Antimisting system for hydrocarbon fluids

An antimisting hydrocarbon solution comprising a hydrocarbon mixed with a copolymer of an alpha-olefin and a vinyl alkylenecarboxylic acid, wherein the concentration of said copolymer in said hydrocarbon is about 0.05 to about 2 grams per 100 ml of said solution, wherein such copolymer has the formula: ##STR1## wherein R.sub.1 is an alkyl group having about 1 to about 25 carbon atoms, R.sub.2 is an alkylene group having about 3 to 17 carbon atoms, Z is a mixture of hydrogen and an alkyl group having about 1 to 25 carbon atoms, x is about 95.0 to about 99.99 mole % and y is about 0.01 to about 5 mole %, wherein hydrogen comprises about 1 to about 45 mole % of Z.

FIELD OF THE INVENTION 
The present invention relates to hydrocarbon, preferably jet fuel solutions 
having antimisting properties in which the hydrocarbon solution contains a 
copolymer of an alpha-olefin and a vinyl alkylenecarboxylic acid. 
BACKGROUND OF THE INVENTION 
Polymeric materials are useful as viscosity enhancers when dissolved in the 
appropriate solvent system. The principle reason for this behavior is due 
primarily to the large volume which a single macromolecular chain can 
occupy within the solvent. An increase in the size of the chain produces a 
concomitant enhancement in the solution viscosity. However, when the 
polymer chain is placed in a shear field, segmental orientation takes 
place in the direction of the shearing force. The viscosity of the fluid 
dramatically drops due to this orientation phenomena. This is a typical 
behavior of most solutions containing dissolved polymeric materials. 
However, if the polymer molecule has a high molecular weight with a 
relatively flexible backbone and the solvent viscosity is sufficiently 
high, different behavior can be anticipated. It has been shown by several 
groups that, with increasing shear rates, the viscosity should show a 
decrease, followed by a minimum value and a small subsequent increase in 
cases where both solvent viscosity and polymer molecular weight are very 
hight. This latter effect gives rise to a slight dilatant behavior. 
However, the above-mentioned conditions required for the appearance of a 
slight shear thickening behavior in these polymeric solution systems are 
not applicable for many technologically interesting fluids. Inmost of the 
common synthetic polymers, it is difficult from a synthetic viewpoint to 
obtain sufficiently high molecular weight and, in addition, most solvents 
(for example, jet fuels) have rather low viscosities. 
U.S. Pat. No. 4,002,436 discloses hydrocarbon jet fuel compositions of 
addition polymers with associative polar bonds. However "the polymers used 
in [that] invention will generally be of the free radical addition type 
since these are the simplest to make in the presence of polar groups" 
(column 4, lines 16-18). Alkene hydrocarbon or alpha-olefin polymers 
usually require post polymerization reaction to introduce the polar groups 
and are thus generally excluded from this invention (column 4, lines 
58-68, and column 5, lines 1-3). Moreover, compositions of U.S. Pat. No. 
4,002,436 make no claims to showing dilatant or shear thickening rheology 
(i.e. instantaneous increase in viscosity, with increasing shear rate). 
This invention discloses the novel and unexpected result that polymers 
containing low levels of carboxylic acid side groups are capable of 
enhancing the viscosity of hydrocarbon solutions under relatively broad 
shear conditions. With these unique polymeric materials, dilatant behavior 
occurs in hydrocarbon fluids which are of broad technological utility and 
useful in antimisting applications, preferably for jet fuel. It is further 
observed that under the identical experimental conditions, the viscosity 
of related copolymer solutions containing no carboxylic acid side groups 
show the normal shear thinning behavior. 
Polymers with very high molecular weight can be used to modify a solvent 
for antimisting behavior. In this invention it is diasloed that an 
alternative to ultra high molecular weight additives are lower molecular 
weight polymers which are capable of associating in solution, thereby 
building a network of a very high molecular weight. A way for achieving 
such networks is the association of polymers containing a low level of 
carboxylic acid side groups. 
In order to avoid phase separation of the associating polymer in solution, 
the acid density along the polymer backbones should be relatively low. The 
resulting solution of such a polymer is then significantly more viscous 
than solutions containing related polymers which do not associate. Upon 
addition of a strongly polar agent such as an alcohol the associations can 
be disturbed and the viscosity reduced. 
It was found that for a given range of the various parameters that may be 
varied in a carboxylic acid containing polymer solution, an unexpected 
shear thickening (dilatant) behavior may be obtained. These parameters 
include: 
Backbone nature of the polymer (or copolymer). 
