MXPA00000746A - Extrudable igniter compositions - Google Patents

Abstract

The present invention relates to an igniter composition which is capable of being extruded to yield a robust igniter extrudate. The composition is particularly useful in the form of an igniter stick or other selected geometry for use in supplemental safety restraint systems designed for use such as in vehicles, ground or airborne, having such systems. The igniter composition is formulated from constituents comprising a water-soluble or water-swellable binder, at least one oxidizing agent, at least one fuel, and, optionally, fibers.

Description

COMPOSITIONS OF IGNITION EXTRU BLES BACKGROUND OF THE INVENTION 1. Field of the Invention the present invention relates to extrudable ignition compositions, and specifically to granules, pellets, small globules, extruded ignition sticks. More particularly, the present invention relates to providing sticks in combination with gas generating compositions suitable for use with gas bag inflators, such as in supplementary safety attenuation systems for vehicles and related apparatus. 2. Background Information Ignition compositions for supplementary safety systems, including "air bags", necessary to meet a number of design criteria. The ignition composition, once it is formed, must be sufficiently robust to remain operable before being used in a safety • system, such as a REF .: 32616 protection for a passenger, a driver, or a passenger. lateral impact system. Compatible with these objectives together with these and other types of safety systems, the ignition compositions, in general the ignition compositions are intended to be used in such quantities to avoid disposal problems and avoid the generation of related products in quantities They possess other dangerous forms of ignition following.

Complementary safety attenuation systems therefore have a number of different ignition systems. One of the commonly proposed ignition systems uses solid particles consisting of B / KNO, which, once ignited, initiate combustion of the specific gas generating composition.

Other new efforts have focused on the development of an alternative of profitable ignition compositions or ignition compositions that can be manufactured more easily. These efforts have included the proposal to use a heat-melted thermoplastic resin matrix, together with a particular ignition composition, such as KN03. This endeavor is to join a commercially available heat-meltable adhesive, such as one designed by so-called "rubber guns", with a common alkaline metal oxidizer. This effort to improve performance was less than satisfactory. Extrusion capability and ignition performance showed difficulties to be controlled, and the desired repeatable ballistic performance for complementary safety attenuation systems has not yet been demonstrated.

Accordingly, despite these and other efforts, commercially relevant objectives remain if achieved. Thus, an ignition composition that is simple and more economical is still desired for use in supplementary safety attenuation systems. In particular, efforts continue to be directed to providing an ignition composition that avoids the need for heat melting of the so-called adhesives, and thus the subsequent risk associated with the processing of a pyrotechnic or explosive material at a high temperature, but that it is easy to manufacture and that it is sufficiently robust. Therefore, this would be a significant advance in providing ignition compositions capable of being used to ignite gas generating compositions, which satisfactorily address these interests in the industry.

BRIEF DESCRIPTION AND OBJECTIVES OF THE PRESENT INVENTION The present invention offers a commercially attractive, viable, extrudable, ignitable composition that covers the above and other objects.

The present extrudable ignition composition is easily and inexpensively manufactured to obtain a physically robust product. The present composition can be manufactured without the use of heat melting or thermoplastic melting mixing equipment, and thus the potential hazard associated with processing at such high temperatures is avoided. further, the ignition formulation is spread as a thick paste with water. Water varies the hazards associated with the processing of ignition compositions. The extrudable ignition composition can be formed at room temperature and, after drying, produce robust products having relatively selectable characteristics that are particularly desired for attenuation systems and the like.

A hollow or solid ignition "stick" for the ignition of a composition that generates gas in a gas generating device, such as an inflator in an air bag system, can be manufactured from the present extrudable ignition composition. . The ignition stick has other configurations such as pellets, small globules or granules that provides the configuration that is constituent with the objectives described herein.

Also contemplated here are the attenuation systems, supplementary safety systems that incorporate these ignition sticks, as well as the vehicles equipped with such systems.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates an exemplary inflator device, which includes an ignition stick formed of an extrudable ignition composition of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The extruded ignition sticks can be characterized because they have a configuration designed for a rapid deflagration, at a high temperature once the ignition. Once the ignition is done, an ignition stick is able to ignite another pyrotechnic composition. In passenger or passenger-side airbag systems, the ignition sticks are of a size that is capable of completing the end-to-end ignition, for example, completing the flame in a short time, such as at least of 10 thousandths of a second. In the form of pellets, small globules or granules; the expandable ignition composition provides grains with a high packing density. This combination of qualities provides a reproducible and controlled ignition. The duration of the ignition can be controlled by the size of the grain. In the case of certain formulations, the flash of sudden sharp ignition is less effective in igniting the gas generator a little slower than the broad ignition pulse.

Ignitable compositions that are capable of being extruded are characterized in that they are obtained from a combination of a binder, an oxidizing agent that can be dispersed in or soluble in water, a fuel that can be dispersed in or soluble. in water, and a selected amount of water. Preferably, the extrudable compositions are essentially homogeneous in composition.

