Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
134-15r 01
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EXPLOSIVE COMPOSITIONS
The present invention relates to explosive
compositions, particularly plastic mouldable
explosive compositions.
A known explosive composition manufactured by
the present Applicants, which composition has been
in service use by the UK Ministry of Defence for
many years comprises RDX, a particulate high
explosive filler, incorporated in a binder which
comprises liquid paraffin gelled to form a grease
together with other minor additives. This
composition is detonator sensitive (ie does not
require a booster initiation) and is a plastic
material which may be moulded like putty under
light pressure by the user into a desired shape eg
to fill a cavity or to line an edge between mating
surfaces.
This known composition suffers from the
problems that the low molecular weight liquid
components of the binder tend to migrate causing
the composition to become brittle during its
service life, the low temperature (-20 C)
mouldability of the material is poor and binder
ingredients tend to exude at elevw.ted temperatures.
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2
It is the purpose of the present invention to provide
a novel plastic mouldable explosive composition in which the
aforementioned problems are reduced or eliminated.
According to the present invention there is provided
a plastic mouldable explosive composition comprising: a binder
and a particulate explosive filler contained in the binder,
wherein the binder comprises a gelled blend of a polyethylene
wax polymer having a molecular weight in the inclusive range
3000 to 15000 and comprising polymerised ethylene groups
forming at least 50 per cent by weight of the polymer together
with a tackifying resin comprising a polyisobutene polymer
having a molecular weight in the inclusive range 5000 to 7000
and comprising polymerised isobutene groups forming at least 50
per cent by weight of the polymer.
By a "polyethylene polymer" is meant a polymer
comprising ethylene optionally copolymerised with one or more
than other compounds, the ethylene content forming desirably at
least 90 per cent by weight of the polymer.
By a "polyisobutene polymer" is meant polyisobutene
optionally copolymerised with one or more other compounds, the
isobutene content forming desirably at least 90 per cent by
weight of the polymer.
The relative proportions of the components of the
binder depend upon the grades of the components employed in the
blend. The most suitable amount of the polyethylene wax
polymer in the blend will in many cases be in the range 2 to 35
per cent by weight especially when the polyethylene polymer has
a molecular weight in the inclusive range 3,000 to 15,000.
However, the amount of the polyethylene wax polymer may be
present in an amount of up to 90 per cent by weight of the
blend with the tackifying resin when the polyethylene polymer
has a low molecular weight, eg. in the range 3,000 to 7,000.
lwu
ls,
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2a
Any liquid polyisobutene having a molecular weight of
from 500 to 7,000, preferably from 500 to 5,000 may be used in
or as the tackifying resin.
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Preferred compositions comprise binders
including polyisobutene having a molecular weight
of from 500 to 5000 Ond a polyethylene having a
molecular weight of from 3000 to 13000,
polyisobutene forming 85 per cent by weight or more
of the polyisobutene/polyethylene blend.
Optional additives to the binder blend in the
explosive composition according to the present
invention comprise:
(a) micrystalline wax forming up to 10 per cent by
weight of the binder;
(b) a plasticiser having a viscosity of less than
50 cst preferably less than 2 cst at 20 C and
having a melting point less than 0 C, the
plasticiser forming up to 20 per cent by weight of
the binder;
(c) an anti-oxidant forming up to 1 per cent by
weight of the binder.
For example, a suitable plasticiser comprising
a quantity of material selected from one or more
known energetic plasticisers such as GAP (glycidyl
azide polymer),
BDNPA/F(bis-2,2-dinitropylacetal/formal),
bis-(2,2-dinitropropyl)formal, bis
(2,2,2-trinitroethyl)formal bis(2-fluoro-2,2
dinitroethyle)formal, diethylene glycol dinitrate,
glycerol trinitrate, glycol trinitrate, triethylene
glycol dinitrate, trimethylolethane trinitrate,
butanetriol trinitrate, or 1,2,4-butanetriol
trinitrate may be added to form the binder.
Alternatively, or in addition the binder may
incorporate one or more known non-energetic
plasticisers such as one or more esters of
phthalic, adipic or sebacic acid. For example the
optional plasticiser may comprise a dialkyl
phthalate eg, dibutyl phthalate or diethyl
phthalate or may be selected from triacetin,
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tricresyl phosphate, polyalkylene glycols and their
alkyl ether derivatives, eg. polyethylene glycol,
polypropylene glycol, diethylene glycol butylether
and dioctyl sebacate.
As suitable optional anti-oxidant compounds
polymerised trimethyl dihydroquinone; or
2,2'-methylene-bis (4-methyl-6-butylphenol); or
peritaerythrityl-tetrakis(3,3,5-ditertbutyl-4-hydroxyp
henyl)propionate may be incorporated in the binder
in an extent of up to 1 per cent, eg. about 0.5 per
cent, by weight of the binder.
