Note: Descriptions are shown in the official language in which they were submitted.
AUS 1343
133~39~ ~
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AN EXPLOSIVE COMPOSITION CONTAINING A POLYMER SOLUBLh ~ `
I . IN THE ORGANIC PHASE COMPRISING ASSOCIATIVE FUNCTIONAL GROUPS -`
¦ ~he invention relates to emulsion explosive
¦ compositions having a discontinuous phase comprising an
¦ 5 oxygen-releasing salt and a continuous liquid organic phase :~
and in particular to emulsion explosives compositions .
containing an oil-soluble polymer having associative groups. :~
Emulsion explosive compositions have been widely ~ `:
' accepted in the explosives industry because of their
j 10 excellent explosive properties and ease of handling. The
emulsion explosive compositions now in common use in the
industry are of the water-in-oil type first disclosed by
Bluhm in US Patent No. 3 447 978 and comprise as components~
(a) a discontinuous aqueous phase oomprising ; ~ ;
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discrete droplets of an aqueous ~olution
of inorganic oxygen- releasing 8a.t8;
(b) a con~inuous water-immi~cible organic
phase throughout which the droplet~ are
dispersed; and
i
(c) an emulsifier which forms an emulsion of
the droplets of oxidizer salt solution
throughout the continuous organic phase.
:, . ,
For some applications, water content of ~ ~
10 the oxidizer phase of the emulsion may be ~ -
! eliminated or reduced to a low level, for
example, to less than 4% by weight of the total
emulsion composition. Such compositions are
conveniently referred to as melt-in-oil or
melt-in-fuel emulsion explosives and have been
described, for example, in US Patent 4 248 644.
The term ~emulsion explosive" i~ used
herein to embrace compositions of both the `~
water-in-oil and the melt-in-oil types. .`~
Emulsion explosives may be handled in
bulk and are easily loaded into boreholes for ;~
large-scale blasting operations. A particular
1 problem however arises where boreholes contain
¦ water, for example, after rain. In such cases, `~
and in particular where boreholes become
~-~ completely or partially filled with water, the -~
explosive performance of emulsion explosives is
severely reduced. This is a particular problem
when using blends of emulsion explosive and a
~"~ 30 solid ad~uvant such as ammonium nitrate prills or :~
ANFO (Ammonium nitrate-fuel oil).
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Indeed, in many cases it i~ difficult tn
detonate an emulsion explosive charge which has
been loaded into a borehole containing water.
Due to these problems it has generally
~5 been the practice to drain water from a ~orehole
-,before loading the explosive. This is both time
consuming and la~our in~ensive.
If emulsion explosives are carefully
]oaded into the bsttom of a borehole via a hose,
it is sometimes possible to displace water from
the bore-hole. However, this again is a time
consuming procedure and unsatisactory for deep
boreholes.
We have now developed an emulsion
explosive composition which i5 highly elastic and
which may be loaded into wet boreholes without
using such procedures.
Further advan~ages of the composition of
~9, the present invention will become eviden~ on
considering the physical properties of the
emulsion explo~ive composition.
Accordingly we provide an emul~ion
explosive composition comprising a ~- -
discontinuous phase comprising at least one
oxygen-releasing salt; a continuous organic
phase; an emulsifying agent; and at least one
polymer soluble in the organic phase and wherein
the polymer comprises associative functional
groups.
Generally the associative functional
groups axe polar groups capable of entering into
1 specific a~sociation with o~her associative
`~ groups.
~ Examples of associative functional group ~ ;
`~35 may be æelected from a group of s ionmer~c
~functional groups; functional group~ which are
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3~3~
capable of protolytic reaction~; and groups
capable fonming hydrcgen bond~.
Examples of functional groups capable of
association through hydrogen bond formation may
be selected from ~he group consis~ing of
hydroxyl, carboxyl and carboxamide functional
groups.
Examples of ionomeric functional groups
include those ~elected from the groups o salts
of sulphonic and carboxylic acids such as metal
and ammonium ion salts thereof, and guaternary ~ `
ammonium salts.
Example~ of groups capable of undergoing
protolytic reaction include acid group~ ~uch as
c rboxylic, sulphonic and phosphoric acid groups
and basic groups such as nitrogen-containing
~ basic groups.
`, Examples of nitrogen-containing basic
groups may be chosen from the groups of formula I
: ~:
~ R
-N
b~R2
..
where Rl and R2 may be aryl,
aralkyl,alkyl cycloalkyl or hydrogen and R and
R2 may together form a S or 5 membered
heteocyclic ring by a linking group of 4 ~r 5
members; and nitrogen containing heteroaromatic
group such as pyridyl, picolinyl, quinolinyl, `
i~oquinolinyl and quinoxalinyl groups and the
salts thereof. Preferred acid and basic groups
I include the carboxylic acid group, sulphonic acid
I group and pyridyl group.
