JP2007531684A - Gas generant and production method thereof - Google Patents

Abstract

The present invention generally relates to a gas generant composition, for example, for an inflator of an occupant restraint system. The extrudable pyrotechnic composition includes a polyvinyl azole used in an airbag gas generator. Fuels include 5-amino-1-vinyltetrazole, poly (5-vinyltetrazole), 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) can be selected from exemplary polyvinyl azoles. The oxidant is combined with the fuel and preferably contains phase stabilized ammonium nitrate. A novel method of forming a composition is also shown, where various ingredients are dissolved and / or wetted and then cured in a polyvinyl azole matrix, thereby forming a closer combination within the gas generant composition . The vehicle occupant protection system 180, and other gas generation systems, incorporate the compositions of the present invention.

Description

This application claims the benefit of US Provisional Application No. 60 / 557,279, filed March 29, 2004.

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 This invention relates to a non-toxic gas generant composition that rapidly produces a gas useful for inflating a safe 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 that exhibits 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.

  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 the explosion of fuels often used with ammonium nitrate, many propellants that incorporate ammonium nitrate will not pass the cap test unless they are made into large disks, which in turn reduces the flexibility of the inflator design.

  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.

  Another concern relates to the environmental impact of manufacturing the gas generant composition. In many manufacturing processes, the gas generant is formed by a solvent based process. Therefore, the residual organic solvent must be treated in consideration of environmental problems.

  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. A preferred group of fuels are polymeric tetrazoles, triazoles and oxadiazoles (furazanes) which have functional groups on the azole pendant group. While compositions containing NH ₃ bonds and carbon / hydrogen content are generally useful, preferred compositions do not contain NH ₃ bonds due to handling problems. Also, carbon and hydrogen content is minimized to inhibit the formation of carbon dioxide and water. 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. The fuel preferably comprises 10-40% 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.

  Other oxidants known to be useful as airbag gas products are also contemplated. The oxidant preferably comprises 60-90% 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.

  In another aspect of the invention, a method for making a gas generant composition incorporating polyvinyl azole is described. Vinyl azole is first added to the container. If necessary, an aqueous or organic, aqueous / organic solvent is provided in an amount effective to dissolve all ingredients added to the container. In a preferred embodiment, the liquid vinyl azole wets completely and / or promotes the solubility of other gas generant components without the use of solvents. An oxidizing agent, preferably non-metallic, is then added. One or more other components / solutes, such as a second fuel, second oxidizer, slag former, processing aid, coolant, and / or burn rate modifier are added to the slurry and stirred. A substantially uniform or homogeneous mixture. Next, an initiator is added to facilitate curing or polymerization of the mixture. The mixture can then be cured statically or without agitation to form a solid or agitation to form granules. If statically cured, the mixture can be poured into a mold, for example, to form the desired propellant shape. When cured with agitation, crushing and particle formation is not necessary due to the formation of unique granules. If desired, the thermoplastic polymer facilitates melt processing for further shaping of the propellant.

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, the pyrotechnic composition includes an extrudable fuel such as polyvinyltetrazole (PVT) for use in a gas generation system, for example, in a high gas yield vehicle occupant protection system. Illustrated as an automotive air bag propellant. 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. A preferred group of fuels includes polymeric tetrazoles, triazoles and oxadiazoles (furazanes) having functional groups on the azole pendant groups. While compositions containing NH ₃ bonds and carbon / hydrogen content are generally useful, preferred compositions do not contain NH ₃ bonds due to handling problems. Also, carbon and hydrogen content are minimized to inhibit the formation of carbon monoxide, carbon dioxide and water. In general, consumption of oxygen from the oxidant is preferentially prohibited with respect to the formation of these gaseous or vapor products. Preferred vinyltetrazoles include 5-amino-1-vinyltetrazole and poly (5-vinyltetrazole), both of which exhibit self-propagating pyrolysis 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 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. The polyvinyl azole fuel preferably 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. Other oxidants known to be useful as airbag gas products are also contemplated. The oxidant preferably comprises 60-95% by weight of the gas generant composition.

  The gas generant components of the present invention are supplied by suppliers known in the art and are preferably mixed by a wet process. 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 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 substantially evaporated off, more preferably once the solvent has 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.

