Auto-igniting booster gas generant composition

Abstract

Auto-igniting booster gas generant compositions according to various implementations include a primary fuel and at least two additives. The fuel may be a tetrazole or salt of tetrazole, such as 5-aminotetrazole, whereas the additives include boron carbide and molybdenum trioxide. The compositions may also include a secondary fuel, preferably potassium salt of 5-aminotetrazole. The auto-igniting booster gas generant compositions have an auto-ignition temperature of 200 degrees Celsius or less, self-igniting in the presence of an external heat source. The compositions may also include an oxidizer, such as potassium nitrate. Optionally, the auto-igniting booster gas generant compositions may include additional components, such as processing lubricants. For example, the compositions may include polyethylene to aid in processing and manufacturing.

Description

[0001] AUTO-IGNITING BOOSTER GAS GENERANT COMPOSITION

[0002] Cross-Reference to Related Application

[0003] This application claims the benefit of U.S. Provisional Application 63 / 511,258, filed June 30, 2023, the contents of which are hereby incorporated in its entirety.

[0004] Technical Field

[0005] The present disclosure relates to safety devices for passenger vehicles. In particular, the disclosure relates to an auto-igniting booster gas generant composition for use in inflatable protection devices, such as airbags. Passenger vehicles may include, for example, automobiles, boats, trains, aircraft, and spacecraft.

[0006] Background

[0007] Inflatable protection devices, such as airbags, have been widely adopted in passenger vehicles for improving the safety of occupants. An inflator is operated by an ignition signal received from the vehicle when a vehicle sensor detects an emergency event, such as a collision, and inflates the inflatable protection device to a position between an occupant and a portion of the vehicle. The inflator is typically required to produce a sufficient amount of inflation gas to inflate the inflatable protection device in a very short period of time. In some inflators, pyrotechnic main gas generant compositions are used which can rapidly combust and produce the required inflation gas. To ignite the main gas generant compositions efficiently, some inflators utilize pyrotechnic booster gas generant compositions.

[0008] Booster gas generant compositions are typically formulated to produce large amounts of heat and solid particulates to assist in igniting and combusting the main gas generant composition. In some cases, it may also be important for the booster gas generant composition to be an auto-igniting composition, meaning that the booster gas generant composition can self-ignite at an appropriate time in the presence of elevated temperatures, such as those caused by a fire. The particular components selected for a booster gas generant composition, and the amounts and ratios of these components relative to each other, can greatly affect the properties of the booster gas generant composition and thus the suitability for use with any particular main gas generant composition. Therefore, it is important to tune the booster gas generant composition to achieve ideal performance alongside the main gas generant composition in the inflator.

[0009] Summary

[0010] In various implementations, an auto-igniting booster gas generant composition comprises 15 to 20% by weight of 5-aminotetrazole. The auto-igniting booster gas generant composition also comprises 3 to 7% by weight of molybdenum trioxide and 3 to 7% by weight of boron carbide. The auto-igniting booster gas generant composition has an auto-ignition temperature of 200 degrees Celsius or less.

[0011] In some implementations, the auto-igniting booster gas generant composition further comprises 0.5 to 3% by weight of a lubricant. The lubricant may be selected from the group consisting of calcium stearate, magnesium stearate, molybdenum disulfide, boron nitride, stearic acid, polyethylene, paraffin, and combinations thereof. In some implementations, the lubricant comprises polyethylene.

[0012] In some implementations, the auto-igniting booster gas generant composition is free of ammonium perchlorate and ammonium nitrate.

[0013] In some implementations, the auto-igniting booster gas generant composition further comprises 60 to 70% by weight of an oxidizer. The oxidizer is selected from the group consisting of metal perchlorates, metal nitrates, basic metal nitrates, and combinations thereof. In some implementations, the oxidizer comprises potassium nitrate, wherein, the potassium nitrate is present at about 65% by weight of the composition.