The polar group densities along the polymer backbones. 
The molecular weight of the polymer. 
The solvent (and cosolvent, if any). 
The concentration of polymer in solution. 
As explained above, most solutions of high molecular weight polymers are 
expected to exhibit a shear thinning behaior. Polymers containing 
carboxylic acid side groups under narrow conditions seem on the other hand 
to possess an ability to establish even larger networks or act as if 
networks are larger under high shear rates resulting in shear thickening. 
Shear thickening behavior can be useful in affecting antimisting 
characteristics. Such a solution can behave as a fairly low viscosity 
fluid at low shear rates. However, the viscosity begins to rise as the 
shear rate is progressively increased. Accordingly, the solution can more 
effectively resist break-up into a mist of minute droplets. This is a very 
desirable attribute in a variety of fluids of technological interest and 
specifically jet fuels. Another desirable attribute is to be able to 
reverse (or erase) the above-mentioned antimisting behavior and render it 
atomizable. With regard to polymers of the instant invention, this is 
readily achieved through addition of a soluble component capable of 
weakening or totally disrupting the associations which hold the network 
together. Such a component should be highly polar, soluble in the solution 
containing the dissolved associating polymer and capable of efficiently 
migrating (and disrupting) the associations. Alcohols and amines and low 
molecular weight carboxylic acids are only a few of many possible 
examples. 
U.S. Pat. No. 3,679,382 teaches the thickening of aliphatic hydrocarbons 
with synthetic organic polymers of alkylstyrene or lauryl acrylate and 
olefinically unsaturated emulsion copolymerizable acids, amides, 
hydroxyacrylic esters, sulfonic acids, etc. It is emphasized in this 
patent (column 3, lines 69-75) that it is critical that in the preparation 
of such polymers, no surface active agent, catalyst or other additive be 
employed which introduces a metallic ion into the system. Therefore, it is 
preferred to employ ammonium or amine salts. This patent also fails to 
teach shear thickening compositions. 
The instant invention contains no alkylstyrenes or lauryl acrylates and the 
instant olefinically unsaturated acids and esters are not emulsion 
copolymerizable. The instant acids and esters have an alkyl spacer group 
separating the acid or ester from the olefinic double bond thus rendering 
them nonpolymerizable by free radical emulsion polymerization. The instant 
copolymers are prepared by Ziegler-Natta polymerization, which do indeed 
use metallic catalysts. Such metallic species are precluded from U.S. Pat. 
No. 3,679,382. The instant invention also teaches shear thickening 
composition. 
Finally, the novel polymeric systems described here are readily soluble in 
aliphatic as well as aromatic hydrocarbons making them useful as additives 
to jet fuels and other distillates of crude oil. 
SUMMARY OF THE INVENTION 
The present invention relates to hydrocarbon, specifically jet fuel, 
solutions having dilatant properties in which the hydrocarbon solution 
contains a copolymer having carboxylic acid side groups. 
GENERAL DESCRIPTION OF THE INVENTION 
The hydrocarbon solution of the instant invention, which exhibits 
antimisting properties, are copolymers of an alpha olefin and a vinyl 
alkenecarboxylic acid. 
The copolymer complex is characterized as having polymer backbones which 
are substantially soluble in the organic liquid, and pendant 
(CH.sub.2).sub.8 COOH alklenecarboxylic acid side groups. 