The binder is preferably a water-soluble binder, although binder materials that expand in water are not excluded, provided that the remaining solid constituents of the lighter are at least substantially homogeneous enough in their distribution here. Typical binders used in the present ignition composition include, by way of example, water-soluble binders such as poly-N-vinyl pyrolidone, polyvinyl alcohol and copolymers thereof, polyacrylamide, sodium polyacrylates, copolymers based on in acrylamide or in sodium acrylate, gums, and gelatin. These water-soluble binders include naturally occurring gums, such as guar gum, acacia gum, modified celluloses and starches. A detailed discussion on "gums" is provided by C.L. Mantell, The Water-Soluble Gums, Reinhold Publishing Corp., 1947, which is incorporated herein for reference purposes. It is presently considered that water-soluble binders allow efficient extrusion and improve mechanical properties or increase clamping force. Although binders that are not miscible can be used in the present invention, it is presently preferred to use water-soluble binders in combination with fuels and / or oxidants suitable for use in the formulation of a lighter. The appropriate fuels and oxidants may or may not be soluble in water. Oxidants and appropriate fuels can be organic or inorganic.

In the formulation of which the stick lighter is formed, in the form of pellets, small globules or granules, the concentration of the binder is such that a sufficiently robust extrudate is obtained mechanically. The extrudate, such as an ignition stick, must be able to retain its shape, for example, maintaining its integrity, before ignition. Preferably, the ignition stick must be capable of being received in a pyrotechnic composition, for example, an appropriately shaped inner surface (for example a central interior surface) in a composition that generates a gas, and of being destroyed or fractured when ignited. Conversely, pellets, small globules or granules will have sufficient strength to 'not be sprayed during the ignition process. In general, the binder may be within the range of, for example, from about 2% by weight to about 10% by weight, and more particularly from about from about 3% by weight to about 7% by weight, in relation to the dry ingredients in the formulation. The binder may be comprised of more than one binder material.

The ignition composition includes at least one oxidant, which is preferably soluble in water or at least dispersible in water. Therefore, the oxidant may be organic or inorganic, although flfc currently it is preferred that the oxidants be inorganic. Organic oxidants that can be dispersed in a binder, such that a sufficiently homogeneous ignition composition is obtained include nitrate amine salts, compounds nitro, nitramine, nitrate esters, and amine perchlorates, of which methyl ammonium nitrate and methyl ammonium perchlorate are exemplary. Other candidates include RDX and HMX, CL-20 and PETN. Inorganic oxidants include species oxidizing ions such as nitrates, nitrites, chlorates, perchlorates, peroxides and superoxides. Models of these inorganic oxidants are metal nitrates such as potassium nitrate or Estonian nitrate, ammonium nitrate, perchlorates Metals such as potassium perchlorate, and metal peroxides such as strontium peroxide. In general, the oxidant may ordinarily be present in an amount effective to ensure oxidation of at least the fuel in the lighter and may be within the range of, for example, from about 40% by weight to about 90% by weight , and more particularly from about 70% by weight to about 85% by weight, relative to the dry ingredients in the formulation.

The ignition composition can be formulated with an additional fuel, considering that the binder may be able to function as a non-primary fuel, but secondary in the ignition composition. These additional fuels include powdered metals, such as aluminum, zirconium, magnesium and / or titanium, powdered, among others; Tale's metal alloys as the 70% alloy: 30% aluminum / magnesium; metal hydrides such as titanium or zirconium hydride; and the so-called metalloids, such as silicon and boron that are sufficiently "capable of dispersing" in the binder. Fuels that can be dispersed or that are soluble in water include, for example, guanidine nitrate, two compounds are missing page 6) cyano compounds, nitramides (RDX and / or HMX) CL-20, tetranitrocarbazoles, organic nitro compounds, and may, if desired, be presented in a "multiple mode" distribution of particle size. Materials that can be dispersed in water can be added substantially equal in the particle size distribution or in distributions of multiple modes depending on the desired ignition characteristics.

The fuels that can be dispersed in water are, by current preference, used in the form of fine particles, such as powder or sediment for being sufficiently fine particles, to ensure adequate distribution during the manufacturing process. Preferably, at least a substantially equal distribution in the resulting ignition composition is desired. In general, the fuel is in a powdery form, such as 100μ or less, such as, for example, from about 1μ to 30μ. Metals in the form of powder can be used and these can have, if desired, a smaller range of particle size, such as from about 1 to 20μ, or even smaller such as from 1 to about 5μ. The amount of fuel - other than the binder - may be within the range of, for example, from about 5 to about 40% by weight, and more particularly about 10% by weight to about 20% by weight, in relationship with the dry ingredients in the formulation.

The present ignition sticks and related grains may incorporate, if desired, a reinforcement. An appropriate reinforcement can be obtained with fibers, such as combustible fibers, which can serve both purposes, to give strength to the extruded ignition stick, and, once you have the proper selection of the reinforcement, improve the performance of the lighter. The fibers preferably generally shorter in length (low aspect ratio). The fibers incorporated in the extrudable ignition formulations include, for example, polyolefin fibers, polyamide fibers, polyester fibers and poly (2, 2- (m-phenylene) -5,5-bisbenzimidazole ("PBI") fibers. Polyolefin fibers include polyethylene ("PE") fibers, such as PE fibers having an outer diameter of about 0.005 mm and greater, such as from about 0.8 mm, and a length within the range of O.lmm up to about 3.2 mm, of which Allied-Signal's Spectra 900 polyethylene fiber band is illustrative.The appropriate polyamide fibers, such as Nylon 6 fibers, may have an appropriately selected diameter, such as 19 microns, and a length from 1.5 mm to about 6.4 mm.The appropriate polyester fibers include high tenacity polyester fibers having lengths from about 1.5 mm to about 6.4 mm, and an appropriate diameter from around 25 microns. PBI fibers include those that have lengths in the order of 0.8 mm to 3.2 mm. Representative ignition sticks and formulations for the same are reported in the Examples.