[0014] In some implementations, the auto-igniting booster gas generant composition further comprises 5 to 10% by weight of a secondary fuel, wherein the secondary fuel is selected from the group consisting of tetrazoles and salts of tetrazoles. In some implementations, the secondary fuel comprises potassium 5-aminotetrazole, wherein the potassium 5- aminotetrazole is present at about 7% by weight of the composition. In some implementations, the 5-aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 2:1 respectively. In other implementations, the 5-aminotetrazole and the potassium 5- aminotetrazole are present in a ratio of 3:1 respectively.

[0015] In other implementations, an auto-igniting booster gas generant composition comprises 60 to 70% by weight of potassium nitrate, 15 to 20% by weight of 5-aminotetrazole, 5 to 10% by weight of potassium 5-aminotetrazole, 3 to 7% by weight of molybdenum trioxide, and 3 to 7% by weight of boron carbide. The auto-igniting booster gas generant composition has an autoignition temperature of 200 degrees Celsius or less.

[0016] In some implementations, the auto-igniting booster gas generant composition further comprises 0.5 to 3% by weight of a lubricant. The lubricant may be selected from the group consisting of calcium stearate, magnesium stearate, molybdenum disulfide, boron nitride, stearic acid, polyethylene, paraffin, and combinations thereof. In some implementations, the lubricant comprises polyethylene.

[0017] In some implementations, the auto-igniting booster gas generant composition is free of ammonium perchlorate and ammonium nitrate.

[0018] In some implementations, the 5-aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 3:1 respectively.

[0019] In other implementations, an auto-igniting booster gas generant composition consists of 60 to 70% by weight of potassium nitrate, 15 to 20% by weight of 5-aminotetrazole, 5 to 10% by weight of potassium 5-aminotetrazole, 3 to 7% by weight of molybdenum trioxide, 3 to 7% by weight of boron carbide, and 0.5 to 3% by weight of polyethylene. The auto-igniting booster gas generant composition has an auto-ignition temperature of 200 degrees Celsius or less.

[0020] Brief Description of the Drawings The drawings are merely exemplary to illustrate structure and certain features that can be used singularly or in combination with other features. The disclosure should not be limited to the implementations shown.

[0021] FIG. 1 is a perspective view of an inflator for use with the auto-igniting booster gas generant compositions disclosed herein.

[0022] FIG. 2 is a cross-sectional view of the inflator of FIG. 1 taken along the line A-A.

[0023] Detailed Description

[0024] Auto-Igniting Booster Gas Generant Compositions

[0025] Disclosed herein are auto-igniting booster gas generant compositions that comprise a primary fuel and at least two additives. The auto-igniting booster gas generant compositions may also include at least one oxidizer. In some implementations, the oxidizer comprises a metal nitrate. In some implementations, the auto-igniting booster gas generant compositions may also comprise a secondary fuel. The primary fuel is selected from tetrazoles and salts of tetrazoles. In some implementations, the secondary fuel is also selected from tetrazoles and salts of tetrazoles. The at least two additives comprise molybdenum trioxide and boron carbide. Also, various other additives can be present in the auto-igniting booster gas generant compositions, such as lubricants, to provide additional beneficial properties.

[0026] Auto-igniting booster gas generant compositions can be formulated with varying oxygen balances by changing the components and / or their relative amounts. Oxygen balance is a term known in the pyrotechnic arts and refers to the degree to which a gas generating composition can be oxidized. In other words, an oxygen balance of 0% means, theoretically, all the atoms of the gas generating composition could be fully oxidized by the oxygen contained in the gas generating composition. A negative oxygen balance means there is not enough oxygen in the gas generating composition for full oxidation while a positive oxygen balance means there is more than enough. For example, carbon atoms will fully oxidize to carbon dioxide (CO2) and hydrogen atoms will fully oxidize to water (H2O). In practical applications however, a 0% oxygen balance will not actually result in complete combustion. Nonetheless, by tuning the oxygen balance of a gas generating composition, one can affect the properties of the gas generating composition, such as the amount of undesirable effluent gases created during combustion. In some implementations, the auto-igniting booster gas generant compositions disclosed herein are formulated with an oxygen balance between -2% and +2%. In some implementations, the auto-igniting booster gas generant composition is formulated with an oxygen balance of 0%.

