US 3817866 A
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United States Patent 3,817,866 ALKYLACRYLATE-ALKANEDIOL METI-IACRY- LATE INTERPOLYMERS AND POUR DE- PRESSED COMPOSITIONS THEREOF Roy Isamu Yamamoto, Wappingers Falls, and George S. Saines, Fishkill, N.Y., assignors to Texaco Inc., New York, N.Y. No Drawing. Filed Nov. 24, 1972, Ser. No. 309,585 Int. Cl. (310m 1/28 US. Cl. 252-56 R 2 Claims ABSTRACT OF THE DISCLOSURE An interpolymer of an n-alkylacrylate mixture and an n-alkanediol dimethacrylate of from to 18 carbons, said interpolymer having a weight ratio of said n-alkylacrylate mixture to said alkanediol dimethacrylate of between about 99.5:0.5 to 95:5 and a molecular weight between about 3000 and 100,000 and wherein the alkyl in said n-alkyl mix is of at least 18 carbons and at least 70 wt. percent of said alkyl is between 20 and 24 carbons inclusively, the C to C alkyl group consisting of between about 2 and 65 wt. percent of C alkyl, between about 18 and 65 wt. percent C alkyl and between about 8 and 35 wt. percent C alkyl; and a waxy heavy petroleum fraction containing between 4 and wt. percent macrocrystalline paralfin wax having incorporated therein a pour depressing amount of said interpolymer wherein said interpolymer is initially introduced in the waxy heavy petroleum fraction at a temperature above the solution point of the macrocrystalline wax component therein.
BACKGROUND OF INVENTION This invention relates to a novel interpolymer n-alkylacrylate mixture-alkanediol dimethacrylate pour depressor and to macrocrystalline wax containing heavypetroleum fractions of reduced pour point containing said pour depressor.
High wax containing heavy petroleum fraction employed in cold climates or exposed to low temperatures frequently require the use of an additive to maintain their fluidity or to meet critical pour point specifications for the oil for the fraction in question. Additives that are effective for this are called pour depressors. The art discloses numerous classes of pour depressors. One class of commonly used pour depressors are high molecular weight organic compositions prepared by the alkylation of benzene, naphthalene or derivatives thereof and by the polymerization of low molecular weight methacrylates. These common additives have not been found entirely suitable because of their high cost, high concentration required or because they are ineffective in reducing the pour point of macrocrystalline parafiin wax containing heavy petroleum fractions.
Although a wide variety of different pour depressants mentioned above are useful for incorporation in heating oils, fuels, and many other liquid hydrocarbon oils, they have been found generally to be ineifective in decreasing the pour point of parafiinic (macrocrystalline) wax containing heavy petroleum fractions. The poor performance of these additives may result from the structural differences of waxes occurring in the petroleum fractions derived from different locations. It is well known, for example, that acrylate and methacrylate monomers of alkanols having 10 to carbons can be polymerized to make high molecular weight products which are soluble in the heavy petroleum fractions and are generally capable of improving pour points of a variety of fractions. However, with the macrocrystalline wax containing fractions these materials are either ineffective or do not provide the pour point reductions required.
In coassigned, copending application, Ser. No. 250,900, filed May 8, 1972, there is disclosed a poly(n-alkylacrylate) pour depressor which is effective in substantially reducing the pour point of macrocrystalline wax containing heavy petroleum fractions. Although this prior pour depressor functions satisfactorily in reducing the pour point of Wax containing heavy petroleum fractions, there is a continuing search for even more effective pour depressors in reducing the pour point of macrocrystalline paraflin wax containing heavy petroleum fractions.
SUMMARY OF INVENTION We have discovered a novel interpolymer having superior properties in reducing the pour point of macrocrystalline wax containing heavy petroleum fractions and to the heavy petroleum fractions containing the novel pour depressor. More specifically, we have discovered the incorporation of a minor amount of alkanediol dimethacrylate of from 10 to 18 carbons in the polymerization of an n-alkylacrylate mixture, wherein the n-alkyl is of at least 18 carbons and at least 70 wt. percent of said n-alkyl is between 20 and 24 carbon inclusively, the C to C alkyl group consisting of between about 2 and 65 wt. percent of C alkyl, between 18 and 65 wt. percent C alkyl and between about 8 and 35 -wt. percent C alkyl, results in a cross-linked interpolymer which is substantially superior in depressing the pour point of heavy waxy petroleum fractions than interpolymers derived from the n-alkylacrylate mix alone.
