U.S. patent application number 11/877973 was filed with the patent office on 2009-04-30 for rdx explosive and method.
This patent application is currently assigned to LOS ALAMOS NATIONAL SECURITY, LLC. Invention is credited to Kenneth Edward Laintz, Kien-yin Lee.
Application Number | 20090107593 11/877973 |
Document ID | / |
Family ID | 40581308 |
Filed Date | 2009-04-30 |
United States Patent
Application |
20090107593 |
Kind Code |
A1 |
Lee; Kien-yin ; et
al. |
April 30, 2009 |
RDX EXPLOSIVE AND METHOD
Abstract
A method for producing particulate RDX is provided. RDX is
dissolved and then precipitated with the precipitated RDX being
separated from the mixture of solvent and anti-solvent and dried.
The RDX has an increased insensitivity, i.e., it is more resistant
to shock or impact stimuli and has a morphology characterized by a
smooth surface and small particle size as formed.
Inventors: |
Lee; Kien-yin; (Santa Fe,
NM) ; Laintz; Kenneth Edward; (Los Alamos,
NM) |
Correspondence
Address: |
HUSCH BLACKWELL SANDERS LLP
720 OLIVE STREET, SUITE 2400
ST. LOUIS
MO
63101
US
|
Assignee: |
LOS ALAMOS NATIONAL SECURITY,
LLC
Los Alamos
NM
|
Family ID: |
40581308 |
Appl. No.: |
11/877973 |
Filed: |
October 24, 2007 |
Current U.S.
Class: |
149/2 ;
149/92 |
Current CPC
Class: |
C06B 21/0066 20130101;
C06B 25/34 20130101 |
Class at
Publication: |
149/2 ;
149/92 |
International
Class: |
C06B 25/34 20060101
C06B025/34; C06B 45/00 20060101 C06B045/00 |
Goverment Interests
STATEMENT REGARDING FEDERAL RIGHTS
[0001] This invention was made with government support under
contract number DE-AC52-06NA25396 awarded by the U.S. Department of
Energy. The government has certain rights in the invention.
Claims
1. A method of making particulate RDX, the method including:
dissolving RDX in a solvent forming a first solution; adding an
anti-solvent to the first solution, said anti-solvent being
substantially miscible with the solvent and agitating the mixture;
precipitating out at least a portion of the RDX; separating the
precipitated RDX from the solvent and anti-solvent; and drying the
separated RDX.
2. The method of claim 1 wherein the solvent being at a temperature
of less than about 5.degree. C. during at least a portion of the
precipitation.
3. The method of claim 1 wherein the agitation and the temperature
of the solvent during at least a portion of the agitation being
sufficient to produce precipitated RDX that after drying the RDX
has an average particle length of less than about 20 microns on
average.
4. The method of claim 3 wherein at least a majority of the dried
RDX particles being generally rod like in shape.
5. The method of claim 4 wherein at least a majority of the dried
particles have a surface substantially free of sharply defined
surface imperfections when viewed under a magnification of
5000.times..
6. The method of claim 4 wherein at least a majority of the dried
particles have a surface substantially free of surface
imperfections larger than about 2 microns.
7. The method of claim 1 wherein the solvent including acetone.
8. The method of claim 7 wherein the anti-solvent including
hexane.
9. The method of claim 8 wherein the solvent being at a temperature
of less than about 0.degree. C. during at least a portion of the
precipitation.
10. The method of claim 1 wherein the dissolving and precipitation
being conducted at a pressure of about one atmosphere absolute.
11. An RDX product in particulate form with the average size of the
particles being less than about 20 microns in length as formed.
12. The RDX product of claim 11 wherein at least a majority of the
particles being generally rodlike in shape.
13. The RDX product of claim 12 wherein at least a majority of the
particles having a surface substantially free of sharply defined
visual imperfections.
14. The RDX product of claim 12 wherein at least a majority of the
particles having a surface substantially free of surface
imperfections larger than about 2 microns.
15. The RDX product of claim 11 wherein the RDX product having a
resistance to impact stimuli of at least 25 cm as measured by Type
12 impact sensitivity testing using an ERL testing machine.
16. The RDX products of claim 11 contained in an explosive
device.
17. An RDX material in as formed particulate form having a
resistance to impact stimuli of at least 25 cm as measured by Type
12 impact sensitivity testing using an ERL testing machine.
