CA1139106A

CA1139106A - Water-in-oil emulsion compositions

Info

Publication number: CA1139106A
Application number: CA000324627A
Authority: CA
Inventors: Rejean Binet; Joseph A.R. Cloutier; Harold W. Holden
Original assignee: Individual
Current assignee: PPG Architectural Coatings Canada Inc
Priority date: 1979-04-02
Filing date: 1979-04-02
Publication date: 1983-01-11
Also published as: ZA801738B; MW1680A1; JPS55136196A; JPH0251873B2

Abstract

ABSTRACT OF THE DISCLOSURE
A water-in oil emulsion explosive composition is provided which is detonator sensitive in small diameters and which retains sensitivity over extended periods of storage.
The composition comprises an aqueous solution of an oxygen-supplying salt, a liquefiable carbonaceous fuel, occluded gas and an emulsification agent which is a mixture of a conventional monomeric emulsifier and a copolymeric emulsi-fier of the type (A-COO)m-B where m = 2, A is the residue of an oil-soluble complex monocarboxylic acid and B is the residue of a polyalkylene glycol.

Description

This invention relates to an emulsion blasting agent of the type having an aqueous salt solution discon-tinuous phase, a liquefiable carbonaceous fuel continuous phase and containing occluded gas bubbles or gas-containiny material as a further discontinuous phase. In particular, the invention describes a gas-containing emulsion explosive composition which has enhanced sensitivity even after pro-longed storage and which, though devoid of any self-explosive ingredient, may be detonated in very small diameter charges.
Emulsion type explosive composi~ions are now well known in the e~plosives art. Bluhm, in United States patent No. 3,447,978, disclose~ a composition comprising all a~ueous discontilluous phase containing dissolved oxygen-~upplying ~alts, a carbonaceous fual continuous phase, an occluded gas and a water-in-oil emulsifying agent. Optional particulate carbonaceous or metal fuel can be included. The composition5 of Bluhm are somewhat limited in utility since detonation is possible only with relatively large diameter charges and the compositions require initiation by means of a substantial primer. Cattermore et al., in United States patentNo 3,674,578 describe a water-in oil emulsion explosive comprising an in-organic salt, a nitrogen-base salt such as an amine nitrate, water, a water-insoluble oil as ~uel, an emulsifier for the oil and incorporated gas bubbles. The composition of Cattermole, while detonable in charges having diameters of as little as 2 inches, requires the use of a nitrogen-base salt, e g. ethylenediamin~ dinitrate, which is per se a self-explosive material. Wade, in United States patent No. 3,715,247, des~ribes a small-diameter cap-sensitive emulsion type explosive composition comprising carbonaceous fuel, water, inorganic '-~i ,3~,;

~13~

salts, an emulsifier, gas bubbles, and a detonation catalyst consisting of a water-soluble salt containing selected metals.
Wada, in United States patent No. 3,765,964, describes an im-provement in the composition of United States patent No.
3,715,247 by including therein a water-soluble strontium compound to provide further sensitivity. In applicant's copending Canadian application Serial No. 317,649 filed on December 8, 1978, there is described a sensitive emulsion type explosive composition containing fuel~ water, salts, gas bubbles, an emulsifier and an emulsification promoter cvmprising a highly chlorinated paraffinic hydrocarbon.
Wade again, in United States patent No. 4,110,134 describes an emulsion type explosive composition devoid of any self explosive ingredient and ovntaining a closed-cell void-containing material as a density controller.
While all of the aforementioned compositions are meritorious, they are not without some disadvantages. The composition of Bluhm, for example, is only suitable for use in large diameter charges and requires strong primer initia-tion. The compositionsof Cattermole et al. and Wade, while useful in small diameter charges, require the use of expensive xaw materials, demand extra handling precautions because of the sensitive nature of the ingredients used and hence lead to increase costs. All these compositions, includiny that of Wade ~United States patent No. 4,110,134) tend to become dry and hard upon aging due to the coalescence of the micro-droplets of the salt solution. Without the addition of sen-sitive perchlorate salt or self-explosives; cap sensitivity can not be expected to be retained for any appreciable period.
It has now been found that all of the aforementioned disadvantages can be overcome The present invention pro-vides an improved small-diameter, water-in-oil emulsion explosive composition which, even when devoid of any sensi-tive self-explosive or perchlorate salt ingredient, is sensi-tive to detonation by means of an ordinary blasting cap, even at densities greater than 1 10 g/cm3, After storage for extended period of time, the composition remains detonator-sensitive and does not show any sign of deterioration. The improved composition of the invention comprises an aqueous solution of inorganic oxygen-supplying salt as the disconti-nuous phase, an insolublel liqueiable carbonaceous fuel as the continuous phase, occluded gas bubbles or gas-containing material, and a water-in-oil type emu~sifying agent which is ablock or graft copolymer of the type (A-COO)m-B, where m = 2, where A i9 the residue of an oil-soluble complex mono-carboxylic acid of mol wt. at least 500 and B i9 the residue of a polyalkylene glycol of mol wt. at least 500 in combina-tion with conventional monomeric water-in-oil emulsifying agents.
More particularly, the block or graft copQlymer emulsifiers suitable for use in admixture with a conventional monomeric emulsifier in water-in-oil emulsion explosives has the general foxmula (A-COO)m-B, wherein m is 2, wherein each polymeric component A has a molecular weight of at least 500 and is the residue of an oil-soluble complex monocarboxylic acid having the general structural formula:

. _ , Rl R-CO -O-C-(R2)n-CO -O-C-(R2)n -COOH (I) H P H

in which R is hydrogen or a monovalent hydrocarbon or substituted hydrocarbon group;
Rl is hydrogen or a monovalent Cl to C24 hydrocarbon group;
R2 is a divalent Cl to C24 hydrocarbon group;
n is zero or l;
p is an integer fxom zero up to 200;
and wherein each polymeric component B has a molecular weight of at least 500 and is the divalent residue of a water-soluble polyalkylene glycol having the geIleral formula:_ . R ~s H - -0-C-CH2 - -O C-CH20H ( I I
H H

in which R3 is hydrogen or a Cl to C3 alkyl group;
q i~ an integer from 10 up to 500.
The units of the formula Rl - O -C- (R2)n- CO -H
which are present in the molecule of the complex monocarboxylic acid as represented by formula I may all be the same or they may be different in respect of Rl, R2 and n~ Similarly, the units of the formula H

which are present in the polyalkylene glycol as represented by formula II may all be the same or they may be different in respect of R3.

9~

The complex monocarboxylic acid, from which the poly-meric components A are derived by the notional removal of the hydrogen on the terminal carboxyl group, is structurally the product of interesterification of one or more monohydroxy-monocarboxylic acids together with a monocarboxylic acid free from hydroxyl groups which acts as a chain terminator The hydrocarbon chains R, Rl and R2 may be linear or branched.
R is preferably an alkyl group containing up to 25 carbon atoms, for example a straight-chain C17H3s-group derived from stearic acid. Rl is preferably a straight-chain alkyl group, and R2 is preferably a straight-chain alkylene gxoup, for example, the unit ~ontaining Rl and R2 may be derived from 12-~hydroxy-stearic acid.
The polyalkylene glycol of the formula II, from which the polymeric component B is derived by the notional removal of the two terminal hydroxyl groups, may be, for example, a polyethylene glycol, a polypropylene glycol, a mixed poly(ethyl-ene-propylene) glycol or a mixed poly(ethylene-butylene) glycol, but preferahly a polyethylene glycol Preferably each of the polymeric components A has a molecular weight of at least 1000 (by "molecular weight" is meant number average molecular weight). Thus where, for example, the group R is derived from stearic acid and the unit containing Rl and R2 together is derived from 12-hydroxy-stearic, p will have a value of at least 2 Similarly, it is preferred that the polymeric component B has a molecular weight of at least 1000. Thus where that component is the residue of a polyalkylene glycol which is derived from ethylene oxide exclusively, q will preferably have a value of at least 23 For optimum results for purposes of the present ~.3L3~9~l06 invention the proportion of polymeric component B in the copolymer is between about 20% to 40%, preferably 25% to 35%
by weight of the total copolymer.
The conventional monomeric water-in-oil emulsifying agents with which the copolymeric emulsifier are combined are, for example, sorbitan mono-oleate, sorbitan sesqui-oleate, mono and diglycerides of fat-forming faltty acids or mixtures o these. It has also been found that a portion of the mono-meric water-in-oil emulsifier may be replaced with a plant lecithin such as a technical grade soybean lecithin. While plant lecithin is not suitable for use by itself in the present explosive composition, its combination in amounts up to 60%
by weight with conventional monomeric water-in-oil emulsifier provides the same emulsifying action as does the monomeric emulsifier when used aloneO
It has been surprisingly discovered that use of the copolymeric emulsifiers in combination with a conventional monomeric emulsifier in an explosive composition of the type described, even in small quantities, substantialLy expedites the dispersion and emulsification of the aqueous phase. It has also been found that the need to employ a high shear mixing apparatus, required heretofore in the manufacture of detonator-sensitive water-in-oil emulsion explosives containing only conventional monomeric emulsifiers, is unnecessary when the copolymeric emulsifiers are use~.
The following examples and tables demonstrate the utility of the present invention.

