JP2008518872A - Gas generant and production method thereof - Google Patents

Abstract

An exemplary gas generating device (10) includes a gas generating composition (12) comprising polyvinyl azole. The gas generation system (200) includes polyvinyl azole therein. The vehicle occupant protection system (180) incorporates a gas generation system (200).

Description

TECHNICAL FIELD The present invention relates generally to gas generant systems and gas generant compositions used in gas generators, eg, for automotive restraint systems.

BACKGROUND OF THE INVENTION The present invention relates to a non-toxic gas generant composition that rapidly produces a gas useful for inflating a safety restraint for an automobile occupant upon combustion. Also, in particular, the present invention is a thermally stable non-azide gas generant that has a relatively high gas volume and solid particulates at an acceptable flame temperature as well as an acceptable combustion rate upon combustion. It relates to a composition showing a ratio.

  The transition from azide-based gas generants to non-azide gas generants is well documented in the prior art. The advantages of non-azide gas generant compositions as compared to azide gas generants are, for example, U.S. Patent Nos. 4,370,181; 4,909,549; 4,948,439; 5,084,118; 5. , 139, 588 and 5,035,757. These patents are referenced and incorporated as part of this specification.

  In addition to fuel components, pyrotechnic non-azide gas generants provide the oxygen required for rapid combustion and oxidants, toxic oxidation of carbon and nitrogen to reduce the amount of toxic gases produced Catalyst, which promotes the conversion of products into harmless gases, and components such as slag forming components that agglomerate solid and liquid products formed during and immediately after combustion into filterable clinker particulates It is out. Other optional additives such as burn rate improvers or ballistic improvers, and ignition aids are used to control the ignition and combustion characteristics of the gas generant.

  One of the disadvantages of known non-azide gas generant compositions is the amount and physical nature of the solid residue formed during combustion. When used in a vehicle occupant protection system, the solids produced as a result of combustion must be filtered or otherwise kept out of contact with the vehicle occupant. It is therefore highly desirable to develop a composition that minimizes the production of solid particulates while providing a large amount of non-toxic gas suitable for inflating safety devices at high speeds.

  For example, it is preferable to use phase stabilized ammonium nitrate as the oxidant. This is because it produces abundant non-toxic gases and minimal amounts of solids on combustion. However, in order to be useful, gas generants for automotive applications must be thermally stable when aged at 107 ° C. for 400 hours or more. The composition must also retain structural integrity when cycled between -40 ° C and 170 ° C. Further, gas generant compositions that incorporate phase stabilized or pure ammonium nitrate sometimes exhibit poor thermal stability, depending on the composition of the accompanying additives such as plasticizers and binders, It produces unacceptably large amounts of toxic gases such as CO and NOx. Furthermore, recent revisions to automotive requirements in the US require a minimum amount of ammonia in the effluent gas.

  Another problem that must be addressed is that US Department of Transportation (DOT) regulations require a “cap test” for gas generants. Because of the sensitivity to explosions of fuels often used with ammonium nitrate, such as triaminoguanidine nitrate, many propellants that incorporate ammonium nitrate will not pass the cap test unless it is made into a large disk, which in turn is the inflator's Reduce design flexibility.

  Another concern relates to the slower cold start ignition of typical smokeless gas generant compositions, which are gas generant compositions that result in less than 10% solid combustion products.

  Thus, ongoing efforts in the design of automotive gas production systems are devoted, for example, to those that do not have the disadvantages mentioned above, produce more gas and produce less solids.

SUMMARY OF THE INVENTION The above problems are solved by a gas generating system comprising a gas generating composition comprising an extrudable polyvinyl azole fuel such as polyvinyl tetrazole, polyvinyl triazole or polyvinyl diazole. Preferred oxidizing agents include non-metallic oxidizing agents such as ammonium nitrate and ammonium perchlorate. Other oxidizing agents include alkali metal nitrates and alkaline earth metal nitrates.

  The fuel is selected from the group of polyvinyltetrazoles, polyvinyltriazoles, polyvinyldiazoles or polyvinylfurazanes and mixtures thereof. An exemplary group of fuels includes polymeric tetrazoles, triazoles, and oxadiazoles (furazanes) that have functional groups on the azole pendant group. Preferred vinyltetrazoles include 5-amino-1-vinyltetrazole and poly (5-vinyltetrazole), both of which exhibit self-propagating pyrolysis. Other fuels include poly (2-methyl-5-vinyl) tetrazole, poly (1-vinyl) tetrazole, poly (3-vinyl) 1,2,5-oxadiazole, and poly (3-vinyl) 1 2,4-triazole. These and other possible fuels are illustrated in structure in the figures included herein. Depending on the design criteria of the gas generant composition and the starting reagents for the synthesis of the polyvinyl azole, the polyvinyl azole may exhibit aromatic character within the pendant or polymer backbone. In the present invention, the fuel typically comprises 5-40% by weight of the gas generant composition.

  The oxidant is preferably selected from the group of non-metal, alkali metal and alkaline earth metal nitrates and mixtures thereof. Nonmetallic nitrates include ammonium nitrate and phase stabilized ammonium nitrate stabilized by known techniques. Examples of alkali metal and alkaline earth metal nitrates include potassium nitrate and strontium nitrate. The use of other oxidants known for their usefulness in airbag gas generant compositions is also contemplated. In the present invention, the oxidant typically comprises 60-95% by weight of the gas generant composition.

  Other gas generant components known for their usefulness in airbag gas generant compositions can be used in effective amounts in the compositions of the present invention. These include, but are not limited to, coolants, slag formers, and ballistic modifiers known in the art.