DETAILED DESCRIPTION OF THE INVENTION The interpolymeric pour depressors contemplated are the interpolymers of n-alkylacrylate mixture, an alkanediol dimethacrylate of from 10 to 18 carbons, said interpolymer having a molecular weight between about 3000 and 100,000, preferably between 4000 and 52,000, most preferably between 15,000 and 35,000, said n-alkyl in said mix being of at least 18 carbons, at least 70 wt. percent of said n-alkyl being of from 20 to 24 carbons, the C to C alkyl group consisting of between about 2 and 65 wt. percent C alkyl, between about 18 and 65 wt. percent C alkyl and between about 8 and 35 wt. percent C alkyl, said alkylacrylate mixture and dimethacrylate monomer components being present in said interpolymer in a weight ratio of between about 99.5 :0.5 and :5.
The interpolymers are derived from normal bulk polymerization techniques such as polymerizing the alkylacrylate-alkanediol methacrylate monomers in the presence of a free radical polymerization catalyst, e.g., azo catalysts such as azobisisobutyronitrile of US. Patent No. 2,471,959 or the well known peroxide catalyst such as benzoyl peroxide and lauroyl peroxide utilizing catalyst quantities of between about 0.1 and '5 wt. percent. Polymerization is normally conducted at a temperature between about 50 and 150 C., preferably between about 80 and C., utilizing a nitrogen blanket to prevent oxidation and free radical catalyst deterioration. During polymerization normal periodic sampling is taken for refractive index (RI) determination. The polymerization reaction is continued until the refractive index remains relatively steady, that is, i 3 units in the fourth decimal place. The reaction time is normally between about 1 and 10 hours.
The n-alkylacrylate mixture employed in the preparation of the pour depressors contemplated herein are prepared by standard esterification techniques through the reaction of a acrylic acid with n-alkanol mixtures wherein the reactive n-alkanols in said mixtures have at least 18 carbons and at least about 70 wt. percent of the n-alkanol portion is of from 20 to 24 carbons, the C to C group consisting of between about 2 and 65 wt. percent eicosanol, between about 18 and 65 wt. percent docosanol and betwen about 8 and 35 wt. percent tetracosanol. One suitable source of alcohol mixtures are the alcohols sold under the tradename Alfols. Alfols are impure mixtures containing the major portion, that is, greater than 50 wt. percent n-alkanols of various chain lengths, the remainder consisting of hydrocarbon ketones and hindered unreactive alcohols. Typical analysis of two suitable examples of the Alfol alcohols are as follows:
Examples of the alkanediol dimethacrylate component contemplated herein are the dimethacrylate derivatives of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,6-hexylene glycol, 1,4-octylene glycol and 1,10- decylene glycol.
A standard means of n-alkylacrylate monomer mixture preparation is reacting (esterifying) the alcohol mixture with acrylic acid in the presence of an esterification catalyst such as p-toluene sulfonic acid, desirably in the presence of an azeotroping agent for water by-product removal such as benzene. The esterification is conducted, for example, at a temperature between about 85 and 95 C. and is continued until the amount of water by-product removed as overhead indicates that esterification is essentially complete.
In the compounding of the pour depressed waxy heavy petroleum fractions of the invention, it is essential that the poly(alkylacrylate-alkanediol dimethacrylate) interpolymer pour depressor be introduced into the fraction at a temperature above the solution point of the macrocrystalline paraffin wax component therein. Often temperatures of above 200 F. or more are required for blending. If the interpolymer pour depressor is contacted with waxed component at temperatures substantially below the solution point of a substantial portion of the wax, there is little or no pour depressing effect afforded by the interpolymer.
As heretofore stated, the base petroleum fractions in the compositions contemplated herein have a Wax content betwen 4 and 15 wt. percent and a pour point of between 40 and 130 F. The contemplated distillate fractions normally have a boiling point between about 400 and 1100+ F. under atmospheric or reduced pressure, e.g., between about 15 and 760 mm. Hg. Specific examples of said fractions are crude oils, residual fuel oils, lubricating oils and vacuum gas oils having the aforementioned properties.
The concentration in which the poly(alkylacrylatealkauediol methacrylate) interpolymers are incorporated in the petroleum fraction base will be widely varied since it is dependent on the nature and the quality of fraction and the degree of pour depressing required. Pour depressing efiect is sometimes evidenced in amounts as small as 0.01 wt. percent and quantities of up to about 3 wt. percent are usually suflicient. Desirably, the waxy fraction contains between about 0.04 and 0.5 wt. percent interpolymer. To facilitate blending of the interpolymer into the petroleum fraction, the interpolymer may be diluted with a solvent such as a light gas oil of a kinematic viscosity (cs.) of between about 2 and 4 at 100 F.
to form between about a 10 and 50 wt. percent lube oil concentrate.
The following examples further illustrate the product and composition of the invention but are not to be construed as limitations thereof.
EXAMPLE I This example illustrates the manufacture of the nalkylacrylate mixture component utilized in the preparation of the pour depressing interpolymers contemplated herein.
