Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF INVENTION
Tnis invention relates to a metho~ of produclng
improved novel interpol~meric poly(n-alkylacrylate) pour
depre6sor, to the pour depressors per se and to wax con-
- taining petroleum fractlons of reduced pour point having `
incorporated therein a pour depressing amount of sald pour
depressor . , - .:. -, .
:, :
Heavy wax petroleum fractions, e.g., residual
fuel oils, lubricating oil, crude oils and vacuum gas oils
10 having a pour point between about 40 and 1~0F. and a macro- ; -
crystalline paraffin wax content aDove 4 wt. % often requlre
the use of additives when employed in "cold climates" or
exposed to low temperatures to maintain their fluidity or to
meet critical pour point speclfications. Additives that are
effective for this are called pour depressors. The art dis-
closes numerous classes of pour depressors. One of the most
ef~ective pour depressors found in significantly reducing s~
the pour of macrocrystalline wax containing heavy petroleum
fractions are the interpolymeric poly(n-alkylacrylate) of a
- 20 molecular weight-between about 3000 and 100,000 wherein the
alkyl portion is of at least 18 carbons and at least 70 wt. -
% of the alkyl is of Detween 20 and 24 carbons incluslvely,
the C20 to C24 alkyl group containing between aDout 2 and
6~ wt. % of C2U alkyl, between about 18 and 65 wt. % C22 `~
alkyl, and between about 8 and 35 wt. ~ C24 alkyl and was
prepared employing a free radical polymerization catalyst -
which i6 added in a si le addition at the initiation of
polymerization.
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Although the aforementioned prior poly(n-alkyl-
acrylate) is a superior pour depressor, thare is a contlnuing
; search for still further lmproved pour depressors, that is,
a maximized pour depression for a given adaitive quantity.
SUMMARY OF INVENTION
have discovered and this constltutes my inven-
. ,.
tion a novel method for producing poly(n-alkylacrylate)
-~ pour deprecsors which results in a novel pour depressor of
improved pour depressing properties and improved pour de-
pressed waxy petroleum fractions. More specifically, my
invention pertains to the dlscovery tnat in the free radical
catalyst polymerization preparation of poly(n-alkylacrylate)
multlple time-spaced addltions of catalysts in the polymeri-
zation as opposed to a single addition of equal catalyst
quantity produces a final polymer product of a molecular -~
distribution substantially different from the molecular
distribution of the poly(n-alKylacrylate) produced from a
single catalyst addition and wherein the former has superior
pour cepressing properties over the latter. It lS theorized
the multi-addition molecular distribution more effectlvely
interferes with or alters the growtn of paraffin crystals
in the petroleum fraction to be pour depressed and thus
more effectively lowers the pour point o~ the waxy petroleum
fractions. I
.'
DETAILED DESCRIPTION OF THE INVENTION
The method of the invention comprises first form-
ing a mixture of n-alkylacrylate monomers prepared through
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the reaction of acrylic acid with n-alkanol mlxtures
wherein the reactive n-alkanols have at least 18 carbons and
70 wt. % thereof in the alkanol group of from 20 to 24 car-
bons, sald group consisting of between about 2 and 65 wt. %
of eicosanol, between about 18 and 65 wt. % docosanol and
between about 8 and 35 wt. % tetracosanol. A standard means -
can be employed to produce the poly(n-alkylacrylate) monomer
3~. .
reaction mixture, namely, by reacting (esterifying) the
aforementioned alcohol mixture with acrylic acid ln the
presence of an esterification catalyst such as p-toluene- -
sulfonic acid and a polymerization inhibitor, e.g., hydro-
quinone, desirably in the presence of an azeotroping agent
for water by-product removal such as benzene. Esterification
is conducted, for example, at a temperature between 85 and
95C. and is continued until the amount of water by-product
is removed as overhead indicates that esterification is . ~-
- ~ - .
essentially complete. The resultant product is a mixture of i
n-alkylacrylate monomers and the alkyl distribution therein
: .
is the same as the alkyl distribution in the alkanol reactant.
