Note: Descriptions are shown in the official language in which they were submitted.
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1 RHEOLOGY CONTROLLED EMULSION
BACKGROUND
1. The Field of the Invention
The present invention relates to methods and
compositions for controlling the rheology of emulsion
compounds and explosives containing an emulsion. More
particularly, the present invention is related to an
emulsion with a polymerizing and/or crosslinking agent
which permits the preselection of a desired rheology of the
subject emulsion compound.
2. Background of the Invention
Explosive compositions are frequently used in
construction and mining related enterprises. The physical
characteristics of explosive compounds vary with the
intended use. In some circumstances it is desirable to
utilize an explosive composition whose viscosity is so low
that the explosive composition may be pumped into its
intended site. On the other hand, it may be desirable to
utilize an explosive composition which alone is rigid
enough to withstand the weight of stacking in storage or as
packaged material, when stacked vertically in a borehole.
In the last few decades, developments in mining
explosive technology have produced explosives far different
from nitroglycerine-based explosives used in the past.
Explosives are now made from components which are much less
expensive, less dangerous to prepare, transport and use.
These developments have resulted in slurries and explosives
containing an emulsion.
The development of slurries has resulted in the use of
thickening agents such as water-soluble gums, especially
guar gum, allowing control of the rheology of continuous
phase of the slurry and, hence, the slurry matrix.
Slurries continue, however, to be plagued with crystal-
lization of the discontinuous phase. Slurries are prone to
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1 crystallization at low temperatures. This compromises the
intimacy of the mixing of the oxidizers and fuels and
results in a loss of sensitivity. This problem is partic-
ularly acute in small diameter applications. Loss of
sensitivity is overcome by employing expensive ingredients
such as paint grade aluminum, TNT, monoethanolamine
nitrate, hexamethylene tetramine nitrate, ethyleneglycol
mononitrate, and the like. What is needed is an exp~osive
composition whose sensitivity is not compromised by
crystallization, but which retains the versatility of
rheology control exhibited by slurries or water-gel
explosives.
Explosives containing an emulsion are now well known
and overcome many of the problems encountered with previous
explosive formulations. The discovery of water-in-oil
emulsions has resulted in pumpable fluid like explosives
containing an emulsion which prove superior to slurries for
~any uses. Generally, emulsions include two separate
phases. These phases comprise a discontinuous internal
phase of an aqueous solution of oxidizers and a continuous
external phase of a carbonaceous fuel, such as oils and
waxes, and an emulsifier. The typical explosive containing
an emulsion also contains sensitizers in order to render
them- detonable. One of the favorable features of
explosives containing an emulsion is the fact that the
surface area of contact between the fuel phase and the
oxidizing phase is increased such that the fuel phase and
the oxidizing phase are more intimately interspersed and,
hence, more sensitive and faster reacting upon detonation.
Emulsions have provided some solutions to problems of
water resistance, separation of components, and loss of
detonability at low temperatures. Explosives containing
water-in-oil emulsions also have other advantages. They
are safer because they are less sensitive to mechanical
shock, and less expensive because the principal component
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1 ingredients of water, oil, ammonium nitrate, emulsifying
agents, and sensitizers are available at relatively lower
cost.
When emulsions are properly prepared, the interspersed
oxidizer droplets of the oxidizing phase are so small tha~
they are able to be supercooled. As a result, a highly
concentrated aqueous solution with a crystallization
temperature well above room temperature can be obtained and
incorporated into the discontinuous oxidizing phase. Such
an aqueous solution will not experience crystallization
upon cooling to e~en well below the crystallization
temperature. This preserves the intimacy of the mixing and
the desired sensitivity. However, currently available
emulsions have limited shelf life because of the tendency
of the aqueous phase to crystallize and for such crystals,
by rupturing the barriers between droplets, to grow. The
emulsion then loses sensitivity.
The rheology of currently available explosives
containing an emulsion is dependent largely upon the
physical consistency of the continuous fuel phase and on
the volume ratio of oxidizer to fuel phases. Rheology
control manipulates the phase volume ratio of the oxidizer
solution of the discontinuous phase to the continuous fuel
phasej and~or selectively varies the size of the droplets
of the oxidizer solution, and/or selectively varies the
viscosity of the continuous fuel phase. The choice of
phase volume ratio dictates the rheology of the emulsions
and explosives containing an emulsion. For example, if the
ratio of oxidizer solution to fuel is large the resulting
emulsions are stiff. Similarly, if the solution droplets
are small the resulting emulsions are stiff. Furthermore,
if the fuel phase comprises a thick oil the resulting
emulsions are highly viscous, or if the fuel phase
comprises a wax the resulting emulsions have a high degree
of plasticity.
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l The ability to control the rheology of the emulsion or
explosive containing an emulsion becomes very apparent when
considering the manufacturing of explosives containing an
emulsion. As stated, oils and waxes are selectively chosen
to obtain the desired rheology of an emulsion or explosive
containing an emulsion. If, for example, it is desirable
to cartridge the explosive containing an emulsion, or to
assure that air bubbles or other discontinuous phases are
held in place, the oils or waxes must be fluid at the
temperature of manufacture in order to form and refine, and
then pour or pump the emulsion. As a result, the rheology
of the final composition is then dependent on temperature.
Even emulsions and explosives containing an emulsion
containing waxes which are relatively stiff at the lower
temperatures of use are relatively and often undesirably
soft at higher temperatures of use. Change in the rheology
with temperature is contrary to the constant environment
needed to effectively disperse or maintain in dispersion a
discontinuous oxidizing phase or sensitizing agent. In
other words, temperature changes work not only a change in
the rigidity of the composition itself, but also
detrimentally influence the ability of the emulsion or
explosive containing an emulsion to hold or lock the
discontinuous oxidizing phase and/or sensitizers in place.
An explosive containing an emulsion whose composition
permitted the user to select the rheology of the ultimate
explosive containing an emulsion, much as is possible with
water-gel explosives, would be much more desirable. Such
a composition would provide an explosive containing an
emulsion which is capable of effectively stabilizing the
continuous and discontinuous phases over a wide range of
temperatures such that the explosive containing an emulsion
would be less sensitive to temperature changes. Similarly,
it would be an advancement in the art if the rheology of a
given emulsion or explosive containing an emulsion would
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l - permit the control of other significant characteristics of
the composition, such as waterproofing, surface adhesion,
and wetness. Indeed, what is needed is a polymerizing
agent or crosslinker which permits the user to select the
desired rheology.