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Examples of the group of formula I
wherein Rl and R2 form a heterocycl~ include
pyrazolinyl~ pyrrolidinyl, peperazinyl and
morpholinyl.
The said polymer may comprise more than
' one type o~ functional group. For example ~aid
1 polymer may comprise a plurality of differ2nt
monomers capable of undergoing dipole-dipole
' interaction or protolytic reaction with one
-l 10 another.
Polymers suitable for use in preparation
of compositions of the invention may be prepared
by conventional polymerization techniques.
Suitable polymer~ may be prepared by addition
polymerization reactions using at least one main
monoethylenically unsaturated monomer and at ~-~
least one associative monomer comprising a
functional group chosen from associative
functional groups as hereinbefore described, and
grQups capable of conversion to said associative
functional groups.
Examples of main monoethylenically
unsaturated monomers (hereinafter referred to as
main monomer) may be selected from the group
consisting of: alkenes, preferably compri~ing
from 2 to 6 carbon atoms such as ethylene and
propylene; higher alkyl acryla~es and
methacrylate~, in which the alkyl group contains
from 4 to 18 carbon atoms, for example 2-ethyl
hexylacrylate, stearyl methacrylate and lauryl 30
methacrylate; styrenes; alkyl styrenes in which
the alkyl group contains from 1 to 12 carbon
at~ms, for example tertiarybutyl s~yrene; and
vinyl esters of fatty acids, such as vinyl
stearate.
Particularly preferred main monomers are -~
i! ~ lauryl methacrylate, styrene and tert~
butylstyrene.
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13~33~3
Examples of as~ociative monomers may be
chosen from the groups consi~in~ of:
vinyl substi~uted nitrogen containing
heteroaromatic compounds such as vinyl pyridines,
vinylpicolines, vinyl quinolines,
vinylisoquinolines and vinyl quinoxalines, ~
hydroxy~Cl to C6)alkyl acrylates and ~`
~ethacrylates, such as hydroxyethyl acrylate and
hydroxy propyl m~thacrylate; acrylic acid,
methacrylic acid and their metal or amine salts;
acrylamide; methacrylamide; acids selected from
the group of styrene sulfonic acid, vinyl
sulfonic acid, 2-acrylamides, propane sulfonic
acid, acrylic acid, methacrylic acid; and the
metal salts of these acids; halide salts o
quaternary ammonium compounds selected from the
group consisting of dimethylammonium
methacrylate, diethylammonium ethyl-methacrylate;
diethylammonium ethyl-methacrylate; and
precursors of these monomer~. Particularly
preferred associative monomers are methacrylic
i acid and metal and amine salts thereof, and
vinylpyridines such as 2-vinylpyridine and
4-vinylpyridine.
Where the associative monomer comprises
an associative grollp precursor, the precursor
will be capable of conversion to an associative
group followinq polymerization.
~ For example, diene~ such a3 norbornene
'~ 30 and butadiene may be used in the preparations of
j polymers, and the monomeric unit~ derived
therefrom may be converted to sulfonic acids and
thence to salts of sulfonic acid~ by procedures
known to those ln the art.
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Emulsion polymerization is a
particularly convenient technique for preparation
o~ copolymers for use in ~he present composition
However, the method of preparation i~ not
S narrowly critical and the skilled artisan will be
well acquainted with a wide variety of techniques
for preparation of suitable polymers.
The polymers can conveniently b~
obtained by aqueous emulsion copolymerisation of
the constituent monomers employing if necessary a
minor proportion of a water-miscible organic
co-solvent, such as acetone, in order to enhance
the solubility of the monomer mixture in the
aqueous continuous phase (the main monomers
described above will inherently have very low
solubilities in water and a measurabl~ degree of -
solubility in the continuous phase is necessary
if the polymerisation i8 to proceed at an
acceptable rate). The polymerisation is
generally carried out at a temperature in the
range 0 - 70C, preferably 10 - 60C, in an inert
j gas atmosphexe and in ~he presence of a
water-soluble free radical initiator sy~tem, such
I as ammonium persulphate or potassium persulphate
¦ 25 in combination with sodium dithionite optimally,
sodium sulphite, sodium thio~ulphate or ascorbic
acid. There may be added to the polymeri~ation ;
mixture water-soluble ~urfactants such as sodium ~;
dodecylbenzenesulphonate, ~odium dioctylsulpho~
succinate, sodium lauryl sulphate or salts of
sulphated nonylphenol-ethylene oxide condensates.
The amount of initiator (or initiator
I combination) used may typically lie in the range
¦ 0.05% to 1%, and the amount of ~urfactant in the
1 35 range 1% to 15%, based on the weight of the
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monomer mixture. The polymerisation may be
effected by a "one-shot" procedure, in which all
the monomer required is introduced into the
reaction mixture at once, or by a "seed and feed"
procedure in which a small proportion of the
total monomer mixture is polymeri~ed initially to
form a "seed" polymer dispPrsion and the
remainder of the monomer is then added gradually.