In the preparation of the interpolymer poly(n-
alkylacrylate), the aforedescribed n-alkylacrylate monomer
mlxture ls optlonally diluted with an inert organic solvent
such as benzene, toluene, xylene or petroleum naphtha, pre-
ferably greater than about 40 wt. % solution. The diluted or
preferably undiluted monomer mixture is then heated to a
temperature of between about 60 and 120C., advantageously
under a blanket of inert gas such as nitrogen to prevent
undesired oxidative side reactions and preferably employing
agitation such as stirring or bubbling nitrogen gas through
the reaction mixture. During the period of the reaction
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free radical polymerizatlon catalyst is lntroduced ln at
least two separate time spaced additions and up to 10 or more
spaced additions, preferably between about 3 and 5 additlons,
~- advantageously each catalyst additlon belng essentially
equal or greater than any subsequent addition in amount.
Under preferred conditions, when the polymerization essenti-
ally ceases following a catalyst addition as indicated by a
levellng off of the refractive index the next catalyst addi-
tion is in order. The polymerization reaction period after
the last catalyst addition is normally continued until the
refractive index remains essentially constant~ that is, +
1.5 units in the fourth decimal, the refractive index being
taken at periodic intervals. Normally, the polymerization
period ranges between about 1.0 and 15 hours, preferably
between about 1.5 and 7 hours.
- At the end of the polymerization period, the
inert solvent, if employed, is removed by distillatlon
otherwise no further workup of the interpolymer product is
generally necessary. The resultant poly(n-alkylacrylate)
polymer product has an n-alkyl moiety distribution throughout
the monomer reactant mix essentially the same as the n-alkyl
distrlbution in the alcohol precursor utilized to manufac-
ture the n-alkylacrylate reactant.
One suitable source of precursor alco~q~mixtures
~d~c ~glf~ls~
are the alcohols sold under the tradoname "AlfolE" by
Continental Oil Company. "Alfols" are impure mixtures con-
taining as the ma~or portion, greater than 50 wt. % n-
alkanols of various chain lengths, the remainder consisting
of hydrocarbons, ketones and hindered unreactive alcohols.
Typical analysis of two suitable examples of the "Alfol"
alcohols are as follows: ;
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-~ Typical Properties Alfol 20+R Alfol 22+R
Approx. homolog distribution
100% alcohol basis, wt. %
C18 2 1 .-
C22 20 60
C24 lo 21
C26 5 9
C28 3 4 -
Alcohol Content, wt. % approx. 70 60 - .
Hydroxyl No. 123 90
Hydroxyl No. 100% alcohol basis 176
Sap. No. 3 6 -
I2 No. 12 13 : ~ `
Carbonyl, wt. % (as C = 0) 0.2 0.3 ,!,. , ':
- Melting range, C. 45-58 45-58
Color, Gardner 12 18
The amount of free radical catalyst employed may
range between about 0.1 and 5 wt. %, preferably between about
0.5 and 2 wt. % basis the monomer reactant. Any of the free
radical liberatlng type of polymerization initiator catalyst
may be employed, but those that are especially suitable are
the azo initiators taught in U. S. Patent No. 2,471,959 and
perioxide and hydrolperoxide initiators.
Although all of the azo catalyst set forth in U. S.
2,471,959 are suitable in the polymerization procedure con-
templated herein, those most particularly suitable are the -
alpha-alpha-azobis(cyanoalkane) wherein the cyano alkyl
` 30 groups are of each from 4 to 11 carbons and particularly
where each carbon attached to both azo and cyano groups is
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tertiary. Examples of such azo compounds are alpha-alpha'
bisisobutyronitrile, alpha-alpha'-azobismethylbutyronitrile,
alpha-alpha'-azobisethylbutryonitrile, alpha-alpha'-azobis-
hexylpropionitrile.
Examples of the peroxide and hydroperoxide free
radical catalysts are the dialkyl peroxides, diacyl per-
oxides, benzoyl peroxides, such as diacetyl peroxides, dido-
decyl peroxide, diethyl peroxide, di-t-butyl peroxide,
caproperoxide, t-butyl perbenzoate, di-t-butyl diperphthal-
ate, diacetyl peroxide and their hydroperoxide counterparts.