  In summary, the present invention provides a gas generant composition that maximizes gas combustion products and minimizes solid combustion products while retaining other design requirements such as thermal stability. Including. These and other advantages will be apparent from the detailed description.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention relates generally to gas generant compositions for inflators of occupant restraint systems. In accordance with the present invention, a pyrotechnic composition includes an extrudable fuel such as polyvinyltetrazole (PVT) for use in a gas generation system, for example, a high gas yield vehicle occupant protection system. Illustrated as an air bag propellant in an automobile. The fuel further functions as a binder. Preferred oxidizing agents include non-metallic oxidizing agents such as ammonium nitrate and ammonium perchlorate. Other oxidizing agents include alkali metal and alkaline earth metal nitrates.

  The fuel is selected from the group of polyvinyltetrazoles, polyvinyltriazoles, polyvinyldiazoles or polyvinylfurazanes and mixtures thereof. An exemplary group of fuels includes polymeric tetrazoles, triazoles and oxadiazoles (furazanes) optionally having functional groups on the azole pendant group. Vinyltetrazoles include 5-amino-1-vinyltetrazole and poly (5-vinyltetrazole), both of which exhibit self-propagating pyrolytic properties. Other fuels include poly (2-methyl-5-vinyl) tetrazole, poly (1-vinyl) tetrazole, poly (3-vinyl) 1,2,5-oxadiazole, and poly (3-vinyl) 1, 2,4-triazole is exemplified. These and other possible fuels are illustrated by the structural formulas shown below, but are not limited thereto.

  Additional benefits have been found for including the fuel of the present invention. It is to avoid difficult cold start ignitions that require a stronger series of ignitions and boosters. For example, poly (5-amino-1-vinyl) tetrazole has no endothermic process before decomposition with exotherm begins. Thus, the heat consumption process that normally accompanies the combustion heat dissipation process, which serves as an energy barrier, is absent in the compositions of the present invention. Other polymeric azoles that function as fuels in the present invention are believed to have the same benefits. In the present invention, the total fuel component of the polyvinyl azole fuel or gas generant composition typically comprises 5-40% by weight of the gas generant composition.

  The oxidant is preferably selected from the group of non-metal and alkali metal and alkaline earth metal nitrates and mixtures thereof. Nonmetallic nitrates include ammonium nitrate and phase stabilized ammonium nitrate stabilized by known techniques. Examples of alkali metal and alkaline earth metal nitrates include potassium nitrate and strontium nitrate. In contrast to many other known compositions comprising unstabilized ammonium nitrate and / or phase stabilized ammonium nitrate, compositions comprising phase stabilized ammonium nitrate according to the present invention provide sufficient thermal stability. Showing gender. The use of other oxidants known for their usefulness in airbag gas generant compositions is also contemplated. However, the oxidizers of the present invention must provide an overall oxygen balance within the combustion reaction in order to minimize the production of carbon monoxide (CO) and nitrogen oxides (NOx). For example, the gas generated upon combustion of gas generants in a vehicle occupant restraint system must minimize or not generate these toxic gases. The oxygen balance in the present invention determined for the oxidant is provided in the range of -4.0% to + 4.0%. For example, in gun propellants, the oxygen balance is such that carbon monoxide is obtained upon combustion of each gun propellant, thereby providing the lowest possible molecular weight gas. In the present invention, the oxidizer or total oxidizer component typically comprises 60-95% by weight of the gas generant composition.

  Other gas generant components known for their usefulness in airbag gas generant compositions can be used in effective amounts in the compositions of the present invention. These include, but are not limited to, coolants, slag formers, and ballistic modifiers known in the art.

  The gas generant components of the present invention are supplied by suppliers known in the art and are preferably mixed by a wet process. Typical known suppliers include Aldrich or Fischer Chemical. The solvent chosen in relation to the polymer fuel substituents is heated to a temperature sufficient to dissolve the fuel, but below the boiling point, for example, just below 100 ° C. However, the ingredients are added and brought to a temperature low enough to prevent the ingredients from self-igniting when subsequently precipitated. Hydrophilic groups can be more efficiently dissolved, for example, by using water as a solvent. Other groups can be more efficiently dissolved in acidic solutions such as nitric acid. Other solvents include alcohols and plasticizers such as polyethylene glycol. Once a suitable solvent is selected and heated, the fuel is slowly added and dissolved. Thereafter, the oxidant is slowly added and at least partially dissolved. Other desirable ingredients are dissolved as well. The solution is heated and continuously stirred. The solvent is boiled off and the fuel and oxidant and other components are co-condensed in a homogeneous solid solution. Once the solvent has been at least substantially evaporated off, more preferably completely evaporated, heating of the condensate is stopped. The composition can then be extruded into pellets or other useful shapes.

  Polymeric fuels can be produced by known processes. For example, the vinylation of tetrazole with vinyl acetate and subsequent polymerization is described in Vereshchagin et al. Org. Chem. USSR (English translation) 22 (9), 1777-83 (1987). The synthesis of various vinyltetrazoles is also described in Russian Chemical Reviews 72 (2), pages 143-164, (2003), which is referenced as part of this specification. The methyl group of the starting tetrazole can be exchanged for an amino group. The vinyl tetrazole is then polymerized using a common polymerization initiator such as azoisobutyronitrile (AIBN). It is believed that similar vinylation of furazane and triazole will give the polyvinyl diazole and polyvinyl triazole of the present invention. The exemplary reactions shown below illustrate how various polyvinyl diazoles, polyvinyl triazoles and polyvinyl tetrazoles are formed. Reaction 1 illustrates a method for forming polyvinyl diazoles. Reaction 2 illustrates a method for forming polyvinyltriazoles. Reaction 3 illustrates a method for forming polyvinyltetrazoles.