[0027] Fuels

[0028] In some implementations, the primary fuel comprises a tetrazole or a salt of a tetrazole. The primary fuel can be present in an amount from 15 to 20% by weight of the auto-igniting booster gas generant composition. In some implementations, the primary fuel comprises 5- aminotetrazole. In one specific example, the 5-aminotetrazole is present at about 17% by weight of the auto-igniting booster gas generant composition. In some implementations, the auto-igniting booster gas generant composition comprises a secondary fuel comprising another tetrazole or salt of tetrazole. In some implementations, the secondary fuel comprises the potassium salt of 5-aminotetrazole, also known as potassium 5-aminotetrazole. The secondary fuel can be present in an amount from 5 to 10% by weight of the auto-igniting booster gas generant composition. In one specific example, the potassium 5-aminotetrazole is present at about 7% by weight of the auto-igniting booster gas generant composition.

[0029] A relatively low auto-ignition temperature of the auto-igniting booster gas generant composition can be achieved by the use of 5-aminotetrazole, especially in combination with molybdenum trioxide, as discussed below. However, in some implementations, the combination of 5 aminotetrazole and potassium 5-aminotetrazole in an appropriate ratio can further reduce the autoignition temperature of the auto-igniting booster gas generant composition. For example, in some implementations, the 5-aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 2:1 respectively. In other implementations, the 5- aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 3:1 respectively. The resulting auto-igniting temperature of the auto-igniting booster gas generant compositions is 200 degrees Celsius or less. Additives

[0030] The auto-igniting booster gas genera nt compositions comprise at least two additives. For example, additives can provide a variety of features: higher combustion gas temperature, increased solids to gas combustion product ratio, lower auto-ignition temperatures, lower sensitivity, and improved processing through lubrication. The auto-igniting booster gas generant compositions disclosed herein comprise at least boron carbide and molybdenum trioxide.

[0031] Boron carbide contributes to a higher combustion gas temperature, a higher solids to gas combustion product ratio, and decreased sensitivity (particularly when compared to compositions comprising elemental boron). These properties are helpful for igniting certain main gas generant compositions in an inflator while maintaining safety for process operators, for example. By producing more heat in the gaseous products and a higher percentage of solids, the auto-igniting booster gas generant compositions are more effective at igniting difficult-to-ignite main gas generant compositions. For example, hot solid particulates impact the main gas generant composition and provide high localized heat via conduction. In some implementations, the boron carbide is present in the auto-igniting booster gas generant compositions at about 3 to 7% by weight. In one specific example, the boron carbide is present at about 5% by weight of the auto-igniting booster gas generant compositions.

[0032] Molybdenum trioxide contributes to a lower auto-ignition temperature for the autoigniting booster gas generant compositions. As mentioned herein, lower auto-ignition temperatures improve the safety characteristics of inflators, allowing for controlled deployment in dangerous situations. When used in conjunction with 5-aminotetrazole and, in some implementations, with potassium 5-aminotetrazole, molybdenum trioxide helps to produce the autoignition temperatures of 200 degrees Celsius or less. In some implementations, the molybdenum trioxide is present in the auto-igniting booster gas generant compositions at about 3 to 7% by weight. In one specific example, the molybdenum trioxide is present at about 5% by weight of the auto-igniting booster gas generant compositions. In some implementations, the auto-igniting booster gas generant compositions can additionally comprise one or more lubricants which can be chosen from calcium stearate, magnesium stearate, molybdenum disulfide, boron nitride, stearic acid, polyethylene, paraffin, and combinations thereof. In some implementations, the auto-igniting booster gas generant compositions can contain the one or more lubricants in an amount between 0.5 to 3% by weight. In one specific example, the one or more lubricants comprise polyethylene at about 1% by weight of the auto-igniting booster gas generant composition.