Therefore, it would be a further advantage and
improvement in the art if the rheology of an emulsion or
explosive containing an emulsion could be controlled to
produce an emulsion or explosive containing an emulsion
which is more stable, l.e., less prone to crystallization
of the oxidizer salts in the solution of the discontinuous
phase and to subsequent growth of the crystals.
Such an emulsion and explosive containing an emulsion
are disclosed and claimed below.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to emulsion compositions
with a polymerizing and/or crosslinking agent and methods
for use in improving the manufacturing, packaging,
transporting, storage and placement of emulsions and
explosives containing an emulsion. More particularly, the
present invention is directed to controlling the rheology
of an emulsion or explosive containing an emulsion by
polymerizing and/or crosslinking the continuous phase of
the emulsion. The present invention provides compositions
and methods of polymerizing and/or crosslinking emulsion
compositions which result in an emulsion or explosive
containing an emulsion whose rheology may be controllably
selected, without compromising the integrity of the
explosive reaction.
The present invention is directed to an emulsion
comprising a fuel phase, an oxidizing phase, an emulsifier,
a selected amount of polymerizable and/or crosslinkable
material, and a coreactant to effect polymerization or
crosslinking reaction in situ.
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l The present invention is also directed to an explosive
containing an emulsion comprising a fuel phase, an
oxidizing phase, an emulsifier, a selected amount of
polymerizable and/or crosslinkable material, a coreactant
to effect polymerization or crosslinking reaction in situ,
a sensitizer, and optional additional fuels or oxidizers.
The composition of the present invention comprises a
water-in-oil emulsion containing a continuous external
carbonaceous fuel phase. The fuel phase contains a
polymerizable and/or crosslinkable polymer which is
polymerized or crosslinked. Dependen~ upon the chemistry
of the polymer or crosslinker, the amount used, temperature
and pH, the polymerizing and crosslinking reaction adjusts
the rheology of the selected emulsion to the desired
rheology and stabilizes the emulsion composition. As a
result, the coalescence, crystallization, agglomeration, or
migration of the discontinuous oxidizing phase of the
emulsion and/or sensitizing agents of the explosive
containing an emulsion is reduced, and the final rheology
~0 of the emulsion or explosive containing an emulsion is
optimal for its intended use.
The rheology control mechanism of the present
invention is one that is not only influenced by the
chemistry of the polymer or crosslinker, the amount used,
temperature and pH, but also by the period of time over
which the polymerization and/or crosslinking reaction
occurs. That is, the rheology change of the continuous
phase of the emulsion may be controlled over time as
desired.
Included within the fuel phase of the present
invention is a crosslinkable and/or polymerizable
carbonaceous oil and/or wax. In one preferred embodiment,
the polymerizable material is hydroxy-terminated
polybutadiene (HTPB). In many cases the HTPB can be
substituted by a butadiene-styrene copolymer, a polymer
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1 with hydroxy functional groups, or other carbonaceous,
polymerizable materials with, for example, epoxy functional
groups.
HTPB and similar polymerizable carbonaceous materials
may be polymerized by reaction with multi-functional
isocyanates. In most cases, a suitable polymerizing
isocyanate may be chosen from the group of high molecular
weight, low vapor pressure isocyanates.- A preferred
isocyanate is Isonate~ 143L. In the case of HTPB and
Isonate~ 143L, they act as coreactants to effect the
polymerization of some of the continuous phase of the
emulsion.
The-- present invention is also- directed to a
crosslinkable carbonaceous material used in conjunction
with or mutually exclusive of the polymerizable
carbonaceous material. A preferred crosslinkable material
is maleic anhydride adducted polybutadiene (131 MA). Other
suitable redundant materials may also be used. The
crosslinkable material is crosslinked employing a suitable
crosslinking catalyst-or coreactant. In the case of 131
MA, a basic reagent, or a multifunctional hydroxy group is
an effective crosslinker. Examples of suitable
crosslinkers include ammonia, ethylene~lycol, polyethylene
glycol, tri- and monoethanolamine, and other alkaline
materials. The presently preferred crosslinker is
triethanolamine. Practice of the invention has revealed
that other crosslinker coreactants aid the crosslinking
process. Suitable crosslinking coreactants include metal
organic compositions, and poly-hydroxy compounds or
polyols.
The internal, discontinuous oxidizing phase of the
emulsion comprises an aqueous solution oxygen-containing
salts. Suitable salts include ammonium nitrate, calcium
nitrate, sodium nitrate, or perchlorate. The salts are
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1 dispersed in the continuous phase so as to provide intimate
contact with the continuous fuel phase.
The emulsifier required by the present invention
comprises any effective water-in-oil emulsifier. Suitable
water-in-oil emulsifiers include known compounds such as
sorbitan monooleate, sorbitan tristearate, sorbitan
sesquileate, polyisobutylene sulphonic acid, and the like.
An explosive containing an emulsion may be compounded
by combining an emulsion as discussed above as a continuous
phase, with l~n~;-csolved, solid oxidizers such as ammonium
nitrate or other nitrates or perchlorates, and solid fuels
such as coal dust, hydrocarbon fuels or aluminum as
discontinuous~phases. A preferred embodiment-of explosives
containing an emulsion phase-and a second reactive phase is
the so-called heavy ANFO explosive which comprise an
emulsion combined with porous ammonium nitrate or with
ANFO.
Sensitizers are typically used in conjunction with
explosives containing an emulsion. Sensitizers and
density-control agents used in conjunction with the present
invention may include, for example, porous prill ammonium
~ nitrate or ANFO, microballons or microspheres, polystyrene
beads, self explosives such as TNT, gassing bubbles from
nitrite or peroxide solutions, perlite, emulsified gassing
2S agents,- and the like. The amount of solid or chemical
density-control agents is chosen to give the emulsion or
explosive containing an emulsion a void volume in the range
from about 4% to about 80% of the final compound. The
amount of void space required in the explosive containing
an emulsion depends upon the required bulk energy of the
explosive and the desired sensitivity.