A series of four water-in-oil emulsion e~plosive compositions was prepared from water, inorganic oxygen-; - 6 ~3~

supplying salts, liquefiable carbonaceous fuels and emulsi-fiers. The method of preparation comprised heating together the liquefiable carbonaceous fuel (wax), hydrocarbon oil, and emulsifiers at a temperature of from 60C to 85C until the wax and copolymeric emulsifier ing:redients were liquefied.
A separate aqueous solution of inorganic oxygen-supplying salts and sodium borate buffer was prepared at a temperature of from 60C to 85C and mixed into the fuel/e~ulsifiers solution to form a water-in-oil emulsion. Hollow glass micro-spheres were then mlxed into the emulsion to form the finalcomposition.
The ingredients of the composition as well a~
the density and sensitivity of the final mixtures are shown in Table I, below, the quantities shown being in percent by weight.

- ~

m r~
X ~i ~ o ~ :~
__ _ .
~ ~ ~ _l o ~ ~ O ~ ~ ~ ~ ~ ~n X ~I ~g o ~ o ~ i + ~
.... _ ~ o ~ ~ O,~ ~ ~
H I ~ ~i 0 0 r~i ~ t~ t~l ~1 0 It- Lf) O IJ
.~ h ~IS
~3 1 , , ..... _ 1~ ~
_I 1:: ~ h O ~ 1 1~ 0 ~ ~ O
E~ I Z ,,,,, " I, . - - ~ E4 ,I~DO~o,l ~ ,lo~n~n O la ~ ~ 1 + ~ a~ u '~ ~
_ _ _ _ . ~ O ~ ~
~ U ~P

al a~ ~ o h U ~ o U~ 4 J ~ ~ h ~ ~ ~7 3~ tS
.IJ ~rl O_ O ~J ~ ~ ~ ~
h ~ a~ ~ g10 ~ p, U U ~ o ~r~l ~rl ~ Id U
~ o ~ " ~ o ~ ,~
h ~ oU E; tJ~ O ~3 h tJ~ ~, U O ,~ U
H ~ C ) t~
c~ 1 ,Q O t~ ~ W ta ~ ~ 1 ,~
~1 Ll Ll Ei h Ll 1~ _I C`l ~) d' E~ O O ~ O O O ~ 11 ) ~3C~

From the results in Table I it is seen that Mix No. 4 containing no polymeric emulsifier failed initia-tion while Mix Nos. 1, 2 and 3 were sensitive to cap initia-tion, A further series of water-in-oil emulsion explosives ; was made in a manner similar to that d~escribed in Example 1 and various copolymer emulsifiexs were added to separate mixes. An amount of plant lecithin was also included.
The sensLtivity of the separate mixes was determined after periods of storage, The results are shown in Table II below, the quantities shown being in percent by weight.

