Les compositions selon l'invention contiennent un faible taux de liant qui n'est pas suffisant pour combler tous les interstices entre les grains de nitrate d'ammonium. De ce fait la mise sous forme de pastilles par compression conduit à des objets présentant une porosité naturelle correspondant à un accroissement de la surface offerte à la combustion, ce qui est très favorable au niveau de la vitesse de combustion de la composition.The compositions according to the invention contain a low level of binder which is not sufficient for fill all the gaps between the nitrate grains ammonium. Therefore putting into the form of pellets by compression leads to objects having a natural porosity corresponding to an increase in the area available for combustion, which is very favorable in terms of the rate of combustion of the composition.
Mais le matériau générateur de gaz doit conserver l'intégralité de ses propriétés dans le temps, notamment après une succession de cycles thermiques. Pour cela il est préconisé d'utiliser des liants oxygénés dits "souples" présentant un allongement en traction à 20°C égal ou supérieur à 15% et un coefficient de dilatation, dans la plage de température comprise entre -40°C et +110°c, au moins égal à 2x10-5 % par °C.However, the gas-generating material must retain all of its properties over time, in particular after a succession of thermal cycles. For this it is recommended to use so-called "flexible" oxygenated binders having a tensile elongation at 20 ° C equal to or greater than 15% and a coefficient of expansion, in the temperature range between -40 ° C and +110 ° c, at least equal to 2x10 -5 % per ° C.
Comme liant époxy souple correspondant à la définition qui vient d'être donnée on citera les liants époxy à base de bisphénol "A" ou "F" contenant un diluant réactif difonctionnel à longue chaíne et une amine aliphatique ou cycloaliphatique.As a flexible epoxy binder corresponding to the definition which has just been given we will mention binders bisphenol "A" or "F" based epoxy containing a long chain difunctional reactive thinner and a aliphatic or cycloaliphatic amine.
Comme liant acrylique souple correspondant à la même définition on citera les liants acryliques à base d'acrylate ou de méthacrylate de méthyle contenant un diluant réactif difonctionnel à longue chaíne (de C8 et C15) ainsi qu'un sel organique métallique comme catalyseur.As flexible acrylic binder corresponding to the same definition, mention will be made of acrylic binders based on methyl acrylate or methacrylate containing a difunctional reactive diluent with long chain (of C 8 and C 15 ) as well as a metallic organic salt as catalyst.
Cette dernière famille de liants est particulièrement intéressante en raison de ses caractérisques anaérobies qui lui permettent de polymériser à 20°C en l'absence d'oxygène.This last family of binders is particularly interesting because of its anaerobic characteristics that allow it to polymerize at 20 ° C in the absence of oxygen.
L'utilisation d'un nitrate d'ammonium stabilisé tel que décrit plus haut favorise également la conservation dans le temps des propriétés du matériau générateur de gaz.The use of a stabilized ammonium nitrate such that described above also promotes conservation properties of the generating material over time gas.
Les exemples qui suivent illustrent certaines possibilités de mise en oeuvre de l'invention.The following examples illustrate some possibilities of implementing the invention.
Dans les exemples qui suivent les abréviations
suivantes signifient :
On a fabriqué dix compositions selon l'invention qui ont été testées en fonctionnement pyrotechnique.Ten compositions according to the invention were manufactured which have been tested in pyrotechnic operation.
Les pourcentages sont exprimés en poids et les
teneurs gazeuses en parties par million après dilution
d'un sac de 60 litres gonflé par les gaz de combustion
dans un volume d'air de 2,7 m3.
Les compositions correspondant aux exemples 9 et 10 concernent l'emploi de nitrate d'ammonium stabilisé par 3% en poids de nitrate de potassium et 0,5% en poids d'amarante comme décrit plus haut. Ces compositions ont été mises sous forme de pastilles et on été soumises à un cycle standard de vieillissement entre -35°C et + 105°C. Après ce cycle, les pastilles ont conservé toutes leurs propriétés mécaniques et pyrotechniques de fonctionnement dans un générateur de gaz.The compositions corresponding to Examples 9 and 10 relate to the use of ammonium nitrate stabilized by 3% by weight of potassium nitrate and 0.5% by weight amaranth as described above. These compositions have have been pelletized and subjected to a standard aging cycle between -35 ° C and + 105 ° C. After this cycle, the pastilles have kept all their mechanical and pyrotechnic properties of operation in a gas generator.
