CN100357236C - Gas generating agent - Google Patents

Abstract

Gas generant compositions including at least one transition metal complex of ethylenediamine 5, 5' -bitetrazole and gas generant compositions including a cobalt (III) nitrate complex fuel with ammonia or water as a ligand, a copper bis (ethylenediamine) dinitrate fuel rate catalyst and a basic copper nitrate oxidizer are provided resulting in compositions having higher burn rates. Corresponding or related gas generating devices and inflatable vehicle occupant safety restraint systems, as well as methods of generating gas, are also provided.

Description

Gas generating agent

field of invention

The present invention relates generally to gas generant materials, such as are used to inflate automotive inflatable restraint air bag cushions. More specifically, how to increase the rate at which such materials burn or otherwise react.

Background of the invention

Gas generants or generant materials can be used in many different fields. An important use of such compositions is the restraint of occupants while driving. For example, it is known to protect vehicle occupants with cushions or airbags, such as "airbag cushions". When a vehicle suddenly slows down, such as in a crash, the gas inflates or expands the bumper or air bag. In such systems, the airbag cushion is typically placed in a deflated and folded state to minimize space requirements. Such systems typically also include one or more crash sensors mounted on the frame or body to detect sudden deceleration of the vehicle and trigger activation of the system via electronic controls. Once the system is activated, the cushion is inflated in no more than a few milliseconds, with the gas being generated or provided by a device commonly referred to as a "gas generator". In practice, such airbag cushions are preferably deployed into positions between the occupants of the vehicle and certain components of the vehicle interior, such as doors, steering wheel, instrument panel, etc., to prevent or prevent the occupants from slamming into these components of the vehicle interior.

A gas generant composition commonly used to inflate automotive inflatable restraint airbag cushions, most commonly previously employed or based on sodium azide. Nitrogen gas is generally generated or formed upon initiation of such sodium azide-based compositions. While current industry specifications, requirements and standards are met with sodium azide and certain other azide-based gas generant materials, certain potential problems may be involved or arise in use, such as those involving such gas generant materials safe and efficient handling, supply and disposal.

Certain economic and design considerations also lead to the need and desire for alternative technologies and alternatives to azide-based pyrotechnic manufacturing techniques and related gas generants. For example, concerns about minimizing or at least reducing the overall space requirements of inflatable containment systems, particularly those associated with gas generator components in such systems, have prompted the search for gas generant materials that Provides a higher gas yield per unit volume than typical or commonly used azide-based gas generants. In addition, competition in the automotive and airbag industries in general has also resulted in the requirement that gas generant compositions satisfy one or more criteria, such as contain or utilize less expensive components or materials, be suitable for processing by more efficient or less expensive gas generants technology for processing.

For the above reasons, great efforts have been made to reduce or avoid the use of sodium azide in gas generators for automobile airbags. Through these efforts, various combinations of non-azide fuels and oxidizers have been proposed for use in or as gas generant compositions. These non-azide fuels are generally required to be less toxic than sodium azide when prepared and used, and thus easier to handle and thus at least in part more acceptable to the public. In addition, combustion of non-azide fuels composed of carbon, hydrogen, nitrogen and oxygen atoms generally produces all gaseous products. Those skilled in the art will understand that fuels high in nitrogen, hydrogen, and low in carbon are generally more suitable for such inflatable confinement protection applications because of their higher gas production (e.g., per 100 g of gas generant material available) measured in moles of gas).

Gas generating agent compositions for automobile airbags generally preferably have higher density and gas yield (for example, it is preferred to produce at least about 3 mol gas yield per 100 g of the composition) and lower combustion flame temperature (for example, the combustion flame temperature is lower than 2000K), and the particulate Yield, batch variance and cost.

Most oxidizing agents known in the art and commonly used in such gas generant compositions are metal salts or metal oxides of oxyanions such as nitrate, chlorate and perchlorate. Unfortunately, following combustion, the metal components of such oxidizers typically end up as solid compounds, such as oxides, thereby reducing the relative yield of gas obtainable therefrom. Thus, the level of such oxidizing agents in a particular formulation generally affects the gas production or productivity of that formulation. However, if oxygen is added to the fuel, it is necessary to reduce the amount of this oxidizing agent and increase the gas production of the formulation.

In addition to low toxicity and high gas yield, the gas generant material is preferably inexpensive, thermally stable (ie preferably only decomposes at temperatures above about 160°C), and has a low affinity for moisture.

Additionally, in addition to the desired properties and characteristics mentioned above, gas generant materials used in automotive inflatable restraint applications must be sufficiently reactive such that, when the reaction is properly initiated, gas generation or reaction occurs quickly enough that the corresponding The inflatable bladder cushion is fully inflated to provide the required impact protection for associated vehicle occupants. Generally, the burning rate of the gas generant composition can be represented by the following formula (1):

r _b = k(P) ⁿ (1)

where r _b = burn rate (linear)

k = constant

P = pressure

n = pressure index, which is the slope of the linear regression line drawn by the log-log plot of firing rate versus pressure.

Gas generant compositions in automotive airbag applications generally preferably provide or obtain a burn rate of 0.3 ips or higher at a pressure of 1000 psi, and compositions with higher burn rates are generally preferred.

