| Gas generant compositions -> Monitor Keywords |
|
|
Gas generant compositionsGas generant compositions description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070246138, Gas generant compositions. 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. 60/795,077 filed on Apr. 25, 2006. TECHNICAL FIELD [0002]The present invention relates generally to gas generating systems, and to gas generant/auto ignition compositions employed in gas generator devices for automotive restraint systems, for example. BACKGROUND OF THE INVENTION [0003]The present invention relates to gas generant/auto ignition compositions that upon combustion produce a relatively smaller 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]It is also required that airbag inflators be subjected to environmental conditioning, such as high temperature heat aging, thermal aging, thermal cycling, thermal shock, humidity cycling, and so forth. These extreme tests can cause many problems, ranging from failure to inflate the airbag to over-pressurization of the inflator leading to rupture. It is therefore desirable to have a gas generant and inflator/gas generating system that performs the same regardless of conditioning. The present invention provides a solution to many of these possibilities. [0006]Related thereto, certain auto ignition compositions, that is those compositions employed to auto ignite at relatively low temperatures (below 200 C), are desirable because of their relatively low melting point and therefore their relatively low auto ignition temperature. Additionally, another emphasis is providing dual functionality with regard to gas generation and auto ignition. Nevertheless, certain chemistry that provides desirable auto ignition temperature unfortunately also contributes to more reactive and less stable compositions after USCAR heat aging testing. Typically, the inflator is subjected to about 400 hours at 107 C, as defined in SAE International Document SAE/USCAR-24 "USCAR INFLATOR TECHNICAL REQUIREMENTS AND VALIDATION", herein incorporated by reference. [0007]It has been found, for example, that otherwise desirable compositions containing hydroxyl functionality exhibit poor thermal stability due to more reactive components included therein. More specifically, and by way of example only, compositions containing glucose and potassium chlorate function exceptionally well as auto ignition material. Nevertheless, when subjected to heat aging testing, the auto ignition temperature is elevated above 200 C and the thermal stability of this composition is compromised. It is believed that although hydroxyl functionality through electron localization increases the acidity of the terminal proton on each glucose molecule, it may have a propensity to produce water as a decomposition product over time when subjected to the extreme heat aging of the USCAR requirements. Glucose in particular has six hydroxyl groups that provide up to six mols of water per mol of glucose. [0008]Accordingly, it would be an improvement in the art to provide compositions that provide both auto ignition and gas generating functionality. Furthermore, these compositions must pass USCAR heat aging requirements while maintaining both thermal stability and auto ignition temperatures at or below 200 C. SUMMARY OF THE INVENTION [0009]The above-referenced concerns are resolved by gas generators or gas generating systems containing auto ignition/gas generating compositions including DL-tartaric acid as a primary fuel; a second fuel selected from carboxylic acids, amino acids, tetrazoles, triazoles, guanidines, and mixtures thereof; and potassium chlorate as an oxidizer. A secondary oxidizer selected from metal nitrates, metal nitrites, metal perchlorates, metal oxides, other known oxidizers, and mixtures thereof may also be employed. Non-hygroscopic oxidizers are preferred. [0010]In further accordance with the present invention, a gas generator or gas generating system, and a vehicle occupant protection system incorporating the auto ignition/gas generant composition are also included. BRIEF DESCRIPTION OF THE DRAWINGS [0011]FIG. 1 is a cross-sectional side view showing the general structure of an inflator in accordance with the present invention. [0012]FIG. 2 is a schematic representation of an exemplary vehicle occupant restraint system containing a gas generant composition in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION [0013]The present invention provides a gas generant system that includes at least one of the following: auto ignition functionality for airbag inflators, enhanced thermal stability, reduced component reactivity, and/or improved sensitivity with respect to impact and friction. The present gas generating system employs a unique advantage to the ignition function of a chlorate-based auto ignition system. This advantage is achieved by reducing the most reactive components of a chlorate based auto ignition system to their minimal functional level while increasing gas yield. Preferred gas generant systems utilize an auto ignition/gas generating composition formed from a mixture of carboxylic acids as fuels, and uses one or more oxidizers selected from potassium chlorate, potassium perchlorate, strontium nitrate, potassium nitrate, and metal oxides. (See table 1) [0014]Although not thereby limited, it is believed that the following explains the theory of operation of the present invention. The primary fuel of choice is DL-tartaric acid. The preferred secondary fuel is succinic acid. The combination of these two carboxylic acids provides the mechanism for desired functionality to the system based on the acidity of the carboxylic acids as indicated by pKa value and by melting point. The degree of hydroxyl substitution on the carboxylic acid provides the necessary reactivity when coupled with the lower melting point of succinic acid. It is believed that this combined interaction with potassium chlorate is the mechanism responsible for auto ignition function. The D and L forms of tartaric acid function equally well within this system. However, it is the racemic mixture of tartaric acid and the effects of hydrogen bonding between the D and L forms that as presently informed provide optimum thermal stability. It must be appreciated that a relatively low auto ignition temperature is achieved by this relationship. The preferred content of tartaric acid is about 5-40 wt %, and more preferably at about 10-25 wt %. [0015]Succinic acid is a preferred co-fuel within this gas generant/auto ignition (AI) system based upon its melting point and lack of hydroxyl substitution. While hydroxyl substitution is typically required for auto ignition function, it is believed that too much hydroxyl substitution exacerbates decomposition, particularly when subjected to USCAR heat aging requirements. Succinic acid, as a co-fuel, provides a preferred compliment to this auto ignition/gas generant system. The preferred content of succinic acid is about 5-30 wt % and more preferably at about 5-20 wt %. [0016]This system will function with other suitable carboxylic acid co-fuels such as, but not limited to, mucic acid, oxalic acid, salicylic acid, malic acid, fumaric acid, malonic acid, barbituric acid, glutamic acid, and adipic acid. Alternate carboxylic acids are generally provided at about 0-20 wt %. [0017]Alternate co-fuels such as amino acids may be incorporated into the gas generant/AI system. Amino acids such as, but not limited to, Glycine, Histidine, Arginine, and Serine are generally provided at about 0-20 wt %. [0018]It has been further demonstrated that carboxylic acid interaction with other co-fuels such as tetrazoles, triazoles, and guanidines provides low auto ignition temperatures based upon depression of melting points between the fuel mixture. For example, DL-tartaric acid (mp 210 C) and 5AT (mp 206 C) interact to create a melting point of 151 C. This same phenomenon is observed between 5AT and succinic acid. This forced melting in the presence of potassium chlorate offers an alternate mechanism for low temperature auto ignition function. Continue reading about Gas generant compositions... Full patent description for Gas generant compositions Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Gas generant compositions 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 compositions or other areas of interest. ### Previous Patent Application: Method of making a structural element for aeronautical construction comprising differential work-hardening Next Patent Application: Composite tire assembly Industry Class: Explosive and thermic compositions or charges ### FreshPatents.com Support Thank you for viewing the Gas generant compositions patent info. IP-related news and info Results in 0.12382 seconds Other interesting Feshpatents.com categories: Electronics: Semiconductor , Audio , Illumination , Connectors , Crypto , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
