Plastic and nonmetallic article shaping or treating: processes – Explosive or propellant article shaping or treating – Extrusion to form sheet or rod
Reexamination Certificate
1998-10-06
2001-04-17
Miller, Edward A. (Department: 3641)
Plastic and nonmetallic article shaping or treating: processes
Explosive or propellant article shaping or treating
Extrusion to form sheet or rod
C149S019920, C149S092000, C264S003100
Reexamination Certificate
active
06217799
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of making high performance explosive compositions that are pressable or extrudable and suitable for high performance, low sensitivity explosive applications. More specifically, this invention relates to a method of making high performance explosive compositions containing CL-20 as an explosive ingredient, non-energetic polymeric binders and plasticizers.
2. Description of the Related Art
Among the litany of high performance explosives that have been used in ordnance and other high impact applications, a relatively new explosive known as CL-20 has been recognized for its superior energy levels that far surpass those of most conventional explosives. CL-20 is also referred to commonly as (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo [5.5.0.0
5,9
.0
3,11
]-dodecane and 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane.
Examples of explosive formulations containing CL-20 as the primary explosive component are disclosed in both U.S. Pat. No. 5,587,553 to Braithwaite et al. and U.S. Pat. No. 5,712,511 to Chan et al. As touched upon in the Chan et al. '511 patent, which relates to explosive compositions for deformable-type warheads and directional ordnances, CL-20 is extremely sensitive to physical impact. Indeed, CL-20 has been associated with high electrical and thermal sensitivities as well. The highly sensitive nature of CL-20 may lead to premature detonation in ordnance applications. The Chan et al. patent apparently compensates for the high sensitivity of CL-20 by incorporating it into high energy shock-insensitive explosive compositions comprised of a relatively low concentration of CL-20, e.g., from about 35 wt % to about 45 wt %.
In contrast, the Braithwaite et al. patent seeks to improve the high performance of the CL-20 explosive by using it in high concentrations and in combination with high molecular weight liquid energetic polymers, especially chain-extended polyglycidyl nitrate (PGN). It has also been known to use CL-20 in combination with other energetic polymers. One such combination commonly known as LX-19 and available from Thiokol Corporation, Inc., now Cordant Technologies, Inc., combines CL-20 with ESTANE (C
5.14
H
7.5
N
0.187
O
1.76
). LX-19 is made by a water slurry process. The performance characteristics, e.g., energy levels, exhibited by LX-19 are generally considered to be excellent. However, the impact, electrical, and thermal sensitivities associated with LX-19 and other formulations using CL-20 in combination with energetic binders are considered to be too high for some applications.
It would, therefore, be a significant advancement in the art to provide a method of making a plastic bonded explosive formulation that contains a sufficient amount of CL-20 to exhibit equal or better high energy performance than LX-19, yet which has sufficiently low impact, electrical, and thermal sensitivities to permit the formulation to be used for a variety of applications without an unacceptable risk of unintentional or premature detonation.
SUMMARY OF THE INVENTION
It is, therefore, an object of this invention to provide a method of making pressable or extrudable high performance explosive formulations that addresses the aforementioned problems associated with the related art and realizes the advancement expressed above.
In accordance with the principles of this invention, these and other objects are attained by providing a water slurry method conducted at or near ambient temperature. In one embodiment of this process, an aqueous dispersion comprising CL-20 and water is prepared, then combined in an addition step with a lacquer comprising at least one non-energetic binder, and at least one plasticizer and at least one solvent to form a slurry. Optionally, at least one surfactant and/or at least one stabilizer (also referred to herein as an antioxidant) may be added directly into the slurry, or into the lacquer and/or aqueous dispersion prior to their combination. The slurry is agitated, such as with a stirrer, in such a manner as to form CL-20 granules coated with at least non-energetic binder and plasticizer. The granules may then be quenched with water to remove residual solvent and prevent unacceptable amounts of agglomeration. The granules are then dried, optionally under partial vacuum and/or elevated temperature conditions.
Generally, the process is preferably controlled to provide a final formulation including about 85 wt % to about 96 wt % CL-20.
This invention also relates to methods of making articles comprising the above-discussed formulations. The formulation is preferably sufficiently pressable or extrudable to permit it to be formed into grains and billets suitable for ordnance and similar applications. The principles of the present invention outlined above are applicable to making a variety of explosive articles, but have particular applicability to the formation of pressed or injection loaded ordnances such as grenades, land mines, missile warheads, and demolition explosives.
These and other objects, features, and advantages of the present invention will become apparent from the accompanying drawing and following detailed description which illustrate and explain, by way of example, the principles of the present invention.
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Chemical Abstracts, Columbus, OH, XP 000664704, vol. 12, (1996) Sep. 30th, CO6B25/34, Wardle et al., “Synthesis of the caged nitramine HNIW (CL-20).”
Braithwaite Paul
Hatch Robert L.
Lee Kenneth E.
Cordant Technologies Inc.
Miller Edward A.
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