Oils of low and high viscosity, and various kinds of
waxes, e.q., paraffin wax or microcrystalline wax, may be
employed in conjunction with the polymerizable or cross-
linkable material to add to the control of the rheology of
~ ~n ~77 ~
the emulsion or explosive containing an emulsion after
polymerization or crosslinking has been effected.
In summary, the invention therefore provides in one aspect
a water-in-oil emulsion for use in an explosive which comprises
a continuous phase comprising a blend of organic fuel
materials, at least one of the fuel materials being at least
partially polymerized to achieve a preselected nonrigid
rheology in the range from a fluid rheology to a nonfluid,
deformable rheology. At least one of the fuel materials is
substantially unpolymerized. The polymerized organic fuel
material comprises a butadiene-styrene homopolymer adducted
with maleic anhydride. There is also a discontinuous phase
comprising water and at least one oxygen-containing salt. In
another aspect, the polymerized organic fuel material comprises
a polymer with epoxy functional groups. In another aspect, the
polymerized organic fuel material comprises a polybutadiene
with hydroxyl functional groups.
In a further aspect, the invention provides for a
water-in-oil emulsion for use in an explosive which comprises
a continuous phase comprising a blend of organic fuel
materials, at least one of the fuel materials consisting of
homopolymeric units being at least partially cross-linked in
situ to achieve a preselected nonrigid rheology in the range
from a fluid rheology to a nonfluid, deformable rheology. At
least one of the fuel materials is substantially
uncross-linked. The cross-linked organic fuel material
comprises butadiene homopolymer adducted with maleic anhydride
and is soluble in the uncross-linked organic fuel material.
There is also a discontinuous phase comprising water and at
least one oxygen-containing salt.
In yet another aspect, the invention provides for a method
of achieving a preselected rheology of an emulsion for use in
an explosive, the method comprising the steps of:
(a) obtaining an emulsion including (i) a continuous phase
comprising a blend of organic fuel materials wherein at least
.,
-9a-
one of the fuel materials is at least partially polymerizable,
and able to impart a non-rigid rheology upon being polymerized,
at least one of the organic fuel materials being substantially
unpolymerized, wherein the polymerizable material comprises
polybutadiene with hydroxy, or alternatively epoxy, functional
groups, and is soluble in the unpolymerized organic fuel
material, and (ii) a discontinuous phase comprising water and
at least one oxygen-containing salt; and
(b) adding a polymerizing agent in sufficient amount to
polymerize at least a portion of the organic fuel material
until the preselected rheology is obtained.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is related to compositions and
methods for preparing an emulsion or explosive containing an
emulsion which are selectively and controllably cross-linked
and/or polymerized in order to control the rheology of the
emulsion composition or emulsion phase of the explosive
containing an emulsion. By employing the present invention
particular physical properties of the emulsion may be chosen
for optimizing the intended manufacturing, packaging,
transporting, storage, and use of the emulsion or explosive
containing an emulsion.
The present invention resides in a crosslinkable and/or
polymerizable emulsion or emulsion phase of an explosive
containing an emulsion. The emulsion comprises principally a
water-in-oil emulsion. The emulsion has a crosslinkable and/or
polymerizable component in the external continuous fuel phase.
It also has an internal discontinuous oxidizing phase. The
explosive containing an emulsion comprises an emulsion phase
and a sensitizer, and may also contain additional fuels,
additional solid oxidizers, and any other necessary or
desirable components to control energy and/or density of the
final explosive product.
Traditionally, in prior art compositions the external
carbonaceous fuel phase of an emulsion comprises fuel oils,
. ,,
~ ,
' -
7 7 7
-9b-
refined or purified hydrocarbons, waxes, halogenated
hydrocarbons, nitrated hydrocarbons or a mixture thereof.
However, when the carbonaceous fuel phase comprises a liquid
which is flowable at, or slightly above, ambient temperatures
the explosive containing an emulsion is not generally suitable
for packaging using conventional explosive packaging or
cartridging methods. Such
~,
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-- 10--
1 explosives may similarly be unsuitable for use in boreholes
with fissures and cracks because flowable explosive
compositlons escape the borehole.
A. Rheoloqy Control Via PolYmerization
1. In the emulsion
Conventional emulsions attempt to provide a continuous
fuel phase which suitably inhibits the crystallization,
coalescence, agglomeration and migration of the
discontinuous phase by including polymers in the continuous
phase or by choosing a particular emulsifier. Conventional
emulsions have not, however, sought to control the rheology
of the continuous phase by polymerizing the continuous
phase in situ in a controlled, predictable, and reliable
reaction. The present invention provides a continuous fuel
phase that includes high molecular weight hydrocarbon
species which can be and are at least partially polymerized
and/or crosslinked in order to effect a change in the
rheology of the emulsion, and, therefore, of the explosive
containing an emulsion, as a whole.
An embodiment of the present invention employs, for
example, a polymerizable organic material with hydroxy or
epoxy functional groups. Particularly, an embodiment of
the present invention comprises polybutadiene as the
polymerizable organic fuel. More particularly, the
preferred embodiment of the present invention employs
hydroxy-terminated polybutadiene (HTPB) as the
polymerizable fuel.
HTPB is characterized by the presence of a polymer of
from about at least fifty (50) repeating monomer units with
at least two functional units capable of bonding with other
molecules. Such a material results in long, flexible
polymer chains whose mass is pliable and can withstand
moderate stress and strain without tearing or crumbling.
The character of the certain polymerized fuel materials
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1 provides the continuous phase of the emulsion with
advantageous preselected elastic properties. Suitable
substitutes for HTPB include carboxy-terminated p~ly-
butadiene, maleic anhydride-terminated polybutadiene,
epoxy-terminated polybutadiene, and similar substances. In
practice, suitable results are obtained when HTPB is
present in amounts ranging up to approximately 5.9~.
Better results are obtained when HTPB exists in the
emulsion ranging from about 0.75% to about 3.0%. In one
preferred embodiment HTPB is present in concentrations
ranging from about 1.0% to about 2.0%.
