Method of stabilizing the density of gas generant pellets containing nitroguanidine

• US 20030127167A1
• Filed: 01/22/2003
• Published: 07/10/2003
• Est. Priority Date: 01/24/2001
• Status: Active Grant

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Canterberry, J. B., Adams, John H., Schmidt, Mark A., Hosey, Edward O., Walsh, Robert K.
• Granted Patent: US 6,887,325 B2
• Time in Patent Office: Days
• US Class Current: 149/109.6
• CPC Class Codes: C06B 21/0066 by granulation, e.g. flaking
• 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

A non azide gas generant composition of nitroguanidine and an oxidizer such as phase stabilized ammonium nitrate is provided. A gas generant having nitroguanidine and phase stabilized ammonium nitrate has many desirable characteristics such as little production of ash and the production of essentially toxic free exhaust gas. When nitroguanidine is compressed into a pellet it has needle shaped crystals that bend or distort. When the gas generant pellets are subjected to thermal cycling some nitroguanidine crystals will return to their native conformation resulting in pellet growth. To eliminate this pellet growth, nitroguanidine is passed through a vibrating ball mill. The media in the vibrating ball mill pulverizes the nitroguanidine into an amorphous crumb.

Claims

1. A process for preparing an azide-free gas generant composition that produces exhaust gases on combustion for inflating a vehicle restraint device, said composition comprising an oxidizer and nitroguanidine, said process comprising the steps of

a. grinding nitroguanidine into an amorphous crumb, and

b. mixing the nitroguanidine with the oxidizer.

2. The process of claim 1, wherein the gas generant comprises about 32-50% by weight of nitroguanidine.

3. The process of claim 1, wherein the gas generant composition further comprises less than 2% by weight of silica and less than 2% by weight of boron nitride.

4. The process of claim 1, wherein the nitroguanidine is pulverized into a crumb by being passed through a vibrating ball mill mill.

5. The process of claim 4, wherein the vibrating ball mill is preloaded with alumina media that pulverizes the nitroguanidine to amorphous crumb.

6. The process of claim 4, wherein the nitroguanidine is passed through the vibrating ball mill twice.

7. A process for preparing an azide-free gas generant composition that produces exhaust gases on combustion for inflating a vehicle restraint device, said process comprising the steps of

a. grinding nitroguanidine into an amorphous crumb, and

mixing the nitroguanidine with an oxidizer.

8. The process of claim 7, wherein the nitroguanidine is pulverized into an amorphous crumb by being passed through a vibrating ball mill.

9. The process of claim 89, wherein the vibrating ball mill is preloaded with alumina media that pulverizes the nitroguanidine.

10. The process of claim 9, wherein the nitroguanidine is passed through the vibrating ball mill twice.

11. A process for preparing an azide-free gas generant composition that produces exhaust gases on combustion for inflating a vehicle restraint device, said process comprising the steps of

a. grinding nitroguanidine by using a mill, wherein the mill converts the structure from a crystalline needle structure to an amorphous crumb, and

b. mixing the nitroguanidine with an oxidizer.