Preferably at least 75% desirably at least 88%
by weight of the explosive filler in the
composition according to the present invention is
constituted by one or more heteroalicyclic
nitramine compounds. Nitramine compounds are those
containing at least one N-NO2 group.
Heteroalicyclic nitramines bear a rina containing
N-NO2 groups. Such ring or rings may contain for
example from two to ten carbon atoms and from two
to ten ring nitrogen atoms. Examples of preferred
heteroalicyclic nitramines are
RDX(cyclo-1,3,5-trimethylene-2,4,6-trinitramine,
hexagen), HMX
(cyclo-1,3,5,7-tetramethylene-2,4,6,8-tetranitramine,
octogen and mixtures thereof. The filler may
alternatively be selected from TATND
(tetranitro-tetraminodecalin, HNS
(hexanitrostilbene) NTO(3-nitro-1,2,4-thiazol-5one),
and TATB 30 (triaminotrinitrobenzene).
Preferably, the explosive filler comprises
from 50% to 100% by weight of RDX.
Other highly energetic filler materials may be
used in place of or in addition to the compounds
specified above. Examples of other suitable known
highly energetic materials include picrite
(nitroguanidine), aromatic nitramines such as
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3 4 1 5 7~1
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tetryl, ethylene dinitramine, and nitrate esters
such as nitroglycerine (glycerol trinitrate),
butane triol trinitrate or pentaerythritol
tetranitrate, trinitrotoluene (TNT), inorganic
oxidisers such as ammonium salts, eg. ammonium
nitrate or ammonium perchlorate, and energetic
alkali metal and alkaline earth metal salts.
Known metallic fuels such as aluminium powder
may be added to form part of the energetic solids
filler, eg. forming 1 to 50 per cent, eg. up to 30
per cent by weight of the total composition.
Alternative metal fuels include magnesium,
magnesium/aluminiujm alloy. Metallic fuel is
preferably included together with RDX or with RDX
and ammonium perchlorate.
The amount of explosive filler incorporated in
the binder in the composition according to the
present invention depends upon the amount of the
filler required to convert the binder from a gel
into a plastic mouldable mass but the explosive
filler content is conveniently in the range 50 to
95 per cent by weight, desirably 85 to 90 per cent
by weight, of the explosive composition.
In the case where the explosive is RDX and the
metallic fuel comprises aluminium, the metallic
fuel preferably comprises up to 30 per cent by
weight of the total composition, being up to 52 per
cent by weight of the energetic filler in
compositions having up to 88 per cent by weight
solids loading.
The compositions according to the present
invention may be made by adding the polyethylene to
the polyisobutene and other optional ingredients at
a temperature above the melting point of the
polyethylene and then mixing the two together until
a homogeneous liquid is produced. The explosive
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filler is then added as a powder optionally in a
water wet condition and optionally with a suitable
single organic solvent added to the binder to
facilitate processing. Following further stirring
to give a further homogeneous mass the product is
cast, pressed, extruded or rolled as appropriate
into suitable shapes which are allowed to cool to
room temperature (25 C).
A compatible coupling agent, in an extent of
up to 2 per cent by weight of the overall
composition, may be added during mixture of the
filler with the binder to improve adhesion between
the two.
Examples of suitable coupling agents are:
(1) silane coupling agents eg
(i) 1,2-ethane-diamine,
N-(ethynylphenylmethyl)-
- N-(3-trimethoxysilyl)propylmonohydrochloride
or (ii) CH2:CHSi(OCH2CH2OCH3)3
(2) organotitanate coupling agents eg isopropyltri
(dioctylphosphate)titanate.
A compatible surfactant in an extent of up to
2 per cent by weight of the overall composition may
be added to improve workability. Examples of
suitable surfactants include eg. (i) lecithin,
(ii) polyoxyethylene(20)sorbitan esters, eg
monolaurate, monopalmitate or mono-oleate; or
(iii) dioctyl ester of sodium sulphonic acid or
(iv) pentaerythritoldioleate (PEDO).
A compatible dye, in an extent of up to 0.5%
by weight of the overall composition, may be added
during mixture of the filler with the binder as an
aid to concealment.
Explosive compositions embodying to the
present invention show useful moulding properties
similar to those shown by the known material
mentioned above, but advantageously show reduced
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migration of liquid binder components (and hence
brittleness) with ageing, reduced exudation at
elevated temperatures and improved low temperature
mouldability.
in addition, the hydrophobic nature of the
binder imparts greater stability, adhesion and
workability when the explosive compositions are
used underwater.
Examples of the preparation and properties of
compositions embodying the present invention will
now be described by way of example as follows.