The polymerizable organic fuel of the present
invention is polymerized with the assistance of isocyanate~
compounds. Because of the hazards associated with the
vapors of low molecular weight isocyanates, high molecular
weight, low vapor pressure isocyanates are preferred. More
particularly, Isonate~ 143L has proven to give superior
results. Satisfactory results using Isonate~ 143 L have
been obtained when present in an amount ranging up to about
0.6%. More suitable results are obtained when Isonate~ 143
L is present ranging from about 0.075% to about 0.3%.
Preferably, IsonateX 143 L is present in an amount ranging
from about 0.1% to about 0.2%.
2. In the exPlosive containinq an emulsion
An explosive containing an emulsion comprises an
emulsion phase, energizing/sensitizing agents, and if
desired, additional fuels and oxidizers. In other words,
the multiphase emulsion discussed above becomes one phase
of the explosive compound. In the same manner that the
polymerization of the continuous fuel phase of the emulsion
chemically changes the rheology of the emulsion,
controlling the rheology of the emulsion phase of the
explosive containing an emulsion changes the rheology of
the explosive containing the emulsion. In this way, the
benefits of controlling the rheology of the emulsion can be
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-12-
l transferred over to controlling the rheology of the
explosive containing the emulsion. Control of the rheology
of the explosive con~ining the emulsion is of great
advantage in the manufacturing, packaging, transporting,
storage and placement in use of the explosive composition.
M;Ying the emulsion with other phases of the
explosive, and packaging the explosive, may now be
accomplished at or near room temperature. The emulsion can
be formulated so that the explosive matrix is more stable
during transportation. The temperature of storage is no
longer necessarily detrimental to the integrity of the
explosive composition. The intended use or placement of
the explosive composition may be optimized by selecting a
rheology most conducive to the intended use or placement.
For these reasons, and other reasons which become apparent
during the practice of the present invention, the rheology
control of the present invention is a significant advance
in the art.
B. Rheology Control Via Crosslinkinq
l. In the emulsion
Some known emulsion systems contemplate the use of
additives to thicken the composition of the emulsion.
Known additives include agents such as natural waxes,
water-soluble gums such as guar gum, and synthetic polymers
or waxes. Many of the conventional uses of thickening
additives emphasize physical rather than chemical rheology
changes.
The present invention provides a change in rheology by
means of a chemical reaction within the continuous fuel
phase of the water-in-oil emulsion. The chemical reaction
adjusts the rheology of the emulsion by chemically
crosslinking at least a portion of the fuel phase. The
crosslinker operates to crosswise connect parallel and/or
adjacent chains of polymerized fuel. The crosslinking may
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1 continue until the polymerized fuel phase is bound by a
matrix mass of crosslinked polymers. The result of the
crosslinking is a relatively fixed continuous phase of the
emulsion. The character of certain crosslinked materials
S provides the continuous phase of the emulsion with
advantageous preselected rigidity properties. For example,
the preselected or desired rigidity may be a rubbery state,
or a stiff, solid state. The fixed nature of the contin-
uous phase operates to lock or hold the discontinuous phase
in its location. This aids to inhibit the crystallization,
coalescence, agglomeration and migration of oxidizing drop-
lets of the discontinuous phase which plague conventional
water-in-oil emulsions. -
In the present invention, it has been determined that
131 maleic anhydride adducted polybutadiene (131 MA) is an
effective crosslink~ble polymer. The reactive sites of the
131 MA provide bonding sites at which the crosslinker
operates to bind the polymer chains together. Other
suitably crosslinkable polymers include compounds having
difunctional moieties which may have active bonding sitesas are found in anhydride or oxarane groups, nitrogen based
groups such as isocyanates, amines, imides, or amides, or
carbonyl or hydroxyl groups which in conjunction with a
catalyst or accelerator bond-with the functional groups of
the polymer.
Suitable examples of crosslinkers include ammonia,
ethyleneglycol, polyethylene glycol, tri- and monoethanol-
amine, and other alkaline materials. Satisfactory results
using monoethanolamine have been obtained when present in
an amount ranging up to about 0.3%. More suitable results
are obtained when monoethanolamine is present ranging from
about 0.05% to about 0.3%. Preferably, monoethano~ amine
is present in an amount ranging from about 0.1% to about
0.3%.
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-14-
l Acceptable results using triethanolamine are obta~ned
when triethanolamine is present in a quantity up to about
0.3% of the emulsion as a whole. More favorable results
are obtained when triethanolamine is present in an amount
from about 0.1% to about 0.3%. Preferred results occur
when triethanolamine is present in quantities from about
0.15% to about 0.2%.
The extent of the crosslinking can be controlled by
the selection of the crosslinkable polymer, the
crosslinker, the choice of crosslinking coreactant, the
amount of crosslinker used, the functional groups added to
the polymerized fuel, and the rate of reaction of the
crosslinking. The application of the present invention
vis-a-vis crosslinkers has resulted in superior results in
controllably altering the rheology of the continuous phase
of the emulsion, and as a result, inhibiting
crystallization, coalescence, agglomeration and migration
of the discontinuous phase or phases of dispersed oxidizing
components.
The rate of reaction of the crosslinker depends upon
the chemistry of the crosslinker, the temperature at which
the reaction occurs, and the pH of the environment in which
the reaction occurs. The crosslinking process may be
enhanced by coreactants including metal organic
compositions, and polyhydric alcohols such as polyethylene
glycol.
2. In the explosive containing an emulsion
For similar reasons as discussed above relative to
polymerization, controlling the rheology of the emulsion by
crosslinking may be transferred over to controlling the
rheology of an explosive by incorporating the emulsion into
the explosive composition. If the rheology controlled
emulsion is a phase of the explosive composition, then as
a result, the rheology of the explosive composition will
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1 also be controllable. Crosslinking the continuous phase of
an emulsion contained in an explosive operates to control
the rheology of the explosive compound as well.
C. RheologY Control Via PolYmerization And/Or
Crosslinking
One example of an e~hoAiment of the present invention
is employing HTPB and 131 MA mutually exclusive of each
other. Satisfactory results have been obtained. Another
example of an embodiment of the present invention is
employing both polymerization and crosslinking. By
combining rheology control via polymerization and
crosslinking, the character of the resulting composition
can provide the continuous phase . Q~. the emulsion with a
combination of the preselected elastic and rigidity
properties optimal for the intended use. An example of a
combination use is when one of the fuels of the continuous
phase is a butadiene homopolymer adducted with maleic
anhydride. Similarly, favorable results are obtained when
a butadiene-styrene copolymer, adducted with maleic
anhydride, is used as one of the fuels of the continuous
phase. Satisfactory results have been obtained when the
polymerization of the fuel polymer of the continuous fuel
phase is achieved by allowing the 131 MA to be polymerized
with the HTPB exclusive of any polymerization enhancer or
component, or crosslink reaction.