18. The RDX material of claim 17 having a resistance to impact
stimuli of at least about 30 cm as measured by Type 12 impact
sensitivity testing using an ERL testing machine.
19. An RDX material in as formed particulate form having a
resistance to impact stimuli of at least equal to HMX as measured
by Type 12 impact sensitivity testing using an ERL testing machine.
Description
BACKGROUND OF INVENTION
[0002] RDX is a common explosive both as a single compound
explosive and as mixed with other explosives and additives. The
explosive is effective in most regards but it has been a desire for
some time to make the explosive more resistant to shock or impact
detonation.
[0003] One of the desirable features of RDX explosives is that it
can be molded in combination with a polymer, to fix the shape of
the explosive for various purposes which are well known in the
industry. Attempts have been made to reduce the sensitivity to
shock or impact stimuli, hereinafter impact stimuli for
convenience. For example, according to the article entitled Reduced
Sensitivity RDX (RS-RDX) Part I: Literature Review and DSTO
Evaluation, issued by DSTO Systems Sciences Laboratory located in
Australia and dated July 2003, attempts were made to reduce the
sensitivity of RDX to impact stimuli. However, according to this
report, success was achieved only for reducing the sensitivity of
the RDX when it was combined with the polymer for subsequent
forming into shapes. The freestanding or natural RDX explosive was
apparently not improved for impact resistance.
[0004] It is therefore an object of the present invention to
provide an improved RDX explosive that is more difficult to
initiate an explosion from impact or shock.
SUMMARY OF INVENTION
[0005] The present invention involves the provision of an improved
RDX explosive that has a resistance to impact stimuli of at least
25 cm. The present invention also involves the provision of an RDX
explosive in particulate form having a substantial portion of the
particles with an average particle size of less than about 20
microns in length and preferably has an exterior surface that is
characterized by a substantial absence of dimples or other surface
imperfections.
[0006] The present invention also involves the provision of a
method of making an improved RDX explosive which involves
dissolving an RDX explosive in a solvent. An anti-solvent and the
RDX solution are then mixed to precipitate the RDX explosive out of
solution in particulate form while the mixture is being agitated.
The anti-solvent is miscible with the solvent. The precipitated RDX
particles are separated and then dried. The dried RDX can be used
as an explosive either as a freestanding explosive, mixed with
other explosive material or in molded form using a polymer as a
binder.
BRIEF DESCRIPTION OF DRAWINGS
[0007] FIG. 1 is a photograph of the inventive RDX explosive taken
with a scanning electron microscope at a magnification of
5000.times..
[0008] FIG. 2 is a photograph of the inventive RDX explosive taken
with a scanning electron microscope at a magnification of
200.times..
[0009] FIG. 3 is a photograph of prior art RDX explosive taken with
a scanning electron microscope at a magnification of
200.times..
DETAILED DESCRIPTION
[0010] The acronym RDX stands for Royal Demolition Explosive. The
chemical name for RDX is 1,3-trinitro-1,3,5-triazacyclohexane. It
is a white powder and very explosive. It can be used alone as an
explosive or mixed with other ingredients and explosives. RDX, in
the method of the present invention, is first dissolved in a
suitable solvent for example, acetone. Preferably, during the
dissolving step and thereafter, the solvent and the formed solution
are agitated with a suitable mixer. In lab experiments, it was
found that a blade mixer operating at about 400 rpms was adequate
to produce the inventive product. Preferably, the process is
conducted at a temperature of less than about 5.degree. C. and
preferably less than about 0.degree. C. The solution forming and
precipitation steps can be conducted at atmospheric pressure, i.e.,
one atmosphere absolute pressure simplifying the production of the
inventive RDX. After the solution of RDX and solvent is made, the
solution and an anti-solvent are combined and agitation of this
mixture is maintained during precipitation of the RDX. The
anti-solvent needs to be substantially miscible and preferably
completely miscible in the solution of RDX and solvent. The
anti-solvent effects precipitation of the RDX out of solution
during agitation of the mixture of solvent, anti-solvent and
precipitating RDX and the RDX remaining in solution. After
precipitation, the precipitated RDX is separated from the liquid
components of the mixture. Separation can be by filtration,
centrifugation or other suitable separating methods. The separated
RDX is then dried by any suitable method and preferably under
vacuum of at least about 17 inches of hg.
[0011] As seen in FIG. 1, the precipitated particulate RDX that has
been separated and dried has somewhat rod like characteristics
having a length to width ratio of at least about 2 to 1 and
preferably at least about 3 to 1 on average in bulk. Preferably, at
least a majority, by weight, of the dried particles are rodlike in
shape. The size of the particles can be determined using scanning
electron micrography where the particles are measured for size (two
dimensionally) visually by comparing the particles to a scale. The
particle size is determined by measuring the width or the minor
dimension of the particles and the length or major dimension (as if
the particles were straight). As seen in FIG. 1, the inventive
particles are somewhat rodlike and can also be branched and/or
curved. The RDX shown in FIG. 3 is a fairly typical RDX and is
comprised of particles having more of an egg (obovoid) shape or
potato shape. It can also be noted in FIG. 3 that the surface of
the prior art RDX particles is rough having numerous so-called
dimples or rather significant surface imperfections 1 with sharply
defined edges. The surface of the inventive RDX seen in FIGS. 1, 2
is smooth and characterized by a substantial lack of the just
mentioned surface imperfections at a magnification of
5000.times..
[0012] The inventive RDX has a higher value of impact sensitivity,
i.e., higher resistance to impact stimuli that is greater than or
equal to currently available HMX
(cyclotetramethylenetetranitramine) and at least 25 cm as measured
by Type 12 impact sensitivity testing using an ERL testing machine
and preferably at least about 30 cm. In bulk, the RDX particles
have the following properties. A substantial portion of the
particles, preferably at least about 75% and more preferably at
least about 90% of the particles, have a size of about 5 microns,
and preferably less than about 2 microns or less in width, W and a
length L of less than about 20 microns and preferably less than
about 15 microns on average as formed by precipitation (and without
particle size reduction as by grinding) as measured on a branch 2
or stem 3. Preferably, a substantial portion and at least the
majority of the particles, more preferably at least about 75% and
most preferably about 90% of the particles are characterized by
having a smooth outer surface characterized by a substantial
absence of surface imperfections as described above. With regard to
the surface imperfections, it is preferred that the surface of at
least a majority of the particles be substantially free of sharply
edged visual imperfections which are detectable visually at a
magnification of 5000.times. and have a size of at least about 2
microns for the major dimension thereof in width or length. The
inventive RDX may be used in an explosive device freestanding, in
conjunction with other explosive materials and/or molded to shape
in conjunction with a polymer binder.
[0013] The present invention is better understood by a description
of a method used in the laboratory to produce the inventive
particles. The process produced micron size particles as described
with the unique as formed morphology described above. A solution of
RDX in an acetone was prepared by dissolving 2.1 gram of
conventional RDX (I-RDX) in 40 ml of acetone. The solution was set
aside. A three necked one liter round bottom jacketed flask
equipped with an overhead stirrer was charged with approximately
300 ml of hexane at 0.degree. C. The jacketed flask can be used to
maintain the temperature of the hexane at 0.degree. C. The overhead
stirrer was operating at approximately 400 rpm mixing the hexane.
The solution of RDX in acetone was quickly poured through a funnel
into the round bottom flask while maintaining agitation with the
stirrer. Agitation was continued while the RDX precipitated out of
the solution. After precipitation was completed, the mixture of
hexane, acetone and precipitated RDX was filtered, and the
precipitated RDX was collected on the filter media. The RDX was
then dried under vacuum at a pressure of 17 mm Hg. This sample was
then visually evaluated using a LEO Model 1525 field emissions
scanning electron microscope. The photograph shown in FIGS. 1 and 2
is a portion of the RDX produced in the above example. FIG. 3 shows
the I-RDX that was used to form the solution. This I-RDX had an
impact resistance of 21 cm as measured by the above identified
test.
[0014] Thus, there has been shown and described several embodiments
of a novel invention. As is evident from the foregoing description,
certain aspects of the present invention are not limited by the
particular details of the examples illustrated herein, and it is
therefore contemplated that other modifications and applications,
or equivalents thereof, will occur to those skilled in the art. The
terms "having" and "including" and similar terms as used in the
foregoing specification are used in the sense of "optional" or "may
include" and not as "required". Many changes, modifications,
variations and other uses and applications of the present invention
will, however, become apparent to those skilled in the art after
considering the specification and the accompanying drawings. All
such changes, modifications, variations and other uses and
applications which do not depart from the spirit and scope of the
invention are deemed to be covered by the invention which is
limited only by the claims which follow.
* * * * *