[0033] Oxidizers

[0034] In some implementations, the auto-igniting booster gas generant compositions comprise at least one oxidizer. The at least one oxidizer can be selected from the group consisting of metal perchlorates, metal nitrates, basic metal nitrates, and combinations thereof. For example, in some implementations, the oxidizer may comprise potassium nitrate. In some implementations, the oxidizer may be selected from other oxidizers known in the art. In some implementations, the at least one oxidizer does not comprise nonmetal perchlorates or nonmetal nitrates. For example, in some implementations, the auto-igniting booster gas generant compositions are free of ammonium perchlorate and ammonium nitrate. The autoigniting booster gas generant composition may include the at least one oxidizer as a first oxidizer in combination with one or more other oxidizers selected from the same oxidizers disclosed above. The at least one oxidizer can be present in the auto-igniting booster gas generant compositions at an amount from 60 to 70% by weight. In one specific example, the at least one oxidizer comprises potassium nitrate and is present at about 65% by weight of the auto-igniting booster gas generant composition.

[0035] Articles

[0036] The auto-igniting booster gas generant compositions disclosed herein can be prepared by mixing the various components in the described amounts. In some implementations, the individual components can begin as powders and be mixed and milled together in a pin mill, vibratory mill, or jet mill, or be separately milled and then blended together in a ribbon blender or tumble blender, for example. In other implementations, the individual components are simply blended together without any milling. The blended and / or milled powder mixture can be compacted and granulated on a roll compactor and subsequent granulator. The resulting granules, or a subset of them (i.e., a desired range of particle size distribution as achieved via a sieve), can be compressed on a traditional tableting press to form tablets. The lubricants disclosed above provide for improved flow of the powder and granules on the roll compactor and tablet press, respectively, thus leading to improved manufacturing rates and lower cost. In other implementations, the granules are the final product and tableting is not necessary.

[0037] Methods of Use

[0038] The auto-igniting booster gas generant compositions in the granule or tablet form can be introduced in a loose bulk fashion or in an oriented fashion into appropriate pressure-proof containers. The granules or tablets are ignited according to conventional methods with the aid of initiator charges or thermal charges wherein the thus-formed combustion gases, heat, and solids cause the combustion of a main gas generant composition and ultimately lead to inflation of an inflatable protection device within fractions of a second. The auto-igniting booster gas generant compositions disclosed herein are especially suited for automobile airbags. In case of an automobile impact, the airbag must fill up within a minimum time period and to a volume of about 50 to 300 liters, depending on the type of airbag, location of the airbag, and automobile size, for example. The auto-igniting booster gas generant compositions are likewise suitable for use in seat belt tightening devices, for example retractors or pretensioners.

[0039] As shown in FIGS. 1-2, an exemplary inflator 100 for providing inflation gas to an inflatable protection device comprises a combustion chamber 114 which includes a main gas generant composition 200. The inflator 100 also comprises a booster chamber 115 which includes an auto-igniting booster gas generant composition 300 in tablet form. To deploy the inflator 100, an ignition signal is sent by a vehicle to an initiator 110 when a vehicle sensor detects an emergency event. The initiator 110 then ignites the auto-igniting booster gas generant composition 300 in the booster chamber 115. The booster chamber 115 is defined by a booster tube 108 and a bore seal 111. Hot combustion gases and solid particulates from the combustion of the auto-igniting booster gas generant composition 300 then flows through booster tube orifices 109, defined by the booster tube 108, and into the combustion chamber 114, thus igniting the main gas generant composition 200, also in tablet form.