D. Oxidizinq, DensitY-Control. And Sensitizinq Aqents
1. In the emulsion
Because oxygen balancing is vital for an optimal
detonation of explosives, the availability of the oxidizing
agent throughout the explosive composition to complete the
reaction is of paramount importance. A crucial part of the
oxidizing agent for detonation of an explosive containing
an emulsion is provided by the discontinuous oxidizing
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l phase of the emulsion. If the oxidizing droplets or
particles of the discontinuous phase of the emulsion
crystallize, coalesce, agglomerate or migrate, the intended
dispersion effect of the oxidizers is obviously diminished.
Many oxidizing agents and phases are used in
conventional emulsions. The preferable forms of oxidizing
agent employed in the present invention include aqueous
forms of ammonium nitrate, calcium nitrate, or sodium
nitrate, or a mixture thereof.
The present invention also contemplates the use of dry
ammonium nitrate-fuel oil prills (ANFO) in conjunction with
the oxidizing agents hereinabove discussed.
2. In the explosive containinq an emulsion
Similarly, homogeneous dispersion of density-control
and sensitizing agents is vital for an optimal detonation
of explosives. Just as dispersion of oxidizing agents is
vital to optimal detonation, the dispersion of density-
control and sensitizing agents throughout the explosive
composition reaction is also of paramount importance. If
dispersed density-control and sensitizing agents of the
explosive composition crystallize, coalesce, agglomerate or
migrate, the intended dispersion effect is defeated and the
air-gap sensitivity and detonation velocity of the
explosive composition are diminished.
Density-control and sensitivity components are
included in an emulsion to make the emulsion more or less
sensitive to shock initiation and to assure that the
velocity of detonation through the emulsion compound is at
a suitable and constant rate. Density-control agents
include substances from the group including solid density
reducing agents such as expanded polystyrene beads,
perlite, microspheres and microballons.
Increased sensitivity can be achieved by using
injected air or gas bubbles, and air or gas bubbles
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l generated in situ from peroxide, nitrite, or carbonate
solutions, emulsified gassing agents, and similar gas-
producing reactions which do not otherwise compromise the
explosive-nature of the explosive containing an emulsion.
Sensitivity is also increased by the inclusion of self-
explosives such as, for example, TNT, PETN, RDX, and the
like.
E. Emulsifiers
Without the presence of an emulsifier the mixed phases
of the compositions may tend to separate to form a layered
or regional mixture which has little utility as an
emulsion.
Suitable emulsifiers for water-in-oil emulsions
comprise an amphiphatic compound. The amphiphatic compound
is one with at least two or more segments, one of which is
only soluble in an oil phase and the other only soluble in
an aqueous phase. In other words, a preferred emulsifier
comprises an organic emulsifier having a hydrophilic
portion and a lipophilic portion, and exhibiting a high
solubility in hydrocarbons and a high tolerance to salt
solutions. In the case of the present invention, the
emulsifier can be selected from the group of known water-
in-oil emulsifiers. Examples of suitable emulsifiers
include, but ~s not limited to, sorbitan monooleate,
sorbitan tristearate, sorbitan sesquioleate, and glycerides
of fat-forming fatty acids, or a mixture thereof.
The effective combination of the above discussed
components of the emulsion of the present invention results
}5 an emulsion or explosive containing an emulsion whose
rheology can be controlled to meet the needs and demands of
the user. This is particularly evident during the course
of the manufacturing, packaging, transporting, storage, and
the ultimate placement of the explosive, where the rheology
of the emulsion composition plays such an important role.
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l For example, during the manufacture of an emulsion
compound, it is vital to homogeneously disperse th~
discontinuous oxidizing phase in the continuous fuel phase.
This is most easily accomplished when the continuous phase
or phases have low viscosity such that the oxidizing phase
can be thoroughly agitated and blended into the continuous
fuel phase. If the rheology of the continuous phase is too
rigid, the task of agitating and blending is made less
efficient and effective. However, once the manufacturing
stage has progressed to a point at which the discontinuous
phase is homogeneously dispersed, it is typically desirable
to have the discontinuous phase remain dispersed in the
continuous phase without the detrimental effects of
crystallization, coalescence, agglomeration or migration of
the discontinuous phase. The present invention permits the
manufacturer/producer to lock the dispersed, discontinuous
phase of the emulsion or other phases of the explosive
containing an emulsion in place by employing the polymer-
izing and/or crosslinking reactions of the present
invention. These reactions can be accomplished at the high
manufacturing temperature of the emulsion or at ambient
temperature after the emulsion phase of the explosive
composition has been allowed to cool. "Locking the
dispersed, discontinuous phase" is meant to describe the
effect of causing a change in the rheology of the
continuous phase such that the crystallization,
coalescence, agglomeration, or migration of the
discontinuous phase is inhibited by a chemical reaction
which structurally alters the host continuous phase.
Similarly, during packaging, it is very difficult to
cause a sticky, highly viscous emulsion to flow into and
fill a cartridge or package. It is most desirable that at
the time of packaging t~ the emulsion be readily pumpable
and formable to the intended package without the
inconsistencies of void and air pockets and without the
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--19--
1 need to maintain the emulsion at unwanted higher temper-
atures. As a result of use of the present invention, high
temperature cartridging can be avoided because the chemical
reaction may occur at or below the manufacturing t~p~r-
ature. Likewise, the ready transporting, storage, andhandling of an emulsion is often dependent upon the rheol-
ogy and temperature of the emulsion.
Furthermore, the ultimate and proper placement of the
explosive at the intended site is vital to the performance
of the explosive. If the intended situs of the detonation
is in a vertically upward borehole in an underground mine,
in a vertically downward borehole in an open pit mine, in
a horizonal borehole on a coal or tunnel face, or in any
shape of borehole at any angle in between, the ability of
the laborer to effectively load, prime, and stem the
borehole is directly related to the handling charact-
eristics of the explosive as dictated by the rheology of
the explosive composition. The rheology of the emulsion or
explosive containing an emulsion is, therefore, critical.