Guanidine nitrate (CH ₆ N ₄ O ₃ ) is a non-azide fuel that has many of the desirable fuel properties identified above. For example, guanidine nitrate is readily available in the market, low cost, non-toxic, has good gas yield due to high nitrogen, hydrogen, oxygen content and low carbon content, and is thermally stable enough to allow spray drying processing. Therefore, guanidine nitrate has been widely used in the automobile airbag industry.

Unfortunately, the burn rate of guanidine nitrate is lower than required for many applications. Accordingly, there remains a need for an azide-free gas generant material that effectively overcomes one or more of the problems or deficiencies described above.

Furthermore, developing new gas generant compositions for pyrotechnic automotive airbag applications often involves a trade-off between gas production and burn rate. For example, in order to compensate for the low burn rate of certain non-azide gas generants previously developed, attempts have consequently been made to solvent extrude such formulations into small porous particles. However, the solvent extrusion process requires drying after extrusion. Studies have shown that the application of this drying step introduces undesired variability in the resulting gas generant composition, with variations in the density of the extruded porous particles. Consequently, it has proven difficult to develop alternatives to azide-based pyrotechnic fabrication techniques and related gas generants that meet both the burning rate and gas yield requirements for automotive airbag applications.

Commonly assigned U.S. Patent Application 09/715,459, filed Nov. 17, 2000, pre-existing U.S. Patent 6,550,808 (Mendenhall), issued Apr. 22, 2003, generally relates to Known as guanyl urea and guanyl urea) gas generant composition. In particular, one advantage of guanylurea nitrate is the higher theoretical density, eg allowing higher packing densities of gas generant materials containing such fuel components. In addition, amidinourea nitrate has good thermal stability, which can be seen from the thermal decomposition temperature of amidinourea nitrate reaching 216°C. Furthermore, guanidinourea nitrate has a very negative heat of formation (ie -880 cal/g), as compared to other similar gas generants containing guanidine nitrate, as a result of which gas generant compositions burn at a lower temperature.

Although the inclusion or use of guanylurea nitrate in the gas generant material avoids reliance on the inclusion or use of sodium azide or other similar azide compounds, while simultaneously increasing the burning rate and overcoming issues such as associated costs, commercial availability, One or more problems, deficiencies, or limitations of low toxicity, thermal stability, and low affinity for moisture, but further enhancement of the burn rate of the gas generant formulation is desired for a particular application.

For some gas generator applications, reducing the shape or shape of the gas generant material to have a greater active surface area can at least partially compensate for the low burn rate of the gas generant formulation. In practice, however, there is a practical limit to the reproducible shape or configuration of the gas generant material, such as the minimum size of a tablet. Therefore, for some applications requiring higher gas generator performance, there is still a need to increase the firing rate.

Commonly assigned US Patent Application Serial No. 09/998,122, filed November 30, 2001, describes the enhancement of burning rate by the addition or use of transition metal complexes of diammonium bistetrazolium. These compounds enhance the burn rate when used as part of a gas generant formulation with a primary fuel such as guanidine nitrate. Although such incorporation of diammonium tetrazolium transition metal complexes can desirably increase the burn rate of the formulation, these compounds are relatively expensive due to the higher cost of the bis-tetrazole moiety.

Accordingly, there remains a need for alternative and lower cost non-azide gas generant formulations having increased burn rates, as well as methods or techniques for increasing the burn rate of gas generant formulations.

In addition, there is a need for gas generant compositions that meet both gas yield and burn rate requirements, and that also meet gas requirements such as combustion flame temperature, particulate production, site variance, and cost.

Summary of the invention

It is a general object of the present invention to provide improved gas generant compositions, and either or both of a corresponding or related method of generating gas and of increasing the burn rate of a gas generant formulation.

A more specific object of the present invention is to overcome one or more of the above-mentioned problems.

In one aspect of the invention, achieved, at least in part, is achieved, at least in part, by a gas generant composition comprising an oxidant component and a fuel component, wherein the fuel component comprises a transition metal complex of ethylenediamine 5,5'-bitetrazole This general purpose of the present invention.

In another aspect of the present invention, the general purpose of the present invention is achieved, at least in part, by a gas generant composition comprising the following components:

About 45-90% by weight of cobalt(III) nitrate complex, the ligand is selected from ammonia and water;

About 2-50% by weight of copper complexes of ethylenediamine dinitrate;

About 5-50% by weight basic copper nitrate.

The prior art generally fails to provide lower cost non-azide gas generant formulations with increased or enhanced burn rates, and methods of increasing the burn rate of gas generant formulations, particularly non-azide gas generant formulations. method or technique. In particular, the prior art generally fails to provide effective methods or techniques for increasing the burning rate of gas generant formulations, particularly non-azide-based gas generant formulations, to sufficient and desired levels for use in inflatable vehicles The application of the protection system is constrained and the manner provided is practical and suitable for such application. Furthermore, the prior art has often failed to provide corresponding or related non-azide gas generant formulations which sufficiently and effectively increase the burn rate required for such vehicle inflatable restraint system applications.

In addition, the prior art often fails to provide gas generant compositions, such as those used to inflate automotive inflatable restraint airbag cushions, that meet both gas production and combustion rate requirements, and also meet requirements such as those related to combustion flame Temperature, particle yield, batch-to-batch variance, and cost are other requirements.