[0040] The main gas generant composition 200 will combust to produce the inflation gas for the inflatable protection device. Inflation gas will flow from the combustion chamber 114 through a filter 103 which cools the inflation gas and captures solid particulates. The filter 103 is disposed between an inner baffle 104 and an outer baffle 105, and between a base 101 and a cap 102. The inflation gas flows through the filter 103 and into a plenum 117 between the cap 102 and the outer baffle 105, and then breaks through seal 106 and exits the inflator 100 and enters into the inflatable protection device via cap orifices 116. A flange 112 defines a fastener opening 113 for mounting the inflator 100 to the inflatable protection device or other structure adjacent the inflatable protection device. An optional cushion 107 can be disposed within the combustion chamber 114 adjacent the main gas generant composition 200 to prevent the main gas generant composition 200 from suffering structural damage due to impacts to, and vibrations of, the inflator 100.

[0041] The above-described method of use is for normal operation of the inflator 100. In some scenarios, the inflator 100 may be exposed to elevated temperatures from an external heat source. This can happen during a fire in a shipping vehicle, for example, and could lead to unsafe operating conditions. The auto-igniting booster gas generant composition 300 will absorb heat from the external heat source conducted through, for example, the cap 102, booster tube 108, and bore seal 111. Once the auto-ignition temperature of the auto-igniting booster gas generant composition 300 is reached, it will self-ignite and operation of the inflator 100 will proceed in a similar manner as described above but without ignition of the initiator 110. The auto-ignition temperature of the auto-igniting booster gas generant 300 is lower than the temperature at which the main gas generant composition 200 will melt or otherwise become structurally compromised, therefore uncontrolled combustion of the main gas generant composition 200 can be prevented.

[0042] Example The following Example is set forth below to illustrate the compositions according to the disclosed subject matter. This Example is not intended to be inclusive of all aspects of the subject matter disclosed herein, and is not intended to exclude equivalents and variations of the present disclosure which will be apparent to one skilled in the art. This Example is not exhaustive of all possible auto-igniting booster gas generant compositions contemplated by the present disclosure.

[0043] In the following Example, the individual components began as powders and were mixed and milled in a vibratory mill. The milled powder was compacted on a roll compactor and then granulated using a granulator. A subset of the granules (e.g., the granules were passed through a sieve to separate desirable larger granules from undesirable smaller granules) were then compressed on a tablet press and the resulting tablets were added to the inflator 100 for testing. The following Example was formulated with an oxygen balance of 0%.

[0044] Example: An auto-igniting booster gas generant composition was prepared comprising 65% potassium nitrate, 17% 5-aminotetrazole, 7% potassium 5-aminotetrazole, 5% molybdenum trioxide, 5% boron carbide, and 1% polyethylene. This auto-igniting booster gas generant composition self-ignited below 200 degrees Celsius when the inflator 100 was submitted to an external heat source, leading to a successful inflator deployment.

[0045] Additional Aspects

[0046] 1. An auto-igniting booster gas generant composition comprising:

[0047] 15 to 20% by weight of 5-aminotetrazole;

[0048] 3 to 7% by weight of molybdenum trioxide; and

[0049] 3 to 7% by weight of boron carbide; wherein the composition has an auto-ignition temperature of 200 degrees Celsius or less.

[0050] 2. The auto-igniting booster gas generant composition of aspect 1, further comprising 0.5 to 3% by weight of a lubricant. 3. The auto-igniting booster gas generant composition of aspect 2, wherein the lubricant is selected from the group consisting of calcium stearate, magnesium stearate, molybdenum disulfide, boron nitride, stearic acid, polyethylene, paraffin, and combinations thereof.

[0051] 4. The auto-igniting booster gas generant composition of aspect 3, wherein the lubricant comprises polyethylene.

[0052] 5. The auto-igniting booster gas generant composition of any of aspects 1-4, wherein the composition is free of ammonium perchlorate and ammonium nitrate.

[0053] 6. The auto-igniting booster gas generant composition of any of aspects 1-5, further comprising 60 to 70% by weight of an oxidizer.

[0054] 7. The auto-igniting booster gas generant composition of aspect 6, wherein the oxidizer is selected from the group consisting of metal perchlorates, metal nitrates, basic metal nitrates, and combinations thereof.