The present composition is readily obtainable in the form of extrudate, for example, by mixing the binder, the fuel, the oxidant and the selected amount of water for a period of time to obtain at least a substantially equal distribution of the fuel, if used, in each part of the binder. One method involves dry mixing a water-soluble binder and the oxidant after adding a selected amount of water and mixing them to a homogeneous mixture to form a premix, and mixing the premix with increasing portions of the binder ( s) to three times. The amount of water is generally such that the resulting product has a consistency that can be extruded, but, preferably, is not slippery. If too much water is present, the grain will tend to weaken and otherwise it will not maintain its shape after extrusion.

The ignition composition thus formed is capable of being extruded to the desired physical geometry.

The extruded ignition composition is preferably non-foamed, ie, a solid.

Ignition compositions that are capable of being extruded are easily adapted for use in ignition systems to be used in combination with airbag inflation technology. The systems may include one or more ignition stick or, in the case of pellets, small globules or pellets, a complete crowd. The technology of airbag inflators include automotive (vehicular) airbag systems, hybrid inflator technology, and, for example, lateral impact systems. Inflatable vehicle safety attenuation systems, for example, automotive, truck or similar, are described in US Patents Nos. 5,536,339, 5,542,704 and 5,668,345 among others, the descriptions of which are incorporated herein for reference purposes. Systems that refer to inflating the airbags or the like are described in U.S. Patent No. 5,441,303, the reference of which is incorporated herein for reference purposes.

An automotive air bag system may comprise a device that generates a gas; a collapsed inflatable airbag connected to the airbag to inflate the airbag, the device generating a gas contains a composition that generates a gas that generates gases suitable for use in an automotive airbag system; and an ignition system that includes stick (s) or pellets, small globules or granules based on the present ignition composition and also in the specifications of the device that generates the gas. The ignition system may also include a detonator.

The technology of hybrid inflators is based on heating a stored inert gas (argon or helium) to a desired temperature by burning a small amount of impeller. Hybrid inflators do not require cooling filters used with pyrotechnic inflators to cool the combustion of gases, because hybrid inflators are capable of providing a gas at a lower temperature. The gas discharge temperature can be changed selectively by adjusting the ratio of the weight of the inert gas to the weight of the impeller. With the increase of the weight of the gas to the proportion of the weight of the impeller, the discharge temperature of the gas is colder. A hybrid gas generation system may comprise a pressure tank having a breakable opening, a predetermined amount of inert gas placed within the pressure tank; a device that generates gas to produce a hot combustion of gases and has a means for rupture of the breakable aperture; and a means for igniting the gas generating composition incorporating the present ignition composition. The tank has a breakable opening that can be broken by a piston when the gas generating device is turned on. The device that generates gas is configured and placed in relation to the pressure tank in such a way that the hot combustion gases are mixed and with the hot inert gas. Suitable inert gases include, among others, argon, helium and mixtures thereof. The mixed and heated gases exit the pressure tank through the opening and finally exit the hybrid inflator and deploy an inflatable bag or balloon or balloon, such as an automotive air bag. Hybrid gas generation devices for a supplementary safety attenuation application are described in Frantom, Hybrid Airbag Inflator Technology, Airbag Int l Symposium on Sophisticated Car Occupant Safety Systems, (Weinbrenner-Saal, Germany, Nov.2-3, 1992 ).

The appropriate attenuation systems also include lateral impact systems. In a vehicle, such as a car or truck, an airbag assembly can be mounted for side impact, including the inflator and the collapsed, inflatable airbag, and stored adjacent to the releasable rear seat, such as a front seat. These air bag assemblies may include an air bag that is deployed forward for the front or rear seat occupants for the rear seat occupant, or air bags for both front and rear occupants. These air bag assemblies can be inflated with single or separate gas generating devices sometimes called inflators in automotive applications. A sensor device can, in general, be mounted on the threshold of a door, or in another desired location to provide an impact signal, for example to a circuit, to activate the deployment of the airbags. In U.S. Patent No. 5,273,308, an exemplary appropriate side impact air bag assembly is described, the entire disclosure of which is incorporated herein for reference purposes.

It is also part of our invention, a vehicle for land or air, equipped with any air bag system (such as a lateral and / or supplemental impact attenuation system) that includes an ignition system including the present ignition stick or another type of grain. For example, the vehicle may contain a supplementary attenuation system itself having an air bag system comprising an inflatable, collapsed air bag; a device that generates gas connected to the air bag to inflate the air bag, the gas generating device contains a composition that generates gas itself that is suitable for use in an airbag system of a vehicle (such as an automobile) , etc.,); and an ignition system for the composition that generates gas, which ignition system can be or include an ignition composition (in stick or other form such as "tape-like" or pellets in cylindrical form, small globules, or granules) based on the present ignition composition. The supplementary safety system can, of course, be based on other airbag technology, including hybrid air bag technology and / or the side impact system.

Suitable solid gas generating compositions are azide-based gas generators, and so-called non-azide compositions that are based on a non-azide fuel and an appropriate oxidant. An example of the latter composition that generates improved gas uses a bitetrazoleamine, or a salt or complex thereof as a non-azide fuel, such as bis- (1 (2) H-tetrazol-5-yl) -amine, which was found to be particularly suitable for use in gas generating compositions. Such suitable compositions are described in U.S. Patent No. 5,682,014, the complete disclosure of which is incorporated herein for reference.