Various suitable materials (the 'gelled
binder" specified above) were first prepared by the
following method, Method A
Method A
Polyisobutene (PIB), and other optional
ingredients such as plasticisers and antioxidants
but not the polyethylene were added to a mixing
vessel at room temperature (20 C). The vessel
was heated to a temperature of 1400 C, slow
stirring being applied at temperatures above 80 C.
When the temperature reached 115-120 C
polyethylene was added in increments to form a
homogenous fluid.
The composition formed was cast into moulds or
storage vessels and allowed to cool
Explosive compositions were prepared from the
resulting binder materials produced by Method A
according to either of the alternative Method B,
Method C or Method D as follows.
An incorporator was heated to a temperature of
95-100 C:
Method B
The binder material was dissolved in an equal mass
of solvent by heating at 60-80 C with stirring to
form a suitable lacquer.
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The explosive filler eg RDX, including any
optional additives such as coupling agent but not
metallic fuel, was provided in a water wet
condition in a mixer which was heated to a suitable
elevated temperature, eg. 80-95 C for RDX.
Binder lacquer was then added carefully followed by
stirring with heating then cooling and drying.
After removal of water and solvent, any required
metallic fuel, eg powdered aluminium, was added.
Method C
An incorporator was preheated at a temperature
of 85 to 950 C. Increments of the solid explosive
filler in water wet form and the binder were added
at intervals followed by mixing
of the ingredients after each addition. Water was
removed optionally under vacuum and the mixture
stirred until homogeneous. The mixture was cooled
optionally under vacuum to room temperature
stirring being continued during cooling, and then
stored in a container for use.
Method D
About one half of the binder ingredients were
added to an incorporation preheated to a
temperature of 95-100 C.
A first increment of wetted nitramine was
added and mixed for about 15 minutes at atmospheric
pressure, allowing water to evaporate.
Further increments of wetted nitramine were
added each being allowed to incorporate for 10-15
minutes before addition of the next. Loose powder
of unmixed composition between additions was
scraped down.
When all explosive has been added aluminium
was put in if required, allowing each increment to
incorporate for approximately 10 minutes with
scraping down between additions.
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The remaining presoftened binder was poured
and then incorporated for approximately 1 hour with
scraping down every 15-20 minutes. A vacuum was
applied if required to ensure complete removal of
water.
The material was removed from the mixer either
whilst hot, or after first cooling to the desired
temperature whilst mixing.
If curing ingredients were to be included the
material was cooled to 60-80 C, curing
ingredients were added and the resultant material
mixed for 15-20 minutes before removal from the
incorporator.
Examples of binders made by Method A are given
in Tables 1 and 2 as follows.
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GELLED-POLYETHYLENE BINDER SYSTEMS
TABLE 1: COMPOSITION
INGREDIENTS
Example Polyethylene Polyisobutene Antioxidant
Number Type (%w/w) Type (%w/w) ($w/w)
Bi P2 7.5 PIB1 92.0 0.5
B2 P2 7.5 PIB2 92.0 0.5
B3 P2 7.5 PIB2 92.0 0.5
B4 P2 20.0 PIB3 92.0 0.5
B5 P2 22.0 PIB3 77.5 0.5
B6 P2 25.0 PIB3 74.5 0.5
B7 P2 27.0 PIB3 72.5 0.5
B8 P2 30.0 PIB3 69.5 0.5
B9 P2 35.0 PIB3 64.5 0.5
B10 P3 89.5 PIB1 10.0 0.5
B11 P3 89.5 PIB2 10.0 0.5
B12 P3 89.5 PIB3 10.0 0.5
B13 P1 59.5 PIB1 40.0 0.5
B14 Pi 59.5 PIB2 40.0 0.5
B15 P1 59.5 PIB3 40.0 0.5
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GELLED-POLYETHYLENE BINDER SYSTEMS (Continued)
TABLE 1: COMPOSITION (Continued)
INGREDIENTS
