US3397970A - Pour point depressant additive - Google Patents

Description

United States ABSTRACT OF THE DISCLOSURE Middle distillate fuel containing a copolymer of ethylene and a C to C olefinically unsaturated ester pour depressant tending to promote the formation of water haze, is inhibited against said haze by a combination of the dimer of linoleic acid and quaternary ammonium salt.

The present invention is broadly concerned with a multipurpose additive for middle distillates. The invention more particularly relates to improving the flow characteristics of middle distillates.,More particularly, the invention is concerned with an additive composition which improves the flow characteristics and the haze characteristics of middle distillates. This additive composition, in essence, comprises a dimer of linoleic acid in conjunction with a quaternary ammonium salt and a copolymer of ethylene and vinyl acetate.

With the increase in the use of hydrocarbon fuels of all kinds, a serious problem has arisen in areas frequently subjected to low temperatures with respect to the cold test characteristics of fuels. Particularly, serious problems have been encountered with heating oils and diesel and jet fuels that have too high a pour point, resulting either in distributional or operating difiiculties or both. For example, the distribution of heatin oils by pumping or syphoning is rendered diificult or impossible at temperatures around or below the pour point of the oil. Furthermore, the flow of the oil at such temperatures from the fuel storage tank to the burner or engine cannot be maintained leading to the failure of the equipment to operate.

Also the low temperature properties of petroleum distillate fuels boiling in the range between about 250 and about 750 F. have attracted increasing attention in recent years because of the growth of market for such fuels in sub-arctic areas and because of the development of turbojet aircraft capable of operating at altitudes where temperatures of 50 F. or lower may be encountered.

It is, therefore, one object of the present invention to produce a pour depressant composition for middle distillates and lighter oils which will greatly enhance the quality of these fuels. In general, these oils boil in the range from about 250 to 750 F.

It is a still further object of the present invention to provide heating oils, diesel fuel oils, kerosenes and jet fuels having low pour points and having other desirable characteristics. Aviation turbo-jet fuels in which the present compositions may be used normally boil between about 250 and about 550 F. and are used in both military and civilian aircraft. Such fuels are more fully defined by U.S. Military Specifications MIL-F-5624C, MIL-F-25554A, M-HrF-25558A, and amendments thereto. Kerosenes and heating oils will normally have boiling ranges between about 300 and about 750 F. and are more fully described in ASTM Specification -D-396-48T and supplements thereto, where they are referred to as No. 1 and No. 2 fuel oils. Diesel fuels in which the polymers may be employed are described in detail in ASTM Specification atent C D-975-53T-and later versions of the same specification. This additive composition, in essence, comprises a dimer of linoleic acid in conjunction with a quaternary ammonium salt and a copolymer of ethylene and vinyl acetate.

Thus one ingredient of the compositions of the present invention are copolymers of ethylene and up to about 50% by weight of an olefinically unsaturated aliphatic monomer containing from about 3 to 5 carbon atoms per molecule. In general, these monomers may comprisevinyl acetate, vinyl propionate, methyl methacrylate, allyl ethyl ether, divinyl ether, acrylonitrile, vinylac etonitrile and the like. The preferred copolymers comprise ethylenevinyl acetate copolymers. It is preferred that the parts by weight of ethylene in the copolymer be in the range from about 60 to 99% as compared to parts by weight of vinyl acetate in the range from about 40 to about 1%. A very desirable ethylene-vinyl acetate copolyrner contains about 15 to 28% by weight of vinyl acetate, as for example about 20 parts by weight of vinyl acetate.

The molecular weights of the ethylene-vinyl acetate copolyrner are critical and should be in the range from about 1,000 to 3,000, preferably in the range from about 1,500 to 2,200. The molecular weights are determined by K. Rasts method (Ber. 55, 1051, 3727 (1922)). These copolymers are generally described in U.S. Patent No. 3,048,479 issued Aug. 7, 1962, entitled, Ethylene-Vinyl Ester Pour Depressant for Middle Distillates. Inventors: Stephan Ilnyckyj and Charles B. Rupar. I

While the copolymer pour depressants as described are very effective and useful, they tend to promote formation of a water haze in the oil. Thus in accordance with one specific adaptation of the present invention, a dimer of linoleic acid is used in conjunction with a quaternary ammonium chloride in conjunction with the ethylene-vinyl acetate pour depressant. In accordance with other specific adaptations of the present invention, it is also much preferred to use other additives in conjunction with these particular compositions.

In order to further illustrate the invention, a dimer of linoleic acid (Santolene C) was added to a number of base fuels with the following results (normally used in fuels as a corrosion inhibitor) Waring blender haze test 2 +5 lbs. of Santolene 0 per 1,0210 barrels Base oil 3 N o Santolene C 1 A solution consisting of about wt. percent dimer of linoleic acid, about 5 wt. percent alkyl phosphate ester and about wt. percent kerosene, so that the total additive contains about 0.40% phosphorus.

200 m1. 011 plus 2 ml. of sea water are mixed in a Waring Blender at high speed for about 2min, and then the mixture is centrifuged for about 10 mm. The readmg is made on a photoelectric colorimeter. The hazy 011 is compared with the filtered sample and the reading taken in lgss o flpercentage of hght transmission (the higher the reading, the hazier o 3 All base oils contained: parts per million of Primene 81R, 10 parts per million of Aliquat 221, b 25 parts per million of H0 32. a

In essence, a primary amine containing mainly 012-014 tertiary alkyl groups. Prepared by reacting triisobutylene with ammonia. (Om-Ole) (normally functions as an antioxidant to improve sediment and color stability in storage).

b A solution of about 25 wt. percent isopropyl alcohol and water, and about 75 wt. percent of dimethyl dlcoco quaternary ammonium chloride. Coco is any alkyl group from coconut oil.