Chain transfer a~ent , such as n-octyl mercaptan,
dodecyl mercaptan or chloroform, may also be
added during the course of the polymerisation,
especially in the later stages when more than 75%
of the monomer has been polymerised, in order to
regulate the formation of the pol~m~r.
Typically, the polymers are prepared
using 0.001 to 30~ associative monomer by weight
of total monomer and preferably 0.01 to 20% w/w.
Typically, the total amount of said
polymer will comprise in the range of 0.001 to
10% by wei~ht of the emulsion composition.
` However, we have found that particularly good
3 results are obtained by using in the ranqe of
0.01 to 2~ of the total emulsion composition.
~, Generally, the amount of polymer will be in the
range of 0.001 to 20% w/w based on the organic
phase and preferably in the range 0.1 to 10%.
However, higher or lower quantitie~ may be used
if desired, the amount of polymer being
determined without undue experimentation based on
the required properties of the emul~ion.
`` As hereinbefore stated the polymer is -~
soluble in the organic phase. Generally, the
polymer will be sol~bla in the org~nic phase at
the polymer~organic phase weight ratio to be u6ed
in the emulsion explo~ive.
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g
Hence the polymer will generally be
soluble in the organic phase at a concentration
of at least 0.001% w/w and preferably at least
O . 1 96 w/w .
One polymer particularly useful for the
preparation of composition of the invention is a
polymer of styrene, lauryl methacrylate and
methacrylic acid.
An example of such a polymer may ~e
derived by emul~ion polymPrization from a mixture
of 10-80% w/w styrene, 10-80~ w/w lauryl
methacrylate and 0.1-10% w/w methacrylic acid. A
particularly preferred compo ition compri~es
50-60~ lauryl methacrylate, 40-50% styrene and
1-4~ methacrylic acid.
As hereinbefore discussed, the emulsion
explosive compositions of the present invention
have advantages over conventional explosives,
making them more suitable for loading in wet
boreholes.
Without wishing to be bound by theory,
we believe that the better wet borehole
perfoxmance of the emul~ions of the invention may -~
be due to their elastic and cohe~ive nature.
Unlike conventional emulsion explo~ives which
tend to break up when loaded into water, the ;~
~ emulsion~ of the present invention pa~s easily
I ~hrough water. The cohesive properties and ~ -
resiliencQ al~o make the emulsion explosive
composition particularly useful in packaged
; products.
Emulsion explo~ive~ cf the invention
typically have an elastic modulus in the range
100-1000 Pa at 20C. Typic~lly, the vi~c08ity is
in the range 120,000 to 800,000 cp at 20C.
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The advantage~ of the emulsion explosive
compositions are particularly apparent when the
polymer has an average weight molecular weight of
at least 1 x 105. Preferably the polymer has an
average molecular weight in the range 5 X 105 to
1 X 107, more pxeferably 1 x 106 to 1 ~ 107. This
is particularly surprising as it wa~ expected
~hat the bulk of high molecular weight polymer
molecules may disrupt the stability of an
emulsion explosive.
For example, in ~he case of water-in-oil
emulsion explosives, it i9i generally ~elieved
tha~ droplets of oxidizer solution in an emulsion
i explosive are separated by bilayars of oil phase
which are 5 to 20 nm thick, hence bul~y polymer
molecules of molecular weight 1 x 106 and higher
; that are typically 100 to 200 nm in diameter were
not expected to be compatible with an emulsion
t explosive.
Suitable oxygen-releasing salts for use
in the discontinuous phase component of the
` composition of the present invention include the
;¦ alkali and alkaline earth metal nitrate~
Jl chlorate~ and perchlorates, ammonium nitrate,
`~ 25 ammonium chlorate, ammonium perchlorate and
; . .
mixtures thereof. The preferred oxygen-releasing
`~ ~alts include ammonium nitrate, ~odium nitrate
and calcium nitrste. More preferably, the
oxygen-releasing salt comprises ammonium n~trate
or a mixture of ammonium nitrate and sodium or
calcium nitrates.
Typically, the oxygen-releasing ~alt
~ component of the composition~ of the present
-¦ ` invention comprise~ from 45 to 95~ and preferably -~
35 from 60 to 90% by weigh~ of the tot~l ~
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composition. In compo3itions wherein the
oxygen-releasing salt comprises a mixture of
ammonium nitrate and s~dium nitrate t the
preferred composition range for such a blend is
from 5 to 80 parts of sodium nitrate for every
100 parts of ammonium nitrate. Therefor,e,, in the
preferred compositions of the present invention,
the oxygen-releasing salt component comprises
from 45 to 90~, by weight (of the total
composition) ammonium, nitrate from 0 to 40% b~
weight (of the total composition) sodium or
calcium nitrates.
