METAL COMPLEXES TO BE USED AS GAS GENERATORSField of the InventionThe present invention relates to complexes of transition metals or alkaline earth metals which are capable of being burned to generate gases. More particularly, the present invention relates to the provision of such compounds which oxidize rapidly to produce significant amounts of gases, particularly water vapor and nitrogen.
Background of the InventionThe gas-generating chemical compositions are useful in several different contexts. An important use for such composition is in the operation of the "air bags". The air bags are gaining acceptance to the point where many of the new cars, if not almost all, are equipped with such devices. Actually, many of the new cars are equipped with multiple airbags to protect the driver and passengers. In the context of automotive air bags, enough gas must be generated to inflate the Ref.26785device within a fraction of a second. Between the time the car is hit in an accident, and the time the driver could otherwise be pushed or projected against the steering wheel, the airbag must inflate completely. As a result, almost instantaneous gas generation is required. There are several important, additional design criteria that must be met. Automobile manufacturers and others have described the required criteria which must be met in detailed specifications. The preparation of gas generating compositions that meet these design criteria is an extremely difficult task. These specifications require that the gas generating composition produce gas at a required rate. The specifications also place strict limits on the generation of toxic or harmful gases or solids. Examples of the restricted gases include carbon monoxide, carbon dioxide, N0X, SOx, and hydrogen sulfide. The gas must be generated at a reasonable temperature and low enough so that an automobile occupant is not burned during the impact with an inflated airbag. If the gas produced is too hot, there is a possibility that the occupant of themotorized vehicle is burned during the impact of an airbag deployed just then. Consequently, it is necessary that the combination of the gas generator and the construction of the air bag isolate the occupants of the automobile from excessive heat. All this is required while the gas generator maintains an adequate burning speed. Other important but related design criteria is that the gas generating composition produces a limited amount of particulate materials. Particulate materials can interfere with the operation of supplementary restraint systems, present a risk of inhalation, irritate the skin and eyes, or constitute a hazardous solid waste that must be treated after the operation of the safety device. In the absence of an acceptable alternative, the production of irritating particulate materials is one of the undesirable, but tolerated, aspects of the commonly used sodium azide materials. In addition to the amounts of limited particulate materials, if any, it is desired that at least the volume of any such particulate material be easily filterable. For example, it is desirable that the composition produces a filterable slag. If the products of the reaction forma filterable material, the products can be filtered and prevented from escaping into the surrounding environment. Both organic and inorganic materials have been proposed as possible gas generators. Such gas generating compositions include oxidants and fuels which react at sufficiently high rates to produce large quantities of the gas in a fraction of a second. In the present, sodium azide is the most widely accepted and common gas generating material. Sodium azide nominally satisfies the rules and specifications of the industry. However, sodium azide presents several persistent problems. Sodium azide is highly toxic as a starting material since its toxicity level is measured by an LD50 of the rat, oral, in the range of 45 mg / kg. Workers who regularly handle sodium azide have experienced several health problems such as severe headaches, shortness or shortness of breath, seizures, and other symptoms. In addition, it does not matter which auxiliary oxidant is used, the products of the combustion of a sodium azide gas generator include caustic reaction products such as sodium oxide, or sodium hydroxide.sodium. Molybdenum disulfide or sulfur have been used as oxidants for sodium azide. However, the use of such oxidants leads to toxic products such as hydrogen sulfide gas and corrosive materials such as sodium oxide and sodium sulfide. Rescue workers and car occupants have complained about both the hydrogen sulfide gas and the corrosive dust produced by the operation of sodium azide gas generants. Increasing problems have also been anticipated in relation to the disposal of supplemental inflated restriction systems with a gas, unused, for example, car air bags, in destroyed cars. The remaining sodium azide in such supplementary restriction systems can be separated by leaching from the destroyed car to become a toxic waste or water pollutant. Indeed, some have expressed concern that sodium azide might form explosive heavy metal azides or hydrazic acid when contacted with battery acids following disposal. Sodium azide-based gas generants are most commonly used for inflation of the air bag, but with the significant disadvantages of such compositions many compositions have been proposedgas generants to replace sodium azide. Most of the proposed sodium azide replacements, however, fail to meet all of the criteria described above. It will be appreciated, therefore, that there are several important criteria for the selection of gas generating compositions for use in automotive supplementary restraint systems. For example, it is important to select starting materials that are not toxic. At the same time, the products of combustion must not be toxic or harmful. In this regard, industrial standards limit the permissible quantities of various gases and particulate materials produced by the operation of supplementary restriction systems. Therefore, it could be a significant advantage to provide compositions capable of generating large quantities of gas, which could overcome the problem identified in the existing art. It could be a further advantage to provide a gas generating composition which is based on substantially non-toxic starting materials and which produces substantially non-toxic reaction products. It could be another advantage in the art to provide a gas generating composition which produces very limited amounts of toxic or irritant particulate debris and undesirable gas products.limited. It could also be an advantage to provide a gas generating composition which forms a solid slag easily filterable during the reaction. Such compositions and methods for their use are described and claimed herein.
Brief description of the inventionThe present invention relates to the use of transition metal or alkaline earth metal complexes as gas generating compositions. These complexes are comprised of a metal cation and a neutral ligand containing hydrogen and nitrogen. One or more oxidizing anions are provided to balance the charge of the complex. Examples of typical oxidizing anions that can be used include nitrates, nitrites, chlorates, perchlorates, peroxides, and superoxides. In some cases the oxidizing anion is part of the coordination complex of the metal cation. The complexes are formed in such a way that when the complexes are burned, a mixture of gases containing nitrogen gas and water vapor is produced. A binder can be provided to improve the resistance to shock deformation and other mechanical properties of the gas generating composition. A cooxidant can also be provided primarily to allowthe efficient combustion of the binder. Importantly, the production of undesirable gases or particulate materials is reduced or substantially eliminated. Specific examples of the complexes used herein include metal nitrite amines, metal nitrate amines, metal perchlorate amines, metal nitrite hydrazines, metal nitrate hydrazines, metal perchlorate hydrazines, and mixtures thereof. Complexes within the scope of the present invention burn or decompose rapidly to produce significant amounts of gas. The metals incorporated within the complexes are transition metals, alkaline earth metals, metalloids, or lanthanide metals that are capable of forming amine or hydrazine complexes. The currently preferred metal is cobalt. Other metals which also form complexes with the desired properties in the present invention include, for example, magnesium, manganese, nickel, titanium, copper, chromium, zinc, and tin. Examples of other usable metals include rhodium, iridium, ruthenium, palladium, and platinum. These metals are not as preferred as the metals mentionedpreviously, mainly because of cost considerations. The transition metal cation or the alkaline earth metal cation acts as a model or template at the center of the coordination complex. As mentioned above, the complex includes a neutral ligand containing hydrogen and nitrogen. The preferred neutral ligands are usually NH3 and N2H4. One or more oxidizing anions can also be coordinated with the metal cation. Examples of the metal complexes within the scope of the present invention include Cu (NH3) 4 (N03) 3 (tetraamine-copper (II) nitrate) Co (NH3) 3 (N02) 3 (trinitrotriaminecobalt (III)) Co (NH3) 6 (C104) 4 (hexamethocobalt perchlorate (III) Co (NH3) 6 (N03) 3 (hexaaminecobalt (III) nitrate) Zn (N2H) 3 (N03) 2 (zinc tris-hydrazine nitrate) Mg (N2H4) 2 (C10) 2 (bis-hydrazine magnesium perchlorate), and Pt (N02) 2 (NH2NH2) 2 (bis-hydrazine nitrite platinum (II)) It is within the scope of the present invention to include metal complexes which contain a common ligand in addition to the neutral ligand.