Another composition that generates gas comprises at least one complex of a metal cation, such as a transition metal or alkaline earth metal cation, and at least one neutral leaving which is comprised of nitrogen and hydrogen, such as ammonia or hydrazine (s), and sufficient oxidation anion to balance the charge of the metal cation.

In general, the fuel generating selected gas is combined, in an effective amount of fuel, with an appropriate oxidizing agent to obtain a composition that generates appropriate gas. With the effective amounts of fuels of an appropriate fuel, the combustion product of a composition that generates gas can be relatively balanced, that is, the product of combustion does not have excessive amounts of low or over oxidized species. Stoichiometric combustion is a generally desired objective. Inorganic oxidation agents are generally desired because they produce a lower flame temperature with an improved filterable slag. Such oxidants include metal oxides and metal hydroxides. Other oxidants include a metal nitrate, a metal chlorate, a metal perchlorate, a metal peroxide, ammonium nitrate, ammonium perchlorate and the like. The use of metal oxides or hydroxy nitrates or hydroxides as oxidizers is particularly useful and such materials include, for example, the hydroxy oxides, hydroxides and nitrates of copper, cobalt, manganese, tungsten, bismuth, molybdenum and iron, such as Cuo, Cu2 (OH) 3N03, Co204, Fe2? 3, M0O3, Bi2Mo? 6, Bi03, and Cu (OH) 2. The oxidizing agents oxides and hydroxides mentioned above may, if desired, be mixed with other conventional oxidants such as Sr (N03) 2, NH4C10 and KN03, for a particular application, such as, for example, providing an increased flame temperature or to modify the gas product produced. The fuel that generates selected gas can, if desired, be combined with a relatively fresh or cold burn compound, which can be a fuel and / or an oxidant. In these compositions, another separate secondary oxidant can, if desired, be dispensed with. Relatively cold burn compounds include guanidine nitrate, triamine guanidine nitrate, aminoguanidine nitrate, and urea among others. For example, a composition that generates appropriate gas may comprise a fuel, such as BTA and / or a complex or metal compound containing amine, and guanidine nitrate. Such compositions may, if desired, include an appropriate binder, which may be the same as or different from the binder used in the preparation of the ignition stick. These compositions can be formulated to include other known additives for inclusion in the gas generating compositions.

Gas generating compositions that can be used in combination with an ignition stick or other ignition bean may also include additives conventionally used in gas, impeller and explosive generating compositions, such as fire speed modifier binders, slag formers , chelating agents, release agents, and additives that effectively remove N0X. Typical burn rate modifiers include Fe203, K2Bi2H2, Bi2Mo6, and graphite carbon fibers. A number of slag forming agents are known and these include, for example, clays, talcs, silicon oxides, and alkaline earth oxides, hydroxides and oxalates, of which magnesium carbonate, and magnesium hydroxide are exemplary. A number of additives and / or agents are known to reduce or eliminate the "nitrogen oxides of the combustion products of a gas generating composition, including alkali metal salts and complexes of tetrazoles, triazoles and the aforementioned nitrogen heterocycles of which the aminotetrazole of potassium, the sodium carbonate and the potassium carbonate are exemplary.The composition may also include materials that facilitate the release of the composition of a mold such as graphite, molybdenum sulphide, or boron nitride.

The compositions that generate appropriate gas may also contain at least one binder. In the North American Application of Hinshaw et al., 08 / 507,552, filed July 26, 1995, the complete description of which is incorporated herein for reference purposes; Exemplary binders are described. Typical binders include lactose, boric acid, silicates including magnesium silicate, polypropylene carbonate, polyethylene glycol, and polymeric binders, including water-soluble polymers such as polyacrylamides. For example, an appropriate binder may comprise, for example, a water-soluble binder such as at least one water-soluble polymer or at least one naturally occurring gum, guar gum or acacia gum. For example, the binder can be used in an amount of 0.5 to 12% by weight of the gas generating composition, and more preferably 2 to 8% by weight of the composition.

The gas generating compositions useful herein may also be formulated with agents that increase the tightening force (other than, or in addition to the binder). Such suitable agents are generally solid in the powder form. For example, a small but effective amount of carbon powder can be used in the formulation of a gas generating composition whereby the tightening force of the composition is able to increase compared to the composition without the carbon powder. The amount of tightening force increase agent can usually be up to 6% by weight of the gas generating composition, although smaller amounts up to about 3% by weight can also be used. A composition that generates exemplary but particularly useful gas comprises hexabalin cobalt (III) nitrate; at least one water-soluble binder; optionally, carbon powder in an amount of about 0.1% up to about 6% by weight of the composition; and optionally, at least one organic and / or inorganic cooxidant, such as guanidine nitrate or copper hydroxy nitrate, respectively.

In a gas generating composition, a co-oxidant and / or co-fuel component (alone or as a mixture of co-oxidants or co-fuels, respectively) may be included in an appropriate amount to obtain the desired combustion products . Generally, such amounts are less than about 50% by weight of the gas generating composition.

In brief, a diverse number of gas generating compositions are suitable for use in combination with an ignition system based entirely or in part on an ignition stick in accordance with the present invention. Appropriate gas generating compositions include those described in US Pat. Nos. 3, 911,562, 4,238,253, 4,931, 102, 5,125,684, 5,197,758, 5,429,691, 5,439,537, 5,472,647, 5,500,059, 5,501,823, 5,516,377, 5,536,399, 5,592,812, 5,608,183, 5,673,935, 5,682,014, and US Applications Nos. 08 / 507,552, filed on July 16, 1995, and 08 / 162,596, filed on December 3, 1993, and Provisional Application No. 60/022645, filed on July 25, 1996, the complete descriptions of which are incorporated herein for reference purposes.

