Note: Descriptions are shown in the official language in which they were submitted.
0 ~ 3
1 The present invention relates to ethylene back~
2 bone copolymers, distillate oil compo~itions cQntaining
3 the copolymers, and an ~mproved method o~ preparing these
4 copolymers for use as pour depressants and flow improvers
for distillate oil, which method involves free radical po
~ 6 lymerization using an ester peroxide~ These copolymers.com-
-; 7 prise about 3 to 40 molar proportions of ethylene per one
8 molar proportion of an unsaturated monomer other than ethy-
9 lene and have number average molecular weights in t~e range
of about 1,000 to 50,000~
11 The commercially most important ethylene~contain-
: - 12 ing pour depressant and flow improvers for distillate oil
: 13 are copolym~rs of ethylene and ethylenically unsaturated
14 ester monomers, such as the copolymers of ethylene`and v~-
nyl alcohol esters, particularly vinyl acetateS which copo~
16 lymers are well known ln the prior artl For example, U~S~
17 Patent 39048,479 teaches copolymers of ethylene and C3 ~o
.~ 18 Cs vinyl esters, e~gO, vinyl acetate9 having molecular
19 weights of about 19000 to 3,000 according to K~ Rast's .
method of determining molO wto (BerO 55~ 1051~ 3727 (1922?)~
21 as pour deprèssants for fuels, specifically heating oils,
.
22 diesel and jet fuelsO The copolymers of the examples of
23 said patent were prepared by free radical catalyeis, using
24 ditertiary~butyl peroxide as the catalyst (although the
25 patent teaches any~peroxide catalyst), at temperatures of
26 280 t~340F., in a solvent~ U~S~ Patent 3,131,168 teach-
27 es a free radical process for making ethylene~vlnyl acetate
28 copolymers as pour depre~san~cs ~or middle distillate using
29 temperatures up to 440Fo ~ a solvent such as toluene or
. 30 he~ane, a~y peroxy compound as catalyst, ~.ut preferably
:
: ~ 2
~ ~ 3~ 4 ~
1 ditertiary butyl peroxide, and adding additional ethylene
2 to the reaction during the polymerization. UOS..Patent
3 3,093,623 teaches still an~t~er method for makin~ ~hese
4 ethylene-vinyl acetate pour depressants for middle distil-
lates by con~inuously adding vinyl acetate and Pthylene
6 during the course of the reaction.- U~SO Pa~ten~..3,250~714
7 teaches ethylene~vinyl acetate copolymers having molecular
8 weights of 3500 to 7000 às V.I. improvers ~or lubricat~ng
9 oils.
More recently~ British Patents 1,263,151 and
11 1,263,152 teach an improvement over the aforesa~d U.SO
12 patents by u~-ing a polymerization temperature below about
13 130C. and acyl peroxide as the initiator, as opposed to
14 the alkyl peroxide, tert. butyl peroxide, and higher tem~
peratures used by the aforesaid U.S. pa~entsO By the tech-
16 .nique of said British patents9 it was found that the amount
~17 of ethylene branching was considerably reduced and copoly-
18 mers produced by this method were generally superior pour
19 point depressant and fl~w improvers to prior art copolymers
prepared at higher temperatures with alkyl peroxidesO Spe-
21 cifically, copolymers prepared with alkyl peroxides and
22 high temperatures, while very effective in treating ~istil;
23 iate fuel oil to lower the pour point, frequently result
- 24 in wax crystals having large particle sizes ranging from
25~ one millimeter up to an inch in their largest dimension,
26 depending upon the exact nature of the distillate oil, e.g.