Some of the typical common ligands include water(H20), hydroxo (OH), carbonate (C03), oxalate (C? O?), Cyano (CN), isocyanate (NC), chlorine (Cl), fluoro (F), and similar ligands. Metal complexes within the scope of the present invention are also proposedto include a common counter or negative ion, in addition to the oxidizing anion, to help balance the charge of the complex. Some of the typical negative ions include: hydroxide (OH "), chloride (Cl"), fluoride (F "), cyanide (CN"), carbonate (CO3"2), phosphate (P04-3), oxalate (C204" 2), borate (BO4"5), ammonium (NH4 +), and the like, it is observed that the metal complexes containing the described neutral ligands and oxidizing anions burn rapidly to produce significant quantities of gases. the application of heat or the use of conventional lighters.
Detailed description of the inventionAs described above, the present invention relates to gas generating compositions containing transition metal or alkaline earth metal complexes. These complexes are comprised of a metal cation template or template and a neutral ligand containing hydrogen and nitrogen. One or more oxidizing anions are provided to balance the charge of the complex. In some cases the oxidizing anion is part of the coordination complex with the metal cation. Examples of typical oxidizing anions that can be used include nitrates,nitrites, chlorates, perchlorates, peroxides, and superoxides. The complexes can be combined with a binder or binder mixture to improve the resistance to shock deformation and other mechanical properties of the gas generating composition. A cooxidant can be provided primarily to allow efficient combustion of the binder. Metal complexes which include at least one common ligand in addition to the neutral ligand are also included within the scope of the present invention. When used here, the term "common ligand" includes the well-known ligands used by inorganic chemists to prepare coordination complexes with metal cations. The common ligands are preferably molecules or polyatomic ions, but some monatomic ions can also be used. Examples of common ligands within the scope of the present invention include water (H20), hydroxo (OH), perhydroxo (02H), peroxo (02), carbonate (C03), oxalate (C204), carbonyl (CO), nitrosyl ( NO), cyano (CN), isocyanate (NC), isothiocyanate (NCS), thiocyanate (SCN), chlorine (Cl), fluoro (F), amido (NH2), imido (NH), sulfate (S04), phosphate ( P04), ethylenediaminetetraacetic acid (EDTA), and similar ligands. See, F. Albert Cotton and Geoffrey Wilkinson, Advanced Inorganic Chemistry, 2 / a. Ed., John Wiley & amp;; Sons, pp. 139-142, 1966 and James E.
Huheey, Inorganic Chemistry, 3 / a. Ed., Harper & Row, pp. A-97-A-107, 1983, which are incorporated herein by reference. Those skilled in the art will appreciate that suitable metal complexes within the scope of the present invention can be prepared containing a neutral ligand and another ligand not listed above. In some cases, the complex may include a common negative ion, in addition to the oxidizing ion, to help balance the charge of the complex. When used here, the common term negative ion includes the well-known anions and cations used by inorganic chemicals as negative ions. Examples of common negative ions within the scope of the present invention include hydroxide (OH "), chloride (Cl ~), fluoride (F"), cyanide (CN "), thiocyanate (SCN"), carbonate(C03-2), sulfate (S04"2), phosphate (PO4" 3), oxalate (C204"2), borate (B04-5), ammonium (NH4 +), and the like.
Whitten, K. W., and Gailey, K.D., General Chemistry, Saunders College Publishing, p. 167, 1981 and James E. Huheey, Inorganic Chemistry, 3 / a. Ed., Harper & Row, pp. A-97-A-103, 1983, which are incorporated herein by reference. The generative ingredients of the gas are formulated in such a way that when the composition burns, nitrogen gas and water vapor are produced. InIn some cases, small amounts of carbon dioxide or carbon monoxide are produced if a binder, co-oxidizer, common ligand or oxidizing anion contains carbon. The total carbon in the gas generating composition is carefully controlled to prevent over generation of CO gas. The combustion of the gas generant is carried out at a rate sufficient to qualify such materials for use as gas generating compositions in automobile air bags and other types of similar devices. Importantly, the production of other undesirable particulate gases or materials is substantially reduced or eliminated. Complexes which are considered within the scope of the present invention include metal nitrate amines, metal nitrile amines, metal perchlorate amines, metal nitrite hydrazines, metal nitrate hydrazines, metal perchlorate hydrazines, and mixtures thereof. The amine and metal complexes are defined as coordination complexes that include ammonia, as the coordinating ligand. The amine complexes may also have one or more oxidizing anions, such as nitrite (N02"), nitrate (N03"), chlorate (C103"), perchlorate (C104"), peroxide (022"), and superoxide (02) "), or mixtures thereof, in the complex. The present invention is alsorelates to similar hydrazine and metal complexes that contain corresponding oxidating anions. It has been suggested that during the combustion of a complex containing nitrite and ammonia groups, the nitrite and ammonia groups suffer from a dinitrogenation reaction. This reaction is similar, for example, to the reaction of sodium nitrite and ammonium sulfate, which is described as follows:2NaN02 + (NH4) 2S04 - > Na2S04 + 4H20 + 2N2Compositions such as sodium nitrite and ammonium sulfate in combination have little utility as gas-generating substances. These materials are observed to undergo metathesis reactions which lead to undesirable ammonium nitrite. In addition, most simple nitrites have limited stability. In contrast, the metal complexes used in the present invention are unstable materials which, in certain cases, are capable of undergoing the type of reaction described above. The complexes of the present invention also produce reaction products which include desirable amounts of non-toxic gases such as water vapor and nitrogen. In addition, a metal or oxide slagMetallic, stable, is formed. Therefore, the compositions of the present invention avoid several of the limitations of the compositions that generate the existing sodium azide gas. Any transition metal, alkaline earth metal, metalloid or lanthanide metal which is capable of forming the complexes described herein, is a potential candidate for use in these gas generating compositions. However, considerations such as cost, reactivity, thermal stability, and toxicity can limit the most preferred groups of metals. The currently preferred metal is cobalt. Cobalt forms stable complexes which are relatively inexpensive. In addition, the reaction products of the combustion of the cobalt complex are relatively non-toxic. Other preferred metals include magnesium, manganese, copper, zinc, and tin. Examples of the less preferred but usable metals include nickel, titanium, chromium, rhodium, iridium, ruthenium, and platinum. Some representative examples of the amine complexes within the scope of the present invention, and the decomposition reactions that generate the associated gas, are as followsCu (NHs) a (N02.) 2 - CuO + 3H + 2N, 2C? (NH,), (NOj),? 2CoO + 9thfi + 6N, + 0, 2Cr (NH,) j (NOj),? Cr? + 9HjO + 6N2 [Cu (NH,) 4] (NO,) 3 - Cu + 3N, + 6H, 0 2B + 3C? (MH,) .C? (NO,) É? 6C0O + BjO, + 27H, 0 * 18N2 Mg + Co (NH,), (NO,) jC? (NH,), (NO,) 4 - »2C? O + MgO + 9HaO + 6N2(C? (NHj) 4 (NOj),] (NO,) + 2Sr (NO,) 2? COOO + 2SrO + 37N, + 60H2 lßCCoíNHs) ,,) (NO,), + 4C j (0H), N0, - I8C0O + 8Cu + 83N, + 16ßH, 02 [Co (NH,) (NO,), + 2NH4N ?, - 2C? Or UN) + 22H20 TiCl4 (NHt) a + 3Ba02 - * Ti02 + 2BaCl2 + BaO + 3HjO + N2 4 [Cr (NH,) $ 0H} (C104) a + [SnCl4 (NH,),]? 