Example Polyethylene Polyisobutene Antioxidant DOS
Number Type (%w/w) Type (%w/w) (%w/w)
B16 P2 22.0 PIB4 77.5 0.5 -
B17 P2 22.0 PIB3 77.5 0.5 -
B18 P1 22.0 P185 77.5 0.5 -
B19 P1 22.0 PIB4 77.5 0.5 -
B20 Pl 22.0 PIB3 77.5 0.5 -
B21 P3 22.0 PIB5 77.5 0.5 -
B22 P3 7.5 PIB3 92.0 0.5 -
B23 P1 7.5 PIB3 92.0 0.5 -
B24 P2 7.5 PIB1 92.0 0.5 -
B25 P3 7.5 PIBl 92.0 0.5 -
B26 P2 5.0 PIB1 94.5 0.5 -
B27 P2 7.5 PIB3 87.0 0.5 5
B28 P2 7.5 PIB1 87.0 0.5 5
B29 P2 7.5 PIB2 92.0 0.5 -
13 'F70
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GELLED-POLYETHYLENE/POLYISOBUTENE BINDER SYSTEMS
TABLE 2: PROPERTIES
Example Softening
Number TMD Point Penetration
(g/cm3) ( C) (mm x 10-1)
B1 0.906 21 273
B2 0.911 23 -
B3 0.916 28 253
B4 0.915 34 218
B5 0.915 35 228
B6 0.915 94 223
B7 0.915 94 213
B8 0.915 98 200
B9 0.915 9R 178
B10 0.907 100 8
B11 0.907 101 6
B12 0.908 98 5
B13 0.906 96 11
B14 0.908 96 11
B15 0.910 101 10
1 3 4 1 57'0
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GELLED-POLYETHYLENE/POLYISOBUTENE BINDER SYSTEMS (Continued)
TABLE 2: PROPERTIES (Continued)
Example Softening
Number Point Penetration
( C) (mm x 10-1)
B16 96
B17 95
B18 60
B19 30
B20 89 4
B21 87 25 )
B22 94 53
B23 25 72
B24 87 55
B25 67 73
B26 57 68
B27 25 60
B28 87 68
B29 92 22 )
In Table 1 the Antioxidant is
2,2'-methylene-bis-(4-methyl-6-butylphenol).
In Table 1 the polyethylene is as follows:
Type P1: Molecular weight n8000.
Type P2: Molecular weight n12000
Type P3: Molecular weight n4000
In Table 1 the polyisobutene type is as follows:
Type PIBl: molecular weight n1300
Type P1B2: molecular weight n2100
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Type PIB3: molecular weight n2400
Type PIB4: molecular weight n3800
Type PIB5: molecular weight n5800.
Type PIB6: molecular weight n780
Type PIB7: molecular weight n1000
In Table 1 DOS is the plasticiser dioctyl
sebacate.
In Table 2 TMD is theoretical maximum density.
In Table 2 the softening point is measured
according to the known standard ASTM D36-8 (British
Standard BS4692:1972)
In Table 2 the penetration is measured
according to the known standard ASTM-2884-82 using a
100g weight and a 20s drop at 25 C.
Examples of explosive compositions made by
Method B or C using binder materials listed in Table
1 are listed in Tables 3 and 4 as follows.
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PLASTIC EXPLOSIVE COMPOSITIONS EMPLOYING
GELLED-POLYETHYLENE/POLYISOBUTENE BINDERS
TABLE 3: COMPOSITION
Explosive Binder Solids Loading
Composition Example $w/w $v/v
Example Number
Number
El B2 88.0 78.8
E2 B1 88.0 78.7
E3 B5 88.0 78.8
E4 B9 88.0 78.8
E5 B16 88.0 78.8
E6 B17 88.0 78.7
E7 B18 88.0 78.8
E8 B22 88.0 78.6
E9 B23 88.0 78.6
E10 B24 88.0 78.6
E11 B26 88.0 78.6
E12 B25 88.0 78.6
E13 B27 88.0 78.7
E14 B28 88.0 78.6
E15 B28 88.0 78.6
E16 B5 88.0 78.8
~3
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PLASTIC EXPLOSIVE COMPOSITIONS EMPLOYING
GELLED-POLYETHYLENE/POLYISOBUTENE BINDERS
TABLE 4: PROPERTIES
TMD Penetration Weight Loss
(g/cm3) (mm x 10-1) on Ageing
El 1.613 16 2.5
E2 1.612 30 2.1
E3 1.615 11 .18
E4 1.615 - .27
E5 1.614 - 0.46
E6 1.612 8 0.00
E7 1.614 11 -
E8 1.611 10 - )
E9 1.611 22
E10 1.610 28
E11 1.610 35
E12 1.610 27 )
E13 1.612 24
E14 1.610 31 1.10 )
E15 1.610 87 )
E16 1.615 - - )
In Table 3 the solids loading comprises particulate RDX
the remainder of the explosive composition being the binder
material (eg. Bl, B2 etc).
In Table 4 penetration is measured to the known
standard ASTM-2284-82 using a 100g weight and a 20s drop at
25 C.
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dxn Table 4 ageing comprises 3 months at a temperature of
60oC.
~ .,.
-At a- t1)_t tF' prn= ar*.a. a c n f
~as1-~Ytm at 250Q _ _
Examples of hazard data for Examples E14 and E15 are as
follows:
E14 figure of insensitiveness: 110 (RDX = 80)
Mallet Friction (steel on steel) 0%
These tests are specified in Sensitiveness
Collaboration Committee (SCC) Manual No 3.