One embodiment of the invention are the pourdepressed waxy heavy fuel fractions containing a pour
depressing amount of the novel poly(n-alkylacrylate) of
products of the method of the invention. Utilizing the
products of the invention, pour depressing effects in the
heavy petroleum fractions are sometimes evidenced in amounts
as small as about 0.01 wt. % and quantities up to 3 wt. %
are usually sufficient. Desirably, quantities ranging be-
tween about 0.04 and 0.5 wt. % polyacrylates are employed.
To facilitate blending of the polyacrylate product to the
petroleum fraction, the polyacrylate may be diluted with
solvent such as a light gas oil of a kinematic viscosity
(cs.) of between about 2 and 4 at 100F. to form between
about a 10 and 50 wt. % polyacrylate lube oil concentrate.
In compounding the waxy heavy petroleum fraction
compositions of the invention, it is essential that the
polyacrylate pour depressor be introduced into the fractlon
at a temperature above the solution point of the macro-
crystalline paraffin wax component. Usually a temperature
of about 200~F. or more is required. If the polyacrylate
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is contacted with the wax petroleum component at a tempera-
ture substantially below the solution point oP a substantial
portion of the wax, there is little or no pour depressing
. effect by the polyacrylate.
The heavy petroleum base fractions contemplated
herein are a macrocrystalline wax content of between about :-
4 and 15 wt. ~, and a pour point of the order of 40-130F.
Examples of these fractions are residual fuel oils, vacuum - -
gas oils and lubricating oils of a boiling point range of
between 400-1100F. (vacuum or atmospheric) meeting the
foregoing wax content and pour point and are more fully
described in the aforementioned, coassigned related appli-
; cations.
- The following examples further illustrate the
method, product and composition of the invention but are not
to be construed as limitations thereof.
- EXAMPLE I
This example illustrates the manufacture of the
n-alkylacrylate monomer reaction mixture.
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Monomeric n-alkylacrylates of two alcohols were
prepared. Composition of these alcohol precursors are as
follows:
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Typical Properties Alkanol A Alkanol B
Approx. homolog distribution
100% alcohol basis, wt. %
n-C18 5 0
n-C20 39 12
n-C 27 47
22
n-C 4 14 21
n-C 7 10
26
28 3 5
Alkanol Content, wt. % 70 60
Hydroxyl No. 123 90
Hydroxyl No., 100% alcohol basis 176 90
Sap. No. 3 6
2 12 13
Carbonyl, wt. % (as C=0) 0.2 0.3
Melting Range, C. 45-55 45-55
-Color, Gardner 12 18
The charge materials in the monomer process are
20 as follows: ~
Material Wt. (g) Moles ~ -
Hydroqulnone 2 0.02 j`
p-Toluenesulfonic acid 5.6 0.036
Alcohol A (Run 1) 952 2
Alcohol B (Run 2) 1245 2 j-
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Acrylic acid, glacial 144 2
Benzene 536 - ~ ;
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All the above charge except the acrylic acid was
melted under nitrogen at about 60C. (140F.). The acrylic
30 acid was then added with stirring and the mixture brought ~ ~
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to reflux with a pot temperature of about 90C. (194F.).
- Air was introduced below the surface of the liquid reaction
mixture at a rate of between about 40 and 45 mls./minute as -
the water of the reaction was azeotroped off at a reflux
rate of 4 mls./minute. About 96 wt. % of the theoretical
amount of water was removed in 12 hours and all the water
was removed in 21 hours. Benzene was removed by stripping
the product to 15 mm Hg. pressure at a pot temperature of
about 160C. (320F.).
The product was a monomer mixture of n-alkyl
acrylate wherein the n-alkyl distribution therein was essen-
tially the same as the alkyl distribution in the alkanol
reactive portion of the alcohol precursor.
Physical data for the monomer mixture products
were as follows:
., .
Physical Data Mono- Mono-
For Monomer Acrylate A Acrylate B
Sap. No. 115 95
Neut. No. 1.3 1.1
20 Hydroxyl No. 8 14
Sp. Grav., 150F./60F. 0.8316 0.8310
Refractive Index 1.4450 1.4465
Kin. Visc., cs. 150F. 7.39 8.84
210F. 3.90 4.50
Dialysis Residue, wt. % 3 3
Melting Point, C. (approx.) 36 49
.. . .