The discontinuous phase may be entirely
devoid of water, in the case of a melt-in-oil
emulsion or may contain water in the case of a
water-in-oil ~mulsion. In the latter case, the
amount of water employed in the compositions of ;~
:~ the present invention is typically in the range
of from 1 to 30~, by weight of the total
composition, Preferably the amount employed is
from 5 to 25%, and more preferably from 6 to 20%,
by weight of the total compc,sition. ~`-
The organic phase component of the `~
composition of the present invention comprises
the continuous "oil" phase of the emulsion
explosive an~ is 8 fuel. P~eferably the organic
phase is water-immiscib~le. Suitable organic
fuels include aliphatic, alicyclic and aromatic
compounds and mixtuxe~ thereof which are in the -~
liquid state at the formulation temperature.
Suitable orqanic fuel~ may be chosen from fuel
oil, diesel oil, distillate, kero~ene, naphtha,
waxes, (eg. microcrystalline wax), paraffin oil~2,
benzene, toluene, xylenes, aEphalti~ materials,
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polymeric oil~ such ~s the low molecular welght
polymers of olefins, animal oils, fish o il8, and
other mineral, hydrocarbon or fatty oils, and
mixture~ ~hereof. Preferred organic fuels are
liquid hydrocarbons generally referred tl~ as
petroleum di~tillates ~uch aR gasoline, kerosene,
fuel oils and paraffin oils.
Typically, the organic fuel or
continuous phase of the emulsion explosive
composition of the present invention compri~es
from 2 to 15% by weight and preferably 3 to lO~
by weight of the total composition.
The emulsifying agent component of the
composition of the present invention may be
chosen from the wide range of emulsifying agents -~
15 known in the art for the preparation of emulsion `~
explosive compositions. Examples of ~uch
emulsifying agents include alcohol alkoxylate~
phenol alkoxylates, poly(oxyalkylene) glycol~
poly(oxyalkylene) fat~y acid esters, amine
20 alkoxylates, fatty acid esters of sorbitol and -
glycerol, fatty acid salts, ~orbitan esters,
poly(oxyalkylene) ~orbitan esters, fatty amine ...
alkoxylhtes, poly(oxyalkylene) glycol esters, ~
fatty acid amides, fat~y acid amide alkoxylates,
fatty amines, quaternary amines, alkylo~azolines,
I alkenyloxa201ines, imidazolines, alkyl~
sulfonates, alkanoylsulfonates, allkylsulfo-
succinates, alkylphosphates, alkenylphosphate~
phosphate esters, lecithin, copolymers of ~:
30 poly(oxyalkylene~ glycol~ and poly(12-hydroxy- :
stearic)acidl polyalkylene succinic acid and
i derivative~ thereof, and mixture~ thereof. Among ~ :~
~ the preferred emulsifying agent~ are the 2-alkyl- :~
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and 2-alkenyl-4,4'-bi~ (hydroxymethyl) oxa~oline,
the fatty acid esters of sorbi~ol, lecithin,
copolymers of poly(oxyalkylen~!) glycols and
poly(12-hydroxystearic acid), and mix~ures
thereof, and particularly sorbitan mono-oleate,
sorbitan sesquioleate, 2-oleyl- 4,4'-bi~
(hydroxymethyl) oxazoline, mixture of ~orbitan
sesquioleate, lecithin and a copolymer of
poly(oxyalkylene glycol and poly
10 (12-hydroxystearic acid~, polyisobutylene ~-
succinic acid and derivatives thereof, and
mixtures thereof.
Typically, the emul~ifying agent
component of the composition of ~he present
lS invention comprises up to 5% by weight of the
- total composition. Higher proportions of the
emulsifying agent may be used and may serve as a
supplemental fuel for the composition but in
~eneral it is not necessary to add more than 5%
by weight of emulsifyinq agent to achieve the
desired effect. One of the advantages of the ``~
compositions of the present inven ion is that
~, stable emulsions can be formed using relatively
low levels of emulsifying agent, and for reasons
of economy it is preferable to keep to amount of
emulsifying agent in the ranse from 0.1 to 2.0%
by weight of the total composition.
If desired, other optional fuel
materials, hereinafter referred to as secondary
fuels, may be incorporated into the compositions
of the present invention in addition to the
water-immiscible organic fuel phase. Examples of
such secondary fuels include finely- divided
solids, and water-miscible organic liguid~ which
can be used to partially replace water as a
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solvent for the oxygen-releasing salts or to
extend the aqueous solvent for ~he
oxygen-releasing salts. Examples of solid
secondary fuels include finely divided materials
such as: sulfur; a:lumin~m; and carbonaceous
materials such as gilsonite, comminuted coke or
charcoal, carbon black, resin acids such as
abietic acid, sugar~ such as glucose or dextrQse ~ :
and other vegetable products such as staxch, nut ::
meal, grain meal and wvod pulp. Examples of
water-miscible organic liquids include alcohols
such as methanol, glycol3 such as ethylene
glycol, amides such as formamide and amines such
as methylamine.
