Copolymer with high chemical homogeneity and use thereof for improving the cold flow properties of fuel oils

Abstract

A copolymer with high chemical homogeneity, consisting of (A) 50 to 30% by weight of ethylene, (B) 50 to 70% by weight of C.sub.4- to C.sub.24-hydrocarbyl ester of (meth)acrylic acid, (C) 0 to 5% by weight of (meth)acrylic acid and (D) 0 to 10% by weight of copolymerizable monomers, obtainable by polymerizing a mixture of 80 to 60% by weight of ethylene, 20 to 40% by weight of (meth)acrylic acid and 0 to 10% by weight of copolymerizable monomers in a backmixing, continuous polymerization apparatus, and subsequently polymer-analogously esterifying the resulting copolymer with C.sub.4- to C.sub.24-hydrocarbinols. The inventive copolymer is suitable for improving the cold flow properties of fuel oils, for lowering the lower mixing temperature of cold flow improver additives into fuel oils, and for improving the filterability of fuel oils comprising cold flow improver additives.

Claims

1. A process for preparing a copolymer with high chemical homogeneity, consisting of (A) 50 to 30% by weight of ethylene, (B) 50 to 70% by weight of a C.sub.4- to C.sub.24-hydrocarbyl ester of acrylic acid or methacrylic acid, or of a mixture of said hydrocarbyl esters, (C) 0 to 5% by weight of acrylic acid and/or methacrylic acid and (D) 0 to 10% by weight of one or more copolymerizable monomers, where all monomer components in the copolymer together add up to 100% by weight, which comprises polymerizing a mixture of 80 to 60% by weight of ethylene, 20 to 40% by weight of acrylic acid and/or methacrylic acid and 0 to 10% by weight of one or more copolymerizable monomers, where all monomer components in the mixture together add up to 100% by weight, in a backmixing, continuous polymerization apparatus, and subsequently polymer-analogously esterifying the resulting copolymer of ethylene and (meth)acrylic acid or of essentially ethylene and (meth)acrylic acid with a C.sub.4- to C.sub.24-hydrocarbinol or a mixture of C.sub.4- to C.sub.24-hydrocarbinols.

2. The process according to claim 1, wherein polymerization is effected at a pressure of 50 to 5000 bar.

3. The process according to claim 1, wherein the mixture of 80 to 60% by weight of ethylene, 20 to 40% by weight of acrylic acid and/or methacrylic acid and 0 to 10% by weight of one or more copolymerizable monomers is polymerized in a backmixing, continuous autoclave.

Description

EXAMPLES

(1) Fuels Used:

(2) To demonstrate the effectiveness of the inventive copolymer as an additive in biofuel oils, two typical commercial biodiesel qualities (test oils B1, B2 and B3) with the following properties were used:

(3) TABLE-US-00001 B1: Type: RME Origin: Perstorp Sweden CP (DIN EN 23015): 4.0 C. CFPP (DIN EN 116) 11 C. PP (ASTM D 97) 12 C. Density at 15 C. (EN ISO 1285): 882.8 kg/m.sup.3 B2: Type: FAME Origin: Rossi Biofuel CP (DIN EN 23015): 3.8 C. CFPP (DIN EN 116) 9 C. PP (ASTM D 97) 6 C. Density at 15 C. (EN ISO 1285): 883.0 kg/m.sup.3 B3: Type: RME Origin: commercial Swedish biodiesel CP (DIN EN 23015): 5.0 C. CFPP (DIN EN 116) 11 C. PP (ASTM D 97) 12 C. Density at 15 C. (EN ISO 1285): 883.1 kg/m.sup.3

(4) Additives Used:

(5) The ter- or copolymers used can be characterized as follows, T-1 (according to WO 2008/059055, commercial product) having been used for comparison and T-2 in accordance with the invention:

(6) TABLE-US-00002 T-1: Composition: 60.0% by weight of ethylene 22.5% by weight of vinyl acetate 17.5% by weight of 2-propylheptyl acrylate Molecular weights: M.sub.n = 3000 g/mol, M.sub.w = 7300 g/mol Viscosity: 170 mPas at 120 C. T-2: Composition: 40.1% by weight of ethylene 58.7% by weight of tridecyl methacrylate 1.2% by weight of methacrylic acid Molecular weights: M.sub.n = 3000 g/mol, M.sub.w = 7000 g/mol Viscosity: <30 mPas at 120 C. prepared by high-pressure polymerization of a monomer mixture of 70.0% by weight of ethylene and 30.0% by weight of methacrylic acid at 220 C. and 1707 bar and subsequent esterification with excess tridecanol (molar ratio of methacrylic acid units to tridecanol: 1:1.2) in the presence of methanesulfonic acid

Example 1: Determination of the Cold Performance

(7) Table 1 below, containing the pour points (PP) determined by means of a standardized test method, shows that the effect of the inventive terpolymer (T-2) is significantly better than that of comparable prior art polymers (T-1).

(8) TABLE-US-00003 TABLE 1 Determination of the PP values [ C.] Test oil B1 B2 B3 Dosage* 900 ppm 900 ppm 500 ppm Additive T-1 15 18 12 Additive T-2 38 36 39 *Polymers T-1 and T-2 were each metered in as a concentrated solution in a customary solvent. The dosage specified in each case is based on the polymer content of the solution.