The present invention also includes a method for increasing the combustion rate of a gas generating agent formulation, the method comprising adding a certain amount of ethylenediamine 5,5'-bi-tetrazole transition metal complex and dinitrogen to the gas generating agent formulation At least one of ethylenediamine copper complexes.

The present invention also includes a method of generating a gas, the method comprising:

A gas generant composition is ignited, the composition comprising a fuel component comprising a transition metal complex of ethylenediamine 5,5'-bitetrazole and an oxidant component.

The present invention also includes a gas generant composition comprising about 45-90% by weight of hexaammine cobalt(III) nitrate; about 2-50% by weight of bis(ethylenediamine)copper dinitrate; about 5-50% by weight % basic copper nitrate, and the combustion rate of the composition exceeds 0.35 ips at a pressure of 1000 psi.

As used herein, reference to a particular composition, component, or material as a "fuel" should be understood to mean a fuel that cannot be completely combusted into _CO2 , _H2O , and _N2 , usually due to lack of sufficient oxygen. chemicals.

Accordingly, reference to a particular composition, component, or material as an "oxidant" should be understood to mean a chemical compound that generally has more oxygen than is sufficient for complete combustion to _CO2 , _H2O , and _N2 substance.

References to a component or material as a "burn rate catalyst", "burn rate enhancer", etc. are to be understood as referring to a component or material which, when added or included as a minor ingredient, is generally Less than 20% by weight, more typically less than 10% by weight, can have a significant effect on the burn rate of compositions to which the component or material has been added, wherein a significant effect on the burn rate generally includes an increase in the burn rate of at least about 20% %. It should be understood that such burn rate catalysts or enhancers, when normally used in combustion reactions, can, and often do, react.

Guaninourea nitrate [NH ₂ C(NH)NHC(O)NH ₂ ·HNO ₃ ] is also commonly referred to as amidinourea and amidinourea.

Unless otherwise stated, the percentages used herein refer to percentages by weight.

Other objects and advantages will be apparent to those skilled in the art from the following detailed description and appended claims and accompanying drawings.

Brief description of the drawings

The Figure is a simplified schematic diagram, partially cutaway, illustrating deployment of an airbag cushion from an airbag module assembly in an automotive interior, according to one embodiment of the present invention.

Detailed description of the invention

The present invention provides improved gas generant compositions and methods of increasing the burn rate and gas generation of gas generant formulations.

As described in detail below, according to a preferred embodiment of the present invention, the improved gas generant composition preferably comprises or includes a transition metal complex of ethylenediamine 5,5'-bitetrazolium.

Transition metals suitable for use in the practice of the present invention include copper, zinc, cobalt, iron, nickel and chromium. The valence of the transition metal is preferably +2. The general empirical formula for these complexes is M(C ₂ H ₈ N ₂ ) ₂ C ₂ N ₈ , where M is a +2 transition metal. Preferred transition metals for use in the practice of this invention include zinc and copper, with copper being a particularly preferred transition metal at present because copper desirably forms metallic copper in use, while zinc is more likely to form an oxide. And thus undesirably consumes or uses at least a portion of the gas generant oxidizer. Thus, a transition metal complex of ethylenediamine 5,5'-bistetrazole particularly suitable for use in the practice of the present invention is Cu(C ₂ H ₈ N ₂ ) ₂ C ₂ N ₈ , considered to be bis(ethylenediamine) 5,5'-copper tetrazole.

In a specific preferred embodiment, the relative content of the transition metal complex of ethylenediamine 5,5'-bitetrazol in the gas generant composition is about 1-100 weight of the fuel component in the gas generant formulation %. According to certain preferred embodiments, transition metal complexes of ethylenediamine 5,5'-bitetrazole are used as burning rate enhancers (hereinafter sometimes referred to as "secondary" fuels or primary fuels, or mixtures or combinations of primary fuels ) is used with fuel, wherein the transition metal complex of ethylenediamine 5,5'-bitetrazolium accounts for about 1-25% by weight of the fuel component in the gas generating agent formulation, the main fuel or the mixture of main fuels or The combination constitutes approximately 75-99% by weight of the fuel component in the gas generant formulation.

Those skilled in the art will understand under the guidance of this specification that the present invention should be implemented by adding a sufficient amount of at least one ethylenediamine 5,5'-linked gas generant formulation containing the main fuel Transition metal complexes of tetrazole desirably increase the burning rate of the resulting formulation relative to the same formulation without the addition of this transition metal complex of ethylenediamine 5,5'-bitetrazole . However, it has been found that, in general, according to the preferred embodiments of the present invention, the relative amount of at least one transition metal complex of ethylenediamine 5,5'-bitetrazolium contained or added in the gas generant formulation is suitable At least 5% by weight, more preferably at least 10% by weight, for the gas generating formulation to increase the burn rate sufficiently to be effective for such inflatable restraint system applications.