27 crude source9 narrowness of the boiling range, etcO While
28 the treated distil~ate oil containing these large wa~ cry
29 stals exhibits ~ pour point significantly under the origi-
nal pour point of the untreated oil, in many cases, the
-- 3 ~
,:
~ ~043Q4~
1 large wax~ crystals will tend to plug filter equipment and
2 lines norm~lly used on del-ivery trucks and fuel oil storag~
~ 3 systems when the oil is cooled below its cloud point, even
- 4 though above its pour point. Thus, as the oil containing
the pour point depressant is cooled, the cloud point (the
point a~ which the oiI becomes- cloudy due to crys~alliza~
7 tion of w~) will generally be reached at a tempera~ure sig-
8 nificantly above the pour po~nt (the point at which the oil
9 can no longer conveniently be poured). As a result, oils
below their cloud point and above their pour point will be
11 pourabLe, but at the-same time the wa~ crystals that have.
;12 formed, if too large, can result in plugging the a~oresaid
13 filter eq~ipment. Copolymerizing ethylene and vinyl ace-
14 tate at a low temperature with the acyl peroxides of said
British Patents was able to give the good pour point redu~-
. 16 tion and in addition form smaller wa~ crystals during cool-
17 ing of the treated oil.
18 The present invention represents a further im
: 19 provement over the two prior art processes noted above, i.e.
: 20 (1) using alkyl peroxide and high temperatures, or (2) acyl
21 peroxides and low temperatures. Thus, the present invention
22 uses an ester peroxide, which in general gi~es a higher
23 yield of pounds of polymer fonmed per pound of peroxide
- 24 ~han either prior art processes (1) and (2). This is im-
25 portant since the cos~ of initiator consumed is a rela~ive~
26 ly large expense in the commercial preparation of these
~27 polymers. In addition, the ester peroxide process of the
; 28 i~vention can give a polymer whlch appears to have better
29 solubility characterist~cs in oil concentrates at low tem-
peratures than similar polymers produced with the acyl per-
- 4 -
~ ~ 3~ 4 ~
1 oxide pr~cess~ i.e., (2) aboveO This characteristic ~s
2 important in handling or storage of the polymer conce~-
3 trates so that separation9 or sediment f~rmation, is avo~d-
4 ed. The effectiveness of the polymers prepared by the pro-
cess of the invention in improving the flow characteristics
6 of distillate fuel oil9 appears generally superior to the
7 polymers prepared by alkyl peroxide and abou~ equal to
8 those prepared with acyl peroxide~
9 In brief, the ester peroxides can significantly.
reduce the initiator cost, as compared to aIkyl or acyl
11 perox-ides, in the polymerizat;on, and can give polymers as
12 effec~ive in flow improvement as those prepared with acyl
13 pero~ides, but with good solubility in concentrates; and
14 can give polymers better in flow improvement than the poly-
mers prepared wi h alkyl peroxidesO
16 The polymers of the lnvention will consist essen-
17 tially of aboùt 3 to 40, and preferably 3 to 20 molar pro~
18 portions of ethylene per molar proport~on of ethylenieally
19 unsaturated monomer, which latter monomer can be a single
monomer or a mixture of such monomers in any proportion,
21 said polymer being oil~soluble and having a number average
22 molecular weight in the range of about 1,000 to 50,000,
23 preferably about 1,000 to about 5,000, as measured by Vapor
24 Phase Osmo~etry, ~or example by using a Mechrolab Vapor
Phase Osmometer Model 310Ao
26 The unsaturated monomers, ~opolymerizable with
27 ethylene, incLude unsaturated mono and diesters of the gen-
28 eral ~ormula: Rl H
.~ ~
29 C ~ C
R2 R3
304~
1 wherein Rl is hydrogen or methyl; R2 is a ~OOCR4 or ~COOR~,
2 group wherein R4 is hydrogen or a Cl to C16, pre~erably a
3 Cl to C4, straight or branched chain alkyl group; and R3 is
4 hydro~n or ~COOR4O The monomer, when R~ and R3 are hydro~
gen and R2 is ~OOCR4 includes vinyl alcohol esters of C2 to
6 C17 monocarboxylic acids, preerably C2 to C5 monocarboxy-
7 lic acids. Examples of such esters include vinyl acetate,
8 vinyl isobu~yrat , vinyl laurate, vinyl myristate, vinyl
9 palmitate, eto. When R2 is -COOR4, such e~ters include
10 method acrylate, methyl metacrylate, lauryl acryl ate, pal~
11 mityl alcohol ester of alpha~methyl acryl~ c acid, C13 ~o
12 alcohol esters of methacrylic acld, etc. Examples of mono-
13 mers where Rl is hydrogen and R2 and R3 are ~COOR4 groups,
14 include mono and di esters of unsaturated dlcarboxylic
15 acids such as mono C13 Oxo fumarate, di C13 Oxo fumarate,
16 di-isopropyl maleate, di~lauryl fumarate, ethyl methyl
17 fumarates, etc.