The copolymer of the instant invention is a copolymer containing an alpha 
olefin and a mixture of a vinyl alkenecarboxylic acid and a vinyl 
alkylenecarboxylic ester having about 4 to about 20 carbon atoms, more 
preferably about 9 to about 18 and most preferably about 10 to about 16, 
wherein an alkyl group is situated between the acid or ester group and the 
carbon of the double bond of the monomer, wherein the resulting 
alklenecarboxylic acid side groups are randomly distributed along the 
alpha-olefin backbone. The alpha-olefin has about 3 to about 27 carbon 
atoms, more preferably about 6 to about 25, and most preferably about 6 to 
about 18. The copolymer contains a mixture of about 0.01 to about 5 mole % 
of the alklenecarboxylic acid and alkylenecarboxylic ester side groups 
more preferably about 0.05 to about 3 and most preferably about 0.1 to 
about 2. The number average molecular weight as measured by GPC of the 
alpha-olefin copolymer is about 10,000 to about 20,000,000, more 
preferably about 50,000 to about 15,000,000, and most preferably about 
100,000 to about 10,000,000. The copolymer of the alpha-olefin and vinyl 
alklenecarboxylic acid is formed by partially hydrolyzing with 
concentrated sulfuric acid or other suitable acids having a sufficiently 
low Ph to effect hydrolysis, wherein the hydrolysis occurs in a solvent 
which is inert itself to hydrolysis such as an aliphatic or aromatic 
hydrocarbon. The copolymer of an alpha-olefin and a vinyl alkylene ester 
is partially hydrolyzed according to the reaction scheme: 
##STR2## 
wherein Z is a mixture of H and R.sub.3, wherein R.sub.3 is an alkyl group 
having about 1 to about 25 carbon atoms, wherein R.sub.1 is an alkyl group 
having about 1 to about 25 carbon atoms, R.sub.2 is an alkylene group 
having about 3 to about 17 carbon atoms, x is about 99.99 to about 95.0 
mole %, more preferably about 99.95 to about 97.0 and most preferably 
about 99.90 to about 98.0, and y is about 0.01 to about 5.0 mole %, more 
preferably about 0.05 to about 3.0 and most preferably about 0.1 to about 
2.0. y comprises a mixture of carboxylic acid and ester containing units, 
since the hydrolysis is only partial, wherein only a portion of the ester 
groups are hydrolyzed to carboxylic acid groups. The final hydrolyzed 
product is a mixture of ester species and acid species, wherein the 
mixture contains about 0.1 to about 45 mole% of the acid species, more 
preferably about 2 to about 40, and most preferably about 4 to about 20. 
The hydrocarbon solution of the copolymer of the alpha-olefin and the 
vinylalklenecarboxylic acid which exhibits antimisting properties is 
formed by forming a solution of the copolymer in an organic liquid, 
wherein the organic liquid which has a solubility parameter of less than 
9.5 and is selected from the group consisting of mineral oil, synthetic 
oil, alkanes, cycloalkanes and aromatics and mixtures thereof. The 
concentration of the copolymer in the solution is about 0.05 to about 2 
grams per 100 ml of organic, liquid, more preferably about 0.1 to about 
0.5. 
The method of the instant invention includes optionally incorporating a 
cosolvent in order to weaken or totally disrupt the associations which 
weld the intercomplex polymer together thereby reserving the shear 
thickening phenomonea. For example, a polar cosolvent can be added into 
the mixture of organic liquid and polymer complex, to solubilize the 
pendant carboxylic acid groups. The polar cosolvent will have a solubility 
parameter of at least 10.0, more preferably at least 11.0, and may 
comprise from 0.1 to 40, preferably 0.5 to 20 weight percent of the total 
mixture of organic liquid, ionomeric polymer, and polar cosolvent. 
There is the additional and important constraint that the polar cosolvent 
be more polar than the organic liquid. This is required in order that the 
proper interaction between polar cosolvent and ionic groups be obtained. 
If we designate the solubility parameter of the organic liquid as S.sub.L, 
and the solubility parameter of the polar cosolvent as S.sub.p, then we 
require that: 
EQU S.sub.p .gtoreq.S.sub.L +1.0 
In other words, the polar cosolvent will be substantially more polar than 
the organic liquid to be thickened. 
Normally, the polar cosolvent will be a liquid at room temperature, 
however, this is not a requirement. It is required that the polar 
cosolvent be soluble ormiscible with the organic liquid at the levels 
employed in this invention. Under normal circumstances, this miscibility 
requirement precludes the use of water as a polar cosolvent. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The following are preferred embodiments of the instant invention.

EXAMPLE 1 
Synthesis of Poly(1-octene) having alkylenecarboxylic acid side chains 
(a) Copolymerization of 1-octene and methyl-10-undecenoate 
A 2-liter flask was charged with a mixture of n-heptane (480 ml), 1-octene 
(500 ml), methyl-10-undecenoate (6.4 g), and diethyl aluminum chloride (72 
mmole), were heated to 60.degree. C. The catalyst containing TiCl.sub.3 
(2.0 g) in n-heptane (20 ml) (described in U.S. Pat. No. 4,240,928) was 
then added. After stirring for 1 hr., the reaction was terminated with a 
small amount of isopropyl alcohol. The polymer was precipitated and washed 
with isopropyl alcohol and vacuum dried at 60.degree. C. to yield 87.9 g 
of colorless material. IR spectrum showed that the copolymer contains 0.8 
mole % of methyl-10-undecenoate unit. The inherent viscosity was 4.3 dl/g 
in a decalin solution. Mn was about 4.6.times.10.sup.6 as measured by GPC. 