While the broad applicability of this aspect of the invention is not necessarily limited to the incorporation or use of such transition metal complexes of ethylenediamine 5,5'-bitetrazolium in specific or particular gas generant formulations, it is considered that the present invention This aspect of has particular benefit or use in gas generant formulations comprising or comprising a primary fuel and a primary oxidant, wherein the primary fuel is guanidine nitrate, hexaamminecobalt(III) nitrate, bis(amidinourea) dinitrate Copper or combinations thereof, the main oxidant being selected from ammonium nitrate; metal basic nitrates such as basic copper nitrate (bCN), basic zinc nitrate and combinations thereof; diammonium copper dinitrate and two or more of the above oxidizing agents The combination. For example, a preferred gas generant formulation that incorporates or uses the transition metal complexes of ethylenediamine 5,5'-bitetrazolium of the present invention includes primary oxidant ammonium nitrate and primary fuel bis(amidinourea )copper. According to certain preferred embodiments of the present invention, the oxidizer component comprises at least one basic nitrate, such as basic copper nitrate (bCN), basic zinc nitrate, and combinations thereof. Thus, a preferred gas generant formulation incorporating or using the transition metal complexes of ethylenediamine 5,5'-bitetrazole of the present invention includes primary oxidizer basic copper nitrate and primary fuel guanidine nitrate. Another preferred gas generant formulation incorporating or using such transition metal complexes of ethylenediamine 5,5'-bitetrazole according to the invention includes hexaamminecobalt(III) nitrate (HACN) and guanidine nitrate as fuel. Thus, metal basic nitrates are preferred oxidizers for use with fuels and fuel combinations in this aspect of the invention. However, the gas generant compositions of this aspect of the invention may employ a considerable number of oxidizing agents, including alkali metal, alkaline earth metal and ammonium salts of nitric and perchloric acids, transition metal oxides and hydroxides, metal bases Nitrates (such as basic copper nitrate, basic zinc nitrate, etc.), metallic basic carbonates and transition metal complexes of ammonium nitrate, and combinations thereof. Generally, the fuel and oxidant are used in similar stoichiometric relative amounts, ie, within about 20 mole percent either side of the stoichiometric equivalence.

Those skilled in the art will also understand under the guidance of this specification that according to this aspect of the invention, the gas generant composition or formulation may also contain other components familiar in the art, such as components used to form slag, Examples include silica, alumina, and other refractory oxides, and processing aids.

Those skilled in the art will also understand under the guidance of this specification that according to this aspect of the invention, when preparing the transition metal complex of ethylenediamine 5,5'-bistetrazole, many different procedures or methods can be used. Reaction flow. The current preferred route for synthesizing ethylenediamine 5,5'-tetrazole copper complex is to react copper tetrazole (produced by the reaction of copper oxide or copper carbonate with tetrazole) with ethylenediamine. Typically, the complex is recovered as the monohydrate. The reaction to form this complex is as follows:

Cu(C ₂ N ₈ )·2H ₂ O(copper tetrazole)+C ₂ H ₈ N ₂ (ethylenediamine)→Cu(C ₂ H ₈ N ₂ ) ₂ C ₂ N ₈ ·H ₂ O+H ₂ O

Table 1 below lists some properties of the 5,5'-bistetrazolium diammonium copper complexes of the present invention.

Table 1

nature value Thermal decomposition onset temperature 275-300℃ color blue/purple powder water soluble Soluble content (mass percentage) -copper 18.18 -carbon 21.21 -hydrogen 4.99 -nitrogen 51.80

It can be seen that gas generant compositions or materials prepared according to this aspect of the invention can be incorporated into or applied to a variety of different structures, assemblies and systems. Representatively, the drawing shows a vehicle 10 with an inflatable occupant safety restraint system (generally indicated by numeral 14 ) disposed inside 12 . It can be seen that, for the convenience of illustration and understanding, some standard components that are not necessary for understanding the present invention have been deleted in the figure.

The occupant safety restraint system 14 comprises an open reaction tank 16 constituting an inflatable vehicle occupant restraint 20 ( Such as the shell of an inflatable airbag cushion). As mentioned above, such gas generating devices are generally referred to as "gas generators".

The gas generator 22 comprises an amount of the gas generant composition or formulation of the present invention, eg, suitably induced to generate or form an amount of gas, eg, for inflating an inflatable vehicle occupant restraint 20 . It will be appreciated that the specific configuration of the gas generator assembly is not limiting on the broad applicability of the present invention, and that such gas generator devices may have various configurations, as is known in the art.

In fact, the deployed airbag cushion 20 can provide protection for the vehicle occupant 24 by restricting the movement of the occupant toward the front of the vehicle, ie, to the right in the figure.

The present invention will be described in more detail with reference to the following examples, which illustrate or simulate the various features involved in practicing the above aspects of the invention. It should be understood that all changes within the spirit of the invention are claimed and therefore the invention is not limited by these examples.

Example

Example 1 Preparation of ethylenediamine 5,5'-copper tetrazolium (laboratory scale)

Bitetrazole dihydrate (50.95 g) was partially dissolved in a beaker containing 200 ml of water. Basic copper carbonate (32.75 g) was added and the temperature of the slurry was equilibrated at 190°F (88°C) and maintained until the reaction was complete (approximately 1 hour). Ethylenediamine (35.55 g) was then gradually added to the beaker, immediately forming a complex (100 g).

Example 2 Preparation of ethylenediamine 5,5'-copper tetrazolium (10 pounds)

A 10 lb sample of copper ethylenediamine 5,5'-bistetrazole was prepared by filling a spray drying mixing tank with water (9080 ml) and then adding bistetrazole dihydrate (2313.4 g) to partially dissolve it then add basic copper carbonate (1486.85 g) to the spray drying mixing tank, equilibrate the slurry temperature at 190°F (88°C), and maintain this temperature until the reaction is complete (about 1 hour); then add to the spray drying mixing tank Ethylenediamine was gradually added to form a complex immediately.