Figure 1 illustrates a device that generates gas 1. In the longitudinal cross-sectional view, housing 2 is an appropriate pressure jacket made of steel or other material capable of being used for a gas generation application, such as bags of air, have an end defined by or closed by the first end piece 3. The envelope is provided with a shape so that the generated gas is released, such as the openings in the side walls of the envelope. The second end piece 4 is installed at the opposite end of the end piece 3. The housing 2 and the end pieces 3 and 4 define a wrap. The end piece 4 is fixed with an ignition detonator 5. The casing can, if desired, be manufactured so that it has fewer parts for the reduction of manufacturing costs. In a preferred embodiment, a solidified ignition stick, which may be solid or hollow, extends axially longitudinally of the detonator 5 through the interior of the gas generating device to the inner side 7 of the end piece 3. The ignition stick 6 it can be formed by extruding the aforementioned extrudable ignition composition and allowing the extrudate to solidify. A composition 8 that generates selected gas surrounds the ignition stick. A so-called rapid deflagration cord, if desired, can be placed longitudinally, for example, as a loose shirt, inside a recessed ignition stick. If desired, more than one ignition stick can be used.

Alternatively, the lighter may be in the form of discrete small beads disposed adjacent the ignition detonator 5 but between the ignition detonator 5 and the gas generating composition.

As illustrated, the gas generating device may, if desired, include more than one filter element 9. The arrangement, geometry and location of a filter element may be selected based on the complete design of a device for generate gas in particular.

Although a device for generating gas is illustrated, other designs are included within the scope of the invention.

In another embodiment, the gas generating device can be connected to a balloon or collapsed but inflatable balloon, or air bag in a safety, attenuation system.

The invention is further described with reference to the following non-limiting examples.

EXAMPLES EXAMPLE 1 One gallon of Baker-Perkins planetary mixer, 1170 g (78%) of potassium nitrate of 35 microns and 105 g (7%) of Cytec Cyanamer®N-300 Polyacrylamide (15 million MW) were added. Then these ingredients were remotely mixed in the dry state for one minute. To this mixture 217.5 g of water (14.5 parts per 100 of the ignition formulation) were added and mixed for five minutes. The mixing blades and the inner surface of the mixing bowl were scraped with Velostat (conductive plastic) spatulas followed by an additional 15 minutes of mixing. To the resulting thick white paste, 225 g (15%) of amorphous boron powder (90-92% purity) were added and remotely mixed for five minutes. The shovels and the new bowl were "scraped" and the formulation was mixed for an additional ten minutes. The coffee material, in the form of the resulting paste, was granulated to -4 mesh and fed into a single screw 25 mm Haake extruder. The ignition formulation was extruded through a 12-point star die with a maximum diameter of 0.33"and a minimum diameter of 0.30". The die included a spindle with a central diameter of 0.080", in this way a rod-like configuration was produced, the extruded formulation was cut into 1" sections. Prior to drying, a 7.5"length 0.07" diameter Teledyne RDC (rapid deflagration cord) was inserted into the 0.08"diameter diameter, the ignition sticks were dried at 165 ° F overnight The central ignition sticks were tested to evaluate their performance as a lighter and inflator which was designed for automotive safety bags of the side passenger.The ignition sticks worked satisfactorily.

EXAMPLE 2 A series of extruded stick stick formulations containing boron, potassium nitrate, a water soluble binder, and optionally, fibers for reinforcement were prepared. These formulations were reported in Table 1. The formulations were first mixed on an IOg scale and then on a 30g scale to determine their sensitivity with stimulus including impact, friction, electrostatic discharge, and heat (Table II). In general, the binders based on carbohydrates showed the highest sensitivity with respect to friction. Also used were formulations containing methyl cellulose, guar gum, and locust bean gum as a binder for the preparation of ignition sticks.

The remaining formulations were mixed on a scale of 325 g in a pint of Baker-Perkins planetary mixer. The potassium nitrate and the respective water-soluble binder were remotely mixed in the dry state for one minute. To this mixture, the respective amount of water was added (table III) and the paste was mixed for five minutes. As in example 1, the bowl and the paddles were "scraped". At this point, the fibers containing the formulations were added and the dough mixed for an additional 5 minutes. All formulations were mixed for an additional 10 minutes before adding boron. At this point one half of the boron was added followed by five minutes of mixing. Then the rest of the boron was added followed by an additional five minutes of mixing. After a final "scraping", the formulation was mixed for an additional ten minutes. The brown, mass-like material was granulated to -4 mesh and fed into a single screw 25 mm Haake extruder. The ignition formulation was extruded through a 12-point star die with a maximum diameter of 0.33"and a minimum diameter of 0.305". The die included a spindle 0.80"centrally located, the extruded ignition formulation was cut into 7" sections. 'Before drying, a Teledyne RDC (rapid deflagration cord) of 7.5"in length and 0.07" in diameter was inserted. Ten additional 2"sections were extruded. The ignition sticks were dried at 165 ° F overnight.