Reaction 1:
This synthesis relates to poly (vinyl-1,2,5-oxadiazole) and is an example of a general method or blueprint for forming polyvinyl diazoles.

Reaction 2:
This synthesis relates to the ionic polymer poly (vinyl-1,2,4-triazole) and is an example of a general method or blueprint for forming polyvinyltriazoles.

式中、Ｒ＝ＣＨ_３、ＮＨ_２など

In the formula, R = CH ₃ , NH _{2 and the} like

Reaction 3:
This synthesis is for substituted polyvinyltetrazole and is an example of a general method or blueprint for forming polyvinyltetrazoles.

  The general polyvinylazole or structure representing the present invention polyvinyltetrazole, polyvinyltriazole and polyvinyldiazole can be represented by the following five-membered aromatic ring.

  The five-membered ring should contain at least two nitrogen atoms, no more than one oxygen atom, and at least one carbon atom.

  In other words, the aromatic ring contains from zero to one oxygen atom, at least two nitrogen atoms, and at least one carbon atom. More preferably, the gas generant composition of the present invention will comprise a polymeric azole and phase stabilized ammonium nitrate. The advantages are high gas yields and low solids production, high energy fuel / binders, and inexpensive oxidizers, thereby reducing the need for gas filtration required when any solid material is produced on combustion. It can be avoided. The composition of the present invention is given the flexible nature of a polymeric fuel and is extrudable.

  The gas generant composition of the present invention can further include a second fuel formed from amine salts of tetrazole and triazole. These are illustrated and described in commonly owned U.S. Pat. Nos. 5,872,329, 6,074,502, 6,210,505 and 6,306,232, which are incorporated herein by reference. Is done. The total weight percent of the first and second fuels or the fuel component of the composition of the present invention is about 10 to 40 weight percent of the total gas generant composition. As shown in the data given in FIGS. 3 and 4, the use of a second fuel provides a burning rate that increases as the pressure increases.

More particularly, the non-metal salts of tetrazole and triazole are in particular the amine, amino and amide salts of tetrazole and triazole, selected from: 5,5′-bis-1H— Monoguanidinium salt of tetrazole (BHT · 1GAD), diguanidinium salt of 5,5′-bis-1H-tetrazole (BHT · 2GAD), monoaminoguanidinium salt of 5,5′-bis-1H-tetrazole ( BHT · 1AGAD), diaminoguanidinium salt of 5,5′-bis-1H-tetrazole (BHT · 2AGAD), monohydrazinium salt of 5,5′-bis-1H-tetrazole (BHT · 1HH), 5 , 5′-bis-1H-tetrazole dihydrazinium salt (BHT · 2HH), 5,5′-bis-1H-tetrazole Monoammonium salt (BHT _· 1NH 3), 5,5'- bis -1H- diammonium salt of tetrazole (BHT _· 2NH 3), 5,5'-bis -1H- tetrazole mono-3-amino-1 , 2,4-triazolium salt (BHT · 1ATAZ), di-3-amino-1,2,4-triazolium salt of 5,5′-bis-1H-tetrazole (BHT · 2ATAZ), and 5,5′- Diguanidinium salt of azobis-1H-tetrazole (ABHT · 2GAD).

Examples of the amine salt of triazole include the following: mono-ammonium salt of 3-nitro-1,2,4-triazole (NTA · 1NH ₃ ), monoguanidinium salt of 3-nitro-1,2,4-triazole (NTA · 1GAD), diammonium salt of dinitrobitriazole (DNBTR · 2NH ₃ ), diguanidinium salt of dinitrobitriazole (DNBTR · 2GAD), and monoammonium salt of 3,5-dinitro-1,2,4-triazole (DNTR · 1NH ₃ ).

The generic tetrazole non-metal salt as shown in Formula I includes a cationic nitrogen-containing component Z and an anionic component comprising a tetrazole ring and an R group substituted at the 5-position of the tetrazole ring. . The generic triazole non-metal salt as shown in Formula II comprises a cationic nitrogen-containing component Z and an anion comprising a triazole ring and two R groups substituted at the 3- and 5-positions of the triazole ring. Contains sexual components. Here, R ₁ may or may not be structurally similar to R ₂ . The R component can be selected from hydrogen or any nitrogen-containing compound, such as amino, nitro, nitroamino, or a tetrazolyl or triazolyl group as shown in formula I or II, respectively, directly or as an amine, diazo or triazo Substituted through a group. Compound Z is substituted at the 1-position in either formula and is formed from the group comprising amines, aminos, and amides; ammonia, carbohydrazide, oxamic hydrazide, and hydrazine; guanidine compounds such as guanidine, aminoguanidine, Diaminoguanidine, triaminoguanidine, dicyandiamide and nitroguanidine; nitrogen-substituted carbonyl compounds or amides such as urea, oxamide, bis- (carbonamido) amine, azodicarbonamide, and hydrazodicarbonamide; and aminoazoles such as 3-amino-1,2,4-triazole, 3-amino-5-nitro-1,2,4-triazole, 5-aminotetrazole, 3-nitroamino-1,2,4-triazole, 5-nitroamido Tetrazole and melamine are included.

Example 1:
The gas generant composition of the present invention is formed by first synthesizing polyvinyl tetrazole. The generic substituted tetrazole and vinyl acetate are combined to vinylate the tetrazole. The vinylated tetrazole was added to a molar equivalent of mercury acetate and boron trifluoride etherate and polymerized. The resulting product can be separated, for example, by oil distillation. The illustrated polyvinyltetrazole can be formed in the same way. Reaction 3 illustrates the above process.