Embodiment 3 and comparative example 1,2

Preparation with basic copper nitrate as oxidant comprises guanidine nitrate and diamine 5,5'-copper tetrazolium as co-fuel (embodiment 3); only comprises guanidine nitrate as fuel (comparative example 1); comprises guanidine nitrate and di( Ethylenediamine) 5,5'-bitetrazolium copper as the gas generant composition of the co-fuel (Comparative Example 2), as shown in Table 2 below. The values in Table 2 all refer to the weight percentage relative to the composition.

Table 2

Element Example 3 Comparative example 1 Comparative example 2 Basic copper nitrate 60.34 47.33 51.05 Guanidine nitrate 28.16 51.17 37.45 Aluminum oxide 1.50 1.50 1.50 Bis(ethylenediamine) 5,5'-bistetrazole copper 10.00 - - Copper Diamine 5,5'-Bitrazolium - - 10.00

Then, the gas generant compositions in Example 3 and Comparative Examples 1 and 2 were measured to obtain the burning rate and density (ρ) shown in Table 3 below. Specifically, the burning rate data is obtained as follows: first press each gas generant formulation sample into a cylinder with a diameter of 0.5 inches with a hydraulic press (12,000 pounds force), usually with a sufficient amount of powder to make the cylinder 0.5 inches long; Krylon flame retardant was applied to all sides of the cylinder except the top surface to help ensure linear burning of the sample in the test setup. In each case, the coated cylinder was placed in a 1-liter closed laboratory vessel that could be pressurized to several thousand psi with nitrogen and equipped with a pressure sensor to accurately measure the closed laboratory vessel pressure in. A small sample of ignition powder is placed on top of the cylinder, and nichrome wires are threaded through the ignition powder and connected to electrodes secured in the lid of the experimental vessel. Then the experimental container was pressurized to the required pressure, and an electric current was passed through the nickel-chromium alloy wire to ignite the sample. During the combustion of each sample, pressure-time data were collected. As each sample burns to produce gas, an increase in the pressure of the test vessel indicates the beginning of combustion, and a "flattening" of the pressure indicates the end of combustion. The time required for combustion is equal to t ₂ -t ₁ , where t ₂ is the end time of combustion and t ₁ is the start time of combustion. The sample length divided by the burn time is the burn rate in inches per second. Burn rates are typically measured at four pressures (900, 1350, 2000 and 3000 psi). Plot the log of the burn rate versus the log of the mean pressure. From this line, the burning rate at any pressure can be calculated using the above gas generant composition burning rate formula (1).

table 3

parameter Example 3 Comparative example 1 Comparative example 2 r _b 0.65 0.39 0.53 no 0.33 0.36 0.32 k 0.068 0.033 0.059 ρ(g/cc) 2.18 1.89 2.06

in:

r _b = burning rate at 1000 psi in inches per second (ips);

n = the pressure exponent in the burn rate equation (1) above, which is the slope of the line derived from the logarithm of the pressure along the x-axis and the logarithm of the burn rate along the y-axis;

k = constant in the burn rate equation (1) above.

Discussion of results

As shown in Table 3, the gas generant composition in Example 3 comprises the copper complex of ethylenediamine 5,5'-bitetrazolium of the present invention, which is different from that in Comparative Example 1 without any burning rate enhancer. Compared to the gas generant composition, even with the gas generant composition in Comparative Example 2 containing diamine 5,5'-bitetrazolium copper complex (submitted on November 30, 2001 as mentioned above The burning rate (r _b ) is significantly improved compared to that described in US patent application 09/998122).

In addition, the pressure sensitivity of the gas generant composition in Example 3 is lowered compared with the gas generant composition in Comparative Example 1, which can be seen from the smaller or lower pressure index (n) obtained, and its The pressure sensitivity was comparable to that of the gas generant composition in Comparative Example 2.

Embodiment 4 and comparative example 3,4

Preparation with basic copper nitrate as oxidant comprises hexaammine cobalt nitrate (III) and two (ethylenediamine) 5,5'-tetrazolium copper as co-fuel (embodiment 4); only comprises hexaammine cobalt nitrate ( III) as a fuel (comparative example 3); the gas generant composition comprising hexammine cobalt (III) nitrate and 5,5'-diammonium tetrazolium copper as a co-fuel (comparative example 4), as shown in the following table 4 Show. The values in Table 4 also refer to the weight percent relative to the composition.

Table 4

Element Example 3 Comparative example 1 Comparative example 2 Basic copper nitrate 23.14 21.50 22.53 Hexaammine cobalt(III) nitrate 66.88 73.50 67.47 Guar Gum - 5.09 - Bis(ethylenediamine) 5,5'-bistetrazole copper 10.00 - - Copper Diamine 5,5'-Bitrazolium - - 10.00

Then, the gas generant compositions in Example 4 and Comparative Examples 3 and 4 were measured in a manner similar to that used in Example 2 and Comparative Examples 1 and 2 above to obtain the burning rate and density (ρ) shown in Table 5 below.

table 5

parameter Example 4 Comparative example 3 Comparative example 4 r _b 0.70 0.25 0.38 n 0.43 0.46 0.42 k 0.036 0.010 0.021 ρ(g/cc) 1.97 1.95 1.97

in:

r _b = burning rate at 1000 psi in inches per second (ips);

n = the pressure exponent in the burn rate equation (1) above, which is the slope of the line derived from the logarithm of the pressure along the x-axis and the logarithm of the burn rate along the y-axis;

k = constant in the burn rate equation (1) above.