Typically, the optional secondary fuel
component of the composition3 of the present
invention comprise from 0 to 30% by weight of the ~ :
total composition.
It lies within the in~ention that there
may also be incorporated into the emulsion
explosive compositions hereinbefore described
~ other substances or mixtures of substances which
i are oxygen-releasing salts or which are
themselves suitable as explosiv~ materials. As 2
typical example of such a modified emulsion
explosive composition, reference is made to
compositions wherein there i8 added to and mixed
with an emulsion explosive composition as
hereinbefore described up to 90~ w/w of a solid
oxidizing salt such as ammonium nitrate or an
explosive composition compriaing a mixture of a
solid oxidizing salt such as Emmonium nitrate and
fuel oil and commonly ref?srred to by those
skilled in the art as "An~?on. The compositions
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of "Anfo" are w211 known and have been de~cribed
at length in the literature relating to
explosives.
Mix~ures of solid ammonium nitrate or
; 5 "Anfo" a-nd the emulsion explosive of the -
; invention are suited to use in wet bore holes and ~`~
water con~aining bore hole~. Mixtures of "Anfo"
~or solid ammonium nitra~e) and conventional
emulsion explosive generally gi~e poor
performance when loaded into bore holes
containing water. The mixture tends to breaX up
on impact with water and this tends to result in
the dissolution of the ammonium nitrate. In
contrast, mixture3 of "Anfo" with the emulsion
lS explosive of the present invention may be used in
bore holes containing water without ~ignificant
loss of performance.
Accordingly there i~ provided an
explosive composition comprising a emul~ion as
hereinbefore described and up to 90% w/w of a
composition comprising an ammon~um nitrate fuel
oil mixture.
Typically, the proportion of ammonium
nitrate or "AnfoN in such compositions will be in
25 the range 20-80% w/w. -~
It also lies within the invention to
have as a further explosive component of the
composition well known explosive material~
comprising one or more of, for example,
trinitrotoluene, nitroglycerine or
pentaerythritol tetranitrate.
`j Accordingly there i~ provided an
~ explosive composition comprising as a first
'1 component an emulsion explosive compo~itlon as ~-
`! 35 hereinbefore described and as a ~econd component
an amount of material which 18 an oxidizing salt
or which i~ in it3 own riqht an explo~iYe
material.
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Generally it i8 not necessary to use
thickening agents in the di3continuous phase of
the present composition as the amount of polymer
may be varied according to the properties
desired. However, if desired, the discontinuous
phase of the compo3itions of the pre~ent
invention may comprise thickening agents which ~-
optionally may be cross-linked. The thickening
agents, when used in the compositions of the
present invention, are suitably polymeric
materials, especially gum materials typified by
the galactomannan gums such as locust bean gum or
guar gum or derivatives thereof ~iuch as
hydroxypropyl guar gum. Other useful but less
preferred gums are the so-called biopolymeric
gums such as the heteropolysaccharide~ prepared
by the microbial transformation of carbohydrate
material, for example the treatment of glucose
` with a plant pathogen of the genus Xanthomonas
typified by Xanthomonas camPestris.
rypically~ where used, the optional
~, thickening agent component of the compositions of
; the present invention comprises from 0 to 2% by
weight of the total composition.
As indicated above, when used in the
~ compositions of the present invention, the
i thickening agent optionally may be cross-linked.
~ It is convenient for this purpose to use
;~ conventional cros~i-linking agent~ such as zinc
chromate or dichromate either as a separate
entity or as a component of a conventional redox
system such as a mixture of potas~iium dichromate
i and potassium antimony tartrate.
`~ Typically, the optional cro~s-linking
agent component of the compositions of the
present invention comprises from 0 to 0.5~ and
~i preferably from 0 to 0.1% by weiyht of the total
~ composition.
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The emulsion explosive compositions of
the presen~ invention may additionally comprise a
discontinuous gaseou~ component.
The methods of incorporating a gaseous
component and the enhanced sPnsitivity of
emulsion explo~i~e compositions comprising such
~aseous components have been previously reported.
Typically, where used the ~aid gaseous component
will be present in an amount required to reduce
the density of the composition to with in the
range 0.8 to 1.4 gm/cc. ;:~
The gaseous componen~ may, or example,
be incorporated into the composition of the
present invention as fine gas bubble~ di~persed
through the composition, as hollow particles
which are often xeferred to as microballoons or :
microsphere~, as porous particles, or as mixtures
thereof.
A discontinuous phase of fine gas
bubbles may be incorporated into the compositions
of the present invention by m~chanical agitation,
in~ection or bubbling the ~as through the
composition, or by chemical generation of the gas
in situ.