Important factors for determining the usefulness of the formulation include grain quality after drying, current operation as a lighter, and drying speed. The separation of a mixture of KNO3 and the binder to the grain surface can occur or occur for some formulations during drying. Drilling separation is not desired. 5 Separation was found to be less important in formulations containing tragacanth gum, Cyanamer® A-370 and Cyanamer® P-21 (Table III). The ignition sticks of the formulations containing Cyanamer® A-370 and Cyanamer® P-21 were evaluated using an inflator device. Relative drying rates of 10: 1.7: 1 were calculated for formulations containing Cyanamer® N-300, Cyanamer® P-21 and Cyanamer® A-370, respectively. Thus, the formulation containing Cyanamer® A-370 showed more drying fast, with a minimum separation of the KN03 that produces a grain that ignites the gas generator with a minimum delay of the ignition. • It is important to develop an extruded 20-ignition stick for automotive airbag systems that withstand decades of shaking and vibration due to handling cars in potholes, uneven roads, etc. Thus, a durability test method was developed for extruded ignition sticks. The durability tests were performed in a 3-point mix, with the load applied in a semi-split. Mixing was selected since tension, compression and shearing forces were all present. In addition, the sample configuration lends itself to this type of loading. A separation of 1.5 inches was used, with the loads applied using pins from 1/8 to 1/4 inch in diameter. A nominal pre-load of 0.7 pounds was applied. The sample was submitted to 1, 000 load cycles with the following conditions: cycle amplitude 0.003 inch, a frequency of 10 Hz. After the load cycles, the samples were tested for failure at a displacement speed of 0.2 inches per minute. The durability of each sample was reported as the area under the load displacement curve. For simplicity, the units were kept as they were calibrated (the load in force-pounds, displacement in mil). Therefore, the reported durability has units of mil-pounds. All tests were performed at room temperature in the laboratory (75 ± 5). The results of the durability tests indicate an increased durability for the formulations containing fibers, for example, formulation # 13 and # 15 in Table III.

Tabl * I. Examples of ignition formulations, designed for extrusion with water • Cyanamcr is a registered trademark of the Cytec Inc. industries especially for polymers of polyacrylamide, sodium polyacrylate copolymers of the same.

Cyanamc N-300: Polyacrylamide from ca. Molecular weight 15 M Cyaname N-300 LMW: Poüacriamide from ca. Molecular weight 5 M Cyaname? -370: Copolymer of acrylamide and sodium acrylate, ca 10:50 by weight .. 2000, 000 Mw Cyaname P-21: Copolymer of acrylamide and sodium acrylate, ca 19: 10 by weight. , 2000, 000 Mw Table II. Safety Characteristics of Exempt Igplcon Formulations 00 1 The units are in centimeters. 2 The units are in poundß.

Table III. summary of the test result for exempt lighters The percent parts of water added to the formulation needed to allow an efficient single screw extrusion 2 Average load on the 2-inch chopstick failure in the durability tests. The units are in mill-inches-pounds J- The percentage of the block perforations was determined from 6 or more of 0.33 ignition sticks L of 0.33"OO, 0.08 ID.

* Formulation number 9 did not extrude well.

EXAMPLE 3 A series of lighters containing fibers were formulated with the purpose of increasing the durability of the extruded ignition sticks as can be seen in Figure IV. All the formulations showed favorable safety characteristics. Samples of (325 g) of each formulation were mixed in a pint of Baker-Perkins mixer with 13.5 parts / 100 of water. After dry mixing the KN03 and the Cyanamer® A-370 for one minute, the water was added after five minutes of mixing. The fiber was then added in two increments and the boron in three increments with three minutes of mixing after each addition. After a final "scraping", the formulation was mixed for an additional ten minutes. The brown material, similar to a resulting mass, was granulated to -4 mesh and fed into a single screw 25 mm Haake extruder. The ignition formulation was extruded through a 12-point star die with a maximum diameter of 0.33"and a minimum diameter of 0.305". The die included a spindle 0.15"diameter centrally located, the extruded ignition formulation was cut into 7" sections. Ten additional 2"sections were extruded. The ignition sticks were dried at 165 ° F overnight.

No KNC / binder separation signs were present outside the ignition grains after drying. The beads were ignited with the ignition plume of an ES013 detonator directly into the 0.15"ID bore in the grain.The ignition grain was maintained in a 0.4" ID wall, 0.49"wall, the cylindrical artifact with approximately 95 holes equally distributed of 0.109"drilled along its length and its diameter. The times required for the frontal flame to reach the opposite end of the grain after ignition by detonating are reported in table V. The times were determined from a video of 1000 structures / second. Generally, only a few thousandths of a second were required. The durability of the 2"long grain was determined as described in Example 2. The results were reported in Table V. Moreover, the formulation containing 2% polyethylene fibers showed greater durability. Inflator were conducted using ignition grains of formulations # 3 and 19 # with RDC inserted into the 0.15"bore. formulation 19 with polyethylene fibers (Allied-Signal polyethylene fibers, Spectra 900 tape) produced at least a delay amount before the gas generator ignited. fifteen • twenty TABLE IV. Igorption formulations containing the Cyanamer A-370 and selected fibers.

TABLE V. Summary of test results for extruded lighters containing fibers 1 the formulation 3 with grains having an ID of 0.125"instead of the nominal ID of 0.15" 3 time required for the front flare in a 7"bead lit at one end to reach the other end.The time is in thousandths of The data was obtained as described in Example 3. 5 The same as in the footer but cured epoxy that blocks the 0.15"ID drilling at the opposite end where the ignition started. "* Average load on chopstick faults of 2" in the durability tests. The sunities are the thousand-polished-pounds.

In the formulations 16,17,18, 19 and 20, respectively, the "ID" fiber can be characterized as a carbon fiber, alumina fiber, an aluminosilicate, polyethylene, and polybenzimidazole.