Example 2:
The gas generant composition of the present invention is formed by first synthesizing polyvinyl triazole. The generic substituted triazole metal or non-metal salt is added to a molar equivalent of a free radical bromination reagent such as n-bromo-succinamide, and a benzoyl peroxide free radical initiator to form a brominated triazole. To do. The brominated triazole is then added to triphenylphosphine to form a Wittig base on the substituted triazole salt. The triazole salt is then added to a metal or non-metallic organic or inorganic base and formaldehyde to form a vinylated triazole salt. The vinylated triazole salt is then added to a free radical polymerization reagent such as azoisobutyronitrile and a catalytic amount of a cationic polymerization reagent or a Ziegler-Natta catalyst such as a metal or titanium complex. Reaction 2 illustrated the above process and described the synthesis of poly (vinyl-1,2,4-triazole).

Example 3:
The gas generant composition of the present invention is formed by first synthesizing polyvinyl diazole. Alkenol containing two —OH groups is added to acetic anhydride to form a substituted diazole. The substituted diazole is then added to a molar equivalent of a free radical bromination reagent such as n-bromo-succinamide and a free radical initiator such as benzoyl peroxide to form the brominated diazole. The substituted diazole is then added to triphenylphosphine to form a Wittig base on the substituted diazole salt. The diazole salt is then added to a metal or non-metallic organic or inorganic base and formaldehyde to form a vinylated diazole salt. The vinylated diazole salt is then added to a free radical polymerization reagent such as azoisobutyronitrile and a Ziegler-Natta catalyst such as a catalytic amount of a cationic polymerization reagent or a metal complex. Reaction 1 illustrates the above reaction and describes the synthesis of poly (vinyl-1,2,5-oxadiazole).

Example 4-9:
Examples 4-9 are shown in the following table, where different types and amounts of gas are produced and compared for several known gas generant compositions and the gas generant compositions of the present invention. Example 4 is a representative gas generant composition formed from 5-aminotetrazole and strontium nitrate according to US Pat. No. 5,035,757, which is incorporated by reference and incorporated herein. Example 5 is a tetrazole amine salt, phase stable, such as diammonium salt of 5,5′-bi-1H-tetrazole, according to US Pat. No. 6,210,505, which is incorporated herein by reference. A typical gas generant composition formed from oxidized ammonium nitrate, strontium nitrate and clay. Example 6 is a tetrazole amine salt, such as a diammonium salt of 5,5′-bi-1H-tetrazole, according to US Pat. No. 5,872,329, which is incorporated by reference and incorporated herein by reference. 2 is a representative gas generant composition formed from stabilized ammonium nitrate. Example 7 is a representative gas generant composition formed from ammonium nitroamine tetrazole and phase stabilized ammonium nitrate according to US Pat. No. 5,872,329, which is referenced and incorporated herein. is there. Example 8 is a representative gas formed from ammonium nitroamine tetrazole, phase-stabilized ammonium nitrate, and a slag former according to US Pat. No. 5,872,329, which is incorporated by reference and incorporated herein. The resulting composition. Example 9 is an exemplary gas generant composition of the present invention formed from 15 wt% ammonium polyvinyltetrazole and 85 wt% phase stabilized ammonium nitrate (ammonium nitrate was co-condensed with 10% potassium nitrate). It is.

  Table 1 shows the produced carbon monoxide (CO), ammonia (NH 3), nitric oxide (NO) and nitrogen dioxide (NO 2) production (ppm) and the amount of gas produced for each example. Number (g) is shown. All examples were burned in a gas generator of substantially the same design.

  The data collected shows that the composition of Example 9 formed in accordance with the present invention provides much lower ammonia than the 35 ppm industry standard and much less than the other examples. It has been found that the composition of the present invention provides a substantially lower amount of ammonia compared to other known gas generants. For many known gas generant compositions, it is often difficult to reduce the total amount of ammonia produced during combustion while maintaining other performance criteria in place.

Examples 10-14:
Theoretical examples 10-14 are shown in the following table, and different types and amounts of gas are compared for several gas generant compositions formed in accordance with the present invention. All phase-stabilized ammonium nitrate (PSAN 10) mentioned in Table 2 was all stabilized by 10% by weight potassium nitrate of the total weight of PSAN. All examples use ammonium poly (C-vinyltetrazole) (APV) as the primary fuel. In a specific example, a non-metallic diammonium salt of 5,5′-bis-1H tetrazole (BHT.2NH3) is used as a secondary fuel. All examples reflect results obtained by combustion of gas generant components (propellant compositions) performed in inflators of similar design or in equivalent heat sink design gas generators.

  Example 10 was found to be thermally stable with only 0.5% mass loss at 400 ° C. for 400 hours. Thus, Example 10 illustrates the unexpected thermal stability of the gas generant composition of the present invention, specifically stabilized with polyvinyl azole and phase stabilized ammonium nitrate (10% potassium nitrate as defined herein). Illustrates the unexpected thermal stability of It should be emphasized that the use of other phase stabilizers as known in the art or recognized in the art is also contemplated.

  Examples 11 to 13 illustrate the use of a metal oxidant and polyvinyl azole. In certain applications, the use of a metal oxidant may be desired for optimization of ignitability, burn rate index, gas generant burn rate, and other design criteria. The example shows that the more metal oxidants are used, the less the number of moles of gas produced upon combustion.

  In contrast, Examples 10 and 14 illustrate that the maximum number of moles of gaseous combustion products is maximized when non-metallic gas generant components are used. Accordingly, preferred gas generant compositions of the present invention comprise at least one polyvinyl azole as a fuel component and a non-metallic oxidant as an oxidant component.