~l3~

o o U t~
,. .. .
a) (D a~
,, ~ ,, .Y
,, ,~
. . I ~ ~ ~
_, . o o pi, a~
_, l , O ~D ~ In ~9 ~ ~1` r~ o Z; , ....... ..... ~
_~ ~9 o ~ o o ~ ~ ~ o o o ~ ~ U~
h h ~1 ~ _ .
~ Id ld ~D ~
. O O O
o t~ s) 1~ o ~ a .......... . ~
~1 ~ O ~ I O I O O ~ c~ ~ ~ ~5 ~
H I X ~9 ~I r-l "~ ,1 ~1 H I .,1 tQ u~ tl l :~ ~
1~1 1 h h h ~ I _ _ _ _ _ m :n m a~ I ~ ~ ~
I L(~
~o ~ ~
E~ I . O O o o o ~ o ~ ~U~
- O
_I ~ o ~ o I I o o ~ ~ ~ o o o X ~ ~l U IU . U
.~ UO UO UO
rl Orl O rl O
_ h C~1~ ~ h O ~O ~ O
a~
,, ~" ~ ~ a)a h h ~1 Id ~ 3 a) ~) a) a~ In O U~
,1~
4~ ~ ~ o a~
a) ~1 ~1 rl I S~~--I ~--I ~ ~1 tq ~q 0~rl a) ~ ~ rl C~ U rl U
ta S~ l ~) ~ ~1 X tn rl h ~ O ~ Q h O h Q
(U ~ rl O ~ P~
.,1 rl O U U U U U
R rl rl rl ~ rlO ~1 0 ~1 O ~
o ~Sh h h (~) ~1 rl ~1 E3 C) oO O C~ O
~-I ~ 1 0 ~ ~ 4 tr~ 1~3 h E! ~3 E3 rl 1) ~ ~ u~
_ ~ O O ~ O O O O ~I td ~ ~1 __ ~3 _ ~

o o ,, X ,i o u~
.
.

Zj~ ~~ o ~J X ,~ o u~

H I _ _ H I U') ~1 ~Z;' O ~ ~1 ~ r-~ O IS) lf~
lC~ I .~ t~

~ h:::

_~ O
U~
~ U U ~ '~ E03 a) u a) ~ ~ :-1-1 rl ~I h 0 ~3 ~ 0 _ O C~

1 '1 From the results in Table II it is seen that a range of polymeric emulsifier types may be employed and in each instance sensitivity to cap initiation was retained even after extended storage, A further series of water-in-oil emulsion explosi-ves was made in a manner similar to that described in Example 1 and varying amounts of polymeric emulsifier/conventional emul-sifier and plant lecithin blends were added to the separate mixes~ The sensitivity of the separate mixes was determined after periods of storage. The results are shown in Table III, the quantities shown being in percent by weight.

~ 13~

_ -- ~o . . ~
o ~
,~ a~
, . ~ \\\\\
O ~ n 1~ r` O ~ ~1 ~ d' h E4 1:4 ~ E4 .-Z .......... ~ ................ I
~ ~ o ~ o o o ~ ~ ~ ~ o u~ ~ ~ o o X
X ~ .
.

_ _ a~
.
. O ~ \ o ~o I` ~ In ~ o ~ ~ o ~ E4 ~ 4 u o ~ o o o ~ ~ ~ ~i o u~ ~ ~
X ~ ,a~ .

. _._ ~
O
H I a~
H I ~ I
H ICO ~:5 . ~ \\~\~ 10 O d' 1~ D ~ O t` I` O ~ r-l O d' ~ ¢~ 4 I~Z. - . . ~ ., .,, , ., 5-~1 ~ O ~ O .~ O ~ ~ ~.~ ~ Lf) Ln t` ~` ~ ~ ~ C~
I X ~
.,~ m m I
_ ~
V
~ o .,, o h ~

h ~ ~ o: _ ~1 3 O
~ S~ ~ 5 a~ ~-- O ~
~n ~ ~ c) ~ ~ ~ ~1 o ~ ~ _ ~: h ~ O1 ~ ~ U U ~-- rl O rl U
CJ ~ ~ l X u~ U ~ r~ ~ Ei u~ o .~ rl ~ d O \ ~ 1 ~1 ~ ) h u~ ~1 0 ~: h tJi --l h ~ 9 h O
a) ~1 o u u u ~ rl ~ E3 h E3 ~ R ~ ,1: h 1::
h td ~l rl ~l Ei ~ ~ n) E3 U~ ~D 0 ~1 ~r~ - - - - c~ o H ~ a) e s~ ~
o~
F~1 h ~ h h d ~ ~ h El ~ ,_ E~ O O 1~l 0 0 ~ ~ 1 a) X (~ 1 -1 ~ Q, O C~ ~ ~

~iL3~

From the results in Table III it i5 seen that various amounts of polymeric and monomeric emulsifiers may be employed while retaining long storage sensitivity of the explosive compositions.

A ~urther series of water~in-oil emulsion explosive compositions was made in a manner similar to that described in Example 1. A combination of polymeric and monomeric emul-sifiers together with plant lecithin was employed~ In one case no polymeric emulsifier was used. The sensitivity of the mixes was tested after extended storage, the re~iults being shown in Table IV, From ~able IV it can be noted that Mix ~o. 12, devoid of the polyme~ic emulsi~ier, failed to initiate with an E.B. cap after three months storage while Mixes 11 and 13 retained sensitivity.