EXAMPLE 4 An extrudable ignition composition was obtained by forming a premix of guar gum (5.0% by weight, 0.25 g) and water (deyonized 15.0% by weight, 1.75 grams); combining the previous mixture with potassium nitrate (with an average particle size of around 26 microns, 75% by weight, 3.75 grams); and adding to this fuel, boron (amorphous, 20.0% by weight, 1.00 grams).

EXAMPLE 5 An extrudable ignition composition was obtained as in Example 4, but 20.0% by weight was used. EXAMPLE 6 An extrudable ignition composition was prepared as in Example 4, except that the amount of fuel, boron, was increased to 22.0% by weight (1.10 grams) and the amount of binder, guar gum, was reduced to 3.0% by weight (0.15 grams).

EXAMPLE 7 An extrudable ignition composition was prepared according to the procedure of Example 4, except that the binder was polyacrylamide (Cytane "N-300" from Cytec, 5.0% by weight, 0.25 grams).

EXAMPLE 8 An extrudable ignition mixture was prepared by adding potassium nitrate ('210' grams) and a polyacrylamide (14 grams; Cytec "N-300" from Cytec) to one cup; adding water (44.8 grams) to the cup and mixing for 1 minute; and adding boron (amorphous, 56.0 grams) followed by mixing for about four minutes. EXAMPLE 9 An extrudable ignition composition was prepared as in example 8, except that the amount of water is 50.4 grams, the potassium nitrate and the binder are first mixed dry before adding the water and mixed for 1 minute. The boron powder is then added and the mixture is continued for four minutes.

EXAMPLE 10 The ignition composition prepared according to Example 8 was granulated, dried and pressed into pellets with a diameter of 1/2 inch per 1 long. The pellets were then inhibited in a complete combustion chamber in a pressurized vessel closed at 1000, 2000 and 3000 psi via ignition of an uninhibited face. Burning speeds of 4.16 ips, and 4.42 ips, respectively, were observed.

EXAMPLE 11 A portion of the wet ignition composition prepared as described in Example 9 was placed in a 2 in. Diameter tightening extruder and an appropriate die was forced to provide a cylindrical extrudate drilled in the center of approximately 0.3 in diameter with a perforation of approximately 0.06 in. This extrudate was partially dried and cut into sections of 7 in. Before final drying. The resulting ignition sticks were then tested on a gas generating device consisting of a tubular metal cylinder approximately 8 in. Long by approximately 2 in. Diameter closed at both ends and provided with radial holes. One of the extreme closures was also provided with an initiation detonator. The ignition stick was retained in the center of a tube and a 7 in. In length rapid deflagration cord (RDC) placed in the central bore of the stick. The gas generating device was then filled with a load of gas generating pellets and tested in a closed tank. Comparable results were obtained with the ignition stick in contrast to those obtained with a conventional ignition train in which a perforated metal tube was filled with a similar amount of ignition powder and the RDC replaces the stick / RDC ignition combination . In all cases the ignition of the pellets that generate gas was observed to occur within 8 thousandths of a second.

EXAMPLE 12 To a pint of Baker-Perkins planetary mixer, 250.9 g (77.2%) of 35 micras of potassium nitrate and 22.75 g (7%) of Cytec Cyanamer® A-370 (90:10) Polyacrylamide / sodium polyacrylate were added: 200,000 MW). Then these ingredients were remotely mixed in the dry state for one minute. To this mixture, 43.8 g (13.5 parts per 100 of the ignition formulation) of water were added and the combination was mixed for five minutes. The mixing paddles and the internal surface of the bowl were scraped with Velostat spatulas (conductive plastic). To the resulting thick white paste, 6.5 g (2%) of Spectra 900 polyethylene fiber tape (0.032"diameter x 0.125" long, Allied-Signal) was added in two parts followed by three-minute mixing cycles. and subsequent scrapes. To this combination, 44.85 g (13.8) of amorphous boron powder (90-92% purity) was added in three parts, remotely mixed for three minutes, followed by subsequent scraping. The shovels and the bowl were again "scraped" and the formulation mixed for an additional ten minutes. The brown, mass-like material was granulated to -4 mesh and fed into a screw extruder. unique Haake of 25 mm. The ignition formulation was extruded through a 12-point star die with a maximum diameter of 0.33"and a minimum diameter of 0.30". The die included a 0.15"diameter center spindle, the extruded ignition formulation was cut into 1" and 2"lengths or lengths, the ignition sticks were placed on a porous pad and dried at 165 ° F for 2 hours. hours and then overnight at 200 ° F. The 1"lengths or lengths worked well as lighters on inflators for passenger side automotive safety bags.

The durability tests were carried out in a three-point mixture, with the load applied in mid-span, in the manner described in example 2. The durability tests indicate a significant increase in the durability of the extruded ignition formulations containing polyethylene fibers, 357 milli-inches-pounds, relative to a comparable formulation without fibers, 96 milli-inches-pounds.