Suitable chemicals for the in situ
generation of gas bubbles include peroxides, such
as hydrogen peroxide, peroxide nitxates, such as
sodium nitrite, nitrosoamines, such as N, ;:
N'-dinitrosopentamethylene tetramine, alkali
metal borohydrides, such as sodium borohyride,
and carbonates, such as sodium carbonate.
Catalytic agent~ such as ~hiocyanate or thiourea ~ :
may be used to accelerate the decomposition of a
nitrite ~assing agent. Suitable amall hollow :~
35 p~rtlcles inolude sm~ll hollow microJphere~ of
,
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glass or re~inous materials, such as
phenol-formaldehyde and urea-formaldehyde.
Suitable porous materials include expanded
minerals, such as perlite.
Where used, the gaseous agent is
prefe~ably added during cooling, after
preparation of the emulsion, and typically
-~; comprises 0.05 to 50% by volume of the total
-, emulsion explosive composition at ,~mbient
temperature and pressure. More preferably, where
;~ used, the gaseous component is present in the
range 10 to 30~ by volume of tha emulsion
explosive composition and preferably the bubble
size of the occluded gas is below ~00 um. More
preferably,at least 50% of the gas componPnt will
be in the form of bubbles or microspheres of 20
to 90 um internal diameter.
The pH of the emulsion explosive
composition of the present invention i8 not
narrowly critical. However, in general the pH is
; between 0 and 8, preferably between 0.5 and 6.
The emulsion explosive composition of
the present invention may be prepared by a number
~ of methods.
f 25 The polymer may be mixed with the oil
phase before preparation of the emulsion.
Alternatively, it may be more convenient to
prepare the emulsion composition of the invention
by mixing o~ a composition comprising at least
one polymer with an emulsion explosive
composition comprising: a discontinuous phase
comprising at least one oxygen releasing salt; a
continuous organic phase; and an emulsifying
agent.
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If desired, the polymer may be added
using both methods, that is adding th~ polymer to
the oil phase ~efore preparation of ~e emulsion
and al~o to the emulsion once prepared.
When a composition comprising the
polymer is added to the prepared emulsion, the
polymer may, for example, be in the form of a
solid such as a powder~ a solution in a suitable
solvent such as a hydrocarbon solvent or a3 an
aqueous dispersion.
i 10 Aqueous dispersions of polymer may be
prepared by methods well known ~o those skilled
in the art. For example, ~uch a dispersion may
be formed by mixing a fine powder of polymer with
an aqueous composition in the presence of a
surfactant.
In a particularly preferred embodiment
of the process~of the invention we therefore
provide a process comprising mixing an aqueous
dispersion of said polymer with an explosive
composition comprising (a) an emulsion explosive
~ comprising a discontinuous aqueous phase
3 comprising an oxygen releasing salt, a continuous
~3 organic phase and an emulsifying agent and
optionally ~b) solid ammonium nitrate or a
mixture of solid ammonium nitrate and fuel oil.
1 Generally, the composition is mixed for a period
¦ following ~dditive of the polymer so as to
facilitate dispersion within the ~nulsion
explosive.
One preferred method of preparing
suitable polymers involves an em~lsion
polymerization technique which produces a latex `~
of the product (i.e., an aqueous di~persion of
i small polymer particles). We have found it to be
¦ 35 particularly convenient in many instances to use
such compo~ition in preparation of the emulsion `~`~
xplosive compo~ition of preseDt invention
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In an embodiment of the invention there
is thus provided a process for the preparation of
an emulsion explosive composition, the process
comprising: -
dissolving said oxygen-relea ing salt in
water at a temperature above the fudge
point of the salt æolution, preferably
at a temperature in the range of 25 to
110C, to give an aqueous salt ~olution;
optionally mixing said polymer with said
water immiscible organic phase;
~. ..
combining said ~alt solution, said
water-immiscible organic phase, said
water-in-oil emulsifying agent. `
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Mixing until the emulsion is uniform and
if said polymer haæ not been added,
adding a ~aid polymer.
The invention i8 now demonstrated by but
in no way limited to the following examples in
20 which all proportions are on a weight basis ;~
unless otherwise specified.
Example 1
A high molecular weight (average
molecular weight in excess of 1 x 1o6j copolymer
of tert-butyI styrene and 4-vinyl pyridine~(97s3
by weiqht) was prepared by emul~ion -~
polymerization.