  Finally, with respect to Example 14, the addition of another non-metallic fuel (BHT.2NH3) to APV and PSAN 10 increases the gas generant burn rate, thereby optimizing the combustion profile of the gas generant composition. It was found that it was possible. The burn rate for Example 14 was recorded at 1.2 inches per second at 5500 psi. Thus, it can be concluded that the addition of non-metallic amine salts of tetrazole and / or non-metallic amines of triazole, as described in 5,872,329, is advantageous with respect to combustion rate and gas production. Furthermore, the flexible nature of APV provides extrudability to the propellant composition. As shown in FIGS. 3 and 4, the addition of a second fuel as described above results in an increased combustion rate with increasing combustion pressure. FIG. 3 illustrates the burn rate as a function of pressure for a formulation containing only polyvinyltetraazole and phase stabilized ammonium nitrate. In contrast, FIG. 4 shows the pressure of a similar composition of FIG. 3 comprising polyvinyltetraazole and phase-stabilized ammonium nitrate with the addition of di-ammonium BHT according to the weight percent ranges described herein. Illustrates the burning rate for. It is concluded that the addition of the second fuel described herein has a significant effect on the combustion rate. The practical effect is the reproducibility of the performance of the produced gas generant and improved ballistic properties.

Examples 15 and 16:
Examples 15 and 16 illustrate the cold start effect of a gas generant composition containing polyvinyl azole. As shown by differential scanning calorimetry (DSR), typical smokeless or non-metallic compositions may exhibit a tendency to endotherm prior to combustion with exotherm. As a result, a relatively larger amount of energy must be used to ignite the gas generant and maintain its combustion. Often, a stronger series of ignition means, possibly including a stronger booster composition, is required to reach the energy level necessary to ignite the gas generant and maintain combustion. Example 15 includes 65% PSAN10 and about 35% BHT. It relates to a composition comprising 2NH3. As shown by the DSC test, the endotherm was maximized at 253.12 ° C. and a heat loss of about 508.30 joules per gram of gas generant was recorded. In contrast, Example 16 relates to a composition comprising about 15% poly (C-vinyltetrazole) and about 85% PSAN10. Unexpectedly, there is no endothermic process as shown by DSC. Accordingly, the combustion proceeds in a manner that is not suppressed. As a result, less energy is required to burn the gas generant composition, thus reducing the requirements for a series of ignition means, ignitions and boosters.

Example 17:
Another advantage of the present invention is illustrated in FIGS. FIG. 5 illustrates the baseline or pre-aging combustion of a gas generant composition made in accordance with the present invention in a modern gas generator. Specifically, the gas generant composition contained 80.6% PSAN, 8.0% PVT and 11.4% BHT-2NH3. On the other hand, FIG. 6 illustrates the combustion after aging of the same gas generant composition in the same gas generator. The curves shown in FIGS. 5 and 6 show the standard driver side in a 60 liter ballistic tank at “hot” or + 85 ° C., “ambient” or 23 ° C., and “cold” or −40 ° C. It relates to the development of inflators. As shown, there is no significant difference between the combustion profiles in the pre-aging and post-aging operations of the gas generant when deployed at three different temperatures. The USCAR standard for “accelerated aging” is 400 hours at 107 ° C. Typically, many car manufacturers around the world require similar aging standards.

  In another aspect of the present invention, the composition of the present invention can be used in a gas generating system. For example, as schematically shown in FIG. 2, a vehicle occupant protection system made in a known manner includes an airbag inflator in the steering wheel, and a collision sensor electrically connected to the seat belt assembly. Contains. The gas generant composition of the present invention can be used as a subassembly of a wider vehicle occupant protection system or within a gas generant system. More particularly, each gas generating device used in an automobile gas generating system can include a gas generating composition as described herein.

  An exemplary gas generant composition includes 5-40% poly (c-vinyltetrazole) as a fuel / binder, more preferably 5-20%. Of course, the weight percentages of each component listed below are applicable to any polyvinyl azole incorporated into the present invention. A variety of poly (c-vinyltetrazoles) can be made by the aqueous manufacturing methods described below. Alternatively, a fuel / binder poly (c-vinyltetrazole) can be formed, for example, as described in US Pat. No. 3,096,312 which is referenced and incorporated herein. Polyvinyltetraazole salts can be metal salts or non-metal salts, but non-metal salts are preferred for the production of more gas and less solids.

  The functionality of the polymer is illustrated by the PVT acid form diagram above. The pseudo-allylic carbon at position 1 of the backbone can be functionalized with a nitro or nitroso group. This position can be functionalized with anything that does not make the oxygen balance more negative or adds a source of fuel. This position can be functionalized with any group to increase its properties (ie plasticity), such as vinyl groups for crosslinking (curing). Nitrogen at the 2-position is acidic with the desired pKa between 3-5. Bound hydrogen can therefore be removed with a mild base, leaving an aromatic tetrazole ring anion. Any suitable base can be used to make a water soluble salt of the polymer as provided in the aqueous methods described below. This position can be functionalized with any group that does not make the oxygen balance more negative or adds a source of fuel. This position can be functionalized with any group to impart desirable material properties, such as vinyl groups for crosslinking. The first oxidant includes phase stabilized ammonium nitrate, potassium nitrate, nitrates of alkaline earth metals such as strontium nitrate; nitrites such as potassium nitrite; chlorates such as potassium chlorate; From the group comprising perchlorates such as potassium chlorate; oxides such as iron oxide and copper oxide; basic nitrates such as basic copper nitrate and basic iron nitrate; and mixtures thereof or combinations thereof Selected. The oxidant component of the present invention typically constitutes 60-95% of the total composition.