(b) Hydrolysis of 1-octene-methyl-10-undecenoate copolymer 
1-Octene-methyl-10-undecenoate copolymer was converted to a respective 
sample having alkylenecarboxylic acid side chains as described below. 
A solution of the copolymer (10 g) in Xylene (500 g) was placed in a 
2-liter flask and heated to 40.degree. C. Concentrated sulfuric acid (20 
ml.) was then added. After stirring for one hour, the reaction mixture was 
cooled down and washed with a mixture of water and isopropyl alcohol three 
times. A white product was obtained by precipitating from the solution 
with isopropyl alcohol. Further purification by reprecipitation and drying 
in a vacuum oven at 50.degree. C. gave 8.0 g of colorless rubbery polymer. 
IR spectrum showed that 3 percent of methyl ester group was converted into 
corresponding acid form. The partially hydrolyzed copolymer was then 
dissolved in xylene at a concentration of 1 wt percent. The resulting 
viscosity of this solution at 25.degree. C. as a function of shear rate 
was: 
______________________________________ 
Shear Rate 
Viscosity 
sec.sup.-1 
cP 
______________________________________ 
3 63 
10 72 
20 99 
30 171 
60 378 
______________________________________ 
These data demonstrate a high effectiveness in viscosification as well as 
dilatancy or shear thickening. The high viscosification can be 
demonstrated by comparing the above viscosity data to viscosity of a high 
molecular weight polyisobutylene (Exxon L-200, with a weight average 
molecular weight above 2 million) in xylene at the same concentration of 1 
weight percent. The later solution has a low shear viscosity of about 24 
cP at 3 sec.sup.-1 and is shear thinning such that the viscosity drops to 
about 14 cP at 300 sec.sup.-1. Another comparison could be made to a 
solution of the non-hydrolyzed copolymer which was used to prepare the 
above partially hydrolyzed copolymer. The viscosity of this last copolymer 
is a xylene solution at 1 weight percent concentration was about 6 cP. 
EXAMPLE 2 
Destruction of Viscosification and Shear Thickening 
A solution of a partially hydrolyzed copolymer of 1-octene and 
methyl-10-undecenoate was prepared in xylene at a concentration of 0.5 
weight percent. The copolymer was similar in molecular architecture to the 
one described in Example 1 except that it had a higher degree of 
hydrolysis conversion of about 13 percent. The viscosity of this 0.5 
weight percent solution was about 30 cP at 6 sec.sup.-1 and 420 cP at 18 
sec.sup.-1 and at 25.degree. C. After adding 0.5 percent by weight of 
methanol to the solution the viscosity dropped to about 2.5 cP. When 0.1 
weight percent of stearic acid was added to the solution rather than 
methanol the viscosity dropped to approximately the same value of 2.5 cP. 
In both cases the modified solutions exhibited a Newtonian nature. 
This example demonstrates that some polar additives such as methanol or 
stearic acid can be effective agents for reversing the viscosification and 
shear thickening exemplified by the class of materials claimed in this 
instant invention. 
EXAMPLE 3 
Flow in a Tubless Siphon For Solutions in Jet Fuel 
A solution of a partially hydrolyzed copolymer of 1-octene and 
methyl-10-undecenoate was prepared in jet fuel. The polymer was the same 
as that in Example 1 and the solution was prepared at a concentration of 
0.5 weight percent. The solution was then studied in a tubless siphon flow 
and the height at which the unsupported fluid column broke was recorded. 
The solution was then diluted to various lower concentrations which were 
also studied in tubless siphon flow. The column heights at break for the 
various concentrations of the polymer solution in jet fuel were: 
______________________________________ 
Polymer Concentration 
Column Height 
(wt %) (mm) 
______________________________________ 
0.5 16 
0.4 12 
0.3 4 
0.2 2-3 
0.1 1-2 
______________________________________ 
The siphon height at break for the 0.5 weight percent solution was changed 
from 16 mm to less than 6 mm upon addition of 1000 ppm of stearic acid. 
Since tubless siphon height has been correlated with antimisting activity, 
this example demonstrates that the polymer of the instant invention is 
expected to be an effective agent for antimisting of jet fuel by virtue of 
its ability to affect a high extensional viscosity in jet fuel solutions. 
The example also shows that a polar additive such as stearic acid can be 
effective for significantly reversing the antimisting characteristics.