Composition to improve cold flow properties of fuel oils

Abstract

The present invention describes a composition comprising at least one polyalkyl(meth)acrylate polymer having a number average molecular weight Mn of from 1000 to 10000 g/mol and a polydispersity Mw/Mn of from 1 to 8 and at least one ethylene vinyl acetate copolymer comprising units being derived from at least one alkyl (meth)acrylate having 1 to 30 carbon atoms in the alkyl residue. The composition is useful as cold flow improver in fossil fuel oil and or biodiesel fuel oil.

Claims

1. A composition, comprising: at least 90% by weight of the composition of a biodiesel fuel oil; and from 0.1 to 0.50% by weight of a copolymer mixture, comprising: i) a polyalkyl(meth)acrylate polymer having a number average molecular weight Mn of from 1000 to 10000 g/mol and a polydispersity Mw/Mn of from 1 to 8; and ii) an ethylene vinyl acetate copolymer comprising in polymerized form an alkyl (meth)acrylate having 1 to 30 carbon atoms in the alkyl residue; wherein the ethylene vinyl acetate copolymer is a graft copolymer comprising an ethylene vinyl acetate copolymer as a graft base and the alkyl (meth)acrylate having 1 to 30 carbon atoms in the alkyl residue as a graft layer; a weight ratio of the polyalkyl(meth)acrylate polymer i) to the ethylene vinyl acetate copolymer ii) is in the range of from 15:1 to 1:1; the polyalkyl(meth)acrylate polymer comprises: (a) 0 to 40% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (I): ##STR00004## wherein R is hydrogen or methyl, and R.sup.1 is a linear, branched or cyclic alkyl residue with 1 to 6 carbon atoms, (b) at least 10% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (II): ##STR00005## wherein R is hydrogen or methyl, and R.sup.2 is a linear, branched or cyclic alkyl residue with 7 to 15 carbon atoms, and (c) 0 to 40% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (III): ##STR00006## wherein R is hydrogen or methyl, and R.sup.3 is a linear, branched or cyclic alkyl residue with 16-40 carbon atoms; the ethylene vinyl acetate copolymer comprises in polymerized form 0.5 to 60 weight % of vinyl acetate; and the alkyl (meth)acrylate having 1 to 30 carbon atoms in the alkyl residue as the graft layer comprises in polymerized form from 30 to 90 weight % of an alkyl (meth)acrylate having 7 to 15 carbon atoms in the alkyl residue.

2. The composition of claim 1, wherein said polyalkyl(meth)acrylate polymer i) comprises at least 50% by weight of polymerized units derived from the alkyl (meth)acrylate monomers of formula (II).

3. The composition of claim 1, wherein the polydispersity Mw/Mn of said polyalkyl(meth)acrylate polymer i) is in the range of from 1.1 to 5.

4. The composition of claim 1, wherein said polyalkyl(meth)acrylate polymer i) further comprises in polymerized form a hydroxyl-containing monomer, a (meth)acrylate of an ether alcohol, or a mixture thereof.

5. The composition of claim 1, wherein said ethylene vinyl acetate copolymer ii) comprises in polymerized form from 2 to 30 weight % of vinyl acetate.

6. The composition of claim 1, wherein said ethylene vinyl acetate copolymer ii) comprises in polymerized form from 1 to 60 weight % of ethylene.

7. The composition of claim 1, wherein said ethylene vinyl acetate copolymer ii) further comprises in polymerized form up to 20 weight % of at least one additional comonomer.

8. The composition of claim 1, wherein said ethylene vinyl acetate copolymer ii) has a number average molecular weight Mn of from 1000 to 120 000 g/mol.

9. The composition of claim 1, wherein the alkyl (meth)acrylate having 1 to 30 carbon atoms in the alkyl residue as graft layer comprises in polymerized form from 60 to 80 weight % of an alkyl (meth)acrylate having 7 to 15 carbon atoms in the alkyl residue.

10. The composition of claim 1, wherein a weight ratio of graft base to graft layer in said ethylene vinyl acetate copolymer ii) is in the range of from 1:1 to 1:8.

11. The composition of claim 1, further comprising a mineral oil.

12. The composition of claim 1, wherein said biodiesel fuel oil comprises a fatty acid ester derived from a monohydric alcohol having 1 to 4 carbon atoms.

13. The composition of claim 12, wherein said biodiesel oil comprises at least 10% by weight of a fatty acid ester derived from methanol, ethanol, or both, and a saturated fatty acid.