4CrCl, + SnO + 35HaO + UNj[Ru (NH,), N2] (NO,) 2 + 3Sr (NO,) 2 - »3Sr0 + lORu + 48Na + 75HjO[Ni (H20) 2 (NH,) 4] (NO, - Ni + 3N2 + 8H20 2 [Cr (01) a (NH,), l + 4 NH4NO, - »7N, + 17H70 + Cr20, ß (Ni (CN) j (NH,)], CiH4 + 43KC104? ßNiO + 43KCl + 64C01 + 12Na-t-36HaO "2 [Sm (02), (NH,)] + 4lGd (NH,),) (C10)? ? 5111.0, + 4GdCl, + 19N, + 5711.0 2Er (NO,)? (NH,) j + 2 (C? (NH,)%] (NO,),? Er20, + 12C? O + 60Na + 117HaOSome of the representative examples of the hydrazine complexes within the scope of the present invention, and the related gas-generating reactions, are the following:SZntt (NO,), + Sr (NO,), - »52nO + 21N, + 30H2O + SrO CßíN? JjíNO,,? CO + 4N2 + 6H20 3Mg (NaH4) 1 (ClO «) a + 2YES, N,? 6YES, + 3MgCl, + ION, + 12H, 0 2Mg (N2H4) j (NO,) a + 2 [C? (NH,) 4 (NOJ) J] N?,? 2MgO + 2CoO + 13N2 + 20Ha0[Mn (N2H «),) (NO,) 2 + Cu (OH) 2 ^ CU + MnO + 4N, + 7HjO2 [The (N2H4) 4 (NO,)] (NO,), + NH4NO, - aaO, + 12N, + 18HaOAlthough the complexes of the present invention are relatively stable, it is also simple to initiate the combustion reaction. For example, if the complexes come in contact with a hot wire, rapid, gas-producing combustion reactions are observed. Similarly, it is possible to initiate the reaction by means of conventional igniter devices. Some types of igniter devices include a number of B / KNO3 pills or granules which are ignited, and which in turn are capable of igniting the compositions of the present invention. Another firing device includes a quantity of granules of Mg / Sr (N03) 2 / nylon. It is also important to note that many of the complexes defined above suffer from "stoichiometric" decomposition. That is, the complexes decompose unreacted with any other material to produce large amounts of nitrogen and water, and a metal or metal oxide. However, for certain complexes it may be desirable to add a fuel or oxidant to the complex to ensure a complete and efficient reaction. Such fuels include, for example, boron, magnesium, boron or aluminum hydrides, carbon, silicon, titanium, zirconium, and other conventional, similar combustible materials, such asconventional organic binders. Oxidizing species include nitrates, nitrites, chlorates, perchlorates, peroxides, and other similar oxidizing materials. Accordingly, although the stoichiometric decomposition is attractive because of the simplicity of the composition and the reaction, it is also possible to use complexes for which stoichiometric decomposition is not possible. As mentioned above, the nitrate and perchlorate complexes are also considered within the scope of the invention. Some representative examples of such nitrate complexes include: C? (NH3) 6 (N03) 3, Cu (NH3 N03) 2, [Co (NH3) 5 (N03)] (N03) 2, [Co (NH3) 5 ( N02)] (N03) 2, [Co (NH3) 5 (H20)] (N03) 2. Some representative examples of the perchlorate complexes within the scope of the invention include [C (NH 3) 6] (Cl 4) 3, [C 1 (NH 3) 5 (N 2)] Cl 4, [Mg (N 2 H 4) 2] (C104) 2- The preparation of the nitrate or metal nitrite amine complexes of the present invention are described in the literature. Specifically, reference is made to Hagel et al, "The Triamines of Cobalt (III)." I. Geometrical Isomers of Trinitrot-Dimonminecobalt (III) ", 9 Inorganic Chemistry 1496 (June 1970); G. Pass and H. Sutcliffe, Practical Inorganic Chemistry, 2 / a. Ed., Chapman & Hull, New York, 1974; Shibata et al., "Synthesis of Nitroammine- and Cyanoamminecobalt (III)Complexes With Potassium Tricarbonatecobaltate (III) as the Starting Material ", 3 Inorganic Chemistry 1573 (Nov. 1964), Wieghardt et al," μ-Carboxylate-μ-hydroxo-bis [triammine-cobalt (III)] ", 23 Inorganic Synthesis 23 (1985); Laing, "mer- and fac- [Co (NH3) 3N02) 3]: Do They Exist?" 62 J. Chem. Educ, 707 (1985); Siebert, "Isomere des Trinitrotriamminkobalt (III)" , 441 Z. Anorg, Allg. Chem. 47 (1978), all of which is incorporated herein by reference.The amine and perchlorate complexes of a transition metal are synthesized by similar methods. of amine of the present invention are generally stable and safe for use in the preparation of gas-generating formulations.The preparation of hydrazine and metal perchlorate complexes, nitrite, and nitrate, is also described in the literature. Patil et al., "Synthesis and Characterization of Metal Hydrazine Nitrate, Azidem and Perchlorate Complexes ", 12 Synthesis and Reactivity In Inorganic and Metal Organic Chemistry, 383 (1982); Klyichnilov et al, "Preparation of Some Hydrazine Compounds of Palladium", 13 Russian Journal of Inorganic Chemistry, 416 (1968); Klyichnikov et al, "Conversion of Mononuclear Hydrazine Complexes of Platinum and Palladium Into Binuclear Complexes", 36 Ukr. Khim. Zh., 687 (1970).
The described complexes can be processed into pellets or granules for use in gas generating devices. Such devices include supplementary restriction systems of the automotive airbag. Such gas generating compositions will comprise an amount of the described complexes and preferably, a binder and a co-oxidant. The compositions produce a mixture of gases, mainly nitrogen and water vapor, during decomposition or burning. The gas generating device will also include means for initiating the burning of the composition, such as a hot wire or lighter. In the case of an automobile airbag system, the system will include the compositions described above; an inflatable, crushed airbag; and means for igniting the gas generating composition within the airbag system. The systems of the automotive airbag are well known in the art. Typical binders used in the gas generating compositions of the present invention include binders conventionally used in propellant, pyrotechnic and explosive compositions including, but not limited to, lactose, boric acid, silicates including magnesium silicate , the carbonatepolypropylene, polyethylene glycol, gums that are naturally present, such as guar gum, acacia gum, celluloses and modified starches (a detailed description of such gums is provided by CL Mantell, The Water-Soluble Gums , Reinhold Publishing Corp., 1947, which is incorporated herein for reference), polyacrylic acids, nitrocellulose, polyacrylamide, polyamides, including nylon, and other conventional polymeric binders. Such binders improve the mechanical properties or provide improved impact deformation resistance. Although water-immiscible binders can be used in the present invention, it is currently preferred to use water-soluble binders. The binder concentration is preferably in the range from 0.5 to 12% by weight, and more preferably from 2% to 8% by weight of the gas generating composition. Applicants have found that the addition of carbon such as carbon black or activated charcoal to the gas generating compositions improves the binding action significantly, perhaps by strengthening the binder and thereby forming a microcomposite. Improvements in resistance to shock deformation from 50% to 150% have been observed with the addition of carbon black to thecompositions within the scope of the present invention. The ballistic reproducibility is improved when the resistance to shock deformation is increased. The concentration of the carbon is preferably in the range of 0.1% to 6% by weight, and more preferably from 0.3 to 3% by weight of the gas generating composition. The co-oxidant may be a conventional oxidant such as perchlorates, chlorates, peroxides, nitrites, and alkali, alkaline earth, lanthanide, or ammonium nitrates, including for example, Sr (N03) 2, NH4CIO4, KN03, and (NH4) 2Ce ( N03) 6. The co-oxidant may also be an oxidizing agent containing a metal, such as metal oxides, metal hydroxides, metal peroxides, metal oxide hydrates, metal oxide hydroxides, metal hydrated oxides, and mixtures thereof, including those described in the Patent. US No. 5,439,537 issued August 8, 1995, entitled "Thermite Compositions for Use as Gas Generants", which is incorporated herein by reference. Examples of metal oxides include, among others, oxides of copper, cobalt, manganese, tungsten, bismuth, molybdenum, and iron, such as CuO, Co203, Co3? 