  The second fuel can be selected from the amine salts of tetrazoles and triazoles as described above, and for example tetrazoles such as 5-aminotetrazole, azoles such as triazoles and furazanes; 5 Metal salts of azoles such as potassium aminotetrazole; non-metal salts of azoles such as mono- or di-ammonium salts of 5,5′-bis-1H-tetrazole; azoles such as 5-aminotetrazole nitrate Nitrates; nitroamine derivatives of azoles such as 5-nitroaminotetrazole; metal salts of nitroamine derivatives of azoles such as di-potassium salt of 5-nitroaminotetrazole; mono- or di- of 5-nitroaminotetrazole Nitroamines of azoles such as ammonium salts Nonmetallic salts of conductors; guanidines such as dicyandiamide; guanidine salts such as guanidine nitrate; nitro derivatives of guanidine such as nitroguanidine; azoamides such as azodicarbonamide; azodicarbonamidine dinitrate Azoamide nitrates; and mixtures and combinations thereof. The second fuel combined with the first polyvinyl azole fuel typically constitutes about 5-40% of the total composition weight as the fuel component. The first fuel comprises about 13-100% of the fuel components, or about 5-40% of the total composition weight. Also, the second fuel comprises about 0-87%, or about 0-35% of the total composition weight.

  Slag formers include silicone compounds such as elemental silicon and silicon dioxide; silicones such as polydimethylsiloxane; silicates such as potassium silicate; natural minerals such as talc, mica and clay and mixtures thereof. Can be selected from. The slag former preferably comprises about 0-10%, more preferably about 0-5% by weight of the total composition.

The extrusion aid can be selected from talc, graphite, borazine [(BN) ₃ ], boron nitride, fumed silica, fumed alumina. The slag former preferably comprises about 0-10%, more preferably about 0-5% by weight of the total composition.

The composition can be dry mixed or wet mixed using known methods. The various components are generally provided in the form of particulates and are mixed with other gas generant components to form a uniform mixture. The mixture is then pelletized or formed into other useful shapes in a known safe manner. Preferred gas generant compositions, 60-95% by weight of phase stabilized ammonium nitrate (10-15% of _KNO 3), and a 5-40% by weight of non-metallic poly (c- vinyltetrazole). For example, the gas generant composition comprises 85% by weight phase stabilized ammonium nitrate and 15% by weight ammonium poly (c-vinyltetrazole). A more preferred gas generant composition is about 8% ammonium poly (c-vinyltetrazole), about 11% diammonium salt of 5,5′-bis-1H-tetrazole, and about 81% phase stabilized. Contains ammonium nitrate. It should be noted that all percentages given herein are weight percentages based on the total weight of the gas generant composition.

  The chemicals described herein can be supplied by companies such as Aldrich Chemical Company and Polyscience Company, for example.

  As shown in FIG. 1, the exemplary inflator incorporates a dual chamber design to adjust the deployment force of the associated airbag. In general, an inflator that includes the first gas generant 12 and the autoignition composition 14 formed as described herein can be manufactured by known techniques. US Pat. Nos. 6,422,601, 6,805,377, 6,659,500, 6,749,219 and 6,752,421 illustrate typical airbag inflator designs, which are referenced and described herein. Incorporated as part of the book.

  Please refer to FIG. The exemplary inflator 10 described above can be incorporated into the airbag system 200. The airbag system 200 includes at least one airbag 202 and an inflator 10 that includes the gas generant composition 12 of the present invention, the inflator being associated with the airbag 202 in fluid communication with the interior of the airbag. The airbag system 200 includes or is connected to a crash sensor 210. The crash sensor 210 includes a known crash sensor algorithm and signals activation of the airbag system 200 in the event of a crash, for example by activation of the airbag inflator 10.

  Please refer to FIG. The airbag system 200 can be incorporated into a wider and more comprehensive vehicle occupant restraint system 180 that includes additional elements such as a safety belt assembly 150. FIG. 2 shows a schematic diagram of one exemplary embodiment of such a restraint system. Safety belt assembly 150 includes a safety belt housing 152 and a safety belt 100 extending from housing 152. A safety belt retractor mechanism 154 (eg, a spring-type mechanism) can be coupled to the end portion of the belt. In addition, a safety belt pretensioner 156 that includes the propellant 12 and the autoignition device 14 can be coupled to the belt retractor mechanism 154 to trigger the retractor mechanism in the event of a collision. Exemplary seat belt retractor mechanisms that can be used with the safety belt embodiment of the present invention are US Pat. Nos. 5,743,480, 5,553,803, 5,667,161, 5,451,008, 4,558,832 and 4,597,546. These patents are referenced and incorporated as part of this specification. Examples of typical pretensioners with which safety belt embodiments of the present invention can be combined are disclosed in US Pat. Nos. 6,505,790 and 6,419,177. These patents are referenced and incorporated as part of this specification.

  The safety belt assembly 150 includes a crash sensor algorithm 158 (e.g., a known crash sensor algorithm that generates an activation signal for the belt pretensioner 156, e.g., upon activation of a pyrotechnic igniter (not shown) incorporated in the pretensioner. Inertial sensors or accelerometers) or can be connected thereto. US Pat. Nos. 6,505,790 and 6,419,177, referenced above and incorporated as part of this specification, provide examples of pretensioners that start in such a manner.

  Although the safety belt assembly 150, the airbag system 200, and the wider vehicle occupant protection system 180 are illustrated, the gas generation system contemplated by the present invention is not limited thereto.