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Emulsion Polvmerization ~ethod - ~pre~aration of
polymer latex)
The surfactant AEROSOL OT (AEROSOL ~8 a
trade mark~ ~available from American Cyanamid),
(0.3 g) and initiator ammonium persulf~te~ (0.10
g) were dissolved in acetone (10.0 g) and water
(50.0 g) the monomer3 (tert-butyl styrene, and
4-vinylpyridine; 20 g) were added, and the
mixture emulsified by ~tirring. The mixture wa~
flushed with nitrogen ~or ten minutes, sealed,
and the tempera~ure raised to 50C and mainta~ned
at that temperature for 24 hour~, w1th gentle
stirring. The re3ulting product was a latex of
polymer. The polymer was fvund to have an ~``
average molular wei~ht of approx. 1.19 x 106 g
mol 1. Powder To prepare the polymer a~ a
, powder a ~mall amount of latex ~10 g) wa~ added
f' dropwise to a large excess of methanol (100 ~3,
and the polymer isolated by filtration. The -~ -
polymer was dried in air and ground to a flne
i ` powder.
i
Examples 2 and 3 and ComParati~e ~xamPle A
These example~ demo~strata the ~ffect on
the viscosity o~ an emulfiion ~xplosive
composition of the addition of a polymQr powdor
prepared according to Example 1.
Example 2
A diesel solut~on for use a8 the orga~ic
phase wa~ prepar~d by dis~olving copolymer powder
~ 30 prepar~d according to Example 1 ln di~el o~l ~t
`~' a tempsrature of 80C to g~ve ~ concentration of
¦ 1% w~w o~ d~esel 801ut~on. `
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An emulslon compo~tion wa~ ~hen
prepared u31ng ~he ~ollowing component~
Part~ w,w
Ammonium nitrate (chemically pure~84.06
Calcium n~trate 75,02
5 distilled w~ter 25.30
die~el solution (1~ w/w copolymer)13.02
emulsifier - sorbitan monooleate 2.60
The method used was as followss
The a~monium nitrate and calcium nitrate were
dissolved in the water at ~ temperature of about
80~C to give the oxidizer phase. The o~idizer
phase was combined with a ~ixture of the diesel
solution and emul3ifier and the resulting mixture
- was stirred rapidly to form an emulsion. ` ~:
Example 3
The procedure of Example 2 wa~ repeated
except that the diesel ~olution wa3 prepase~
using 2~ w/w of copolymer prepared according to
, Example 1.
ComParativ~ Example A
: .
The procedure of Example 2 wa~ repeated
~' except that copolymer was not u8ed in th~ or~anic
phase. ;~
The viscoslt~e~ of tha e~ulsions of Example~ 2, 3
and Comparati~Q Example A were measured at rocm
temperature ~20&) with a ~R~OKFIELD*instr~ment
using spindle ~7 on speed 5 rpm and the re~ult~
are shown ln th~ ~able 1 ~elow. ~-
* Trade Mark
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Copolymer Vi~co~ity
:~ concen~ration (cp)
, (~ w~w of
-i 5 orqanic phase~
~, ,.
Comparat~ve Exsmple A/ - 48,00Q
Example 2 1 75,200 :~
Exampl2 3 2 122,400
i ExamPle 4 and Com~arative Example B
This example demonstrate3 a method of
`, preparation of an emul~on of the invention by i::~
addition of a polymer powder to a preformed
emulsion.
An emulsion having the following
components was prepared according to E~ample 2,
~i the orgsnic phase not containing dissolved
~ polymer. . ~ `
t` Prilled ammonium nitrate (~Nitropril*") 84.06 :~:
Calcium nitrate 75.02
. 20 Distilled water 25.30
`~ Distillate oil 13.42
Emulsifier ~ 2.60 :.`
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`~ * The emulsifier was ~ 1s1 ~olar condensate of ::
`~ poly(i~obutylene) ~uccinic anhydride and
25 ethanolamine and had an average molecular weig~t -
in the ran~e of 800 to 1200. `~
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A sample of the compo~t~on was set a~ide for
cQmparison (Compara~ive Example B~
* NITROPRIL is ~ trade mark. .
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To ~ sample of the prep~rfed emulsion (200 g) at
: 80C wa~ added polymer powder (0.24 g, 2~ w/w on
dies~!l) prepared according to Example 1. ~he
S compG~ition wa~ hea~ed at 80 for four hours with
occasional ~tirring, then allowed to cool. Th~
compo3ition was stored at room temperature
overnight.
TABLE 2
Copolymer Yiscosity
% w/w diesel (cp)
Comparative Example B 091,400
Example 4 2~ 24~,800
Exam~les 5 to 7 and ComDarative ExamPles C and D
:
.~ 15 The following example~ demonstrate thf
highly viiscoela~tic nature of the explosive~ of
the invention.
~ COmDaratiVe ExamPle C
An emulsion compo~itio~ having the
following component~ was prepared according to
Example 2, the or~anic phase being free of
polymer.
Parts w/w
Chemically pure ammonium nitrate 84.06
, 25 Calcium nitrate ~5.02 ; :~
Di~tilled water 25.30 ~ -
Dist~llate oil 13.02 .
Emulslfier ~ 2.60
Ihe emulslfier wa8 a 1~1 mo~ar co~den~ate of '!~'"
poly(isobutylene)succinlc anhydride And
ethanolamlne and h~d ~n ~verage ~olecular welght
in the range 800 to 1200.