18 As previously mentioned, about 3 to 40 moles of
:: 19 ethylene will be used per mole of other monomer, wh~ch
other monomer is preferably an ester as hereinbefore de~
21 fined, or a mixture of about 30 to 99 mole % ester and 70
22 to 1 mole % of a C3 to C16~ preferably C4 to C14, b~anched
23 or straight chain alpha monoolefin. Examples of such ole~
24 fins include propylene~ n~octene-l, n decene-l, étc.
Xn general, the polymerizations can be carried
26 out as follows: Solvent and a portion of the unsaturated
27 ester, e.g., 0~50~ preferably 10 to 30 wto %~ of ~he total
28 amoun~ of unsaturated ester used in the batch, are charged
29 to a stainless qteel pressure vessel which is equipped with
a stirrer. The temperature of the pressure vessel is then
: - 6 -
-
1~43~8
1 brought to the desired reacti~n temperature and pressured.
2 to the desired pressure with ethylene. Then ini~iator and
3 additional amounts of unsaturated ester are added t~ ~he
4 vessel continuously, or at least periodically, during the
reaction time, which continuous addi~ion gives a more homo-
6 geneous copolymer product as compared to adding all ~he un-
7 saturated ester at the beginning of the reaction~ Also
8 during this reaction time, as ethylene is consumed in the
9 polymerization reaction, additional ethylene is supplied
through a pressure controlling regulator so as to maintain
11 the des~red reaction pressure fairly constant at all timesO
12 Following the completion of the reaction, the liquid phase
13 o~ the pressure vessel is dlstilled to remove the solvent
14 an~ other volatile constituents of the reacted mixture3
leaving the polymer as residueO
16 ~ Usually, based upon 100 parts by weight of copoly-
17 mer to be produced, then about 100 to 600 parts by weight of
18 solvent9 and about 0.1 to 5~ eOg., about .5 to 3 parts by
19 weight of initiator~ will be used.
The solvent can be any substantially non~reactive
21 organic solvent for furnishing a liquid phase reaction
22 which will not poison the ini~ia~or or otherwise interfere
23 with the reaction. Exa~ples of solvents which may be used
24 include Cs to C10 ~ydrocarbons, whioh can be aromatic such
as benzenep toluene, etc~; aliphatic such as n~eptane, n-
26 hexane, n-oc~ane, isooç~a~e~ etc.; eyeloaliphatic such as
27 cyclohexane, cyclopentane, etcO Varlous polar solvents may
28 also be used such as hydro~arbyl esters, ethers and ketones
29 of 4 to 10 carbon atoms such as ethyl acetate, methyl bu-
tyra~e, acetone, dloxane, etc. may also be used. A parti-
.
~ - 7 -
1~)4304~
1 cularly preferred sol~ent is cyclohexane which i~ easily
2 handled-an~ ~h-ich gave very good utilization of the initi-
3 ator.
4 The temperature usecl during the reaction will
generally be in the range of 150 to 350F., e.g. 200-270F.,
6 pre~era~ly about 200 to 250Fo
7 Preferred free radical ini~lators are those which
8 have a half life of less than about s~x hours at 1~0G.