14. The composition of claim 1, wherein the copolymer mixture consists of i) and ii).

15. The composition of claim 1, wherein the polyalkyl(meth)acrylate polymer comprises 0.1 to 30% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (I).

16. The composition of claim 1, wherein the polyalkyl(meth)acrylate polymer comprises 25 to 100% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (II).

17. The composition of claim 1, wherein the polyalkyl(meth)acrylate polymer comprises 0.1 to 30% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (III).

18. The composition of claim 1, wherein the polyalkyl(meth)acrylate polymer comprises: 0.5 to 20% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (I); 70 to 99% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (II); and 0.5 to 20% by weight of polymerized units derived from one or more alkyl(meth)acrylate monomers of formula (III).

19. The composition of claim 1, which comprises at least 98% by weight of the composition of a biodiesel fuel oil.

Description

EXAMPLES 1 TO 6 AND COMPARATIVE EXAMPLES 1 TO 7

(1) The polymers obtained according to the Preparation Examples mentioned above had been used to prepare compositions of the present invention. The polymers had been blended by stirring at 60-80 C. for minimum 1 hour. The colourless mixtures had been stable and had been used directly as fuel additives. For the following tests RME (2008/518) from ADM Hamburg AG with CFPP=14 C. had been used as fuel oil.

(2) The Comparative Example 6 has been performed according to US 2005/0183326. An additive mixture of EVA copolymer containing about 27% by weight of vinyl acetate and dialkyl maleate was used. The additive mixture contained about 30% by weight of dialkyl maleate and 70% by weight of EVA. The molecular weight of the polymer was about Mn=4,350; Mw=9,750 Da; PDI=2.24.

(3) The Comparative Example 7 has been performed according to U.S. Pat. No. 5,743,923. An additive mixture of EVA copolymer containing 33% weight of vinyl acetate and about 10% weight of C.sub.16-18 phthalimide salt had been used. The molecular weight of the polymer was about Mn=2,200 Da; Mw=8,300 Da; PDI=3.69.

(4) Table 1 describes the improvement of the cold flow properties of RME using the polymers described above. The cold flow properties of the fuel oils comprising different amounts of polymers had been determined according the cold filter plugging point (CFPP) test measured to ASTM D6371.

(5) TABLE-US-00001 TABLE 1 Additive treat rate CFPP Additive [% by weight] [ C.] Comparative EVA-1 (100%) 0.10 12 Example 1 0.20 14 0.50 13 Comparative EVA-2 (100%) 0.10 14 Example 2 0.25 15 0.50 15 Comparative PAMA-1 (100%) 0.10 17 Example 3 0.25 21 0.50 19 Comparative PAMA-2 (100%) 0.10 17 Example 4 0.25 22 0.50 21 Comparative PAMA-3 (100%) 0.10 16 Example 5 0.25 18 0.50 21 Comparative EVA (70%) 0.10 14 Example 6 and 0.25 20 dialkyl maleate 0.50 13 (30%) Comparative EVA (90%) 0.10 18 Example 7 and 0.25 19 phthalimide salt 0.50 13 (10%). Example 1 PAMA-1 (75%) 0.10 19 and 0.25 21 EVA-1 (25%) 0.50 21 Example 2 PAMA-1 (85%) and 0.10 19 EVA-1 (15%) 0.25 23 0.50 23 Example 3 PAMA-1 (90%) 0.10 19 and 0.25 22 EVA-1 (10%) 0.50 22 Example 4 PAMA-1 (75%) 0.10 19 and 0.25 22 EVA-2 (25%) 0.50 21 Example 5 PAMA-2 (75%) 0.10 19 and 0.25 22 EVA-1 (25%) 0.50 23 Example 6 PAMA-3 (75%) 0.10 18 and 0.25 21 EVA-1 (25%) 0.50 22

(6) The results clearly showed an obvious advantage of using the new cold flow improvers. The new composition provides a very low cold filter plugging point. The temperature of the cold filter plugging point is much below the temperature of each of the components. Regarding that issue, the EVA-1 used without any coadditive does not provide any improvement at all as shown in Comparative Example 1. The data also showed that the new additives give significant benefit compared to conventional PAMA-based or EVA-based additives. The prior art compositions provide only at very specific concentration an acceptable low temperature performance. Compared to conventional additives, the working treat rate of the new additives is much wider. Furthermore, a high performance can be achieved by using only small amounts of expensive EVA copolymers.