4, CoFe2? 4, Fe203, Mo03, Bi2Mo06, and Bi203. Examples of metal hydroxides include, among others, Fe (OH) 3,Co (OH) 3, Co (OH) 2, Ni (OH) 2, Cu (OH) 2, and Zn (OH) 2. Examples of metal oxide hydrates and metal hydrated oxides include, among others, Fe203 * xH20, Sn02 «xH20, and Mo03» H20. Examples of metal oxide hydroxides include, among others, CoO (OH) 2, Fe 0 (0H) 2, MnO (OH) 2 and MnO (OH) 3. The co-oxidizer can also be a basic metal carbonate such as metal carbonate hydroxides, metal carbonate oxides, metal carbonate hydroxide oxides, and hydrates and mixtures thereof and a basic metal nitrate such as metal hydroxide nitrates, metal oxides metal nitrate, and hydrates and mixtures thereof, including those oxidants described in US Pat. No. 5,429,691, entitled "Thermite Compositions for Use as Gas Generants" which is incorporated herein by reference. Table 1, which is given below, lists the examples of the basic metal carbonates capable of functioning as co-oxidants in the compositions of the present invention:Table 1Basic Metal CarbonatesCu (CO,) l.Jl «Cu (OH) j ,, p.e. , CUCO, «Cu (OH), (malachita)Eg, 2C? (CO,) -3C? (0H), - H, O C?, P?, (COs) to (OH) 2 # e.g.,Na, [Co (CO,) a] * 3H20 Zn (C03) l I (OH) 2β, e.g., 211, (00,) (OH), BiAMga (CO,) c (OH), lf p.e.,Fe (CO,) (OH) fc p.e., Fß (CO,) t ,, j (? M) 2? Cu,., Zn, (COs),., (OH) ". e.g., Cu. 42 .tt (CO,) (OH),e.g., C? M.? Cu «,." (CO,)! > (OH),., Ti? BipíCO ^ .ÍOíDyíOÍ ^^ O) ,, p.e. , TiBi4 (C0,) 2 (0H) 20, (H, O), (BIO), CO,Table 2, which is given below, lists the examples of the basic metallic nitrates capable of functioning as co-oxidants in the compositions of the present invention:Table 2Basic Metal NitratesCu2 (OH), NO, (gardite)Cu.CO,., (OH), NO "eg, CUCO (OH), HO, Zn, (OH), NO, Mn (OH) aNO, Fe (NO,). (OH), _, pe, F * 4 (0H) "N0, -2H, O Mo (NO,) aOa Bi0N0, -H, O Ce (OH) (NO,), - 3H, 0In certain cases, it will also be desirable to use mixtures of such oxidizing agents to improve the ballistic properties or maximize the filterability of the slag formed from the combustion of the composition. The present composition may also include the additives conventionally used in gas generating compositions, propellants, and explosives, such as burn rate modifiers, slag formers, release agents, and additives which remove in a effective the N0X. Typical burn rate modifiers include Fe203, K2B? 2H? 2, Bi2Mo? 6, and powder or graphite carbon fibers. Various slag forming agents are already known and include, for example, clays, talcs, silicon oxides, alkaline earth oxides, hydroxides, oxalates, of which magnesium carbonate, and magnesium hydroxide are exemplary. Various additives and / or agents for reducing or eliminating oxides or nitrogen from the combustion products of a gas-generating composition are also already known, including alkali metal salts and complexes of tetrazoles, aminotetrazoles, triazoles and related nitrogen heterocycles. of which aminotetrazole potassium, sodium carbonate and potassium carbonate are exemplary. The compositionit may also include materials which facilitate the release of the composition of a mold such as graphite, molybdenum sulphide, calcium stearate, or boron nitride. Burning speed modifiers / ignition adjuvants, typical, which may be used here, include metal oxides, nitrates and other compounds such as, for example Fe203, K2B? H? 7? H20, BiO (N03) , Co203, CoFe204, CuMo04, Bi2Mo06, Mn02, Mg (N03) 2 * xH20, Fe (N03) 3 * xH20, Co (N03) 2 # xH20, and NH4N03. The coolants include magnesium hydroxide, cupric oxalate, boric acid, aluminum hydroxide, and silicotungstic acid. Coolants such as aluminum hydroxide and silicotungstic acid can also function as slag improvers. It will be appreciated that many of the foregoing additives can effect multiple functions in the gas generating formulation such as a co-oxidant or as a fuel, depending on the compound. Some compounds can function as a co-oxidant, a burn-rate modifier, refrigerant, and / or slag former. Several important properties of the compositions that generate the typical hexaamine-cobalt (III) nitrate gas within the scope ofpresent invention have been compared with those of the commercial sodium azide gas generating compositions. These properties illustrate the significant differences between the conventional sodium azide gas generating compositions and the gas generating compositions within the scope of the present invention. These properties are summarized belowThe term "gas fraction of the generator" means the fraction by weight of the gas generated by weight of the gas generator. The typical hexaamine-cobalt (III) nitrate gas generating compositions have more preferred flame temperatures in the range of 1850 ° K to 1900 ° K, the gas fraction of the generator in the range of 0.70 to 0.75, the content of total coal in the generator in the range from 1.5% to 3.0% of the burn rate of the generator to 70.37 kg / cm2 (1000 psi) in the range from 0.2 ips to 0.35 ips, and the surface area of the generator in the range from 2.5 cm2 / g up to 3.5 cm2 / g. The gas generating compositions of the present invention are readily adapted for use with the technology of the hybrid air bag inflator. The technology of the hybrid inflator is based on heating a stored inert gas (argon or helium) to a desired temperature by burning a small amount of the propellant. Hybrid inflators do not require the cooling filters used with pyrotechnic inflators to cool the combustion gases, because the hybrid inflators are capable of providing a lower temperature gas. The discharge temperature of the gas can be changed selectively by adjusting the gas weight ratioinert with respect to the weight of the propellant. The higher the ratio of the weight of the gas to the weight of the propellant, the colder the discharge temperature of the gas will be. A hybrid gas generating system comprises a pressure tank having a breakable opening, a predetermined amount of inert gas placed inside this pressurized tank; a gas generating device for producing hot combustion gases and having means for breaking the breakable opening; and means for igniting the gas generating composition. The tank has a breakable opening which can be broken by a plunger when the generating device is turned on. The gas generating device is configured and positioned in relation to the pressure tank so that the hot combustion gases are mixed and the inert gas is heated. Suitable inert gases include, among others, argon, helium, and mixtures thereof. The hot and mixed gases leave the pressure tank through the opening and finally through the outlet of the hybrid inflator and deploy an inflatable bag or balloon, such as a car air bag. Preferred embodiments of the invention give combustion products with a temperature greater than about 1800 ° K, the heat of which istransferred to the inert gas cooler causing a further improvement in the efficiency of the hybrid gas generation system. Hybrid gas generating devices for supplementary safety restriction applications are described in Frantom, Hibrid Airbag Inflator Technology, Airbag Int'l Symposium on Sophisticated Car Occupant Safety Systems, (Weinbrenner-Saal, Germany, 2-3 November 1992 ).
EXAMPLESThe present invention is further described in the following non-limiting examples. Unless otherwise specified, the compositions are expressed in percent by weight.