9 These initiators are hyddocarbon soluble, ester peroxides
o the general formula:
11
12 R~C~O~O~R'
13 where R and R' are each hydrocarbon group~5 such as alkyl,
14 aryl, alkaryl, cycloalkyl, etcO, preferably alkyl groups,
either straight chain or branched chain, of 2 to 20, eOgO,
16 4 to 12 csrbon~atoms each. Usually the ester peroxide ~ill
17 contain a total of 4 to 24, preferably 6 to 18 carbon atomsO
18 Some specific examples of such ester peroxides ~nclude: t~
19 butyl peroxypivalate, t-butyl peroctoate (iOeO,~t~butyl
~20 pero~y~2~-ethylhexanoate)~ t~butyl peroxyisobutyrate5 t-
21 ~butyl peraceta~e, t-bu~yl perbenzoate, etc~
22 The pressures e~ployed can range between 500 to
23 30,000 psig. However7 relatively moderate pre~sures of 700
24 to about 3000 p5ig will generally suffice with vinyl esters
such as vinyl acetate~ In the case of esters having a high-
:
~- 26 ~er relative reactivi~y to ethylene, such as methyl me~tha-
27 crylate, than somewhat higher pressures~ ~uch as 3,000 to
: 28 10~000 psi have been found to give more optimum results
29 than lower pressures. In general, the pressure should be
at least suf~ieient to main~ain a liquid phase medium under
.;~ .
1~)431~48
1 the reaction conditions, and to maintain the desired con~
2 centration ~f eth~Lene in solution in-thé solvent.
3 The time of reaction will depend upon, and is in~
4 terrelated to, the temperature of the reaction, the choic.e
of catalyst~ and the pressure employed. In general, how-
6 ever, 1/2 to 109 usually 2 ~o 5 hours will complete the
7 desired réac t ion.
8 ; The polymers of the invention will generally be
9 added to distilla~e hydrocarbon oils in amounts of .001 to
2 wt. %, generally .005 to about 0.5 wt. %, said wt. J/O be-
11 ing based upon the weight of the oil to be treated.
. . .
12 The distillate hydrocarbo~ oils, which are treat-
13 ed f~r pour depression with the polymers of ~his invention,
14 inc~ude craeked and virgin distillate oils boil~ng in the
range oP 250 to 750F., such as heating oil and diesel
16 fuel oil.
17 The polymers of the invention may be used alone
18 as the sole oil additive, or in co~b~nation with o~her oil
19 additi~es such a~ other pour depressants or dewaxin~ aids;
corrosion inhlbitors; antioxidants; sludge inhibitors;- etc.
21 ~XAM~LE I
22 A stirred autoclave was charged with 4500 ml. of
23 cyclohexane as solvent and 500 ml. of vinyl acetate. The
24 autocIave was then purged with nitrogen and then with ethy-
lene. The autoclave was then heated to 105C. (about 220F.)
26 while et~ylene was pressured into the autoclave until the
27 pressure was raised ~o 1050 psigo Then, while maintaining
28 a temperature of 105C. and said 1050 psig pressure~ 1249
29 ml. of vinyl acetate was injected a~ a constan~ rate over
a two hour 2criod. At the same time3 30 grams of t~butyl
-- g _
. .
~0 4 ~V ~
1 peroctoate diluted with 757 ml. of cyclohexane was al50
2 slowly pumped into the reactor over the two hour period
3 a~ a constant rate. At the end of said two hour period,
4 and after the last o~ said vinyl acetate and peroxide was
injected, the batch was maintained a~ 105C. for an addi-
6 tional 10 minutes. Then, the temperature of the reac~or
7 contents was lowered to about 60Co~ the reactor was de-
8 pressurized, and the con~ents were discharged ~rom the-
9 autoclave. The product was then stripped o~ the solvent
and unreacted monomers. The f~nal stripped product C0~8-iS-
11 ted-of about 1577 grams of copolymer of ethylene and vinyl
12 ace~ate.
13 ~XANPLES II T0 VII
14 Examples II to VII were carried out following
the general procedure of E~ample I, except ~hat changes in
16 pres~ure, temperature, or amount of peroxide wçre made.
