Method of formulating a gas generant composition

• US 6,475,312 B1
• Filed: 04/07/2000
• Issued: 11/05/2002
• Est. Priority Date: 04/07/1999
• Status: Expired due to Fees

• Current Assignee: Automotive Systems Laboratory, Incorporated (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Automotive Systems Laboratory, Incorporated (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Khandhadia, Paresh S., Burns, Sean P.
• Primary Examiner(s): Carone, Michael J.
• Assistant Examiner(s): FELTON, AILEEN BAKER
• Application Number:
  US09/544,694
• Time in Patent Office: 942 Days
• Field of Search: 149/109.6, 149/46, 149/61
• US Class Current: 149/109.6
• CPC Class Codes: C06B 25/34 the compound being a nitrated acyclic, alicyclic or heterocyclic amine
• CPC Class Codes: C06D 5/06 by reaction of two or more solids

Abstract

Preferred gas generant compositions incorporate a combination of 5-aminotetrazole nitrate and an oxidizer. The oxidizer may be selected from a group including nonmetal and metal nitrates, nitrites, chlorates, chlorites, perchlorates, and oxides. 5-aminotetrazole nitrate is characterized as an oxygen-rich fuel and is therefore considered to be a self-deflagrating fuel. To tailor the oxygen balance in certain applications, however, the use of an oxidizer is preferred. Methods of formulating the compositions are also described. These compositions are especially suitable for inflating air bags and actuating seatbelt pretensioners in passenger-restraint devices.

Claims

1. A method of formulating a gas generant composition comprising the steps of:

chilling a predetermined amount of nitric acid to 0-20 degrees Celsius;

adding a fuel selected from the group consisting of 5-aminotetrazole, diaminotriazole, azodicarbonamide, hydrazodicarbonamide, semicarbazide, carbohydrazide, biuret, 3,5-diamino-1,2,4-triazole, dicyandiamide, and 3-amino-1,2,4-triazole to the chilled nitric acid thereby forming a mixture wherein the nitric acid is diluted with water and is provided in a molarity and quantity at least sufficient to form a mononitrate of the fuel;

adding at least one oxidizer selected from the group consisting of nonmetal, alkali metal, and alkaline earth metal nitrates to the mixture;

stirring the mixture to form a wet paste wetted by nitric acid and/or water thereby precipitating a solid solution of the mononitrate of the fuel and the oxidizer;

forming the paste into a desired shape; and

drying the wet formed paste to remove any residual nitric acid and/or water.

2. The method of claim 1 wherein at least one oxidizer is selected from the group consisting of ammonium nitrate, potassium nitrate, and strontium nitrate.

3. The method of claim 1 wherein the nitric acid has a molarity of 15.9M or less.

4. A method of formulating a gas generant composition comprising the steps of:

chilling a predetermined amount of nitric acid to 0-20 degrees Celsius;

adding 5-aminotetrazole to the chilled nitric acid to form a slurry, the nitric acid diluted by water and provided in at least a sufficient molarity and quantity to form 5-aminotetrazole nitrate;

adding ammonium nitrate and potassium nitrate to the slurry wherein potassium nitrate is about 10% by weight of the combined weight of the ammonium nitrate and the potassium nitrate;

stirring the slurry to form a wet paste, thereby forming a solid solution containing 25-95% 5-aminotetrazole nitrate and 5-75% phase stabilized ammonium nitrate;

forming the paste into a desired shape; and

drying the formed paste to remove any residual nitric acid and/or water.