Method of Manufacture The fuel of the present invention can be formed by an aqueous method of synthesizing polyvinyl tetraazoles as described below. The aqueous process includes the following steps. First, prepolymers containing pendant nitrile or cyano groups are provided. Any prepolymer of cyano or nitrile functionality can be used in the synthesis. Examples include poly (cyanoacrylate), poly (haloacrylonitrile) where the halogen is fluorine, chlorine, bromine or iodine, poly (crotononitrile), poly (triallyl cyanurate), cellulose cyanoethyl ether and poly (methacrylonitrile) Can be given. Certain copolymers or block copolymers containing nitrile functional groups are also contemplated for use as prepolymers. These copolymers include poly (butadiene / acrylonitrile) and poly (styrene / acrylonitrile), and polymer blends of any polymer or oligomer containing nitrile. These polymers and copolymers can be purchased from known manufacturers such as Polysciences (www.polysciences.com). Although any useful backbone chain can be used, the preferred polymer backbone chain is a polyethylene chain. Nitriles cannot be part of the backbone and must always be pendant groups. Further, the material can be classified as a prepolymer containing pendant nitrile. The prepolymer can exhibit aromatic character.

Thereafter, the prepolymer is a divalent zinc halide azide, in the presence of water and a surfactant, such as sodium azide are reacted with ZnX _2. Under high temperature and pressure, a zinc tetrazole organometallic complex bound to the polymer is formed. The polymer intermediate complex is then filtered from the reaction media, washed, and then treated with concentrated acid to convert to the corresponding tetrazoleic acid. The poly (tetrazole) acid can then be converted to a water-soluble salt by reacting with a suitable base. All process steps are performed in water.

  For example, the azide can be any metal azide such as sodium azide. The surfactant can be essentially any useful surfactant. One exemplary surfactant is ammonium lauryl sulfate provided by Rhodia. Other surfactants include various soaps or detergents (eg, Dial®), phase transfer catalysts such as quaternary ammonium salts (eg, tetrabutylammonium bromide from Aldrich Chemical Company). The zinc halide can be zinc chloride, zinc bromide or zinc iodide. The concentrated acid can be an organic acid such as hydrogen chloride, hydrogen bromide, nitric acid, sulfuric acid, and acetic acid. Preferably, any acid that provides a polymer suspension solution having a pH of about 1-3 can be used. For example, these acids are available from Aldrich Chemical Company. The base used can be selected from the group comprising ammonium hydroxide, hydroxylamine, hydrazine and other suitable amines that give a pKb compatible to form a stable salt with the polymer. For example, these bases are available from Aldrich Chemical Company.

  Process conditions can be described as follows: 1.0 molar equivalent of polyacrylonitrile (eg, a prepolymer from Polysciences) is added to 0.5 mole of zinc bromide dihydrate (Aldrich). Equivalent, 1.1 equivalents of sodium azide (Aldrich) and 0.0025 molar equivalents of ammonium lauryl sulfate as a 28 wt% aqueous solution. The final molar amount based on the amount of polymer in water is about 1.0. An exemplary batch uses 47.7 grams of nitrile-containing prepolymer, 64.29 grams of azide, 117.41 grams of zinc and 2.25 ml of surfactant. All ingredients were mixed in 900 ml water. The ratio can be varied as long as an excess of azide is present and at least 0.5 equivalents of zinc is present. The amount of the surfactant can also be varied within the range of 0.1 equivalent or less and 0.000001 equivalent or more. The amount of water can vary between a 5.0 molar solution and a 0.1 molar solution. All reagents are mixed in a pressure reactor and sealed inside, in any order. The contents are stirred and heated to 170 ° C. The pressure reaches between 80-100 psi. The mixture was then allowed to react for about 24-48 hours (preferably 24 hours) and then cooled to room temperature. The milky contents are then preferably filtered with a Buchner funnel and washed with an equal volume of water.

  The contents are then dispersed in about 1.0 to 10.0 liters, more preferably 3.0 liters of cold water (range 0-24 ° C.) and stirred rapidly. Sufficient acid is added to bring the pH of the suspension to 1-3 and the mixture is continuously stirred for about 20 minutes. The suspension is then filtered again in a Buchner funnel using a nylon screen and washed with an equal volume of water. This leaves an elastic moist material in the funnel. Take it out and cut it into small pieces using standard scissors. This material is then suspended in 1.0 liter of water and excess ammonium hydroxide (Aldrich) is added while stirring the suspension. At least one molar equivalent of ammonium hydroxide is used, and larger amounts of ammonium hydroxide are used if desired.

  The suspension will slowly melt on its own. However, it can be heated to facilitate the process. The temperature at this time may be in the range of 25-100 ° C. The mixture dissolves and becomes very sticky. The agitation is then stopped. The solution is then poured onto a flat metal sheet to remove any excess ammonia by air drying. The material is then further dried in an oven to a thin film and then pulverized with a ball mill. In essence, after the addition of ammonium hydroxide, the product is completely reacted. Another subsequent step is to simply dry and process the material.

  The use of an aqueous system eliminates the need for expensive, toxic and / or flammable organic solvents. Thus, the overall cost is dramatically reduced while at the same time safety is increased. The intermediate product zinc complex is easily filtered from the reaction media, easily converted to the corresponding acid, or further converted to a water-soluble polyelectrolyte salt.

  It will be appreciated that the method of forming polyvinyl tetraazole described above is for exemplary purposes only and other methods of forming the polyvinyl azole described herein can be used.

  The descriptions herein are for illustrative purposes only and should not be construed in any way to limit the scope of the invention. Accordingly, one of ordinary skill in the art appreciates that various modifications can be made to the embodiments described herein without departing from the scope of the invention as defined in the claims.

FIG. 1 is a cross-sectional side view showing a general structure of an inflator of the present invention. FIG. 2 is a schematic diagram showing an example of a vehicle occupant protection system including the gas generant composition of the present invention. FIG. 3 is a graph showing the fuel velocity with respect to the fuel pressure of the gas generating composition. FIG. 4 is a graph showing the fuel velocity with respect to the fuel pressure of the gas generating composition. FIG. 5 shows the fuel profile of the same gas generant composition before aging at 107 ° C. for 400 hours. FIG. 6 shows the fuel profile of the same gas generant composition after aging at 107 ° C. for 400 hours.