The alcohol utilized in the preparation of the monomers mix herein was designated as Alcohol A and is of the following analysis:
Typical Properties (Approx. homolog distribution alcohol basis,
wt. percent): Alcohol A I1-C18 5 n-C 39 n-C 27 H-C24 n-C 7 Iii-C2 3 n-C3o 5 n-alkanol content, wt. percent 70 Hydroxyl No. 123 Hydroxyl No., 100% alcohol basis 176 Sap. No. 3 I No. 12 Carbonyl, percent (as C=O) 0.2 Melting range, F. 113-135 Color, Gardner 12.
To a 3 liter round bottomed flask equipped with an overhead stirrer, trap, condenser, thermometer, heating mantle, nitrogen-air inlet tube, and drying tubes, there was charged 816 grams of Alcohol A, 487 grams of benzene, 5.6 grams of p-toluenesulfonic acid, 0.44 grams of hydroquinone and 0.44 grams of methylether hydroquinone. The mixture was brought to reflux for one hour while purging with 40 mls./minute of prepurified nitrogen and stirring. Water entrapped in the alcohol in the system was separated and discarded. The mixture was cooled to about 65 C. and 158.4 grams of acrylic acid were added. After bringing the mixture to reflux, -40 mls./minute of dry air was introduced below the surface of the liquid instead of nitrogen. After 14.5 hours, 29 mls. of water (83% of theory) had been recovered and the reaction was terminated. Nitrogen was again introduced at a rate of 40 mls./minute while the pot temperature was reduced from 97 to 65 C. The reaction mixture was then washed with mls. of water, which was preheated to 65 C., using a stirring speed of about 60 r.p.m. and the mixture was further worked up utilizing a separatory funnel to separate the organic layer. Benzene and residual water from the organic layer was removed by stripping the product to 15 mm. Hg pressure at 60 C. A resultant mixture of n-alkylacrylate was recovered in an amount of 882 grams designated as Monoacrylate A and gave the following The percentage distribution of the n-alkylacrylate monomers in Monoacrylate A was essentially the same distribution as the alcohol distribution found in the starting Alcohol A mixture, i.e., about 5 wt. percent C n-alkylacrylate, 39 wt. percent C n-alkylacrylate, 27 wt. percent n-C alkylacrylate, 14 wt. percent n-C alkylacrylate, 7 wt. percent C n-alkylacrylate, 3 wt. percent C n-alkylacrylate and 5 wt. percent C n-alkylacrylate.
EXAMPLE II This example illustrates the bulk of polymerization preparation of the interpolymeric pour depressors contemplated herein.
In four separate runs 200 grams of Monoacrylate A of Example I and respectively 2 (Run A), 2 (Run B), 4 (Run C) and (Comparative Run D) grams of dimethacrylate of ethylene glycol were charged to a 1-liter resin kettle equipped with overhead stirrer, condenser, nitrogen inlet tube, thermocouple and constant heat unit. The system was purged with prepurified nitrogen for about 25 minutes utilizing nitrogen rate of 120 mls./minute while heating to 85 :1" C. The nitrogen flow as reduced to 30 mls./minute and alpha-alpha-azobisisohutyronitrile in an amount of 2 grams was added to the kettle. The polymerization was monitored by taking refractive index readings at 54 C. at /2 hour intervals. After 1.5 hours the refractive index remained stable indicating completion of polymerization. The reaction was continued for an additional 1.5 hours to verify completion. The products of Runs A, B and C were cooled, analyzed and identified as poly(n-alkylacrylate-ethylene glycol dimethacrylate) interpolymers having an n-alkyl distribution in the interpolymer essentially that of the Alcohol A precursor. The Run D product was identified as poly(n-alkylacrylate) wherein the n-alkyl distribution is that of Alcohol A. The products of Runs A, B, C and D were respectively designated as Polymer A, Polymer B, Polymer C and Polymer D of the following analysis:
Polymer A B C D Test:
Kinematic viscosity, cs. at:
150 F 168. 7 287.6 196 210 F 73. 120. 0 81 Melting point, C 42-44 42-44 43-44 39 Dialysis, wt. percent resid 49. 9 57. 1 58. 0 42 M.W. of dialysis residue (M.W. by
membrane osmome 700 30, 500 35, 000 29, 000 Melting point dialysis residue, 0-- 45-50 43-4 42-44 Sp. gram, 150 F.l60 0.8605 0.8561 0.8655 0. 8580 R1 at 54 C 1. 4531 1. 4546 4. 4549 1.4545 Component content, wt. perce n-Alkylacrylate 99 99 98 100 n-Ethylene glycol dimethacrylate... 1 1 2 0 1 Too viscous.