Discussion of results

As shown in Table 5, the gas generant composition in Example 4 contains the copper complex of ethylenediamine 5,5'-bitetrazolium of the present invention, which is different from that in Comparative Example 3 without any burning rate enhancing co-fuel. Compared with the gas generant composition of , even with the gas generant composition in Comparative Example 4 containing diamine 5,5'-bistetrazole copper complex (submitted on November 30, 2001 as mentioned above The burning rate (r _b ) is very significantly increased compared to that described in Japanese patent application 09/998122).

In addition, the pressure sensitivity of the gas generant composition in Example 4 is lowered compared with the gas generant composition in Comparative Example 3, which can be seen from the smaller or lower pressure index (n) obtained, and its The pressure sensitivity is only slightly higher than that of the gas generant composition in Comparative Example 4.

From the above discussion it can be seen that the present invention provides effective methods or techniques for desirably increasing the burn rate of gas generant formulations, particularly non-azide gas generant formulations, to sufficient and desired levels , for use in an inflatable restraint system application for a vehicle, and provided in a manner that is practical and suitable for such application. In addition, the present invention provides corresponding or related non-azide gas generant formulations which are capable of substantially and effectively increasing the burn rate required for such automotive inflatable restraint systems.

According to another preferred embodiment, the present invention generally also provides improved gas generant compositions, such as for inflating cushions of inflatable restraint air bags for vehicles. The composition satisfies both gas production and burning rate requirements, and may also meet other requirements such as combustion flame temperature, particulate production, batch-to-batch variation, and cost.

Such gas generant compositions generally comprise ligands selected from cobalt(III) nitrate complexes of ammonia and water, copper complexes of ethylenediamine dinitrate and basic copper nitrate. In particular, according to a preferred embodiment of the present invention, the formulation generally comprises:

About 45-90% by weight of cobalt(III) nitrate complex, the ligand is selected from ammonia and water;

About 2-50% by weight of copper complexes of ethylenediamine dinitrate;

About 5-50% by weight basic copper nitrate.

According to a preferred embodiment of the present invention, the cobalt(III) nitrate complex is the main component in the composition, so its relative content is higher than all other components in the composition. Those skilled in the art, guided by this specification, will also recognize that the cobalt(III) nitrate complex in the subject compositions generally functions as a fuel, as described above.

According to a preferred embodiment of the present invention, the cobalt(III) nitrate complex is a hexa-dentate cobalt(III) nitrate complex, preferably a hexa-neutral-dentate cobalt(III) nitrate complex. Hexaamminecobalt(III) nitrate, cobalt(III) pentaamminemonohydrate and mixtures thereof are particularly preferred cobalt(III) nitrate complexes according to the invention.

The preferred ethylenediamine copper dinitrate complex of the present invention is bis(ethylenediamine)copper dinitrate. Additionally, such ethylenediamine copper dinitrate complexes may advantageously function as burn rate catalysts in the subject gas generant compositions, as described in detail below.

In such gas generant formulations of the present invention, basic copper nitrate is preferably used to provide the oxygen required for complete combustion of the copper ethylenediamine dinitrate complex.

As described in detail below, it has been found advantageously that the gas generant compositions of the present invention provide burn rates exceeding 0.35 ips at 1000 psi pressure, and that, at least in certain preferred embodiments, the burn rate at 1000 psi pressure is at least About 0.4ips.

While the broad practice of the invention need not be limited to specific methods of preparation or handling, the compositions of the invention are advantageously amenable to handling by simpler means. For example, the ethylenediamine copper dinitrate complex in such subject gas generant formulations can be formed by the in situ reaction of copper nitrate with ethylenediamine, such as in a spray-dried mixing tank. According to a preferred embodiment of the present invention, the gas generant composition of the present invention can be formed by the following steps:

Mix the following ingredients to form a mixture;

a. Cobalt (III) nitrate complexes with ligands selected from ammonia or water;

b. Sufficient copper nitrate and ethylenediamine to form copper bis(ethylenediamine)dinitrate;

c. Basic copper nitrate;

The mixture is spray dried to form a powdered gas generant composition.

The gas generant composition powder may then be suitably compressed into the desired form, such as a tablet or pellet.

It can be seen that gas generant compositions or materials prepared in accordance with this aspect of the invention can be incorporated into or applied to a variety of different structures, assemblies and systems, as shown in the above figures. As noted above, the Figures illustrate a vehicle 10 with an inflatable occupant safety restraint system (generally indicated at 14 ) disposed within the interior 12 .

The vehicle occupant restraint system 14 includes an open reaction tank 16 constituting an inflatable passenger restraint 20 ( Such as the shell of an inflatable airbag cushion). As mentioned above, such gas generating devices are generally referred to as "gas generators".