[0055] 8. The auto-igniting booster gas generant composition of aspect 7, wherein the oxidizer comprises potassium nitrate.

[0056] 9. The auto-igniting booster gas generant composition of aspect 8, wherein the potassium nitrate is present at about 65% by weight of the composition.

[0057] 10. The auto-igniting booster gas generant composition of any of aspects 1-9, further comprising 5 to 10% by weight of a secondary fuel, wherein the secondary fuel is selected from the group consisting of tetrazoles and salts of tetrazoles.

[0058] 11. The auto-igniting booster gas generant composition of aspect 10, wherein the secondary fuel comprises potassium 5-aminotetrazole. 12. The auto-igniting booster gas generant composition of aspect 11, wherein the potassium 5-aminotetrazole is present at about 7% by weight of the composition.

[0059] 13. The auto-igniting booster gas generant composition of aspect 11 or 12, wherein the 5- aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 2:1 respectively.

[0060] 14. The auto-igniting booster gas generant composition of aspect 11 or 12, wherein the 5- aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 3:1 respectively.

[0061] 15. An auto-igniting booster gas generant composition comprising:

[0062] 60 to 70% by weight of potassium nitrate;

[0063] 15 to 20% by weight of 5-aminotetrazole;

[0064] 5 to 10% by weight of potassium 5-aminotetrazole;

[0065] 3 to 7% by weight of molybdenum trioxide; and

[0066] 3 to 7% by weight of boron carbide; wherein the composition has an auto-ignition temperature of 200 degrees Celsius or less.

[0067] 16. The auto-igniting booster gas generant composition of aspect 15, further comprising 0.5 to 3% by weight of a lubricant, wherein the lubricant is selected from the group consisting of calcium stearate, magnesium stearate, molybdenum disulfide, boron nitride, stearic acid, polyethylene, paraffin, and combinations thereof.

[0068] 17. The auto-igniting booster gas generant composition of aspect 16, wherein the lubricant comprises polyethylene.

[0069] 18. The auto-igniting booster gas generant composition of any of aspects 15-17, wherein the composition is free of ammonium perchlorate and ammonium nitrate. 19. The auto-igniting booster gas generant composition any of aspects 15-18, wherein the 5-aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 3:1 respectively.

[0070] 20. An auto-igniting booster gas generant composition consisting of:

[0071] 60 to 70% by weight of potassium nitrate;

[0072] 15 to 20% by weight of 5-aminotetrazole;

[0073] 5 to 10% by weight of potassium 5-aminotetrazole;

[0074] 3 to 7% by weight of molybdenum trioxide;

[0075] 3 to 7% by weight of boron carbide; and

[0076] 0.5 to 3% by weight of polyethylene; wherein the composition has an auto-ignition temperature of 200 degrees Celsius or less.

[0077] A number of implementations have been described. The description in the present disclosure has been presented for purposes of illustration but is not intended to be exhaustive of, or limited to, the implementations disclosed. It will be understood that various modifications and variations will be apparent to those of ordinary skill in the art and may be made without departing from the spirit and scope of the claims. Accordingly, other implementations are within the scope of the following claims. The implementations described were chosen in order to best explain the principles of the auto-igniting booster gas generant compositions and their practical application, and to enable others of ordinary skill in the art to understand the auto-igniting booster gas generant compositions and how they may be used for various implementations with various modifications as are suited to the particular use contemplated.