EXAMPLE 13 To one gallon of Baker-Perkins planetary mixer, 2069.2 g (73.9%) of potassium nitrate of 20 microns and 154 g (5.5%) of Cytec Cyanamer® A-370 (90:10 polyacrylate / sodium polyacrylamide: 200,000 were added. Mw). These ingredients were then remotely mixed in the dry state for one minute. To this combination, 400 g (12.5% of the complete mixture by weight) of water was added and the combination was mixed for five minutes. To the resulting thick white paste, 576.8 g (20.6%) of amorphous boron powder (90-92% purity) were added in three parts, remotely mixed for five minutes followed by subsequent scraping. The brown material, similar to a resulting mass, was mixed for an additional ten minutes. After it sat through the night, the material was forced through a 10 mesh filter into a Stokes granulator. The resulting sticky, wet granules were watered in an aluminum pan 2 'wide x 3' long x 1"deep in line with the plastic and placed inside a rack in a" walk-in "oven at 135 ° F. The granules were dried for 40 minutes and then re-granulated to 10 mesh in the Stokes granulator.The lighter was placed back into the oven at 135 ° F and dried overnight. They were classified in a Sweco® screen at -10 / + 24 mesh, obtaining a production of 70% by weight of the granules of -10 / + 24 mesh.

EXAMPLE 14 To a gallon of Hobart mixer, were added 522 g (58%) of potassium nitrate of 20 microns and 36 g (4.0%) of Cytec Cyanamer® A-370 (90:10 polyacrylate / polyacrylamide: 200,000 MW). These ingredients were then combined remotely in the dry state for one minute. To this combination, 107 g of water were added and the combination was mixed for 5 minutes. To the thick white paste, resulting, 203.2 g of a cobalt (III) hexaamine nitrate (HACN) / water slurry (11.5% water in watery litter, 20% by dry weight of HACN in the formulation) were added and remotely mixed for five minutes . Two parts 162 G (18%) of amorphous boron powder (90-92% purity) were added in two parts, remotely mixed for five minutes, followed by subsequent scraping. The brown material, similar to a dough, was mixed for an additional five minutes, 9 grams of water were added, the paste was mixed for five more minutes followed by another 9 grams of water. After five more minutes of mixing, the formulation had a consistency of small globules. The small globules were watered in a pan 2 'wide x 3' long x 1"deep lined with plastic and placed inside a rack in a" walk-in "oven at 135 ° F and dried overnight The small globules (granules) were then sorted into a Sweco® screen at -24/200 mesh.

It is noted that in relation to this date, the best method known by the applicant, to carry out the aforementioned invention is that it is clear from the manufacture of the objects to which it relates.

Having described the invention as above, property is claimed as contained in the following:

Claims (20)

1. A gas generating device itself that is part of a supplementary attenuation system for use in a vehicle, characterized in that it comprises a housing, a gas generating composition within said housing, and a lighter comprising at least one extruded ignition element , which serves to ignite said composition that generates the gas, said extruded ignition element that is formed of an extrudable ignition composition is formulated of constituent constituents; at least one polymeric binder soluble in water or at least one water soluble gum, at least one oxidizing agent, at least one fuel, and optionally fibers.

2. The device of claim 1, characterized in that said water-soluble polymeric binder comprises poly-N-vinyl pyrrolidone.

3. The device of claim 1, characterized in that said water-soluble polymeric binder comprises polyvinyl alcohol.

4. The device of claim 1, characterized in that said extrudable ignition composition includes rubber.

5. The device of claim 1, characterized in that said water-soluble polymeric binder comprises at least one member selected from the group consisting of polyacrylamide and copolymers thereof.

6. The device of claim 1, characterized in that said oxidant is present in an amount of from about 40% to about 90% by weight in relation to the dry ingredients used in the formulation of said extrudable ignition composition.

7. The device of claim 1, characterized in that said oxidant comprises at least one ionic species selected from the group consisting of nitrate, nitrite, chlorate, perchlorate, peroxides, and superoxides.

8. The device of claim 1, characterized in that said extrudable ignition composition contains fibers.

9. The device of claim 8, characterized in that said fiber comprises at least one polyolefin fiber, polyamide fibers, polyester fibers, or poly (2, 2 '- (m-phenylene) -5,5-bisbenzimidazole fibers.

10. The device of claim 1, characterized in that (a) said binder comprises at least one member selected from the group consisting of poly-N-vinyl pyrrolidone, polyvinyl alcohol or copolymers thereof, and gum; (b) said oxidant is present in an amount from about 40% by weight to about 90% by weight relative to the dry ingredients used in the formulation of said extrudable ignition composition, and said oxidant comprises at least one ionic species selected from the group consisting of nitrate, nitrite, chlorate, perchlorate, peroxides, and superoxides; (c) said extrudable ignition composition contains fibers of low aspect ratio, said fibers comprising at least one of the polyolefin fibers, polyamide fibers, polyester fibers, or poly (2, 2 '(m-phenylene) -5,5 fibers. - bisbenzimidazole.

11. A vehicle equipped with a supplementary safety, attenuation system, having the gas generating device of claim 1.

12. A vehicle equipped with a supplementary safety attenuation system, having the gas generating device of claim 2.

13. A vehicle equipped with a supplementary safety attenuation system, having the gas generating device of claim 3.

14. A vehicle equipped with a supplementary safety attenuation system, having the gas generating device of claim 4.

15 A vehicle equipped with a supplementary safety attenuation system, having the gas generating device of claim 5.

16. A vehicle equipped with a supplementary safety, attenuation system, having the gas generating device of claim 6.

17. A vehicle equipped with a supplementary safety attenuation system, having the gas generating device of claim 7.

18. A vehicle equipped with a system of 10 attenuation, supplementary safety, which has the F- the gas generating device of claim 8.

19. A vehicle equipped with a system of attenuation, supplementary safety, which has the The gas generating device of claim 9.

20. A vehicle equipped with a supplementary safety attenuation system, having the gas generating device of claim 10.