The compositions and methods of the present invention
provide for an emulsion whose physical characteristics such
as surface adhesion, water resistance, viscosity and
surface moisture may also be regulated as desired by the
user. Because-these physical characteristics are closely
related to rheology, such physical characteristics may also
be selected in accordance with the optimum use and perform-
ance of the emulsion. For example, in some circumstances
it is desired to have an emulsion which has a greasy
consistency. In another situation, a nongreasy, yet sticky
emulsion may be -optimal. In another situation, a thin
syrupy emulsion may be desired. In yet another situation,
a rigid emulsion may be advantageous. Similarly, any phase
state in-between may be desirous ultimately or at some
stage of the life of the emulsion.
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l The mechanism for polymerizing or crosslinking the
continuous phase of the emulsion of the present invention
to control the rheology of the emulsion varies. In some
cases, polymerization of the continuous phase is sufficient
to attain the desired rheology. In other cases
crosslinking is required to stabilize the emulsion
phase(s). Polymerizing and/or crosslinking the continuous
phase of the emulsion permits one to control the rheology
of the emulsion.
Polymerizing or crosslinking the continuous phase of
the emulsion provides an emulsion whose rheology may be
chosen corresponding to the desired and intended
manufacturing, packaging, transporting, handling, storage,
use and the like. The range of the rheology is determined
by controlling the period of time over which the polymer-
ization takes place or by choosing the appropriate cross-
linker which will provide the desired crosslink of the
continuous phase of the emulsion.
Crystallization, coalescence, agglomeration and
migration of dispersed particles ~ ~ function of the
affinity of the dispersed element to the interfacing
substance, of gravity, of density, and of the rheology of
the continuous phase. Maintaining the dispersed nature of
an oxidizing agent is important to the most desirable
performance of the emulsion vis-a-vis oxygen balancing of
the blasting reaction. By polymerizing and/or crosslinking
the continuous fuel phase the discontinuous phases of the
emulsion or explosive containing an emulsion are
stabilized.
The ability to control the change of rheology of the
present invention focuses on a chemical reaction which is
less dependent on temperature than the rheology control of
known emulsion and emulsion-containing compounds. In
addition, once the desired rheology is attained by
employing the present invention, the steady state of the
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-21-
1 rheology is also less effected by changes in ambient
temperature than the steady state of currently available
emulsion compounds. This is a result of the chemical
bonding between the polymeric components of the emulsion.
Conventional emulsions relied primarily upon the physical
mixture of the substituent elements and any help that the
emulsifier might provide in maintaining the steady state of
the phase distinctions. The chemical reaction of the
present invention operates to interconnect and bind
together at least some of the monomers and polymers of the
continuous phase in such a way that the discontinuous
phases are locked or held in place as if they resided in
interstitial space in a molecular structure. In this way,
the discontinuous phases remain dispersed throughout the
continuous phase, thereby maintaining the intimate contact
between the fuel phase and oxidizing phase of the emulsion
and promoting the detonability of the explosive containing
an emulsion.
In addition to the selection of the rheology of the
emulsion, the present invention is directed to the ability
of the user of the present invention to select a range of
rheology of the subject emulsion over a period of time, if
desired, by controlling the rate of reaction of the
polymerization or crosslinking. It is a well known fact
that the rate of many chemical reactions can be controlled-
by factors such as concentration, temperature, pH, and the
like. In the case of polymerizable or crosslinkable
polymers, the ratio of functional groups on the polymer to
the function groups on the crosslinker or polymerizer plays
a significant role in the rate of reaction of the polymer-
ization or crosslinking. The present invention permits the
controlled variation in the rate of reaction of polymer-
ization and crosslinking. In this case the extent of
polymerization or crosslinking determines the rheology of
the emulsion at any given time. If it is desired that the
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-22-
l emulsion be fluid for a certain period of time and later
set to a more rigid state, the extent and rate of polymer-
ization and/or crosslinking is controlled by choosing the
appropriate polymer and polymerization process and the
corresponding crosslinking reaction.
EXAMPLES
The following examples are given to illustrate the
general scope of the present invention, but these examples
are not intended to limit the scope of the invention.
Similarly, while the following examples represent a range
of composition substituents of suitable emulsions and
emulsion phases of explosives containing an emulsion, other
ranges of composition substituents outside the ranges
illustrated by the following examples also provide suitable
emulsions and emulsion phases of explosives containing an
emulsion.
The emulsions in the following examples were allowed
to cool to room temperature before other ingredients were
added. This practice was convenient in the laboratory, but
does not imply that similar compositions could not be
obtained by incorporating all ingredients into the final
composition with the emulsion still at its elevated
temperature of mixing.
In each example, the number of days of curing is
quoted. This is the time at which the ultimate rheology
was examined, and not the time taken for the crosslinking
or polymerization reaction to become effective.
ExamPle l
An explosive containing a polymerized emulsion
compound was prepared by mixing the following ingredients:
Inqredients Percentage
Ammonium Nitrate 63.2
Sodium Nitrate 13.9
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1 Water 12.0
Emulsifier 1.0
Diesel Oil 5.3
HTPB 1.5
Isonate~ 143 L O.1
Perlite 3.0
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and sodium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added with vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier
and fuel oil, until an emulsion was formed. The emulsion
was allowed to cool to room-temperature. Thereafterj the
Perlite and the Isonate~ 143 L were added with stirring.
The explosive containing the emulsion cured for one (l)
day.
The thus formed explosive containing an emulsion
resulted in a discontinuous oxidizing phase uniformly
dispersed in a polymerized continuous fuel phase. The
consistency of the explosive was non-tacky rubber.