An oil solution consisting of about 25 wt. percent light mineral 011 and about 75 wt. percent of tallow (stearate) fumarate/Ca oxo chloropzigopylene oxy maleatelvinyl acetate copolyrner (sludge dispersan TABLE II.SANTOLENE C AND ALIQUAT 221 REDUCE HAZING DUE TO POUR DEPRESSANT Copolymer Extra Waring B ase oil pour aliquat, Santolene C blender depressant, p.p.m. p.p.m. haze p.p.m.

A None None None 13 250 None None 92 500 None None 03 600 10 None 36 500 None 16. 5 89 500 10 16. 5 9 E None None None 16 250 None None 92 500 None None 95 500 10 None 28 500 None 16. 5 28 500 10 16. 5 4

1 Pour depressant was a copolymer oi ethylene and vinyl acetate having 28% of vinyl acetate present and a molecular Weight of about 2,000. The pour depressant was used in a solution consisting of about 50 wt. percent kerosene containing about 50 wt. percent of the copolymer. The amount of actual copolymer is half the p.p.m. shown in the table.

9 Samples already contained 10 p.p.m. aliquat.

From the above it is apparent that using the copolymer pour depressant in conjunction with Santolene C (dimer of linoleic acid) and in conjunction with Aliquat 221 (quaternary ammonium salt), unexpected desirable results are secured.

Thus very desirable additive compositions to he used are the following:

TABLE III Range Additive compositions P.p.n1. Range (p.p.m.)

(p.p.m.) active ingredient Santolene C (dimer of linoleic acid). 16. 5 2-40 9-18 Aliquat 221 (quaternary salt) 20.0 5-30 3%-22. 5 H 32 (tallow iumarate) 25. 0 10-100 -50 Primene 81 R (primary amine, etc.) 75. 0 5-100 5-100 Copolymer pour depressant (ethylene-vinyl acetate) 500. 00 100-1, 000 50-500 From the foregoing it is apparent that the haze-forming tendency of the copolymer pour depressant is materially improved by using in conjunction therewith a dimer of linoleic acid and a quaternary ammonium chloride salt.

While the foregoing is very excellent, it has also been discovered that the haze promoting tendency of the copolymer may be controlled by adding to the base fuel in conjunction with the ethylene-vinyl acetate copolymer from about 4 to 25 p.p.m., preferably to p.p.m. of dicoco dimethyl ammonium nitrite. Other tests were conducted using various amounts of the copolymer in conjunction with various amounts of A-liquat 221. The results of these tests are as follows:

Haze after 10 min. centrifuging, p.p.m. Aliquat 221 P.p.m. of Copolyrner (ethylene-vinyl acetate) 11 11 7 5 20 10 7 7 (i5 16 8 6 6 7 67 36 13 9 6 8 .T 8 (i4 20 12 8 5 7 6 From the above it is apparent that when using as high as 800 parts per million of the copolymer pour depressant solution, the haze can be materially lowered by the utilization of from about 5-35 parts per million of the Aliquat 221.

Thus, the present invention is concerned with an improved middle distillate oil of improved pour characteristics and being substantially haze free. The middle distillate contains an effective amount of an ethylene-vinyl acetate copolymer pour depresssant and an eiiective amount of a quaternary ammonium salt. Preferred middle distillate compositions contained eifective amounts of an ethylene-vinyl acetate copolymer pour depressant used with effective amounts of dimers of linoleic acid and also in conjunction with a quarternary ammonium salt. Highly desirable compositions are middle distillate compositions containing an ethylene-vinyl acetate copolymer pour depressant in conjunction with a dimer of linoleic acid, in conjunction with a quaternary ammonium salt, in conjunction with a primary amine containing mainly C -C tertiary alkyl groups and a tallow stearate fumarate vinyl acetate copolymer.

What is claimed is:

1. A petroleum distillate oil boiling in the range of 300 to 750 F. containing a pour depressing amount of a copolymer of 60 to 99 wt. percent of ethylene and within the range of 1 to 40 wt. percent of an olefinically unsaturated C to C aliphatic ester monomer, said copolymer having a molecular Weight of about 1,000 to 3,000 and tending to promote the formation of water haze in said oil, and as an inhibitor of said haze about .9 to 18 parts per million of dimer of linoleic acid and quaternary ammonium salt selected from the group consisting of 3% to 22.5 p.p.m. of dicoco dimethyl ammonium chloride and 4 to 25 p.p.m. of dicoco dimethyl ammonium nitrite.

2. A composition according to claim 1, wherein said ester monomer is vinyl acetate, said salt is dicoco dimethyl ammonium chloride, and said oil has a natural pour point of -10 F. and higher.

References Cited UNITED STATES PATENTS 2,861,874 11/1958 OKelly et al 44-62 3,008,813 11/1961 Siegel 44-62 3,048,479 8/ 1962 Ilnyckyj et a1. 44-62 DANIEL E. WYMAN, Primary Examiner.

Y. H. SMITH, Assistant Examiner.