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A sample of ~mulslon was set ~s~de for
comp~rison and the bulk of the emulsion was used
in prepar~t~on of the following compo6itlon8.
ExamDles 5 t~ ?
S To three samples of emulsion prepare~ :
above were added polymer ~atexes prepared ~.
according to the proce~ure of example 1
using the monomer compositions shown in Table 3
below (numbers in brackets ~how the proportion of
each monomer based on the total monomer
mposition). The average molecular weight of
polymers used ~n Examples 6 and 7 waQ measured
and found to be 1.23 x 166 ~ mol~l for example 6 ~:~
and 0.82 x 106 g mol 1 for example 7.
, 15 In each case ~he appropriate latex was
; added to the emulsion to give a polymer
concentration of approx. 6~ w/w on the orqanic
phase and the latex was thoroughly mixed with the
emuls~on.
20 Comparative Exam~le D ~ ~`
An emulsion explosive composition wa~
prepared using the above procedure except that . .
~, the polymer added wa~ a polymer of tert-butyl ~.-
styrene prepsred accordinq to Example 1 ~the
associative monomer ~4-vinyl pyridine) Wa8
! omitt~d1.
~ The visco~ity of the emulsion
i compositions was mea ured at room temperature
u~ing a BXOOXFIELD instrument spLndle ~7 at 8peed
5.
1 The yield stresg ~nd el~stic modulu~ of
:~, th2 compo8~tion8 wa8 me~sured u~ing ~ BOHLIN *
Rheometer.
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. * Elonqation i~ a comparative measure of
-, ~iscoelasticity of the emul~ion
, compo~itions and was determined using
! the following method:-
A spatula havj.ng ~ 1 cm wid~h blade was
inserted into a bulk sample of emul~ion
at an angle of about 45 to the surface ~ ~
to a depth of about 1 cm. :` :-
The spatula wa~ rai~ed vertically from
the emulsion at a rate of about 1 cm S 1 ~ :~
until the thread of emul~ion between the :~
~ spatula and bulk sample broke or became
i less than 1 mm in thickness. The h0ight
of the spatula above the bulk emul~ion ~`
was measured at this ~tage.
Composit~ons of the invention typically
have an elongation in the range 2 to
30 cm (preferably 4 to 20 cm).
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~xamPle~ 8 ~o 10 and comParatiye Example ~
These examples demonstrat~ the advantage
of using explo~ivec~ of the present inven~ion when
loading into w~t boreholes.
Comparative Exam~e E
An emulsion explo3ive prepared according
~' to Comparative Example C (7.5 kg) was mi~ed with
ANFO" (ammonium nitrate fuel oil mixture)
(7.5 kg)t The mixture was gasse~ usiny an
1~ in-situ nitrite ga~sing agent.
.~ .
~ ExamPle 8
, :
An amulsion explo~iv~ prepared aceording
to Comparative Example C wa~ (7.5 Xg) was
throughly mixed with polymer latex (37.5 g latex
containing ~.38 g of ~polymer) to ~ive a polymer
concentration of 0.13~ w/w on total emul~ion.
This emulsion mixture ~as combined and mixed with
7.5 kg of "ANFO" and the compo~ition was gass~d
using an in-situ nitrite gassing agent.
Exam~le 9
, :
An emulsion~ANFO mix was prepared
according to Example 8 axcept that ?5 g o~ latex
18.75 g ~polymex was add~d.
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* The polymer lHtex UQed in ~xample3 ~ and 9 wa,~
prepared according to th~ procedure of ~x,ampl~ 1
'~ u3ing the monomer~ styrene (47~ uryl
m~thacrylate ~50%) ~nd methacrylic acid S3~)
lpercenta~a~ ba8~d on w/w of total monomerl
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Example 10
An emul~ion~ANF0 mix wa~ preparedaccording to Example 8 except that the quantityof Latex was ad~u~ted to provide a polymer
concentration of 0.5~ w~w on total emulsion prior
, to addition of ANF0.
t ~he performance of the explosives
prepared in Examples ~, 9 and Comparative
Example E on loading into wet borehole~ wa~
tested using the followinq procedure~
The explosive sample wa~ dropped 3
metres into water 2 metre~ deep. ~he explosive
was allowed to settle and was ~hen removed from
~! the water. After 2 hour~ the total detonation
energy of the explosive wa~ tested.
't Re~ults of the te~ts are shown ~n $a~1e 4.
; TABL~ 4
J ;
Example No. Tests Polymer Energy
. conc. % w/w ~J Xg-l
of emulsion
CE E 2 0.38 + ~-
8 3 0.13 1.09 +
9 2 0.26 1.12 +
2 0.50 1.50
The above results clenrly ~how the
uperiority in performance of the co~po~itions of
the pre3ent invention over corre~ponding
;i .
~t compositions devoid of polymer.