Exam~le 2
An explosive containing a polymerized emulsion
compound was prepared by mixing the following ingredients:
Ingredients Percentage
Ammonium Nitrate 24.4
Calcium Nitrate 18.3
Water 10.0
Ammonium Nitrate Prills 38.8
Emulsifier 0-9
Diesel Oil 5-5
HTPB 1.2
Isonate~ 143 L 0.2
Polystyrene Beads 0.7
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-24-
l The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added with vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier
and fuel oil until an emulsion was formed. The emulsion
was allowed to cool to room temperature. Thereafter, the
Isonate~ 143 L, the ammonium nitrate prills and the
polystyrene beads were added with stirring. The explosive
containing the emulsion cured for over seven (7) days.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized
continuous fuel phase. The consistency of the thus formed
explosive was firm and rubbery. The explosive remained
detonable by l50g of Pentolite in 3 inch diameter tubes for
at least 4 weeks.
Example 3
An explosive containing a polymerized emulsion
20 compound was prepared by mixing the following ingredients:
Inqredients Percentage
Ammonium Nitrate 24.5
Calcium Nitrate 18.4
Water l0.0
Ammonium Nitrate Prills 39.0
Emulsifier 0-9
Diesel Oil 5-5
HTPB l.2
IsonateX 143 L 0.2
Nitrite Solution 0-3
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier
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-25-
1 and fuel oil until an emulsion was formed. The emulsion
was allowed to cool to room temperature. The ammonium
nitrate prills were added with stirring. Thereafter, the
Isonate~ 143 L was added with stirring. The explosive
containing the emulsion cured for over fourteen (14) days.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized
continuous fuel phase. The consistency of the explosive
was firm and rubbery.
ExamPle 4
An explosive containing a crosslinked emulsion
compound was prepared by mixing the following ingredients:
Ingredients Percentage
Ammonium Nitrate 21.95
Calcium Nitrate 16.38
Water 8.76
Ammonium Nitrate Prills 44.90
Emulsifier 0.53
Diesel Oil 5.77
131 MA 1.09
Triethanolamine 0.12
Polystyrene Beads 0.50
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
crosslinkable 131 MA, to which had been added the
emulsifier and fuel oil until an emulsion was formed. The
emulsion was allowed to cool to room temperature.
Thereafter, the ammonium nitrate, polystyrene beads and
triethanol amine were added with stirring. The explosive
containing the emulsion cured for six (6) days.
The thus formed emulsion phase of the explosive
resulted in a discontinuous oxidizing phase uniformly
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l dispersed in a crosslinked continuous fuel phase, with the
consistency of non-tacky rubber. The consistency of the
explosive was firm and rubbery.
Exam~le 5
An explosive containing a crosslinked emulsion
compound was prepared by mixing the following ingredients:
Inqredients Percentage
Ammonium Nitrate 51.l
Calcium Nitrate 27.4
Water l0.5
Emulsifier l.5
Diesel Oil 3.9
131 MA 2.4
Triethanolamine 0.2
Perlite 3.2
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
crosslinkable 131 MA, to which had been added the
emulsifier and fuel oil until an emulsion was formed. The
emulsion was allowed to cool to room temperature.
Thereafter, the perlite and triethanol amine were added
with stirring. The explosive containing the emulsion cured
for two (2) days.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a crosslinked
continuous fuel phase, with the consistency of non-tacky
rubber. The thus formed explosive had a consistency
similar to that of its emulsion phase.
Exam~le 6
An explosive containing a crosslinked emulsion
compound was prepared by mixing the following ingredients:
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-27-
1 Ingredients Percentaqe
Ammonium Nitrate 52.2
Calcium Nitrate 28.0
Water 10.7
Emulsifier 1.5
Diesel Oil 4.0
131 MA 2.4
Triethanolamine 0.2
Polystyrene Beads 1.0
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an- aqueous phase.
This aqueous phase was added by vigorous stirring to the
crosslinkable 131 MA, to which had been added the
emulsifier and fuel oil until an emulsion was formed. The
emulsion was allowed to cool to room temperature.
Thereafter, the triethanolamine and polystyrene beads were
added with stirring. The explosive containing the emulsion
cured for two (2) days.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a crosslinked
continuous fuel phase, with the consistency of non-tacky
rubber. The explosive containing the emulsion had a
consistency of non-tacky rubber. -
Exam~le 7
An explosive containing a crosslinked emulsion
compound was prepared by mixing the following ingredients:
Inqredients Percentage
Ammonium Nitrate 24.6
Calcium Nitrate 6.2
Water 8.4
Ammonium Nitrate Prills 53.0
Emulsifier 0-4
Diesel Oil 5-4
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1 131 MA 0 g
Triethanolamine O.l
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
crosslinkable 131 MA, to which had been added the
emulsifier and fuel oil, until an emulsion was formed. The
emulsion was allowed to cool to room temperature.
Thereafter, the ammonium nitrate prills and the
triethanolamine were added. The explosive containing the
emulsion cured for one ~l) day.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a crosslinked
continuous fuel phase, with the consistency of a firm
substance. The explosive had a similar but firmer
consistency.
ExamPle 8
An explosive containing a polymerized emulsion
compound was prepared by mixing the following ingredients:
Ingredients Percentaqe
Ammonium Nitrate 48.7
Calcium Nitrate 30.7
Water l0.8
Emulsifier l.O
Diesel Oil l.0
HTPB 0.5
Isonate~ 143 L 0.l
Microballons 2.0
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier
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-29-
1 and fuel oil until an emulsion was formed. The emulsion
was allowed to cool to room temperature. Thereafter, the
Isonate~ microballoons and 143 L were added. The explosive
containing the emulsion cured for one (1) day.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized
continuous fuel phase, with the consistency of sticky
rubber. The explosive had a similar consistency.
Example 9
An explosive containing a polymerized emulsion
compound was prepared by mixing the following ingredients:
Inqredients Percentage
Ammonium Nitrate - 40.4
Calcium Nitrate 25.5
Water 7.6
Ammonium Nitrate Prills 15.0
Emulsifier 1.6
Diesel Oil 4-9
HTPB 1.6
Isonate~ 143 L 0.2
Nitrite solution 0.2
H-30 Aluminum 3.0
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier
and fuel oil until an emulsion was formed. The emulsion
was allowed to cool to room temperature. Thereafter, the
remaining ingredients Isonate~ 143 L were added with
stirring. The explosive containing the emulsion cured for
one (1) day.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized
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-30-
l continuous fuel phase, with the consistency of non-tacky
rubber. The explosive was firm and rubbery.