~3~

. ~ .... ~

~1 a) . U~
o ~ I~ ~ ~ ~ CO ~ _~
...... . .. o ...
o ~ o o o, ~ ~ ~ ,, o Ln U~
X ~ +~

_ . _ _ _ ~, o ,' o ,~
O o ~ u~ ul r~l t~ u~ ~1 U) ~ r-l ~ d' ~: .. , . . ..... ...
0~0~ 1 ~ oo~,~ ~ou~u~ ,~
XUl ~1 ~1 +
~ O
_ ~ , _ ~1 ~,~

O ~ d' ~ ~ d' I ~i ...... ..... ...
~ g o ~ o o o o ~7 ~1 ~ r-l O In Ln ~ I X Ll~ ~:~
E l I ~ N O O
~'1 ,U ,~ , h sd .. 1 ~ ~ h a~ o ~ ~ a~
I O U~ ~ ~ O ~1 o ~ ~ o o rl ~ Lg~r~ u D~ ~ o ~ ~ ~
s~ ~ U U ~-- .,~ O U, ~ ~ ~ I X u~ U ~rl la 0 rl h n~ ~ O rl 1~ U ~ (~ ~ ~J ~-1 ~1 rl .~ ~ ~ 5~u~,1 1` O 3 5~ h O la ~1 0 U U U --~ O :1 ~ U _ al E~ ~ ~ E~
o ,~ ~l e ~ ~ ~ o, e a u H o~ t5~
~ 1 h ~ ,_ ~
e o o ~ o o ~ 3 X ~ a~ ~ r~
_ ~ a o ._ ~, ~
I J

- - ~ -~m m m ~
oo o ~ ~ ~
X ~ 1 o .
_l m ~ ~m~
~ COCO~
_ o ~I
: ~ l _~
H I O ~ ~O
~ ~ Zi E~ m m _1 ~: I ~ ~ t _ _ .

.

U~ fd :~
~ .
~ ~ ~o H . .

'1 ~

~3~

The ratio of the polymeric emulsifier to the conventional water-in-oil monomeric emulsifier (including lecithin) is preferably in the range of 1:6 to 1:2. The total amount of emulsifier (polymeric plus monomeric plus lecithin when used) found suitable for use in from 0~8% to 2~5%, preferably 1 2% to 2% by weight of the ~otal explosive com-position.
The emulsion explosive composition of the invention may be made using conventional mixing apparatus normally used in the preparation of aqueous slurry explosive manufacturing processes. The use of high shear mixing apparatus ha been found to be unnecessary In preparation, the carbonaceous fuel and mixed emulsifiers are first added to the mixer bowl and heated to a temperature of from 60C to 85C until liquefaction is achieved. A solution of oxidizer salt, water and any buffering agent is separately prepared and added to the liquefied fuel in the mixer at a temperature of from 60C to 85C. Mixing is continued until a viscous water-in-oil emulsition is formed.
Where the inorganic salt used contains additives such as anti-caking materials and the like, the solution of oxidizer salt is preferably filtered before addition to the liquefied fuel in order to remove any insoluble matter which may be present.
Such insoluble matter has been noted to adversely affect the emulsification and stability of the final composition. During cooling, air is whipped into the mixture by further agitation or in-situ gas-generating reagents arP dispersed therein.
Air-containing particulate material such as glass microspheres, if used, can also be added at any time after the emulsion is formed. The amount of gas or air-containing particulate material employed will be sufficient to maintain the density of the composition between 1.00 and 1.35 grams/cc. After mixing, the product may be cartridged or carried to the blasting site and pumped directly in boreholes.
The preferred inorganic oxygen-supplying salt suitable for u~e in the improved explosive composition of the invention is ammonium nitrate; however a portion of the ammonium nitrate may be replaced by other inorganic oxygen-supplying salts such as sodium nitrate, calcium nitrate ~0 and potassium nitrate.
Suitable water-immiscible emulsifiable fuels for u~e in the composition include petroleum oils such as ~o. 2 uel oil, paraffin oil, mineral oil and vegetable o;ils.
Liquefiable waxes such as paraffin waxes, microcrystalline waxes and mineral waxes are also suitable fuels. Particularly preferred i9 a mixture of paraffin wax and paraffin oil of medium viscosity in order to pro~ide good stability The quantity of oxygen-supplying salt used in the composition may range from 55% to 85% by weight. The amount of liquid or li~uefiable carbonaceous fuel may be used in an amount of from 2% to 10% by weight Water in an amount of from 10% to 25% is suitable. A preferred composition comprises 75% to 83% by weight of oxidizing salts, 10% to 16% by weight of water, 3% to 6% by weight of liquefiable fuel, 1.2% to