17 COMPARISON EXAMPLES A A~D B
18 These comparison examples were carried out using
19 the same general technique as in Example I, except that
54.5 grams of dilauroyl peroxide, usually designated as
21 lauroyl peroxide (an acyl peroxide)~ was used in place of
22 the 30 gra~s o~ tert~ butyl peroctoate. Al~o, the lauroyl .
23 peroxide (as it is a solid) was added as a solution dissol-
24 ved in 757 ml. of cyclohe~ane so it sould be pumped.
Concentrates of all the above polymers were made
26 by dissolving 45 wt. % of ~he polymer in 55 wt. % of a
27 heavy aromatic naph~ha (HAN) for ease in further handling.
28 The polymers were tested for flow imprQving abil~
29 ity at temperatures below the cloud point in a "Cold ~ilter
Plugging Point Test" (CFPPT) which i~ described in detail
- 10 -
~6~4;~ 8
1 in Journal of the Institute of Petrol~um, Volume 52, Nu~ber
2 510, June 1966, pp. 173;18S. In brief, the Cold Filter
3 Plugging Point Test is carried out with a 45 ml.-sample of
4 the oil to be tested which is cooled in a bath maintained
at-ab~u~ -30F. Every ~wo degrees drop in ~emperature~
6 starting from 4F~ a~ove the cloud point, the oil is tested
7 with a test device consisting of a pipette to whose lower
8 end is attached an inverted funnel. Stretched across the
9 mouth of the funnel is a 350 mesh screen having an-area.of
about 0.45 square inch. A ~acuum of abou~ 7" of water ls
11 applied to the upper end of the pipette by means o a va~
12 cuum line while the screen is immersed in the oil sampLe~
13 Due ~o th~ vacuum, oil is drawn across ~he screen up into
14 the pipette to a mark indicating 20 ml. of oil. The tes~
is repeated with each ~wo degrees drop in tempera~ure un~
16 ~il the v~cuum fa~ls to fill the pipette to the aforesaid
17 mark due to clogging of the screen with wax crystals. The
18 results of the test are reported as the "operability limit"
19 or cold filter plugging point (CFPP), which is the tempera~
ture at which the oil no longer flows.
21 Test Fuel A was a diesel fuel boiling in the
22 range of about 17Z to 353C., having a cloud point of -3C.,'
23 an aniline point of 73C., a specific gravity o 0.8193
24 and a viscos~ty of 2.64 cs. at 100F. This fuel in the
CFPPT ga~ a plugging poin~ of about +28F.
26 A series of blends of 0.02 wt. % of the afore-
27 ~aid polymer concentrates in Fuel A were made up and then
28 tested in duplicate using the CFPPT procedure. The f.ollow-
29 ing Table summarizes the preparation details of the afore-
said Example~, and Compari~ons A and B, along with the
16~43~4B
1 yLelds and eiiectiveness in Test Fuel A.
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- 13 -
~04304~ 1
1 As seen from the Table, the use of the t~butyl
2 peroctOate (i.e., t-butyl peroxy 2-ethyl-hexanoate) ga~e
3 higher yields of polymer per amount of ini~iator than the
4 dilauroyl peroxide. Specifically, ~xamples I to VII gave
yields r~nging from 50.9 to 145 grams of polymer per gram
6 of initiator, as compared to the dilauroyl peroxide which
7 in Comparisons A and B gave 36.5 and 36~1 grams of polymer
8 per gram of initiator, respectivelyO Since the molecular
9 weight of the peroctoate peroxide is about 54% that of t~e
dilauroyl peroxide, one could have expected ab~utan 85%
11 lncrease in yieldO Yet, Examples V to VII show a much
12 greater yield using the peroctoate than would have been
13 expected from mere molecular weight differences. At the
14 same time, the se~s of duplicate runs in the CFPPT show
that about comparable flow improvement could be obtained
16 with the polymer prepared by the peroctoate as opposed to
17 the dilauroyl peroxide.
.
~ - 14 -