Claims (12)

Polyvinylazole as fuel provided at about 5-40% of the total weight of the gas generant composition; and phase stabilized ammonium nitrate, alkali and alkaline earth metal nitrates and perchlorates, and basic An oxidizer selected from the group comprising transition metal nitrates, as well as mixtures thereof, provided in about 60-95% of the total weight of the gas generant composition;
The oxidant is provided in an amount that provides an oxygen balance of -4.0% to + 4.0%.
Gas generating composition. Monoguanidinium salt of 5,5′-bis-1H-tetrazole (BHT · 1GAD), diguanidinium salt of 5,5′-bis-1H-tetrazole (BHT · 2GAD), 5,5′-bis-1H— Monoamino guanidinium salt of tetrazole (BHT · 1AGAD), diaminoguanidinium salt of 5,5′-bis-1H-tetrazole (BHT · 2AGAD), monohydrazide of 5,5′-bis-1H-tetrazole Nium salt (BHT · 1HH), dihydrazinium salt of 5,5′-bis-1H-tetrazole (BHT · 2HH), monoammonium salt of 5,5′-bis-1H-tetrazole (BHT · 1NH ₃ ), 5, Diammonium salt of 5′-bis-1H-tetrazole (BHT · 2NH ₃ ), mono-3-amino of 5,5′-bis-1H-tetrazole -1,2,4-triazolium salt (BHT · 1ATAZ), di-3-amino-1,2,4-triazolium salt of 5,5′-bis-1H-tetrazole (BHT · 2ATAZ), 5,5 ′ - diguanidinium salt (ABHT · 2GAD) of azobis -1H- tetrazole, 3-nitro-1,2,4-monoammonium salt of triazole (NTA · _1NH 3), of 3-nitro-1,2,4-triazole Monogu Anidinium salt (NTA · 1GAD), diammonium salt of dinitrobitriazole (DNBTR · 2NH ₃ ), diguanidinium salt of dinitrobitriazole (DNBTR · 2GAD), and 3,5-dinitro-1,2,4-triazole It is selected from the group comprising the monoammonium salt (DNTR · 1NH _3), Oyo tetrazoles Further comprising a second fuel selected from the group comprising non-metal salts of triazoles, claim 1 Gas generating composition. The gas generant composition of claim 1, wherein the polyvinylazole is selected from a tetrazole polymer, a triazole polymer, a diazole polymer and a furazane polymer. The gas generating composition according to claim 1, wherein the polyvinyl azole is selected from polyvinyl diazoles, polyvinyl furazanes, polyvinyl triazoles, and polyvinyl tetrazoles. The polyvinyl azole is poly (5-vinyl) tetrazole, poly (3-vinyl) 1,2,5-oxadiazole, poly (1-vinyl) tetrazole, poly (3-vinyl) 1,2,4-triazole. 2. Selected from the group comprising poly (5-amino-1-vinyl) tetrazole, poly (2-methyl-5-vinyl) tetrazole, and poly (c-vinyltetrazole), and mixtures thereof. Gas generating composition. Tetrazoles such as 5-aminotetrazole, azoles such as triazoles and furazanes; metal salts of azoles such as 5-aminotetrazole potassium; mono- or di of 5,5′-bis-1H-tetrazole Non-metal salts of azoles such as ammonium salts; nitrates of azoles such as 5-aminotetrazole nitrate; nitroamine derivatives of azoles such as 5-nitroaminotetrazole; azoles such as 5-nitroaminotetrazole dipotassium Metal salts of nitroamine derivatives of the class; nonmetal salts of nitroamine derivatives of azoles such as the mono- or di-ammonium salt of 5-nitroaminotetrazole; and guanidines such as dicyandiamide; guanidines such as guanidine nitrate Salts; Nitrogue A second fuel selected from the group comprising: nitro derivatives of guanidines such as nidin; azoamides such as azodicarbonamide; nitrates of azoamides such as azodicarbonamidine dinitrate; and mixtures and combinations thereof. The gas generant composition according to claim 1, further comprising: 4. A composition according to claim 3, wherein the polyvinyl azole is selected from polyvinyl azoles exhibiting pendant aromaticity. 4. The composition of claim 3, wherein the polyvinyl azole is selected from the group comprising polyvinyl azoles that exhibit aromatic character along the backbone of the polymer contained within the polyvinyl azole to be bonded. A vehicle occupant protection system having a gas generator comprising a gas generant composition, the gas generant composition comprising:
Polyvinyl azole as fuel; and an oxidant selected from the group consisting of phase stabilized ammonium nitrate, nitrates and perchlorates of alkali and alkaline earth metals, nitrates of basic transition metals, and mixtures thereof Including
The oxidant is a gas generant composition provided in an amount that provides an oxygen balance of -4.0% to + 4.0%.
Vehicle occupant protection system. The vehicle occupant protection system according to claim 6, wherein the basic metal nitrate is basic copper nitrate and the alkali metal perchlorate is potassium perchlorate. The gas generant composition of claim 1, wherein the polyvinyl azole is selected from the group comprising polyvinyl diazoles, polyvinyl furazanes, polyvinyl triazoles, and polyvinyl tetrazoles. The polyvinyl azole is poly (5-vinyl) tetrazole, poly (3-vinyl) 1,2,5-oxadiazole, poly (1-vinyl) tetrazole, poly (3-vinyl) 1,2,4-triazole. 2. Selected from the group comprising poly (5-amino-1-vinyl) tetrazole, poly (2-methyl-5-vinyl) tetrazole, and poly (c-vinyltetrazole), and mixtures thereof. Gas generating composition.

Images