任意の場所に、少なくとも２つの窒素原子、１より多くない酸素原子、少なくとも１つの炭素原子を含む。

It contains at least two nitrogen atoms, no more than one oxygen atom, and at least one carbon atom at any location.

  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.

More particularly, the non-metal salts of tetrazole are in particular the amine, amino, and amide salts of tetrazole and triazole, selected from the following: the monog of 5,5′-bis-1H-tetrazole Anidinium salt (BHT · 1GAD), diguanidinium salt of 5,5′-bis-1H-tetrazole (BHT · 2GAD), monoaminoguanidinium salt of 5,5′-bis-1H-tetrazole (BHT · 1AGAD) ), 5,5′-bis-1H-tetrazole diaminoguanidinium salt (BHT · 2AGAD), 5,5′-bis-1H-tetrazole monohydrazinium salt (BHT · 1HH), 5,5 ′ -Dihydrazinium salt of bis-1H-tetrazole (BHT · 2HH), monoammonium salt of 5,5′-bis-1H-tetrazole (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′-azobis-1H— Diguanidinium salt of 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 with an amine, diazomatatri Substituted via an azo 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 benzoyl peroxide free radical initiator to form a 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 slag former according to US Pat. No. 5,872,329, which is incorporated by reference and incorporated herein. The resulting composition. Example 9 is a representative gas generant composition of the present invention formed from ammonium polyvinyltetrazole and phase stabilized ammonium nitrate (ammonium nitrate co-coagulated with 10% potassium nitrate).

  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 (Gg) 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% 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-1-H 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 is also contemplated, as is known in the art or recognized in the art.

  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 to be. 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.

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 in FIG. 1, 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. 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.

  In another aspect of the present invention, as illustrated herein, the compositions of the present invention can be used in a gas generation 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 generator used in an automobile gas generation system can include a gas generant composition as described herein.

In a different aspect of the present invention, a method for producing a gas generant composition polymerizes a polymer binder / fuel monomer component at least in the presence of an oxidant, thereby providing a solid composite of a homogeneous gas generant formulation. Forming. The polymer binder / fuel is generally selected from, for example, vinyltetrazole, vinyltriazole, vinyloxadiazole (furazane), and a myriad of polymer azoles including copolymers thereof, as described above. Functional groups can be present on the azole pendant. However, preferred compositions avoid HN ₃ binding due to sensitivity issues. Furthermore, preferred compositions have a relatively small amount of carbon / hydrogen, thereby producing a cooler formulation that is believed to contribute to reducing the amount of water and carbon dioxide formed during combustion. make it easier. Polymeric binders / fuels include poly (vinyl-5-amino) tetrazole, poly (vinyl-5-methyl) tetrazole, poly (5-amino-1-vinyltetrazole), poly (5-vinyltetrazole) and poly (5- Illustrated by several polyvinyltetrazole compounds, including vinyl-bitetrazolamine) or mixtures thereof. Other polymer azole fuels have been exemplified above. Other fuels contemplated for use in the present invention include metal salts and composites of the azole polymers described above.

  The polymeric azoles can be purchased from suppliers known in the art. Furthermore, they can be produced by vinylation of azoles with vinyl acetate. For example, vinylation of tetrazole with vinyl acetate and subsequent polymerization provides the desired polyvinyl tetrazole.

式中、Ｒ＝ＣＨ_３、ＮＨ_２など

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

  The procedure is described in Vereshchagin et al., J. MoI., Referenced and incorporated herein by reference. Org. Chem. USSR (English Translation), 22 (9), 177-83 (1987). The methyl group in the starting material tetrazole can be exchanged for an amino group. The vinyl tetrazole is then polymerized using a common polymerization initiator such as azoisobutyronitrile (AIBN). Other synthetic methods can also be used. It is believed that vinylation of furazane and triazole will provide the desired polymer as well.

  The oxidizing agent is preferably selected from exemplary compounds including preferably alkali metals, alkaline earth metals, transition metals and non-metallic nitrates and perchlorates. Specific oxidizing agents include ammonium nitrate, phase stabilized ammonium nitrate, potassium nitrate, strontium nitrate, potassium perchlorate, ammonium perchlorate, sodium nitrate, sodium perchlorate and mixtures thereof.

  In preparing the composition, the monomer / copolymer and oxidant are added to an inorganic solvent such as water or an organic solvent such as dimethylformamide, depending on the chemical nature of the monomer / copolymer. When water is used, an aqueous polymerization initiator, such as ammonium persulfate, is used in the aqueous slurry to give a relatively dilute, hardly hard slurry. When an organic solvent is used, an organic solvent based initiator such as azobisisobutyronitrile (AIBN) is used in the organic slurry to give a relatively thicker or more viscous slurry.

  Typically, the azole monomer or azole copolymer is a suitable solvent, water, a mixture of water and a miscible solvent (ethanol, methanol or other alcohols; acetone, tetrahydrofuran (THF), dimethylformamide (DMF), dimethyl Sulfoxide (DMSO)), or an ether such as dimethyl ether and diethyl ether, and further solvated in a water immiscible organic solvent selected from the group comprising aromatic compounds such as toluene and benzene. Adding other known additives, such as slag formers, coolants, burn rate improvers, second fuels and second oxidants, in known effective amounts to the solvent to form a slurry in the solvent. Can do. Slag formers, processing aids, coolants, and / or burn rate modifiers include stearates such as magnesium stearate, graphite, clay, mica, talc, silicates, aluminates and other functional The same components can be mentioned in Secondary fuels include tetrazoles, triazoles, imidazoles, pyrazoles, oxyadiazoles, guanidines such as nitroguanidine and guanidine nitrate, and other components that function as fuel components in the present invention. It is done. The second oxidizing agent includes metallic and non-metallic chlorates, perchlorates, nitrates, nitrites, oxides, and other compounds having an oxidizing function. The polymerization initiator is then selected from known initiators and added after all additions of the other components. For example, a preferred free radical initiator is 2,2'-azobisisobutyronitrile (AIBN), which can be used in a known manner. The use of other types of initiators such as ammonium persulfate is also contemplated. Generally, the polymerization initiator is provided at about 100-250 mg per batch. However, the amount required is relatively small compared to the total weight of the mixture and free radical formation is easy.

  Thereafter, the polymerization is self-propagating. The temperature can be increased or decreased to adjust to the desired curing time. At room temperature, the cure period can be 3 to 24 hours. A preferred temperature range is 10 to 90 ° C. Although the apparently cured material is obtained in a relatively short time, the curing process may continue for many hours. After the ingredients are mixed to form a substantially homogeneous slurry, it is cured at rest to ultimately produce a solid block propellant that, when stirred during the curing process, produces small granules.

  Depending on the temperature of the monomer / copolymer and the solvent, a 10-50% by weight propellant mixture per unit solvent is desirable. By evaporation, the solvent can be removed during or after the curing process. If the monomer / copolymer is a liquid, a solvent may not be necessary. In essence, the liquid monomer or copolymer must be in an amount effective to “wet” the solid to which it is added. As used herein, “wet” is meant to at least partially solvate the components added to the fuel, more preferably fully solvate. Thus, the effective liquid monomer / copolymer amount can be repeatedly determined on a weight percent basis, based on the fuel characteristics, the propensity of the fuel to wet the remainder of the components. If a solvent is still required to wet the components, the solvent can be added to ensure wetting of the solid components in the container. In general, various components can be added to the slurry in the following weight percentages: azole monomer / copolymer 5-20%; oxidizer 50-90%; additional fuel 0-25%; and 0-10% Processing aids, slag formers and / or burning rate improvers. The weight percent is based on the total weight before being added to the slurry or before mixing them.

  The composition thus formed provides consistent and repeatable performance based on an intimate combination of ingredients resulting from the mixing and curing process. Compared to other gas generant synthesis, the gas generant manufacturing process is simplified, thus reducing the associated costs. In addition to the above advantages, another advantage is that many compositions have melt moldability if the monomer / copolymer used has thermoplastic properties. Furthermore, the flexible nature of the composition facilitates flexibility for containment for many compositions of the present invention so that the propellant or gas generant 12 is compressed and stored in a cavity in the inflator. Thereby optimizing the use of available space. As a result, the size of the inflator is effectively reduced while maintaining the same effective amount of gas production, thereby maintaining the same inflation pressure profile as typically represented in a relatively larger inflator.

Stoichiometric amounts of fuel and oxidant are preferably incorporated into the slurry, thereby providing a balanced combustion reaction. An exemplary balanced combustion reaction of ammonium nitrate and poly (5-amino-1-vinyl) tetrazole is shown below:
2C ₃ H ₅ N ₅ + 17NH ₄ NO ₃ → 6CO ₂ + 22N ₂ + 39H ₂ O

  The weight percent of fuel and oxidizer is about 14% PV5AT and about 86% AN. Other oxidizing agents such as strontium nitrate, potassium perchlorate, ammonium perchlorate can also be used depending on the application design criteria. In general, the fuel / oxidizer weight percent ratio ranges from 45/50 to 5/90.

  For example, the polymerization process can be accelerated by the amount of initiator used and by applying heat. Other acceleration methods are also contemplated.

  In addition, the compositions of the present invention are intended for use in airbag modules, including airbag modules, airbag inflators, seat belt pretensioners, or vehicle occupant restraint systems, all shown schematically in FIG. All configurations and designs are known in the art. For example, more generally, the compositions of the present invention include vehicle occupant protection comprising inflatable levitation devices, inflatable aircraft slides, fire extinguishers, and seat belt assemblies with airbag devices and / or pretensioners. It can be provided in a gas generation system designed for various applications such as the system. As shown in FIG. 1, the exemplary inflator is designed to incorporate two chambers to adjust the deployment force of the associated airbag. In general, an inflator containing gas generant 12 formed as described herein can be manufactured as is known in the art. US Pat. Nos. 6,422,601, 6,805,377, 6,659,500, 6,749,219 and 6,752,421 illustrate typical airbag inflator designs, these patents being referenced And incorporated as part of this specification.

  Please refer to FIG. The exemplary inflator 10 described above can be incorporated into an 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. Further, a safety belt pretensioner 156 including a propellant 12 can be coupled to the belt retractor mechanism 154 to start 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 a belt pretensioner 156 activation signal, e.g., upon activation of a pyrotechnic igniter (not shown) incorporated in the pretensioner. Inertial sensors or accelerometers). 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.

  It should be understood that the descriptions of embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. As such, the various structural and operational aspects disclosed herein can be modified in many ways by those skilled in the art without departing from the scope of the present invention.

FIG. 1 is an exemplary airbag inflator that includes a gas generant composition formed in accordance with the present invention. FIG. 2 is a schematic diagram of an exemplary vehicle occupant restraint system incorporating the inflator of FIG. 1 containing the gas generant of the present invention.

Claims (11)

Providing a solvent effective to dissolve a fuel comprising an azole of a polymer selected from the group consisting of vinyltetrazoles, vinyltriazoles and vinylfurazans, wherein the solvent is present on the polymer azole Selected in relation to the solvability of the functional group in some cases, the solvent being placed in a mixing vessel;
Adding fuel to the mixing vessel;
Adding an oxidizing agent to the mixing vessel;
Stirring the mixture;
A method of forming a gas generating composition comprising: adding an initiator to initiate polymerization of the slurry to a mixing vessel; and curing the mixture. The method of claim 1, further comprising adding an additive to the mixing vessel prior to adding the initiator. The method of claim 1, further comprising heating the mixing vessel to a temperature below the boiling point. The method of claim 1, wherein the step of adding the solvent and the step of adding the fuel to the mixing vessel constitute the same step, and the fuel further functions as a solvent. A gas generation system comprising a gas generant produced by the method of claim 1. Providing a solvent effective to dissolve a fuel comprising an azole of a polymer selected from the group consisting of vinyltetrazoles, vinyltriazoles and vinylfurazans, wherein the solvent is present on the polymer azole Selected in relation to the solvability of the functional group in some cases, the solvent being placed in a mixing vessel;
Adding fuel to the mixing vessel;
Adding an oxidizing agent to the mixing vessel;
Stirring the mixture;
Adding an initiator to initiate polymerization of the slurry to the mixing vessel; and curing the mixture;
A gas generation system comprising a gas generant composition formed by a forming method. The gas generation system of claim 6, wherein the system is a vehicle occupant protection system. The gas generation system of claim 6, wherein the system is an airbag system. The gas generation system of claim 6, wherein the system is a seat belt assembly system. The gas generation system of claim 6, wherein the system operates an inflatable buoyant device. The gas generation system of claim 6, wherein the system is a fire extinguishing system.
Gas generant and manufacturing method

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