~ EXAMPLE II
,~ This example illustrates the method of the
invention, the products resulting therefrom and pour de-
30 pressed compositions containing the poly(n-alkylacrylate)
_g_
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pour depressors manufactured by the method of the inventlon.
In three separate runs 200 grams of Monoacrylate
A prepared in Example I were heated to 85C. (185F.) under
prepurified nitrogen introduced into the reaction system at
a rate of30 mls./minute. The further procedure in each of
the three runs was as follows, Run 1 and 2 representative
of the method of the invention and Run 3 being comparative
method. The runs are as follows:
1. Run 1 - The reaction period was for 7 hours
and a total of 3 additions of azobisisobutyronitrile i~ a
total amount of 1 wt. % was added during this 7 hour period.
There was initially added 0.5 wt. % catalyst. At the third
hour of reaction the refractive index became constant and
there was added an additional 0.25 wt. % of catalyst. At
the 4.5 hour of reaction the refractive index again became
constant and an additional 0.25 wt. % of catalyst was added. ~'
The polymer product was designated as Polyacrylate 1. ~ - -
2. Run 2 - Four additions of azobisisobutyroni- ;~
trlle were made in this run over a 6 hour 45 minute period.
Initially there was added 0.25 wt. % catalyst. At the end ~,
of two hours an additional 0.25 wt. % was added. At the
end of 4 hours and 40 minutes an additional 0.25 wt. % was
added and at the end of 6 hours and 45 minutes an additional
0.25 wt. % was added. The reaction was conducted for a
total period of ~0 hours. The polymer product was designated
as Polyacrylate 2. ,
3. Run 3 - In this comparative run there was
only one addition of the azoisobutyronitrile catalyst and
thls was introduced at zero hours of reaction. The reactlon
period was for 3 hours. The polymer product was designated
as Polyacrylate 3. -
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In all the foregoing three procedures the reac-
tion mixture was continuously stirred and periodic refrac-
tive index measurements of the mixture were taken. The
reaction was continued until the refractive index remained
constant after the final catalyst addition, the refractive
index being deemed constant when the variation is less than
+ 1.5 units in the fourth decimal place.
The products prepared were cooled and analyzed
and the resultant (poly(n-alkylacrylate) gave the following ~-
analysis:
Physical Data Poly- Poly- Poly-
(Av. Value) Acrylate 1 Acrylate 2 Acrylate 3 ,
RI at 54C . 1.4545 1.4545 1.4545
Sp. Grav., 150F./60F. 0.8580 0.8573 0.8580
Melting Point, C. (approx.) 43-44 43-45 39
Kin. Visc., cs 150F . 222.5 206.1 196
210F. 91.9 85.6 81
Dialysis, wt. % Residue 58 55.3 42
Melting Point of 47-51 47-51
20 Dialysis Res., C (approx.)
Mol wt. of Dialysis 24,200 28,000 29,000
Residue*
*Membrane Osmometry
The distribution of the alkyl groups in the polymer was
essentlally that found in the reactive n-alkanol of the
alcohol precursor reactant.
The re~ultant polyacrylate products were diluted
with a light hydrocarbon oil having a pour point of about
0F. and a kinematic viscosity at 100F. of about 3 to form
30 a 25 wt. % oil concentrate solution of the polyacrylate.
The compositions were then prepared by incorporating the
formed polyacrylate concentrates in a heavy waxy residual
- ~
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fuel oil fractlon comprising 50 volume % macrocrystalline
wax containing vacuum petroleum residuum and 50 volume %
non waxy hydrotreated gas oil having a boiling point of
between about 400 and 652F., an API gravity of 35.3 and a
pour point of about -5F. The waxy base fuel fraction
(F-30) had the following propertles:
Physical Tests Results
Pour Point, F. 85
Wax Content, wt. % 12.7
10 SUS Visc. at 150F. 70.2 ~
API, Gravity 24.1 ~ -
Wt. Sulfur 0.18 `
In the preparation of the polyacrylate contain-
ing residual fuel compositions, the following procedure -~
was employed.