Claims (11)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9608050A FR2750422B1 (en) | 1996-06-28 | 1996-06-28 | PYROTECHNIC COMPOSITIONS FOR GENERATING OWN GASES AND APPLICATION TO A GAS GENERATOR FOR AUTOMOTIVE SAFETY |
FR9608050 | 1996-06-28 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0816307A1 true EP0816307A1 (en) | 1998-01-07 |
EP0816307B1 EP0816307B1 (en) | 2001-06-06 |
Family
ID=9493508
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19970401483 Expired - Lifetime EP0816307B1 (en) | 1996-06-28 | 1997-06-26 | Clean-gas generating pyrotechnic compositions and use thereof in a gas generator employed in a protection system in motor vehicles |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0816307B1 (en) |
JP (1) | JP2927757B2 (en) |
DE (1) | DE69705090T2 (en) |
FR (1) | FR2750422B1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0913375A1 (en) * | 1997-03-24 | 1999-05-06 | DAICEL CHEMICAL INDUSTRIES, Ltd. | Gas generator composition and molding thereof |
EP0924177A1 (en) * | 1997-12-22 | 1999-06-23 | Societe Nationale Des Poudres Et Explosifs | Pyrotechnic composition for generating of a clean gas with a low nitrogen oxide content and pellets thereof |
WO2004024653A2 (en) * | 2002-09-12 | 2004-03-25 | Textron Systems Corporation | Multi-stage gas generator and gas generants |
FR2853872A1 (en) * | 2003-04-15 | 2004-10-22 | Seva Technologies | Device for actuating a safety system for the protection of goods and/or occupants of a vehicule comprises a gas generation system to fill an inflatable cushion |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2761982B1 (en) * | 1997-04-11 | 1999-05-07 | Livbag Snc | PROCESS FOR ENSURING A PROGRESSIVE DEPLOYMENT OF A PYROTECHNIC PROTECTION AND LOADING CUSHION FOR ITS IMPLEMENTATION |
FR2778576B1 (en) | 1998-05-15 | 2000-06-23 | Poudres & Explosifs Ste Nale | FIRE EXTINGUISHING DEVICE COMPRISING A THERMOCHEMICAL GAS GENERATOR |
JP4337254B2 (en) | 2000-09-22 | 2009-09-30 | 日油株式会社 | Gas generating agent |
KR20020044854A (en) * | 2000-12-07 | 2002-06-19 | 채재우 | explosive composition for an electric blasting |
US6884307B1 (en) | 2002-04-12 | 2005-04-26 | Diehl Munitionssysteme Gmbh & Co. Kg | Insensitive explosive molding powder, paste process |
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- 1996-06-28 FR FR9608050A patent/FR2750422B1/en not_active Expired - Fee Related
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- 1997-06-26 EP EP19970401483 patent/EP0816307B1/en not_active Expired - Lifetime
- 1997-06-26 DE DE1997605090 patent/DE69705090T2/en not_active Expired - Fee Related
- 1997-06-30 JP JP9173729A patent/JP2927757B2/en not_active Expired - Fee Related
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Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0913375A1 (en) * | 1997-03-24 | 1999-05-06 | DAICEL CHEMICAL INDUSTRIES, Ltd. | Gas generator composition and molding thereof |
EP0913375A4 (en) * | 1997-03-24 | 2000-08-23 | Daicel Chem | Gas generator composition and molding thereof |
US6505562B1 (en) | 1997-03-24 | 2003-01-14 | Daicel Chemical Industries, Ltd. | Gas generator composition and molding thereof |
EP0924177A1 (en) * | 1997-12-22 | 1999-06-23 | Societe Nationale Des Poudres Et Explosifs | Pyrotechnic composition for generating of a clean gas with a low nitrogen oxide content and pellets thereof |
FR2772750A1 (en) * | 1997-12-22 | 1999-06-25 | Poudres & Explosifs Ste Nale | PYROTECHNIC COMPOSITION CLEAN GAS, LOW NITROGEN OXIDE CONTENT, AND PELLETS OF SUCH A COMPOSITION |
US6024811A (en) * | 1997-12-22 | 2000-02-15 | Societe Nationale Des Poudres Et Explosifs | Pyrotechnic composition generating clean gases with low levels of nitrogen oxides, and pellets of such a composition |
WO2004024653A2 (en) * | 2002-09-12 | 2004-03-25 | Textron Systems Corporation | Multi-stage gas generator and gas generants |
WO2004024653A3 (en) * | 2002-09-12 | 2004-09-23 | Textron Systems Corp | Multi-stage gas generator and gas generants |
FR2853872A1 (en) * | 2003-04-15 | 2004-10-22 | Seva Technologies | Device for actuating a safety system for the protection of goods and/or occupants of a vehicule comprises a gas generation system to fill an inflatable cushion |
WO2004091981A1 (en) * | 2003-04-15 | 2004-10-28 | Seva Technologies | Device for using a safety element for the protection of goods and/or people |
US7651126B2 (en) | 2003-04-15 | 2010-01-26 | Seva Technologies | Device for implementing a security element for the protection of goods and/or persons |
Also Published As
Publication number | Publication date |
---|---|
FR2750422B1 (en) | 1998-08-07 |
JPH1059792A (en) | 1998-03-03 |
JP2927757B2 (en) | 1999-07-28 |
FR2750422A1 (en) | 1998-01-02 |
EP0816307B1 (en) | 2001-06-06 |
DE69705090D1 (en) | 2001-07-12 |
DE69705090T2 (en) | 2002-02-07 |
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