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Gas generantRelated Patent Categories: Explosive And Thermic Compositions Or Charges, Containing Nitrated Metallo-organic Compound, Nitrated Organic Compound Of LeadGas generant description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070084531, Gas generant. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application Ser. No. 60/721,873 filed on Sep. 29, 2005. TECHNICAL FIELD [0002] The present invention relates generally to gas generating systems, and to gas generant compositions employed in gas generator devices for automotive restraint systems, for example. BACKGROUND OF THE INVENTION [0003] The present invention relates to gas generant compositions that upon combustion produce a relatively small amount of solids and a relatively abundant amount of gas. It is an ongoing challenge to reduce the amount of solids and increase the amount of gas thereby decreasing the filtration requirements for an inflator. As a result, the filter may be either reduced in size or eliminated altogether thereby reducing the weight and/or size of the inflator. [0004] An equally important challenge is to manufacture gas generants that exhibit relatively low sensitivity with regard to impact, friction, or electrostatic discharge stimuli. [0005] Yet another challenge with gas generant compositions that produce relatively small amounts of solids, sometimes known as "smokeless" compositions, is that not all non-metallic constituents contribute to stable ballistic performance when subjected to environmental conditioning. In fact, one fuel that is favored because of its propensity to produce all or mostly gas is the mono-ammonium salt of bis-1(2)H-tetrazol-5-yl)-amine (BTA-1NH3). When combined with other gas generant constituents such as an oxidizer, and formed into a gas generant composition, this fuel contributes to greater amounts of gas upon combustion of the composition. It has nevertheless been discovered that BTA-1NH3 contributes to an unacceptably aggressive ballistic performance as measured after thermal cycling and thermal shock testing defined in SAE International Document SAE/USCAR-24 "USCAR INFLATOR TECHNICAL REQUIREMENTS AND VALIDATION", herein incorporated by reference. [0006] Accordingly, it would be an improvement in the art to provide compositions that contain BTA-1NH3 that contribute to a "smokeless" gas generant composition, or one that when combusted produces 90% or more of gas as a product, while yet passing all thermal shock requirements as set forth in USCAR standards. SUMMARY OF THE INVENTION [0007] The above-referenced concerns are resolved by gas generating compositions including BTA-1NH3, an oxidizer such as phase stabilized ammonium nitrate, and a fumed oxide such as fumed silica or fumed alumina. It has been found that the addition of fumed silica or fumed oxides to compositions containing BTA-1NH3 has resulted in compositions that are now able to withstand the thermal cycling/thermal shock tests required by USCAR standards. Other constituents including processing aids such as graphite, may be included in relatively small amounts. [0008] In further accordance with the present invention, a gas generator and a vehicle occupant protection system incorporating the gas generant composition are also included. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is a cross-sectional side view showing the general structure of an inflator in accordance with the present invention; [0010] FIG. 2 is a schematic representation of an exemplary vehicle occupant restraint system containing a gas generant composition in accordance with the present invention. [0011] FIGS. 3 and 4 are graphical representations of a composition containing 0.25% by weight fumed silica. [0012] FIGS. 5 and 6 are graphical representations of a composition containing 0.50% by weight fumed silica. [0013] FIGS. 7 and 8 are graphical representations of a composition containing 0.75% by weight fumed silica. DETAILED DESCRIPTION [0014] The present invention includes gas generant compositions that in accordance with the present invention, incorporate an additive into compositions containing BTA-1NH3 that, when added at relatively low levels, stabilizes the propellant grains when subjected to thermal cycling or thermal shock conditioning, as required for use in the automotive industry. These formulations generally contain the following: [0015] A first oxidizer selected from the group including nonmetal and metal nitrate salts such as ammonium nitrate, phase-stabilized ammonium nitrate, potassium nitrate, strontium nitrate; nitrite salts such as potassium nitrite; chlorate salts such as potassium chlorate; metal and nonmetal perchlorate salts such as potassium or ammonium perchlorate; oxides such as iron oxide and copper oxide; basic nitrate salts such as basic copper nitrate and basic iron nitrate; and mixtures thereof. The first oxidizer is generally provided at about 0.1-80 wt% of the gas generant composition, and more preferably at about 10-70 wt%. [0016] An optional secondary oxidizer may also be provided and selected from the oxidizers described above, and when included is generally provided at about 0.1-50 wt%, and more preferably at about 0.1-30 wt%. The total oxidizer component, that is the combined weight percent of all oxidizers, will nevertheless only range from 0.1 to 80 wt%. [0017] A first or primary fuel consists of mono-ammonium salt of bis-(1(2)H-tetrazol-5-yl)-amine (BTA-1NH3) and is generally provided at about 0.1-50 weight percent or wt%, and more preferably at about 10-30 wt%. [0018] An optional secondary fuel is selected from the group containing derivatives of bis-(1(2)H-tetrazol-5-yl)-amine, including its anhydrous acid and its acid monohydrate, from metal salts thereof including the potassium, sodium, strontium, copper, boron, zinc salts of BTA-1NH3, and complexes thereof; azoles such as 5-aminotetrazole; metal salts of azoles such as potassium 5-aminotetrazole; nonmetal salts of azoles such as mono-or di-ammonium salt of 5, 5'-bis-1H-tetrazole; nitrate salts of azoles such as 5-aminotetrazole nitrate; nitramine derivatives of azoles such as 5-nitraminotetrazole; metal salts of nitramine derivatives of azoles such as di-potassium 5-nitraminotetrazole; nonmetal salts of nitramine derivatives of azoles such as mono- or di-ammonium 5-nitraminotetrazole and; guanidines such as dicyandiamide; salts of guanidines such as guanidine nitrate; nitro derivatives guanidines such as nitroguanidine; azoamides such as azodicarbonamide; nitrate salts of azoamides such as azodicarbonamidine dinitrate; and mixtures thereof, and when included is generally provided at about 0.1-49.9 wt%, more preferably 0.1-30 wt%. The total fuel component, that is the combined amount of all of the fuels of the composition, will nevertheless only range from 0.1-50 wt%, and more preferably about 0.1-30 wt%. Continue reading about Gas generant... Full patent description for Gas generant Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Gas generant patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Gas generant or other areas of interest. ### Previous Patent Application: Gas generant Next Patent Application: Gas generant Industry Class: Explosive and thermic compositions or charges ### FreshPatents.com Support Thank you for viewing the Gas generant patent info. 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