The petroleum vacuum residuum component of the
fuel fraction was heated to 200F. with stirring for ~ ;~
1/2 hour during which time the polyacrylates prepared above
were added. Subsequently, the hydrotreated gas oil was
blended into the mixture at 150F. followed by stirring at
155F. for an additional 0.5 hour.
The effectiveness of the three polyacrylates
(PAA), that is, representative Polyacrylates 1 (PAA-l) and
2 (PAA-2) and comp~rative Polyacrylate 3 (PAA-3) in depress-
ing the pour point of the waxy fuel is set forth below in
the following table and demonstrates the superiority of the
polyacrylates formed from the method of the invention
utilizing multiple free radical catalyst addition as
opposed to the polyacrylate prepared by the single catalyst
30 addition prior method. The pour points in the following !~
-12-
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table were measured in accordance with ASTM Tests D-97.
Further, the pour points were measured after 5 days, 7 days,
12 days and 44 days. The test results are as follows:
-----Pour Point, F., after--------
Polymer
Conc. wt.% Avg. 5 Days 7 Days 12 Days 44 Days
Sample
PAA-l 0.07 50 45 55 5 5
0.06 45 50 55 45 35
0.05 60 55 70 70 55 ~ -
0.04 65 65 70 75 55
-3 60 60 75 75 35
0.02 70 65 75 75 65 -
0.01 74 65 85 75 80
PAA-2 0.07 4 35 5 45 35
o.o6 50 55 70 40 35 -
0.05 50 55 55 50 35
0.04 60 50 70 65 55
0.03 60 50 70 65 55 ;
0.02 65 65 70 60 65
0.01 80 75 85 85 85
PAA-3 5 65 65 80 60 60
0.03 80 80 80 80 75
.., . `' .
I EXAMPLE III
This example further illustrates the method,
product and composition of the invention.
The procedures, materials out llned ln Example
II were essentially employed with the followlng modifica-
tions.
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Two polyacrylates were prepared representative
Polyacrylate 4 (PAA-4) prepared by the multiple catalyst
addition method of the invention and comparative Polyacrylate
5 (PAA-5) prepared by the single catalyst addition method: -
1. Run 4 - The total reaction period was 10 hours
and a total amount of 0.92 wt. % azobisisobutyronitrile was
added to the polymerization mixture. There was added to 0.62
wt. % catalyst initially followed by 0.1 wt. % additions
after 3.5 hours, 5 hours and 7 hours. ~ ~
2. Run 5 - In the comparative run all the cata- ~ -
lysts, namely, 0.92 wt. % was added initially and the reac-
tion period was for 3 hours.
The prepared Polyacrylate 4 (PAA-4) and 5 (PAA-5)
respectively from Runs 4 and 5 gave the following analysis: :
Physical Data .
(Av. Value) PAA-4 PAA-5 -
RI at 54C. 1.4545 1.4545 -~
Sp. Grav., 150F./60F. 0.8642 0.85Bo
Melting Point, C. (approx.) 42-43 39
20 Kin. Visc., cs 150F. 430.9 196
210F. 168.5 81
Dialysis, wt. % Residue 60.9 42
Mol. wt. % of Dialysis Residue 29,000 29,000 ~-
Melting Point Dialysis 43-46
Residue, C. (approx)
The n-a~kyl distribution in the respective Poly-
acrylates 4 and 5 was of Alcohol A described in Example I.
Representative PAA-4 and comparative PAA-5 were -
incorporated in the residual fuel oil base fraction descrlbed
~ . . . .
in Example II in the manner described therein and the pour
points of the resultant compositions were measured over a
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period of 5 to 12 days. The following data illustrates the
superior properties re pour depressing of the product result-
ing from a multiple catalytic addition as opposed to one pre-
pared from a single dose. The results are as follows:
-----Pour Point, F. after------- . - .
Polymer
Conc. wt.% Avg. 5 Days 7 Days 12 Days
Sample
PAA-4 0.07 30 35 3 25
0.06 35 35 45 30 ~ :
0.05 45 45 45 45
0.04 35 40 35 25
0.03 40 35 4 5 :~
0.02 65 70 55 ~0
0.01 80 80 80 85
PAA-5 0.05 50 40 55 50
0.03 55 45 60 55
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