Example 1An amount (132.4 g) of Co (NH3) 3 (N02) 3, prepared in accordance with the teachings of Hagel et al., "The Triamines of Cobalt (III) I. Geometrical Isomers of Trinitrotriamminecobalt (III)", 9 Inorganic Chemistry 1496 (June 1970), becomes a suspension in 35 ml of methanol with 7 g of a 38 weight percent solution of vinyl alcohol / ethyl acetate polymeric resin.pyrotechnic grade vinyl commonly known as VAAR dissolved in methyl acetate. The solvent was allowed to partially evaporate. The paste-like mixture was forced through a 20 mesh screen, allowed to dry to a stiff consistency, and forced through a screen again. The resulting granules were then dried in vacuo at room temperature for 12 hours. Pills of 1.27 cm (half inch) of the dry material were prepared by compression. The pills were burned at various different pressures ranging from 42.22 kg / cm2 to 232.22 kg / cm2 (600-3,300 psig). The burn rate of the generator was found to be 0.60 cm (0.237 inches) per second at 70.37 kg / cm2 (1,000 psig) with an exponent of the pressure of 0.85 over the range of the pressure tested.
Example 2The procedure of Example 1 was repeated with100 g of Co (NH3) 3 (N02) 3 and 34 g of 12 weight percent of the solution of nylon in methanol. The granulation was carried out by means of 10 and 16 mesh sieves followed by air drying. The drying rate of this composition was found to be 0.74 cm (0.290)inches) per second at 70.37 kg / cm2 (1,000 psig) with an exponent of the pressure of 0.74.
Example 3In a manner similar to that described in Example 1, 400 g of Co (NH3) 3 (N02) 3 were converted to a suspension with 219 g of a 12 weight percent solution of the nitrocellulose in acetone. The nitrocellulose contained 12.6 percent nitrogen. The solvent was allowed to partially evaporate. The resulting paste was forced through an 8-mesh screen followed by a 24-mesh screen. The resulting granules were dried overnight with air and mixed with sufficient agent for release of the calcium stearate mold to provide 0.3 percent in weight in the final product. A portion of the resulting material was compressed into 1.27 cm (0.5 inch) pills and found to exhibit a burn rate of 0.698 cm (0.275 inches) per second at 70.37 37 kg / cm2 (1,000 psig) with an exponent of pressure from 0.79. The rest of the material was compressed into 0.3175 cm (1/8 inch) by 0.1778 cm (0.07 inch) tablets on a rotary tablet press. The density of the pill was determined to be 1.88 g / cc. The temperature of the theoretical flame of thiscomposition was of 2,358 ° K and was calculated to provide a fraction of the gas mass of 0.72.
Example 4This example describes the preparation of a reusable stainless steel test device or accessory, used to simulate the driver's side gas generators. The test device, or simulator, consisted of an ignition chamber and a combustion chamber. The ignition chamber was located in the center and had 24 openings 0.254 cm (0.10 inches) in diameter that go to the combustion chamber. The ignition chamber was equipped with a lighter detonator. The lighter chamber wall was coated with a 0.00254 cm (0.001 inch) thick aluminum foil before the 24-fold + 60 mesh lighters were added. The wall of the external combustion chamber consisted of a ring with nine outlet openings. The diameter of the openings was varied by changing the rings. Starting from the internal diameter of the ring of the external combustion chamber, the combustion chamber was equipped with an 0.01016 cm (0.004 inch) aluminum filler plate, a 30 mesh stainless steel sieve lift stroke, four riser runs of one14 mesh stainless steel screen, a baffle ring, and the gas generator. The generator was kept intact in the combustion chamber using a "donut" from a 18 mesh stainless steel screen. An additional deflector ring was placed around the outside diameter of the external combustion chamber wall. The simulator was fitted to either a 60-liter tank or a car air bag.The tank was equipped with openings for pressure, temperature, ventilation and drainage. Car airs have a maximum capacity of 55 liters and are built with two ventilation openings of 1.27 c (0.5 in.) The simulator tests involving an air bag were configured in such a way that they could test the pressures of the bag The temperature of the surface of the outer layer of the bag was verified during the inflation event by infrared radiometry, thermal imaging, and a thermocouple.
Example 5Thirty-seven and a half grams of the 0.3175 cm (1/8 inch) diameter pills prepared as in Example 3 were burned in atest of the ventilated inflator in a 60-liter collection tank as described in Example 4, with the additional incorporation of a second sieve chamber containing 2 rises of a 30-mesh sieve and 2 rises of a sieve 18. The combustion produced a combustion chamber pressure of 140.74 kg / cm2 (2,000 psia) and a pressure of 2.74 kg / cm2 (39 psia) in the collection tank of 60 1. The temperature of the gases in the the collection tank reached a maximum of 670 ° K in 20 milliseconds. The analysis of the gases collected in the 60 1 tank showed a nitrogen oxides concentration (N0X) of 500 ppm and a carbon monoxide concentration of 1.825 ppm. The total expelled particulate material as determined by rinsing the tank with methanol and evaporating the rinsing material was found to be 1,000 mg.
Example 6The test of Example 4 was repeated except that the 60 1 tank was replaced with a 55 liter ventilated bag as typically employed in the driver side automotive inflator restraint devices. A combustion chamber pressure of 133.70 kg / cm2 (1,900 psia) was obtained whenThere was a complete inflation of the bag. An internal bag pressure of 0.14 kg / cm2 (2 psig) maximum was observed in approximately 60 milliseconds after ignition. The surface temperature of the bag was observed to remain below 83 ° C which is an improvement over the azide-based inflators, while the operation of the bag inflation is very typical of conventional systems.
Example 7The nitrate salt of the copper tetraamine was prepared by dissolving 116.3 g of copper (II) nitrate semipentahydrate in 230 ml of concentrated ammonium hydroxide and 50 ml of water. Once the resulting hot mixture has been cooled to 40 ° C, one liter of ethanol is added with stirring to the precipitate to give the tetraamine nitrate product. The dark blue-purple solid was collected by filtration, washed with ethanol, and dried with air. The product was confirmed to be Cu (NH3) 4 (N03) 2 by elemental analysis. The burn rate of this material as determined from the compressed 1.27 cm (0.5 inch) diameter pills was 0.4572 cm (0.18 inches) per second at 70.37 kg / cm2 (1,000 psig).
Example 8The copper tetraamine nitrate prepared in Example 7 was formulated with several supplemental oxidants and tested to verify the rate of burning. In all cases, 10 g of the material was converted to a suspension with approximately 10 ml of methanol, dried, and compressed into 1.27 cm (0.5 inch) diameter pills. The burn rates were measured at 70.37 kg / cm2 (1,000 psig), and the results are shown in the following table.
Example 9An amount of the hexaamine-cobalt (III) nitrate was prepared by replacing an ammonium chloride with the ammonium nitrate in the process to prepare the hexaamine-cobalt (III) chloride as taught by G.
Pass and H. Sutcliffe, Practical Inorganic Chemistry, 2 / a. Ed., Chapman & Hull, New York, 1974. The prepared material was determined to be [Co (NH3) 6] (N02) 3 by elemental analysis. A sample of the material was compressed into 1.27 cm (0.5 inch) diameter pills and a burn rate of 0.66 cm (0.26 inch) per second was measured at 140.74 kg / cm2 (2,000 psig).
Example 10The material prepared in Example 9 was used to prepare three batches of gas generant containing hexaamine-cobalt (III) nitrate as the fuel and ceric ammonium nitrate as the co-oxidant. The lots differ in the processing mode and in the presence or absence of additives. The burn rates were determined from 1.27 cm (0.5 inch) pills. The results are summarized below:Example 11The material prepared in Example 9 was used to prepare several mixtures of 10 g of the generant compositions using several supplementary oxidants. In all cases, the appropriate amount of hexaamine-cobalt (III) and the co-oxidant (s) were mixed in approximately 10 ml of methanol, allowed to dry, and compressed into 0.5-inch (1.27 cm) pills. diameter. The pills were tested to verify the burn rate at 70.37 kg / cm2 (1,000 psig), and the results are shown in the following table.