The gas generator 22 comprises an amount of the gas generant composition or formulation of the present invention, eg, suitably induced to generate or form an amount of gas, eg, for inflating an inflatable vehicle occupant restraint 20 . It will be appreciated that the specific configuration of the gas generator assembly is not limiting to the broader applicability of the invention, and such gas generator assemblies may have various configurations, as known in the art.

In fact, the deployed airbag cushion 20 can provide protection for the occupant 24 by restricting the movement of the occupant toward the front of the vehicle, that is, to the right in the figure.

The present invention will be described in more detail with reference to the following examples, which illustrate or simulate the various features involved in practicing the above aspects of the invention. It should be understood that all changes within the spirit of the invention are claimed, and therefore the invention is not limited by these examples.

Embodiment 5 and comparative example 5,6

In Example 5, the gas generant composition of the present invention as shown in the following Table 6 (component content unit is wt %) was prepared, and compared with the gas generant pyrotechnic composition in Comparative Examples 5 and 6, Comparative Examples 5 and 6 are also listed in Table 6 below.

Table 6

Composition (weight%) Example 5 Comparative Example 5 Comparative example 6 Basic copper nitrate 22.53 22.53 46.62 Di(ethylenediamine)copper dinitrate 10.00 - - Hexaammine cobalt(III) nitrate 67.47 73.5 - Guanidine nitrate - - 50.36 Guar Gum - 5.00 - Aluminum oxide - - 2.70 silica - - 0.30

Then, the gas generant pyrotechnic compositions in Example 5 and Comparative Examples 5 and 6 were measured, and the burning rate and density shown in Table 7 below were obtained. Specifically, the burning rate data is obtained as follows: first press each gas generant formulation sample into a cylinder with a diameter of 0.5 inches with a hydraulic press (12,000 pounds force), usually with a sufficient amount of powder to make the cylinder 0.5 inches long; Krylon flame retardant was applied to all sides of the cylinder except the top surface to help ensure linear burning of the sample in the test setup. In each case, the coated cylinder was placed in a 1-liter closed laboratory vessel that could be pressurized to several thousand psi with nitrogen and equipped with a pressure sensor to accurately measure the closed laboratory vessel pressure in. A small sample of ignition powder is placed on top of the cylinder, and nichrome wires are threaded through the ignition powder and connected to electrodes secured in the lid of the experimental vessel. Then the experimental container was pressurized to the required pressure, and an electric current was passed through the nickel-chromium alloy wire to ignite the sample. During the combustion of each sample, pressure-time data were collected. As each sample burns to produce gas, an increase in the pressure of the test vessel indicates the beginning of combustion, and a "flattening" of the pressure indicates the end of combustion. The time required for combustion is equal to t ₂ -t ₁ , where t ₂ is the end time of combustion and t ₁ is the start time of combustion. The sample length divided by the burn time is the burn rate in inches per second. Burn rates are typically measured at four pressures (900, 1350, 2000 and 3000 psi). Plot the log of the burn rate versus the log of the mean pressure. From this line, the burning rate at any pressure can be calculated using the above gas generant composition burning rate formula (1). In addition, the gas productivity and flame temperature of the gas generant compositions in Example 5 and Comparative Examples 5 and 6 were calculated/measured, and are similarly shown in Table 7.

parameter Example 5 Comparative Example 5 Comparative Example 6 Gas yield (mol/100g) 3.3 3.3 2.9 Flame temperature (K) 1800 1805 1850 Burning rate (ips@1000psi) 0.40 0.25 0.4-0.5 Density(g/cc) 1.97 (pressed, pellets) 1.95 (compressed into tablets) 1.95 (compressed into pellets) particle Low Low Low batch difference Low (spray dried/pressed) high (extruded) Low

Discussion of results

As shown in the results in Table 7, the gas generant pyrotechnic composition of the present invention (i.e., Example 5) advantageously combines the advantages of the gas generant pyrotechnic compositions in Comparative Examples 5 and 6 without the presence of these compositions. or known disadvantages, and there was no significant difference in composition density. More specifically, the gas generant pyrotechnic composition of the present invention (such as Example 5) provides or obtains a higher gas yield (consistent with the gas generant pyrotechnic composition of Comparative Example 5), while also Provided or resulted in higher burn rates and low batch-to-batch variation (consistent with the gas generant pyrotechnic composition in Comparative Example 6). Those skilled in the art will understand under the guidance of this specification that the combustion rate of the gas generant pyrotechnic composition of the present invention (such as Example 5) is significantly improved compared with the gas generant pyrotechnic composition of Comparative Example 5 , for the reasons described above.

Accordingly, the present invention also provides gas generant compositions, such as those that can be used to inflate a vehicle inflatable restraint airbag cushion, that simultaneously satisfy the gas yield (for example, the gas yield is at least about 3.0 mol/100 g composition, preferably at least about 3.3 or more mol/100g composition) and burning rate (for example, the burning rate under 1000psi exceeds 0.35ips, preferably at least about 0.4ips), and should also meet the requirements such as relevant combustion flame temperature, particle production, batch variance and other requirements such as cost.

The invention having been described above is illustrative, and the invention is suitable for practice in the absence of any element, part, step, component or ingredient not specifically described.

Although the present invention has been described above in detail in conjunction with certain preferred embodiments of the present invention, and many details have been given for the purpose of illustration, those skilled in the art should understand that the present invention has other embodiments without departing from the present invention. Some of the details described herein may vary considerably without departing from the underlying principles.