ExamPle lO
An explosive containing a polymerized emulsion
compound was prepared by mixing the following ingredients:
Ingredients Percentage
Ammonium Nitrate 12.2
Calcium Nitrate 7.7
Water 2.3
Ammonium Nitrate Prills 81.0
Emulsifier 0.2
Diesel Oil 6.l
HTPB 0 5
Isonate~ 143 L 0.l
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier
and fuel oil until an emulsion was formed. The emulsion
was allowed to cool to room temperature. Thereafter, the
ammonium nitrate prills and Isonate~ 143 L were added with
stirring. The explosive containing the emulsion cured for
twenty-one (2l) days.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized
continuous fuel phase. The explosive had the consistency
of a coherent mass of prills.
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-3l-
1 Example 11
A polymerized and crosslinked emulsion compound
suitable for use in an explosive was prepared by mixing the
following ingredients:
Inqredients Percentage
Ammonium Nitrate 41.1
Calcium Nitrate 30.7
Water 16.4
Emulsifier 1.5
Diesel Oil 7.3
HTPB 1.5
131 MA 1.5
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate, and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier,
and fuel oil until an emulsion was formed. The emulsion
was allowed to cool to room temperature. The 131 MA was
gently stirred into the emulsion. This emulsion cured for
twenty-two (22) days.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized and
crosslinked continuous fuel phase, with the consistency of
non-tacky rubber.
Example 12
A crosslinked emulsion compound suitable for use in an
explosive was prepared by mixing the following ingredients:
Inqredients Percentaqe
Ammonium Nitrate 71.1
Water 16.6
Emulsifier 1.0
Diesel Oil , 10.0
131 MA 1.0
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l Monoethanolamine 3.0
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate in the water at elevated
temperature to form an aqueous phase. This aqueous phase
was added by vigorous stirring to the crosslinkable 131 MA,
to which had been added the emulsifier, and fuel oil until
an emulsion was formed. The emulsion was allowed to cool
to room temperature. Thereafter, the monoethanolamine is
added. This emulsion cured for eight (8) weeks.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a crosslinked
continuous fuel phase, with the consistency of a rubbery
nontacky gel.
Example 13
A polymerized emulsion compound suitable for use in an
explosive was prepared by mixing the following ingredients:
Ingredients Percentaqe
Ammonium Nitrate 48.2
Calcium Nitrate 30.4
Water l0.3
Emulsifier l.0
Mineral Oil 3.9
HTPB 2.9
ZS IsonateX 143 L 0.3
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier,
and mineral oil until an emulsion was formed. The emulsion
was allowed to cool to room temperature. Thereafter, the
Isonate~ 143 L was added. This emulsion cured for twenty-
one (2l) days.
'S
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l The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized
continuous fuel phase, with the consistency of non-tacky
rubber.
Example 14
A polymerized emulsion compound suitable for use in an
explosive was prepared by mixing the following ingredients:
In~redients Percentage
io Ammonium Nitrate 50.3
Calcium Nitrate 31.9
Water 9-7
Emulsifier 1.5
Diesel Oil 1.5
Paraffin Wax - 4.0
HTPB 1.0
Isonate~ 143 L 0.1
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier,
diesel oil, and paraffin wax until an emulsion was formed.
The emulsion was allowed to cool. Thereafter, the Isonate~
143 L was added. The explosive containing the emulsion
cured for one (1) day.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized
continuous fuel phase with the consistency of a moldable
nontacky putty; rehealable rubber.
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-34-
l Exam~le 15
A polymerized emulsion compound was prepared by mixing
the following ingredients:
Ingredients Percentage
Ammonium Nitrate 49.l
Calcium Nitrate 31.0
Water 9 5
HTPB 5.9
Isonate~ 143 L 0.6
The emulsion was made in the conventional manner by
dissolving the ammonium nitrate and calcium nitrate in the
water at elevated temperature to form an aqueous phase.
This aqueous phase was added by vigorous stirring to the
polymerizable HTPB, to which had been added the emulsifier
until an emulsion was formed. The emulsion was allowed to
cool. Thereafter, the Isonate~ 143 L was added. The
explosive containing the emulsion cured for four (4) hours.
The thus formed emulsion resulted in a discontinuous
oxidizing phase uniformly dispersed in a polymerized
continuous fuel phase with the consistency of a thick,
stiff wax.
While the foregoing examples de facto illustrate
ranges of the substituent ingredients of the emulsion or
emulsion phase of an explosive containing an emulsion,
ranges of substituent ingredients outside the ranges
illustrated above also provide suitable emulsions or
emulsion phases of explosives containing an emulsion.
Summary
It can be seen, therefore, that the present invention
compositions and methods for polymerizing and/or cross-
linking the continuous phase of the emulsion or the
emulsion phase of an explosive containing an emulsion.
This is accomplished by not only choosing polymerizable
and/or crosslinkable polymers as components of the fuel
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l phase of the emulsion, but actually polymerizing and/or
crosslinking the monomers and polymers of the continuous
phase to lock or hold the discontinuous phase in its
dispersed position, thereby, inhibiting crystallization,
coalescence, agglomeration or migration of the
discontinuous oxidizing or sensitizing phase.
It will be appreciated that the advancement of the
present invention provides several improvements over
conventional emulsions and explosives containing an
emulsion. For example, by choosing the appropriate
polymerizable or crosslinkable polymer, and by polymerizing
and/or crosslinking the polymer, a desired rheology of the
subject emulsion may be obtained to suit the particular
need of the user. Similarly, the matrix of the desired
emulsion can be polymerized and/or crosslinked chemically
at room temperature and the resulting emulsion is not as
sensitive to changes in ambient temperature as the
currently available emulsions are. Furthermore, the rate
of reaction of the polymerization or crosslinking can be
controlled so as to permit the selection of different
rheologies of the same emulsion over a given period of time
to the advantage of the manufacturing, packaging,
transporting, storage, and use processes and procedures.
The present invention may be embodied in other
spécific forms without departing from its spirit or
essential characteristics. The described embodiments are
to be considered in all respects only as illustrative and
not restrictive. The scope of the invention is, therefore,
indicated by the appended claims rather than by the
foregoing description. All changes which come within the
meaning and range of equivalency of the claims are to be
embraced within their scope.
What is claimed is:
