U.S. patent application number 10/093885 was filed with the patent office on 2004-11-11 for desensitisation of energetic materials.
This patent application is currently assigned to Royal Ordnance PLC.. Invention is credited to Wagstaff, Douglas C..
Application Number | 20040221934 10/093885 |
Document ID | / |
Family ID | 10854917 |
Filed Date | 2004-11-11 |
United States Patent
Application |
20040221934 |
Kind Code |
A1 |
Wagstaff, Douglas C. |
November 11, 2004 |
Desensitisation of energetic materials
Abstract
An energetic material comprises an energetic crystalline
material substantially coated in an energetic plasticiser material.
Advantageously the energetic material comprises from 90 to 99% by
weight of an energetic crystalline material and from 1 to 10% by
weight of an energetic plasticiser material comprising a
plasticiser selected from the group comprising Butane Triol
trinitrate (BTTN), Trimethylanol ethane trinitrate (TMETN),
Diazidonitrazapentane (DANPE), Glycidyl Azide Polymer (Azide
Derivative) (GAP Azide), Bis(2,2-dinitropropyl)acetal/bis(2,2-dini-
tropropyl)formal (BDNPA/F) or mixtures of two or more of these
plasticisers. The inventors have found that the combination of just
a small quantity of energetic plasticiser material to the energetic
crystalline material prior to incorporation into the bulk
plasticiser, binder and filler mixture of an explosive or
propellant composition has unexpected and advantageous effects.
Inventors: |
Wagstaff, Douglas C.;
(Kidderminster, GB) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Assignee: |
Royal Ordnance PLC.
|
Family ID: |
10854917 |
Appl. No.: |
10/093885 |
Filed: |
February 21, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10093885 |
Feb 21, 2002 |
|
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|
09552521 |
Mar 23, 2000 |
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Current U.S.
Class: |
149/19.2 |
Current CPC
Class: |
C06B 21/0025 20130101;
C06B 45/24 20130101; C06B 45/105 20130101; C06B 45/22 20130101 |
Class at
Publication: |
149/019.2 |
International
Class: |
C06B 045/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 1999 |
GB |
9913262.3 |
Claims
1. An energetic material an energetic crystalline material
substantially co ed in an energetic plasticiser material.
2. An energetic material imed in claim 1 wherein the energetic
crystalline material is particulate, the energplasticiser
substantially coating individual particles of the energetic
crytalline material.
3. An energetic material as claimed in aim 2 wherein the energetic
material is in powder form.
4. An energetic matal as claimed inan precedi claim wherein the
energetic material comprises from 9 to 99% by weight of the
energetic crystalline material and from 1 to 10% by weight of the
energetic plasticiser material.
5. An energetic material as claimed in any preceding claim wherein
the energetic plasticiser is selected from a group comprising
Butane Triol trinitrate (BTTN), Trimethylanol hane trinitrate
(TMETN), Diazidonitrazapentane (DANPE), Glycidyl Azide Polymer
(Azide Derivative) (GAP Azide),
Bis(2,2-dinitropropyl)acetal/bis(2,2-dinitropropyl)formal (BDNPA/F)
or mixtures thereof.
6. An energetic material as claimed in any preceding claim wherein
the energetic crystalline material
hexanitrohexaazaisowurtizane.
7. A method facturing an energetic material according to any
preceding claim comprising; (i) wet mixing 1 to 10% weight of a
energetic plasticise material with 99 to 90% by weight energetic
crystalline material, and (ii) drying the wet mixed material to
form a powder.
8. A method for manufacture pellant material containing an
energetic crystalline material comprising; (i) mixing 1 to 10% by
weight of an energetic plasticiser material, with 99 to 90% by
weight energetic crystalline material (ii) mixing and/or blending
the resant product of step (i) with additional quantities of
plasticiser and binder material as appropriate for the end
application of the propellant material, (iii) curing thresultant
product of step (ii).
9. A method for manufacture of a propellant material as claimed in
claim 8, wherein the energetic plasticiser material and energetic
crystalline material are preliminarily mixed by a wet mixing
process.
10. Use of an energetic material according to any one of claims 1
to 6 in the manufacture of an explosive or propellant composition.
Description
[0001] This invention relates to the desensitisation of energetic
crystalline materials, in particular hexanitrohexaazaisowurtizane
(HNIW) (also designated CL20) but also other nitramine explosives
such as cyclotrimethylene trinitramine (RDX) and
cyclotetramethylene tetranitramine (HMX).
[0002] HNIW comprises a high density caged molecule recognised as a
suitable energetic filler for propellant materials and explosives.
Its use as a potential replacement for existing fillers such as RDX
and HMX in cast double base, composite and novel propellants and
other explosive materials has been postulated.
[0003] Propellant compositions used for launching relatively high
mass projectiles are desirably highly energetic and energetically
dense i.e. a small volume of the material will produce high
potential kinetic energy via rapid gasification on ignition. In
general, such a propellant composition comprises three component
materials; an energetic filler, a plasticiser and a binder, the
latter two components primarily provide the desirable mechanical
properties of the resultant propellant material. Choice of
plasticiser and binder for a particular energetic filler will
depend on a number of factors such as the projection range for the
projectile, the extremes of temperature under which the end product
is expected to operate and the chemical and physical interactions
of the materials.
[0004] However, aside from the functional performance of the
propellant material as an end product, industrial manufacturers of
novel materials must consider the safety issues associated with the
incorporation and manufacture of these filler, binder or
plasticiser materials into rocketry. Thus, whilst from a
performance point of view an energetic material may appear
desirable for use as either a binder plasticiser or filler in the
predicted propellant formulation, the material must be safe for
incorporation, processing and transportation. If an unsafe
energetic material was to be incorporated into a propellant or
explosive system, the unsafe material might initiate during either
the manufacturing process or during transportation of the end
product. This initiation might be via accidental friction or impact
stimulation leading to deflagration or possibly a deflagration to
detonation transition within the explosive material sufficient to
cause an unwanted premature explosion. For this reason of safety,
most known propellant materials (e.g. Ammonium Perchlorate/hydroxy
terminated polybutadiene based composite propellant) comprise,
comparatively, energetically inert plasticiser and binder
components.
[0005] In general, solid propellant materials such as those based
on Ammonium Perchlorate, Hydroxy terminated polybutadiene (binder)
and dioctyl sebacate (plasticiser) are manufactured by a dry mixing
and blending process:this means that no additional desensitising
solvent s (e.g. water) are added to this mix other than those that
will be incorporated into the final propellant formulation. This
dry mix, once manufactured, is treated to facilitate curing of the
binder material to provide the desirable mechanical properties for
the propellant material. This method is generally considered
preferable to a wet mixing process (where additional solvent is
included as transport media or processing aid or as a desensitiser
to improve safety) as it provides better homogeneity of mixing, and
minimises delays in cleaning mixing equipment or drying out of the
mixed end product prior to further processing (e.g. casting and
curing).
[0006] Typically, existing propellant materials comprise around 6%
by weight plasticiser to 85% by weight energetic filler. The
propellant material will also generally comprise around 9% by total
weight of binder and other filler materials. HNIW is a highly
friction sensitive material having a rotary friction test Figure of
Friction (F of F) of 0.7 and produces a highly ferocious response
on reaction via friction stimuli. The exceptionally low F of F of
HNIW (when compared against other ingredients routinely used in
propellant/explosive formulations) poses a considerable risk in the
initial process of dry mixing the plasticiser, binder and filler,
as is conventional in solid propellant manufacture. The low FofF
value excludes the use of CL20 in large scale propellant
manufacture in some explosive companies. Thus, the manufacturer is
challenged with the task of providing a safe process by which HNIW
can be incorporated into explosive and propellant materials whilst
having minimal effect on the overall performance characteristics of
the end product.
[0007] In the first aspect, the invention is an energetic material
comprising an energetic crystalline material substantially coated
in an energetic plasticiser material.
[0008] Preferably the energetic crystalline material is
particulate, the energetic plasticiser substantially coating
individual particles of the energetic crystalline material.
[0009] The energetic material is advantageously in powder form, the
powder comprising particles of energetic crystalline material
substantially coated in an energetic plasticiser material.
[0010] Advantageously the energetic material comprises from 90 to
99% by weight of an energetic crystalline material and from 1 to
10% by weight of an energetic plasticiser material.
[0011] The inventors have found that the combination of just a
small quantity of energetic plasticiser material to the energetic
crystalline material prior to incorporation into the bulk
plasticiser, binder and filler mixture of an explosive or
propellant composition has two unexpected and advantageous effects.
Firstly, plasticiser addition leads to a reduction in the friction
sensitivity of the energetic crystalline material to equivalent or
less than that of many commonly used energetic filler materials
such as ammonium perchlorate and secondly, the plasticiser addition
also results in reduced ferocity of response on stimulation. The
resultant novel intermediate of the energetic crystalline material
and plasticiser can then be more safely used as a starting material
for the dry mixing/blending/curing processes previously described
used in the manufacture of known propellant and explosive
compositions. These novel intermediate, plasticiser added,
energetic crystalline material products are also more safely
handled and transported than the pure energetic crystalline
material.
[0012] In one particular method in accordance with the present
invention, to manufacture an energetic material comprising an
energetic crystalline material/energetic plasticiser mix, desirably
the energetic crystalline material and energetic plasticiser
material are mixed via a wet mixing process with the plasticiser
material being added to, for example, water wet HNIW. The inherent
characteristics of wet mixing reduces the friction arising within
the mixture during the mixing process and thus minimises the risk
of explosive reaction in the energetic crystalline material by
friction stimuli. After mixing, the water wet, plasticised
energetic crystalline material mix can be left to dry to a powdery
state, the resultant dry powder formed being finely coated with the
energetic plasticiser component. The resultant energetic
crystalline material/energetic plasticiser mixture formed is a
relatively friction insensitive energetic material when compared
against pure, dry energetic crystalline material.
[0013] The inventors have found that the combination of just a
small quantity of plasticiser material to an energetic crystalline
material such as HNIW in manufacture of an explosive or propellant
composition has an unexpected and advantageous effect of reducing
the friction sensitivity of HNIW to equivalent or less that of
commonly used energetic filler materials such as Ammonium
perchlorate or HMX. The resultant novel intermediate products
manufactured by this desensitisation method can then be more safely
used as a starting material for the dry mixing/blending/curing
processes conventionally used in the manufacture of known
propellant and explosive compositions. These novel intermediate
products are also more safely handled and transported than the pure
product. Another unexpected yet advantageous characteristic of
these novel materials is that, once initiated, they display a
reduced ferocity of response compared to that of the pure
product.
[0014] The energetic plasticiser is preferably selected from the
group comprising Butane Triol trinitrate (BTTN), Trimethylanol
ethane trinitrate (TMETN), Diazidonitrazapentane (DANPE), Glycidyl
Azide Polymer (Azide Derivative) (GAP Azide),
Bis(2,2-dinitropropyl)acetal/bis(2,2-dini- tropropyl)formal
(BDNPA/F) or mixtures of two or more of these plasticisers. As well
as bringing about the desired desensitisation effect, these
plasticisers add energy to the propellant system compared to the
use of inert analogues. As a consequence, the intermediate material
produced has a higher energy density compared to inert analogues :
this is a desirable characteristic of materials for use in
rocketry/explosive programs as all constituents of the subsequent
explosive/propellant formulation manufactured using the
intermediate contribute energetically to the final formulation. The
use of energetic crystalline materials desensitised with
energetically inert plasticisers would have comparatively less
energy than that of the proposed, energetic plasticisers
formulations.
[0015] The energetic plasticiser material may comprise 100% of any
of the plasticisers listed above, mixtures of those plasticisers
listed above or optionally may be a blend of energetic plasticiser
and a binder material (e.g. Poly(3-Nitromethyl-3-Methyloxetane)
(PolyNIMMO), Poly Glycidyl Nitrate (PolyGLYN) or Glycidyl Azide
Polymer (GAP)) of proportions encompassing from minimum quantity of
10% by weight plasticiser to 90% binder, to 100% plasticiser to 0%
binder. The term "energetic plasticiser material" as referred to
hereinafter should be construed accordingly with the above
description.
[0016] Preferably, the novel energetic material will comprise
between 1% and 5% by weight of energetic plasticiser material and
most preferably between 3% and 5% by weight of energetic
plasticiser material.
[0017] For mixed binder/plasticiser systems, preferably the
energetic plasticiser material will comprise between 30% and 100%
energetic plasticiser and 70% to 0% binder. Most preferably the
plasticiser content will be in the range 60% to 100%.
[0018] Thus the present invention provides a method for manufacture
of a highly energetic, intermediate material based on a energetic
crystalline material desensitised for safe incorporation into
propellant or explosive formulations.
[0019] In a second aspect, the present invention provides a method
for manufacture of a propellant material containing an energetic
crystalline material comprising;
[0020] (i) mixing 1 to 10% by weight of an energetic plasticiser
material with 99 to 90% by weight of the energetic crystalline
material,
[0021] (ii) mixing and/or blending the resultant product of step
(i) with additional quantities of plasticiser and binder material
as appropriate for the end application of the propellant
material,
[0022] (iii) curing the resultant product of step (ii).
[0023] The energetic plasticiser material preferably contains a
plasticiser selected from Butane Triol trinitrate (BTTN),
Trimethylanol ethane trinitrate (TMETN), Diazidonitrazapentane
(DANPE), Glycidyl Azide Polymer (Azide Derivative) (GAP Azide),
Bis(2,2-dinitropropyl) acetal/bis (2,2-dinitropropyl) formal
(BDNPA/F) or mixtures of two or more of these plasticisers.
[0024] In a third aspect the invention is an explosive or
propellant composition made from a an energetic material
comprising;
[0025] (i) from 90 to 99% by weight HNIW; and
[0026] (ii) from 1 to 10% by weight of an energetic plasticiser
material comprising a plasticiser selected from the group
comprising; Butane Triol trinitrate (BTTN), Trimethylanol ethane
trinitrate (TMETN), Diazidonitrazapentane (DANPE), Glycidyl Azide
Polymer (Azide Derivative) (GAP Azide),
Bis(2,2-dinitropropyl)acetal/bis(2,2-dinitropropyl)formal
(BDNPA/F), or mixtures of two or more of these components.
[0027] In order to more fully illustrate the novel methods,
products and applications of this invention and their associated
advantages, experimental data for some specific embodiments of the
invention are now given by way of exemplification only. Although
all analyses were carried out using Epsilon form HNIW, it is
anticipated that this method of desensitisation would be effective
on other crystal polymorphs of HNIW as well as known energetic
crystalline materials such as cyclotrimethylene trinitramine (RDX)
and cyclotetramethylene tetranitramine (HMX).
[0028] 1) Rotary friction testing of HNIW in the Epsilon crystal
form was carried out and a Figure of Friction (FofF)=0.7 was
achieved. The sample response during testing was a violent report
and flash.
[0029] 2) 0.25 g of TMETN stabilised with 1% 2-Nitrodiphenylamine
(2NDPA) was added to 5 g of dry Epsilon form HNIW and mixed. The
material formed was a light orange powder. The material was
assessed by rotary friction and the FofF achieved=2.2. In addition
to the reduction in friction sensitiveness, the violence of
response was reduced from a violent report/flash for the pure HNIW
material to a mild report without flash.
[0030] 3) Replicate analysis of the formulation example given in
example 2 were carried out with the substitution of TMETN with
BTTN, a mixture of BTTN and TMETN, DANPE, GAP Azide, BDNPA/F,
PolyNIMMO, PolyGLYN and GAP. All materials appeared as white/yellow
powders. For these mixtures, the friction sensitiveness determined
were established as given in Table 1.
1 TABLE 1 Sample FofF CL20:TMETN 2.2 CL20:BTTN 2.1 CL20:BTTN/TMETN
(50/50) 2.4 CL20:GAP Azide 2.1 CL20:DANPE 1.9 CL20:PolyGLYN 2.2
CL20:PolyNIMMO 1.9 CL20:GAP 1.6
[0031] 4) Replicate analysis of the formulation given in example 2
were carried out but with the substitution of TMETN with mixed
binder: plasticiser formulations. All mixtures formed white/light
yellow powders. For these mixtures, the friction sensitiveness
determined were established as shown in Table 2:
2 TABLE 2 Solid Binder Plasticiser FofF CL20 PolyGLYN GAP Azide 2.7
CL20 PolyGLYN DANPE 2.5 CL20 PolyGLYN BTTN/TMETN (80:20) 2.7 CL20
PolyGLYN BDNPA/F 2.1 CL20 PolyNIMMO GAP Azide 2.9 CL20 PolyNIMMO
DANPE 2.9 CL20 PolyNIMMO BTTN/TMETN (80:20) 3.1 CL20 PolyNIMMO
BDNPA/F 2.4 CL20 GAP GAP Azide 2.8 CL20 GAP DANPE 2.7 CL20 GAP
BTTN/TMETN (80:20) 2.8 CL20 GAP BDNPA/F 2.7
[0032] 5) 40 g of CL20 was wetted to 25% moisture content with
deionised water and mixed thoroughly. 2 g of TMETN (stabilised with
2% 2NDPA) was added and again mixed thoroughly. The final
CL20/water/TMETN/2NDPA mixture was placed on the open bench to
allow water evaporation and final water was removed under vacuum
storage at 80.degree. C. for 2 hours). Friction sensitiveness
assessment of the dry powder formed was carried out and an FofF=2.4
determined.
[0033] The skilled reader will understand that the principles
involved in this invention may be equally applicable to any future
energetic materials of a similar chemical nature to HNIW which are
yet themselves to be manufactured.
* * * * *