Claims (28)

1. gas generant composition, it comprises:

Oxidant constituents;

Comprise quadrol 5, the fuel element of 5 '-bistetrazole transition metal complex.

2. the described gas generant composition of claim 1 is characterized in that, quadrol 5,5 '-bistetrazole transition metal complex comprise the metal that is selected from copper, zinc, cobalt, iron, nickel, chromium and their combination.

3. the described gas generant composition of claim 1 is characterized in that, quadrol 5,5 '-bistetrazole transition metal complex are quadrols 5, the copper complex of 5 '-bistetrazole.

4. the described gas generant composition of claim 3 is characterized in that quadrol 5, and the copper complex of 5 '-bistetrazole is formed by bistetrazole copper and reacting ethylenediamine.

5. the described gas generant composition of claim 3 is characterized in that quadrol 5, and the copper complex formazan empirical formula of 5 '-bistetrazole is Cu (C ₂H ₈N ₂) ₂C ₂N ₈

6. the described gas generant composition of claim 1, it is characterized in that, described fuel element comprises 1-100 weight % quadrol 5,5 '-bistetrazole transition metal complex and 0-99 weight % second fuel, and wherein wt percentage ratio is based on described fuel element gross weight.

7. gas generating equipment, it comprises the described gas generant composition of claim 6.

8. inflatable vehicle occupant security constraint securing system, it comprises for to bag cushion inflation, the described gas generating equipment of claim 7 that links to each other with the inflatable bladders pad.

9. the described gas generant composition of claim 1, it is characterized in that, described fuel element comprises 1-25 weight % quadrol 5,5 '-bistetrazole transition metal complex and 75-99 weight % second fuel, and wherein wt percentage ratio is based on described fuel element gross weight.

10. the described gas generant composition of claim 9 is characterized in that second fuel comprises the material that is selected from Guanidinium nitrate, nitric acid six cobaltammines (III), dinitric acid two (guanylurea) copper and their combination.

11. the described gas generant composition of claim 9 is characterized in that second fuel comprises nitric acid six cobaltammines (III).

12. a gas generating equipment, it comprises the described gas generant composition of claim 9.

13. an inflatable vehicle occupant security constraint securing system, it comprises in order to inflate the described gas generating equipment of claim 12 that links to each other with the inflatable bladders pad to bag cushion.

14. the described gas generant composition of claim 1 is characterized in that, described oxidant constituents comprises an alkali metal salt, alkaline earth salt and the ammonium salt that is selected from nitric acid and perchloric acid; Transition metal oxide and oxyhydroxide; The metal subcarbonate; The transition metal complex of ammonium nitrate; The oxygenant of metal subnitrate and their combination.

15. the described gas generant composition of claim 1 is characterized in that, described oxidant constituents comprises at least a metal subnitrate.

16. the described gas generant composition of claim 15 is characterized in that at least a metal subnitrate is selected from basic copper nitrate, alkali formula zinc nitrate and their combination.

17. a method that produces gas, described method comprises:

Light gas generant composition, described composition comprises fuel element and oxidant constituents, and described fuel element comprises quadrol 5, the transition metal complex of 5 '-bistetrazole.

18. the described method of claim 17 is characterized in that quadrol 5,5 '-bistetrazole transition metal complex comprises the metal that is selected from copper, zinc, cobalt, iron, nickel, chromium and their combination.

19. the described method of claim 17 is characterized in that quadrol 5,5 '-bistetrazole transition metal complex is a quadrol 5, the copper complex of 5 '-bistetrazole.

20. the described gas generant composition of claim 19 is characterized in that quadrol 5, the copper complex of 5 '-bistetrazole is formed by bistetrazole copper and reacting ethylenediamine.

21. the described gas generant composition of claim 17 is characterized in that quadrol 5, the copper complex formazan empirical formula of 5 '-bistetrazole is Cu (C ₂H ₈N ₂) ₂C ₂N ₈

22. the described method of claim 17 is characterized in that described fuel element comprises 1-100 weight % quadrol 5,5 '-bistetrazole transition metal complex and 0-99 weight % second fuel, and wherein wt percentage ratio is based on described fuel element gross weight.

23. the described method of claim 17 is characterized in that described fuel element comprises 1-25 weight % quadrol 5,5 '-bistetrazole transition metal complex and 75-99 weight % second fuel, and wherein wt percentage ratio is based on described fuel element gross weight.

24. the described method of claim 23 is characterized in that second fuel comprises the material that is selected from Guanidinium nitrate, nitric acid six cobaltammines (III), dinitric acid two (guanylurea) copper and their combination.

25. the described method of claim 23 is characterized in that second fuel comprises nitric acid six cobaltammines (III).

26. the described method of claim 17 is characterized in that described oxidant constituents comprises an alkali metal salt, alkaline earth salt and the ammonium salt that is selected from nitric acid and perchloric acid; Transition metal oxide and oxyhydroxide; The metal subcarbonate; The transition metal complex of ammonium nitrate; The oxygenant of metal subnitrate and their combination.

27. the described method of claim 17 is characterized in that described oxidant constituents comprises at least a metal subnitrate.

28. the described method of claim 27 is characterized in that at least a metal subnitrate is selected from basic copper nitrate, alkali formula zinc nitrate and their combination.