Example 12The binary compositions of hexaamine-cobalt (III) nitrate ("HACN") and several supplemental oxidants were combined in batches of 20 grams. The compositions were dried for 72 hours at 93.33 ° C(200 ° F) and compressed into 1.27 cm diameter pills(0.5 inches). Burning speeds were determined by burning the 1.27 cm (0.5 inch) pills at different pressures ranging from 70.37 to 281.48 kg / cm2 (1000-4000 psi). The results are shown in the following table.
Example 13A processing method was contemplated to prepare small parallelepipeds ("pps") of the gas generator at a laboratory scale. The equipment necessary to form and cut the pps included a cutting table, a cylinder or roller and a cutting device. TableCutting consisted of a sheet of 22.86 cm (9 inches) x 45.72 cm (18 inches) of metal with spacers of paper of 1.27 cm (0.5 inches) placed as tapes along the longitudinal edges. The spacers have a cumulative height of 0.109 cm (0.043 inches). The cylinder or roller consisted of a Teflon cylinder 0.3048 cm (1 foot) long, 5.08 cm (2 inches) in diameter. The cutting device consisted of a shaft, cutting blades and spacers. The shaft was of a 0.635 cm (0.25 inch) bolt on which a series of seventeen washers of 1.905 cm (0.75 inches) in diameter, 0.0127 cm (0.005 inches) thick, were placed as cutting blades. Between each of the cutting blades, four brass spacer washers of 1,676 cm (0.66 inches) in diameter, 0.508 cm (0.020 inches) in thickness were placed and the series of the washers were fixed or secured by means of a nut. The repetition distance between the circular cutting blades was 0.2159 cm (0.085 inches). A gas-generating composition containing a water-soluble binder was mixed dry and then batches of 50-70 g were mixed on a Spex mill / mixer for five minutes with sufficient water so that the material when mixed had a similar consistency to a pasta.
A sheet of plastic velostat (synthetic material) was placed by tapping the cutting table and the paste ball of the generator mixed with the water was crushed by hand on the plastic. A sheet of polyethylene plastic was placed on the generant mixture. The cylinder was placed parallel to the spacers on the cutting table and the paste was crushed to a width of approximately 12.7 cm (5 inches). The cylinder was then rotated 90 degrees, was placed on top of the spacers, and the paste was crushed to the maximum amount that the cutting table can allow. The polyethylene plastic was carefully detached from the generator and the cutting device was used to cut the dough both lengthwise and widthwise. The plastic sheet of synthetic material (velostat) on which the generator has been rolled and cut is defied from the cutting table and placed longitudinally on a cylinder of 10.16 cm (4 inches) in diameter in a convection oven at 57.22. ° C (135 ° F). After about 10 minutes, the sheet was taken from the oven and placed on a rod 1.27 cm (0.5 inch) in diameter, so that the two ends of the plastic sheet formed an acute angle with respect to the rod or rod. The plastic was moved back and forth on the rod or rod ofso that cuts between the parallelepipeds ("pps") open upwards. The sheet was placed across a 4-inch diameter cylinder in the convection oven at 57.22 ° C (135 ° F) and allowed to dry for another 5 minutes. The cuts were opened between the pps. above the diameter rod 1.27 cm (0.5 inches) as above. At this moment, it was quite easy to disengage the pps. of plastic. The pps. they were separated from each other additionally by rubbing them gently in a 0.568 liter cup (1 pint) or on screens of a 12 mesh screen. This method breaks the pps. in simple parts with some remaining double or double elements. The double elements were divided into simple elements by the use of a razor. The pps. They were then placed in a convection oven at 73.88-107.22 ° C (165-225 ° F) to dry them completely. The resistance to shock deformation (on the edge) of the pps. thus formed were typically as large as or greater than those of the 0.3175 cm (0.125 inch) diameter pills with a convex radius of 0.635 cm (0.25 inches) and a maximum height of 0.1778 cm (0.070 inches), which were formed on a rotating press. This is remarkable since the latter are three times as bulky as those.
Example 14A gas generating composition was prepared using hexaamine-cobalt (III) nitrate, [(NH3) 6Co] (N03) 3, powder (78.07%, 39.04 g), granules of ammonium nitrate (19.93%, 9.96 g), and ground polyacrylamide, MW 15 million (2.00%, 1.00 g). The ingredients were mixed dry in a Spex mill / mixer for one minute. Deionized water (12% dry weight of the formulation, 6 g) was added to the mixture which was mixed for an additional five minutes on the Spex mixer / mill. This led to a material with a pulp-like consistency which was processed in parallelepipeds (pps.) As in Example 13. Three additional batches of the generator were mixed and processed in a similar manner. The pps. of the four lots were combined. The dimensions of the pps. they were 0.132 cm (0.052 inches) x 0.1828 cm (0.072 inches) x 0.2133 cm (0.084 inches). The standard deviations on each of the dimensions were of the order of 0.0254 cm (0.010 inches). The average weight of the pps. it was 6.62 mg. The volumetric density, the density as determined by the displacement of the solvent, was determined to be 0.86 g / cc, 1.28 g / cc, and 1.59 g / cc, respectively. Resistance to impact deformation of 1.7 kg (on the narrowest edge)were measured with a standard deviation of 0.7 kg. Some of the pps. They were compressed into 1.27 cm (0.5 inch) diameter pills weighing approximately three grams. From these pills, it was determined that the burning rate will be from 0.13 ips to 70.37 kg / cm2 (1000 psi) with an exponent of the pressure of 0.78.
Example 15A simulator was constructed according to Example 4. Two grams of a stoichiometric mixture of Mg / Sr (N03) 2 / nylon lightener granules were placed in the igniter chamber. The diameter of the openings that extend towards the wall of the external combustion chamber was 0.476 cm (3/16 inches). Thirty grams of the generant described in Example 14 in the form of parallelepipeds were fixed or secured in the combustion chamber. The simulator was fixed to the 60 1 tank described in Example 4. After ignition, the combustion chamber reached a maximum pressure of 161.85 kg / cm2 (2300 psia) in 17 milliseconds, the 60 1 tank reached a maximum pressure of 2.39 kg / cm2 (34 psia) and the maximum tank temperature was 640 ° K. The levels of N0X, CO and NH3 were 20, 380,and 170 ppm, respectively, and 1600 mg of the particulate material were collected from the tank.
Example 16A simulator was constructed with exactly the same lighter and type of generator and load weight as in Example 15. In addition, the diameters of the outlet opening of the external combustion chamber are identical. The simulator was attached to an automotive safety bag of the type described in Example 4. After the ignition, the combustion chamber reached a maximum pressure of 140.74 kg / cm2 (2000 psia) in 15 milliseconds. The maximum pressure of the inflated airbag was 0.063 kg / cm2 (0.9 psia). This pressure was reached 18 milliseconds after power up. The maximum temperature of the surface of the bag was 67 ° C.
Example 17A gas generating composition was prepared using hexaamine-cobalt (III) nitrate powder (76.29%, 76.29 g), granules of ammonium nitrate (15.71%, 15.71 g, Dynamit Nobel, granule size: <350 microns), cupric oxide powder formed pyrometallurgically (5.00%, 5.00 g) and guar gum (3.00%, 3.00 g). Theingredients were mixed dry in a Spex mixer / mill for one minute. Deionized water (18% dry weight of the formulation, 9g) was added to 50 g of the mixture which was mixed for an additional five minutes on the Spex mixer / mill. This led to a material with a paste-like consistency which was processed in parallelepipeds (pps.) As in Example 13. The same process was repeated for the other 50 g of the dry blended generator and the two lots of the pps . They mixed together. The average dimensions of the pps. mixed were 0.1778 cm x 0.2057 cm x 0.2235 cm (0.70 x 0.081 x 0.088 inches). The standard deviations for each of the dimensions were of the order of 0.0254 cm (0.01 inches). The average weight of the pps. It was 9.60 mg. The volumetric density, the density as determined by dimensional measurements, and the density as determined by the displacement of the solvent were determined to be 0.96 g / cc, 1.17 g / cc, and 1.73 g / cc, respectively. Impact strengths of 5.0 kg (on the narrowest edge) were measured with a standard deviation of 2.5 kg. Some of the pps. They were compressed into pills weighing approximately three grams. From these pills the burn rate that is going to be 0.20 was determinedips at 70.37 kg / cm2 (1000 psi) with a pressure exponent of 0.67.