EXAMPLE HI This example illustrates the outstanding pour depressing effect in a petroleum fraction of the representative acrylate-methacrylate pour depressors prepared in Example II (Polymer A, B and C) in petroleum fractions and further demonstrates the general pour depressing superiority of the representative acrylate-methacrylate interpolymers over the non-methacrylate containing polymer (Polymer D). The pour points were measured in accordance with ASTM Test D-97 and were measured over a period of 42 to 44 days with intermittent readings in said period. Since pour points do have some degree of variability even within the same samples only those samples evaluated at the same time can be directly compared. Therefore, this accounts for the three following tables and the variations between the tables. Meaningful comparisons must be within each table and not between tables in respect to the pour depressing effect of the representative acrylate-methacrylate interpolymers and the comparative acrylate polymer.
The petroleum base fraction employed was a heavy Waxy residual fuel oil comprising 50 vol. percent macrocrystalline wax containing vacuum petroleum residuum and 50 vol. percent non-waxy hydrotreated gas oil having a boiling point of 400-652 F., and API Gravity of 35.3
and a pour point of about '-5 F. The base fuel composition 'had' the following properties:
Physical Tests: Results Pour point, F. -1. .Wax content, wt percent 12.7 SUS visc. at 150 F. 70.2 APP, gravity 24.1 Wt. percent, sulfur 0.18
In the preparation of the pour depressed fuel compositions the vacuum residuum component of the base fuel was heated to 200 F. with stirring for about 0.5 hour during which time the polymers prepared in Example 11 were added. Subsequently, the hydrotreated gas oil fraction of the base fuel was blended into the mixture at 150 -F. followed by stirring at 150 F. for an additional 0.5 hour. The effectiveness of the three representative poly(acrylate-methacrylate) polymers A, B and C and comparative polymer D produced in Example II in depressing the pour point of the waxy petroleum fraction 1s set forth below in following Tables I, II and III:
TABLE I Pour point, F., after- Polymer cone, wt. 5 7 12 44 Polymer (Ex. I) percent Avg. days days days days Bun B Polymer containing 1 wt. percent E GMDA l 0. 07 35 35 35 25 45 0. 06 40 30 45 45 45 0. 05 40 30 40 45 45 0. 04 45 45 45 45 50 0. 03 45 35 40 45 65 0. 02 50 45 50 45 65 0. 01 65 70 60 65 60 Run D Polymer containing 0 wt. percent EGDMA 0. 04 50 40 55 50 45 0. 03 55 45 60 55 65 l E GDMA=Ethylene Glycol Dimethacrylate.
TABLE II Pour point, F., atter Polymer conc., wt. 3 7 17 28 42 Polymer (Ex. 11) percent Avg. days days days days days Run A containing 1 wt. percent EGDMA 1 0. 05 40* 45 60 25 40 Run 0 containing 2 wt. percent EGDMA l 0. 05 30- 40+ 30 30 30 Run D containing 0 wt. percent EGDMA 0. 05 55- 45 55 50 70 50 1 EGDMA=Ethylene Glycol Dimethacrylate.
TABLE III Pour point, F., after- Polymer conc., wt. 3 17 28 42 Polymer (Ex. H) percent Avg. days days days days Run A containing 1 wt.
percent E GDMA l 0. 075 35+ 35 40 35 35 Run 0 containing 2 wt.
percent EGDMA 0. 075 35* 35 55 30 10 Run D containin 0 wt.
percent E GD h. 0. 075 55- 45 50 50 55 1 E GDMA= Ethylene Glycol Dlmethacrylate.
1. A composition comprising a wax containing heavy petroleum fraction in major amounts containing between 4 and 15 wt. percent macrocrystalline paraffin wax of a pour point between 40 and F. containing between about 0.01 and 3 wt. percent of an interpolymer of an n-alkylacrylate mixture and alkanediol dimethacrylate of a molecular weight between about 3000 and 100,000 wherein the alkanediol dimethacrylate moiety is of from 10 to 18 carbons, said n-alkyl is at least 18 carbons and at least 70 wt. percent of said n-alkyl in said mixture is from 20 to 24 carbons consisting of between about 2 and 65 wt. percent C20, between about 18 and 65 wt.
7 percent C alkyl and between about 8 and 35 wt. percent C alkyl, said interpolymer having a weight ratio of n-alkylacrylate mixture moiety to dimethacrylate moiety of between about 99.5:0.5 to 95 :5, said interpolym'er introduced into said composition at a temperature 5 above the solution point of said wax therein.
2. A composition in accordance with claim 1 wherein said alkanediol dimethacrylate is 1,2-ethanediol dimethacrylate and said n-alkyl distribution includes about 39 wt. percent C about 27 wt. percent C and about 14 10 wt. percent C 8 References Cited UNITED STATES PATENTS 3,729,296 4/1973 Miller 25256 R 3,244,631 4/1966 Vander Voort 25257 WILLIAM H. CANNON, Primary Examiner US. Cl. X.R. 44-62