[0078] The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated steps, features, operations, elements, and / or components, but do not preclude the presence or addition of one or more other steps, features, operations, elements, components, and / or groups thereof. When describing ratios, it should be understood that a ratio chosen should be reduced to its lowest value relative to 1, such that a ratio of 6:3 should be read as 2:1, or a ratio of 3:2 should be read as 1.5:1, for example. Similarly, a ratio of 3:6 should be read as 1:2, or a ratio of 2:3 should be read as 1:1.5. When describing ranges of components, any value within the range can be chosen, regardless of decimal points, including the end points of the stated range. For example, a range of 1 to 10 includes 1, 10, and 3.14, or further includes a sub-range of 2.6 to 7.88

Claims

CLAIMSWhat is claimed is:

1. An auto-igniting booster gas generant composition comprising:15 to 20% by weight of 5-aminotetrazole;3 to 7% by weight of molybdenum trioxide; and3 to 7% by weight of boron carbide; wherein the composition has an auto-ignition temperature of 200 degrees Celsius or less.

2. The auto-igniting booster gas generant composition of claim 1, further comprising 0.5 to 3% by weight of a lubricant.

3. The auto-igniting booster gas generant composition of claim 2, wherein the lubricant is selected from the group consisting of calcium stearate, magnesium stearate, molybdenum disulfide, boron nitride, stearic acid, polyethylene, paraffin, and combinations thereof.

4. The auto-igniting booster gas generant composition of claim 3, wherein the lubricant comprises polyethylene.

5. The auto-igniting booster gas generant composition of claim 1, wherein the composition is free of ammonium perchlorate and ammonium nitrate.

6. The auto-igniting booster gas generant composition of claim 1, further comprising 60 to 70% by weight of an oxidizer.

7. The auto-igniting booster gas generant composition of claim 6, wherein the oxidizer is selected from the group consisting of metal perchlorates, metal nitrates, basic metal nitrates, and combinations thereof.

8. The auto-igniting booster gas generant composition of claim 7, wherein the oxidizer comprises potassium nitrate.

9. The auto-igniting booster gas generant composition of claim 8, wherein the potassium nitrate is present at about 65% by weight of the composition.

10. The auto-igniting booster gas generant composition of claim 1, further comprising 5 to 10% by weight of a secondary fuel, wherein the secondary fuel is selected from the group consisting of tetrazoles and salts of tetrazoles.

11. The auto-igniting booster gas generant composition of claim 10, wherein the secondary fuel comprises potassium 5-aminotetrazole.

12. The auto-igniting booster gas generant composition of claim 11, wherein the potassium 5-aminotetrazole is present at about 7% by weight of the composition.

13. The auto-igniting booster gas generant composition of claim 11, wherein the 5- aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 2:1 respectively.

14. The auto-igniting booster gas generant composition of claim 11, wherein the 5- aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 3:1 respectively.

15. An auto-igniting booster gas generant composition comprising:60 to 70% by weight of potassium nitrate;15 to 20% by weight of 5-aminotetrazole;5 to 10% by weight of potassium 5-aminotetrazole;3 to 7% by weight of molybdenum trioxide; and3 to 7% by weight of boron carbide; wherein the composition has an auto-ignition temperature of 200 degrees Celsius or less.

16. The auto-igniting booster gas generant composition of claim 15, further comprising 0.5 to 3% by weight of a lubricant, wherein the lubricant is selected from the group consisting of calcium stearate, magnesium stearate, molybdenum disulfide, boron nitride, stearic acid, polyethylene, paraffin, and combinations thereof.

17. The auto-igniting booster gas generant composition of claim 16, wherein the lubricant comprises polyethylene.

18. The auto-igniting booster gas generant composition of claim 15, wherein the composition is free of ammonium perchlorate and ammonium nitrate.

19. The auto-igniting booster gas generant composition of claim 15, wherein the 5- aminotetrazole and the potassium 5-aminotetrazole are present in a ratio of 3:1 respectively.

20. An auto-igniting booster gas generant composition consisting of:60 to 70% by weight of potassium nitrate;15 to 20% by weight of 5-aminotetrazole;5 to 10% by weight of potassium 5-aminotetrazole;3 to 7% by weight of molybdenum trioxide;3 to 7% by weight of boron carbide; and0.5 to 3% by weight of polyethylene; wherein the composition has an auto-ignition temperature of 200 degrees Celsius or less.

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