Example 18A simulator was constructed according to Example 4. One gram of a stoichiometric mixture of Mg / Sr (N03) 2 / nylon and two grams of slightly overoxidized B / KN03 lighter granules were combined and placed in the firing chamber. The diameter of the openings that leave the wall of the combustion chamber was 0.4216 cm (0.166 inches). Thirty grams of the generator described in Example 17 in the form of parallelepipeds were fixed or secured in the combustion chamber. The simulator was fixed to the 60 1 tank described in Example 4. After the ignition, the combustion chamber reached a maximum pressure of 178.74 kg / cm2 (2540 psia) in 8 milliseconds, the 60 1 tank reached a maximum pressure of 2,533 kg / cm2 (36 psia) and the maximum tank temperature was 600 ° K. The levels of NOx, CO, and NH3 were 50, 480, and 800 ppm, respectively, and 240 mg of the particulate material was collected from the tank.
Example 19A simulator was constructed with exactly the same lighter and type of generator and load weight as in Example 18. In addition the diameters of the outlet opening of the external combustion chamber were identical. The simulator was fixed to a car safety bag of the type described in Example 4. After the ignition, the combustion chamber reached a maximum pressure of 189.99 kg / cm2 (2700 psia) in 9 milliseconds. This pressure was reached 10 milliseconds after power up. The maximum surface temperature of the bag was 73 ° C.
Example 20A gas generating composition was prepared using hexaaminecobalt (III) powder (69.50%, 347.5 g), trihydroxy copper (II) nitrate, [Cu2 (OH) 3N03], in powder form (21.5%, 107.5 g), 10 microns of RDX (5.00%, 25 g), 26 microns of potassium nitrate (1.00%, 5 g) and guar gum (3.00%, 3.00 g). The ingredients were mixed dry with the aid of a 60 mesh screen. Deionized water (23% dry weight of the formulation, 15 g) was added to 65 g of the mixture which was mixed for an additional five minutes over theSpex mixer / mill. This led to a material with a paste consistency which was processed in parallelepipeds (pps.) As in Example 13. The same process was repeated for two additional batches of 65 g of the dry blended generator and the three batches of pps. They were mixed together. The average dimensions of the pps. were 0.1447 cm x 0.1981 cm x 0.2133 cm (0.057 x 0.078 x 0.084 inches). The standard deviations on each of the dimensions were of the order of 0.0250 cm (0.010 inches). The average weight of the pps. it was 7.22 mg. The volumetric density, the density as measured by the dimensional measurements, and the density as determined by the displacement of the solvents was determined to be 0.96 g / cc, 1.23 g / cc, and 1.74 g / cc, respectively. Resistance to impact deformation of 3.6 kg (on the narrowest edge) were measured with a standard deviation of 0.9 kg. Some of the pps. They were compressed into 1.27 cm (0.5 inch) diameter pills weighing approximately three grams. From these pills it was determined that the burn rate will be from 0.27 ips to 70.37 kg / cm2 (1000 psi) with an exponent of the pressure of 0.51.
Example 21A simulator was constructed according to Example 4. 1.5 grams of a stoichiometric mixture of Mg / Sr (N03) 2 / nylon and 1.5 grams of lightly over-oxidized B / KN03 lighter granules were combined and mixed in the ignition chamber. The diameter of the openings that go to the wall of the external combustion chamber was 0.4495 cm (0.177 inches). Thirty grams of the generant described in Example 20 in the form of parallelepipeds were fixed or secured in the combustion chamber. The simulator was fixed to the 60 1 tank described in Example 4. After ignition, the combustion chamber reached a maximum pressure of 214.62 kg / cm2 (3050 psia) in 14 milliseconds. The levels of NOx, CO, and NH3 were 25, 800, and 90 ppm, respectively, and 890 mg of the particulate material were collected from the tank.
Example 22A gas generating composition was prepared using a hexaamine-cobalt (III) powder (78.00%,457. 9 g), trihydroxy copper (II) nitrate powder (19.00%, 111.5 g), and guar gum (3.00%, 17.61 g). The ingredients were combined dry and then mixedwith water (32.5% dry weight of the formulation, 191 g) in a 0.568 1 (1 pint) Baker-Perkins mixer for 30 minutes. To a portion of the resulting wet cake (220 g), 9.2 grams of additional trihydroxy copper (II) nitrate and an additional 0.30 grams of guar gum were added as well as 0.80 g of carbon black (Monarch 1100). This new formulation was mixed for 30 minutes on a Baker-Perkins mixer. The wet cake was placed in a ram extruder with a barrel diameter of 5.08 cm (2 inches) and a diameter of the die orifice of 0.2295 cm (0.09038 inches). The extruded material was cut into lengths of approximately 0.3048 cm (1 foot), allowed to dry under ambient conditions overnight, placed in a closed container containing water to moisten and thus soften the material, cut it into lengths of approximately 0.254 cm (0.1 inches) and dry at 73.88 ° C (165 ° F). The dimensions of the resulting extruded cylinders were of an average length of 0.2870 cm (0.113 inches) and an average diameter of 0.2311 cm (0.091 inches). The volumetric density, the density as determined by the dimensional measurements, and the density as determined by the displacement of the solvent were 0.86 g / cc, 1.30 g / cc, and 1.61 g / cc, respectively. Resistors of impact deformation of 2.1 and 4.1kg were measured on the circumference and the axis, respectively. Some of the extruded cylinders were compressed into 1.27 cm (0.5 inch) diameter pills weighing approximately three grams. From these pills it was determined that the burn rate will be from 0.22 ips to 70.37 kg / cm2 (1000 psi) with an exponent of the pressure of 0.29.
Example 23Three simulators were constructed according to Example 4. 1.5 grams of a stoichiometric mixture of Mg / Sr (N03) 2 / nylon and 1.5 grams of lightly over-oxidized B / KN03 granules were mixed and placed in the igniter chambers. The diameter of the openings that extend to the wall of the external combustion chamber were 0.4495 cm (0.177 inches), 0.4216 cm (0.166 inches), and 0.3860 cm (0.152 inches), respectively. Thirty grams of the generator described in Example 22 in the form of extruded cylinders were fixed or secured in each of the combustion chambers. The simulators were, in succession, fixed to the 60 1 tank described in Example 4. After ignition, the combustion chambers reached a maximum pressure of 111.53, 117.16 and 133.7 kg / cm2 (1585, 1665, and 1900 psia) , respectively. The pressurestank maximums were 2.25, 2.39, and 2.46 kg / cm2 (32, 34, and 35 psia), respectively. The NOx levels were 85, 180, and 185 ppm while the CO levels were 540, 600, and 600 ppm, respectively. The NH3 levels were below 2 ppm. The levels of particulate materials were 420, 350, and 360 mg, respectively.
Example 24The addition of small amounts of carbon to the gas generating formulations has been found to improve the resistance to impact deformation of the parallelepipeds and extruded pills formed as in Example 13 or Example 22. The following table summarizes the improvement of the resistance to impact deformation with the addition of carbon to a typical gas generating composition within the scope of the present invention. All percentages are expressed as percent by weight.