2.0% by weight of mixed emulsifiers and up to 1% by weight of an emulsification promoter.
The present invention thus provides a composition detonable in small diameter charges without the aid of any booster or primer. Because of composition is devoid of any self-explosive or ~ther sensitive material, it may be manu-~3~

factured safely and at low cost and stored and shipped with minimum risk, and unlike the water-in-oil emulsion explosive compositions of the prior art, the composition may be stored for unusually long periods without significant loss of sensi tivity. The composition lends itself to preparation in the explosive factory where it may be packaged for use or it may be prepared at the blasting site in a mobile mixing facility.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A water-in-oil emulsion explosive composition which is cap-sensitive in small diameter charges, which comprises (a) an aqueous solution of inorganic oxygen-supplying salt as a discontinuous emulsion phase;
(b) a water-immiscible liquefiable emulsifiable carbonaceous fuel as a continuous emulsion phase;
(c) occluded gas or gas-entrapping material dispersed in said emulsion as an additional discontinuous phase; and (d) an emulsification agent selected from a com-bination of 1) the group consisting of monomeric emulsifiers comprising sorbitan mono-oleate, sorbitan sesqui-oleate, mono and diglycerides or fat-forming fatty acids or mixtures thereof; and 2) block or graft copolymeric emulsifiers of the type (A-COO)m-B, where m = 2, where B is the residue of a polyalkylene glycol of molecular weight at least 500, and where A is the residue of an oil-soluble complex mono-carboxylic acid of molecular weight at least 500 having the formula:

in which R is hydrogen or a monovalent hydrocarbon or substituted hydrocarbon group;
R1 is hydrogen or a monovalent C1 to C24 hydrocarbon group;
R2 is a divalent C1 to C24 hydrocarbon group;
n is zero or 1;
p is an integer from zero up to 200;
and wherein the polyalkylene glycol has the formula:

in which R3 is hydrogen or C1 to C3 alkyl group;
q is an integer from 10 up to 500.

2. A composition as claimed in Claim 1 where the units of the formula present in the molecule of complex monocarboxylic acid may, with respect to R1 R2 and n, all be the same or different.

3. A composition as claimed in Claim 1 wherein the units of the formula present in the polyalkylene glycol may, with respect to R3, all be the same or different.

4. A composition as claimed in Claim 1 wherein the inorganic oxygen-supplying salt is selected from the group consisting of the nitrates of ammonia, sodium, potassium and calcium and mixtures thereof.

5. A composition as claimed in Claim 1 wherein the water-immiscible emulsifiable fuel is selected from group consisting of petroleum oil, paraffin oil, mineral oil, vegetable oil, paraffin wax, microcrystalline wax and mineral wax and mixtures thereof.

6. A composition as claimed in Claim 1 wherein up to 60% by weight of the said monomeric emulsification agent is replaced by plant lecithin.

7. A composition as claimed in Claim 1 also containing gas containing particular matter.

8. A cap-sensitive water-in-oil emulsion explosive composition comprising essentially from 10% to 25% by weight of water, from 55% to 85% weight of an inorganic oxygen-supplying salt, from 2% to 10% by weight of a water-immiscible liquefiable carbonaceous fuel, from 0.8% to 2.5% by weight of a mixed monomeric and polymeric water-in-oil emulsifica-tion agent as claimed in Claim 1 and occluded gas.

9. A composition as claimed in Claim 8 also containing gas-containing particulate material sufficient to maintain the density of the composition between 1.00 and 1.35 gramms/cc.

10. A composition as claimed in Claim 8 also containing up to 1% by weight of an emulsification promoter.

11. A composition as claimed in anyone of Claims 1 and 8 wherein the ratio of polymeric emulsifier to monomeric emulsifier is in the range 1:6 to 1:2.