Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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INTRODUCTION
This invention relates to a new and improved method for
the thickening of hydrocarbon oil slurries of ammonium nitrate
explosives, through the use of a latex of an elastomer In the
practice of this invention, a latex containing elastomer is added
to a hydrocarbon oil slurry of ammonium nitrate. Through the use
of a surfactant, preferably oil soluble and of a high HLB value,
the latex is inverted, causing the polymer contained in it to
solublize into the hydrocarbon slurry and give a thickening
effect.
U.S. 3,639,108 teaches the thickening of gasoline with
latex compositions. It has been long known in the art that the
addition of an oil soluble polymeric composition ~ ill increase the
viscosity, and cause a thickening of the solvent in which it is
placed. However, the polymer so used has been in inconvenient
forms, either solid material which takes long dissolution times
before use is practical, or as dilute solutions of the polymer of
high viscosity, which due to their low solids content make shipping
uneconomical.
The use of hydrocarbon oil slurries of ammonium nitrate
explosives is well known in the art. It is common practice to use
these slurries in a gel form or at least substantially thickened
in order that they retain their shape for a temporary period of
time. It would be an advantage if the hydrocarbon oil slurry of
ammonium nitrate could be prepared close to where it is used,
quickly, and with simple apparatus.
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The method of this invention, involves an improved method
¦ for the thickening of hydrocarbon oil slurries of ammonium nitrate
¦ explosives. The method of this invention involves adding to a
hydrocarbon oil slurry of ammonium nitrate explosives a latex of
¦ an elastomer,followed by inverting the latex into the hydrocarbon
¦ oil slurry. The method of this invention, provides to the art a
¦new and improved rapid method for thickening hydrocarbon oil slurries
of ammonium nitrate explosives in a short period of time, as well
i as providing a more economical means.
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¦ OBJECTS ~
It is therefore an object of this invention to provide
an improved method for thickening hydrocarbon oil slurries of
ammonium nitrate explosives.
Another object of this invention is to provide a method
for thickening hydrocarbon oil slurries of ammonium nitrate
explosives by inverting a latex of a polymer selected from the
group consisting of cis-1-4-polyisoprene and polyisobutylene into
a hydrocarbon oil slurry of ammonium nitrate.
Other objects will apear hereinafter.
THE INVENTION
` This invention involves a method for thickening hydrocarbcn
oil slurries of ammonium nitrate explosives by adding to such
slurry a latex containing a finely divided polymer of either
cis-1-4-polyisoprene and/or polyisobutylene, followed by inverting
the polymer so as to make it soluble in the oil phase with the use
of an oil soluble high HLB surfactant.
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This invention involves the use of either natural or
synthetic latices of elastomers. Specifically, the elastomers
involved include cis-l 4-polyisoprene and polyisobutylene, Latices
of these polymers are well known in the art and typically contain
5 to 75% by weight polymer, 25 to 75% by weight water, and .01 to
5% by weight of a surfactant which is water-soluble. For the
purposes of my invention, it is desirable to use a latex containing
as much polymer by weight as possible while still maintaining a
stable emulsion. In the practice of my invention, the preferred
surfactants used to invert the emulsion are those which are oil
soluble and have high HLB values. The surfactant chosen to invert
the polymer must be soluble in the particular oil that is used in
making the hydrocarbon oil slurry of ammonium nitrate which is
desired to be thickened. Suitable emulsifiers include diesters of
polyethyleneglycol, with molecular weights of between 200 to 600,
with fatty acids containing 14 to 18 carbon atoms. Specifically,
the preferred emulsifier is polyethyleneglycol of a molecular
- weight of about 400 which has been diesterified with oleic acid.
It is important to note however, that the choice of a surfactant
for inverting the emulsion will depend on several characteristics, ~ -
including: the emulsifier used to produce the polymer latex;
other organic additives present in the hydrocarbon oil slurry of
ammonium nitrate; and the characteristics of the polymer used.
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Based on this, it is advisable to run small-scale tests before
; choos7nga surfactant to be used in larger scale batches~
The HLB system, (hydrophobic-lipophilic balance values),
formulated by Atlas Industries is a mechanism by which the
hydrophobicity and lipophilicity of surfactants
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¦aremeasured. Typically, latices of elastomers are made with Surfac-
¦~ants having a low HLB value (0 to 7). In the choice of an emulsi-
¦fier to be used for inverting the latex, a surfactant with an HLB
¦value "opposite" the one used to form the original polymer latex
¦should be used.
I The oil soluble surfactant used for inverting the
¦polymer latex may be added directly to the latex, or to the
¦hydrocarbon oil slurry of ammonium nitrate either before or after
¦the latex of the polymer is added. Typically, from .01 to l~/o by
¦weight of the surfactant used for inverting is added based on the
¦polymer present in the latex. The most preferred amount of surfac-
¦tant to be added is from .01 to 5% of the weight based on the poly-
Imer contained in the latex. Typically, the amount of polymer used
¦will depend upon the amount of hydrocarbon or oil solvent present
¦in the ammonium nitrate slurry. For best results, I believe that
¦the percent polymer should be greater than 0.1% based on the weight
¦of the total slurry. However, due to characteristics of these
¦solutions and different ways of manufacturing the ammonium nitrate
¦slurries, the level of polymer will vary on a case-by-case basis.
¦The slurries of ammonium nitrate used in this invention may contain
¦either granular powdered or prilled ammonium nitrate. Since the
form of ammonium nitrate used will vary the consistancy of the
slurry, more polymer may be needed in cases where granular or prilled
ammonium nitrate is used rather than powdered ammonium nitrate.
In some cases, using extremely concentrated ammonium nitrate
slurries, the polymer content necessary to gel the slurry may be
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under 3% of the total hydrocarbon or oil solvent. In most cases,
however, a level greater than 3% is preferred, and this amount may
be increased to as high as 20% for slurries containing small
amounts of ammonium nitrate.
In order to prepare a thickened sample of an organic
solvent based explosive, the following are procedures that would
be followed:
EXAMPLE 1
To a 1,000 g. sample of a 75% by weight NH4N03 slurry
in No. 2 fuel oil would be added 1.0 g. of polyethyleneglycol
(400) dioleate with agitation. Immediately thereafter 60.0g.
of a 50% natural rubber latex would be added to the resulting
slurry with agitation. The mixture should thicken within
5 minutes.
EXAMPLE 2
To a lOOOg. sample of a 50% by weight slurry of
NH4N03 in kerosene would be added 0.5g. of polyethyleneglycol
(400) dioleate with agitation. After mixing, 70g. of a 50% by
weight latex of polyisobutylene (available commercially) would
be added with agitation. The resulting mixture should thicken
wi~hin 5 minutes.
I claim:
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