Preparation of strengthened ammonium nitrate propellants

• US 6,726,788 B2
• Filed: 12/13/2001
• Issued: 04/27/2004
• Est. Priority Date: 01/19/1994
• Status: Expired due to Fees

• Current Assignee: Goodrich Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Universal Propulsion Company Incorporated (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Olander, Donald E., McSpadden, Hugh J., Fleming, Wayne C.
• Primary Examiner(s): Miller, Edward A.
• Application Number:
  US10/013,446
• Publication Number:
  US 20040050467A1
• Time in Patent Office: 866 Days
• Field of Search: 149/19.92, 149/109.6
• US Class Current: 149/19.92
• CPC Class Codes: C06B 23/006 Stabilisers (e.g. thermal stabilisers) processes C06B21/0091; foam stabilisers C06B23/002
• CPC Class Codes: C06B 31/28 the salt being ammonium nitrate
• CPC Class Codes: C06B 31/30 with vegetable matter; with resin; with rubber
• CPC Class Codes: C06B 45/105 The resin being a polymer bearing energetic groups or containing a soluble organic explosive

Abstract

The present invention is directed to an age-stabilized and/or strengthened ammonium nitrate propellant composition wherein the strengthening agent is selected from the group consisting of azodicarbonamide, dicyandiamide, oxamide and mixtures thereof and wherein the age-stabilizing agent is a molecular sieve having a pore size of 13 angstroms or less.

Claims

1. A process of forming a strengthened propellant composition comprising the steps of:

providing ammonium nitrate; and

forming a primary mixture by adding a strengthening agent and a binder to the ammonium nitrate, wherein the amount of the binder is sufficient to form the primary mixture into a desired shape.

2. The process of claim 1, further comprising the step of:

grinding the ammonium nitrate prior to the forming the primary mixture.

3. The process of claim 2, wherein the step of grinding comprises ball milling, fluid energy milling, or micropulverizing.

4. The process of claim 1, wherein the binder is selected from the group consisting of thermoplastic elastomers, hydroxy terminated polybutadiene, hydroxy terminated polyether, polyglycol adipate, glycidylazide polymer, poly bis-3,3′

-azidomethyl oxetane, poly-3-nitratomethyl-3-methyl oxetane, polyethylene glycol, polypropylene glycol, cellulose acetate, and mixtures thereof.

5. The process of claim 1, wherein the binder is provided in an amount from about 3 percent to about 40 percent by weight of the composition.

6. The process of claim 5, wherein the binder is provided in an amount from about 3 percent to about 20 percent by weight of the composition.

7. The process of claim 1, wherein the strengthening agent is selected from the group consisting of azodicarbonamide, dicyandiamide, oxamide, and mixtures thereof.

8. The process of claim 1, wherein the strengthening agent is provided in an amount of about 2 percent to about 20 by weight of the composition.

9. The process of claim 8, wherein the strengthening agent is provided in an amount of about 3 percent to about 12 by weight of the composition.

10. The process of claim 1, wherein the ammonium nitrate is provided in an amount from about 40 percent to about 85 percent by weight of the composition.

11. The process of claim 1, further comprising the step of:

adding at least one additional component to the primary mixture selected from the group consisting of a synthetic zeolite, a nitroplasticizer, an energetic additive, a nitrate ester stabilizer, an opacifier, a curing agent, a cure catalyst, an opacifier, an antioxidant, and mixtures thereof.

12. The process of claim 11, wherein the additional component is selected from the group consisting of a nitroplasticizer, an energetic additive, and mixtures thereof.

13. The process of claim 12, wherein the binder and the additional component combined are present in an amount from about 20 percent to 35 percent by weight of the composition.

14. The process of claim 12, wherein the nitroplasticizer is selected from the group consisting of trimethylol ethane trinitrate, triethylene glycol dinitrate, triethylene glycol trinitrate, butanetriol trinitrate, diethyleneglycol dinitrate, ethyleneglycol dinitrate, nitroglycerine, diethylene glycerin trinitrate, dinitroglycerine, nitrobenzene, N-butyl-2-nitratoethylnitramine, methyl-2-nitratoethylnitramine, ethyl-2-nitratoethylnitramine, and mixtures thereof, and wherein the energetic additive is selected from the group consisting of cyclotrimethylene trinitramine, cyclotetramethylene tetranitramine, dinitroxyethylnitramine, and mixtures thereof.

15. The process of claim 1, wherein the composition is substantially smoke free upon combustion.

16. The process of claim 2, wherein the ammonium nitrate is present in an amount from about 40 percent to about 80 percent by weight of the composition, wherein the strengthening agent comprises azidocarbonamide and is present in an amount from about 8 percent to about 12 percent by weight of the composition, wherein the binder comprises polyglycol adipate, and wherein the mixture comprises an additional component selected from the group consisting of trimethylol ethane trinitrate, triethylene glycol dinitrate, triethylene glycol trinitrate, butanetriol trinitrate, diethyleneglycol dinitrate, ethyleneglycol dinitrate, nitroglycerine, diethylene glycerin trinitrate, dinitroglycerine, nitrobenzene, N-butyl-2-nitratoethylnitramine, methyl-2-nitratoethylnitramine, ethyl-2-nitratoethylnitramine, cyclotrimethylene trinitramine, cyclotetramethylene tetranitramine, dinitrooxyethylnitramine, and mixtures thereof.

17. The process of claim 16, wherein the polyglycol adipate is provided in an amount from about 3 percent about 20 percent by weight of the composition.

18. The process of claim 16, wherein the additional component is selected from the group consisting of trimethylol ethane trinitrate, triethylene glycol dinitrate, cyclotrimethylene trinitramine, cyclotetramethylene tetranitramine, and mixtures thereof.

19. The process of claim 18, wherein the combined amount of the polyglycol adipate and the additional component is from about 20 percent to about 35 percent by weight of the composition.

20. The process of claim 16, wherein the composition is substantially smoke-free upon combustion.

21. The process of claim 2, wherein the step of grinding ammonium nitrate comprises the steps of:

mixing ammonium nitrate and a synthetic zeolite to form a first mixture, wherein the synthetic zeolite is provided in an amount from about 0.2 percent to about 6 percent by weight of the composition; and

grinding the first mixture.

22. The process of claim 1, further comprising the steps of:

providing a molecular sieve;

forming a preliminary mixture of the molecular sieve and the ammonium nitrate prior to forming the primary mixture, wherein the molecular sieve is present in an amount from about 0.2 percent to about 6 percent by weight of the composition;

aging the preliminary mixture for a first aging period;

forming the primary mixture by adding a strengthening agent and a binder to the preliminary mixture, wherein the binder is present in an amount from about 5 percent to 30 percent by weight of the composition; and

aging the primary mixture for a second aging period.

23. The process of claim 22, wherein the step of forming the preliminary mixture comprises mixing and grinding the ammonium nitrate and the molecular sieve.

24. The process of claim 22, wherein the molecular sieve comprises a synthetic zeolite having a pore size from about 3 angstroms to about 5 angstroms.

25. The process of claim 22, wherein the first and second aging periods are less than about 48 hours.