Table 3Improvement of Resistance to Impact Deformation with the Addition of CoalHACN = hexaaminecobalt (III) nitrate, [(NH3) 6Co] (N03) 3, (Thiokol) CTN = trihydroxy copper (II) nitrate, [Cu2 (OH3) N03](Thiokol) Guar = guar gum (Aldrich) Carbon = carbon black "Monarch 1100" (Cabot) EP = extruded pill (see Example 22) pps. = parallelepipeds (see Example 13) Resistance = resistance to impact deformation of the pps. or pills extruded in kilograms.
Example 25The hexaamine-cobalt (III) nitrate was compressed into four-gram pills with a diameter of 1.27 cm (0.5 inches). One half of the pills were weighed and placed in an oven at 95 ° C for 700 hours. After aging, the pills were weighed again. No weight loss is observed. The burning rate of the pills maintained at room temperature was 0.16 ips to 70.37 kg / cm2 (1000 psi) with a pressure exponent of 0.60. The burn rate of the pills maintained at 95 ° C for 700 hours was from 0.15 to 70.37 kg / cm2 (1000 psi) with a pressure exponent of 0.68.
Example 26A gas generating composition was prepared using hexaamine cobalt (III) nitrate powder (76.00%, 273.6 g), trihydroxy copper (II) nitrate powder (16.00%, 57.6 g), 26 micras of potassium nitrate (5.00% , 18.00), and guar gum (3.00%, 10.8 g). Deionized water (24.9% dry weight of the formulation, 16.2 g) is added to 65 g of the mixture which was mixed for about five additional minutes on the Spex mixer / mill. This led to a material with apaste-like consistency, which was processed in parallelepipeds (pps.) as in Example 13. The same process was repeated for the other batches of 50-65 g of the dry blended generator and all of the lots of pps. They were mixed together. The average dimensions of the pps. they were 0.1651 cm x 0.1879 cm x 0.2082 cm (0.065 x 0.074 x 0.082 inches). The standard deviations on each of the dimensions were of the order of 0.0127 cm (0.0005 inches). The average weight of the pps. It was 7.42 mg. The volumetric density, the density as determined by the dimensional measurements, and the density as determined by the displacement of the solvent, were determined to be 0.86 g / cc, 1.15 g / cc, and 1.68 g / cc, respectively . Resistance to impact deformation of 2.1 kg (on the narrowest edge) was measured with a standard deviation of 0.3 kg. Some of the pps were compressed into ten 1.27 cm pills(0.5 inches) in diameter weighing approximately three grams. Approximately 60 g of pps. and five 1.27 cm (1/2 inch) diameter pills were placed in an oven maintained at 107 ° C. After 450 hours at this temperature, losses of 0.25% and 0.41% of weight were observed for the pps. and the pills, respectively. The rest of the pps. and the pills were stored under ambient conditions. Speed dataBurned were obtained from both sets of pills and are summarized in Table 4.
Table 4Comparison of Burning Speed Before and After Accelerated AgingConditions of Burning SpeedExponent of Storage at 70.37 kg / cm1 pressure 24-48 hours e 0. 1S ips 0.72 temp.amb. 450 hours at 107 ° C 0.15 ips 0.70Example 27Two simulators were constructed according to Example 4. In each ignition chamber, a combined mixture of 1.5 g of a stoichiometric mixture of Mg / Sr (N03) 2 / nylon and 1.5 grams of the lightly blended B / KN03 lightener granules was placed. The diameter of the openings that go to the wall of the external combustion chamber in each simulator were 0.4495 cm (0.177 inches). Thirty grams of the aged generator at ambient conditions described in Example 26 in the form of parallelepipeds were fixedor insured in the combustion chamber of a simulator while 30 grams of the pps. Generants aged at 107 ° C were placed in the other combustion chamber. The simulators were attached to the 60 1 tank described in Example 4. The results of ignition or test fire are summarized in Table 5 given below.
Table 5Results of the Test Start for the Aged GenerantExample 28A mixture of 2 Co (NH3) 3 (N02) 3 and Co (NH3) 4 (N02) 2Co (NH3) 2 (N02) was prepared and compressed into a pill having a diameter of approximately 1.28 cm (0.504 inches) . The complexes were preparadwithin the scope of the teachings of Hagel, et al, reference indicated above. The pill was placed in a test pump, which was pressurized to 70.37 kg / cm2 (1,000 psi) with nitrogen gas. The pill was ignited with a hot wire and the burn rate was measured and it was observed that it will be 0.965 cm (0.38 inches) per second. The theoretical calculations indicated a flame temperature of 1805 ° C. From theoretical calculations, it has been predicted that the main products of the reaction would be solid CoO and gaseous reaction products. The main gaseous reaction products were predicted to be as follows:Product Volume%H20 57. 9 N2 38. 6 02 3. 1Example 29An amount of Co (NH3) 3 (N02) 3 was prepared according to the teachings of Example 1 and was tested using differential scanning calorimetry. HEobserved that the complex product produced a vigorous exotherm at 200 ° C.
Example 30Theoretical calculations were made for Co (NH3) 3 (N02) 3. These calculations indicated a flame temperature of approximately 2,000 ° K and a gas yield of about 1.75 times that of a composition that generates sodium azide gas, conventional, based on an equal volume of the generation composition ("operating relationship"). The theoretical calculations were also made for a series of compositions that generate gas. The data of the composition and theoretical operation are described in Table 6 below.
Table 6The operating ratio is a normalized ratio for a unit volume of the gas generator based on sodium azide. The theoretical gas yield for a typical sodium azide-based gas generator (68% by weight of NaN3, 30% by weight of MoS2, 2% by weight of S) is approximately 0.85 g gas / cc of NaN3 generant.
Example 31Theoretical calculations were carried out on the reaction of [Co (NH3) 6] (C104) 3 and CaH2 as listed in Table 6 to evaluate its use in a hybrid gas generator. If this formulation is allowed to undergo combustion in the presence of 6.80 times its weight in argon gas, the temperature of the flame decreases from 2577 ° C to 1085 ° C, assuming a 100% efficiency of heat transfer. The exhaust gases consist of 86.8% by volume of argon, 1600 ppm by volume of hydrogen chloride, 10.2% by volume of water, and 2.9% by volume of nitrogen. The weight of the total slag would be 6.1% by mass.
Example 12The complexes of pentaamine-cobalt nitrate(III) were synthesized, which contain acommon ligand in addition to NH3. Acuopentaaminecobalt (III) nitrate and pentaaminecarbonatecobalt (III) nitrate were synthesized according to Inorg. Syn., Vol. 4, p. 171 (1973). Pentaaminehydroxocobalt (III) nitrate was synthesized according to H.J.S. King, J. Chem. Soc, p. 2105 (1925) and O. Schmitz, et al, Zeit. Anorg. Chem., Vol. 300, p. 186 (1959). Three sets or batches of the gas generant were prepared using the pentaamine-cobalt (III) nitrate complexes described above. In all cases guar gum was added as a binder. Trihydroxy copper (II) nitrate, [Cu2 (OH) 3N04], was added as the co-oxidant where necessary. Burning speeds were determined from burning pill of 1.27 cm (0.5 inch) in diameter. The results are summarized in Table 7.
Table 7Formulation Containing [Co (NH3) 5X] (N0) 3Brief Description of the InventionIn summary, the present invention provides gas generating materials that overcome some of the limitations of conventional azide-based gas-generating compositions. The complexes of the present invention produce non-toxic gaseous products that include water vapor, oxygen, and nitrogen. Certain of the complexes are also capable of efficient decomposition to a metal or metal oxide, and nitrogen and water vapor. Finally, the reaction temperatures and burn rates are within acceptable ranges.
It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.
Having described the invention as above, property is claimed as contained in the following