Additives for improving the cold properties of fuel oils

Abstract

The invention provides terpolymers of ethylene, at least one ethylenically unsaturated ester and propene, which a) contain from 12.0 to 16.0 mol % of structural units derived from at least one ethylenically unsaturated ester,b) contain from 1.0 to 4.0 methyl groups derived from propene per 100 aliphatic carbon atoms, andc) have fewer than 6.5 methyl groups stemming from chain ends per 100 CH2 groups. and also their use as cold additives for middle distillates.

Description

EXAMPLES

Effectiveness of the Additives as Cold Flow Improvers

The superior effectiveness of the inventive additives for mineral oils and mineral oil distillates is described with reference to the CFPP test (Cold Filter Plugging Test to EN 116).

The following additives were used:

Characterization of the Ethylene Copolymers Used

Process A): in a continuous tubular reactor, ethylene, propene and vinyl acetate were copolymerized at 200 MPa and a peak temperature of 220° C. with addition of the molecular weight regulator specified in table 1. The polymer formed was removed from the reaction mixture and then freed of residual monomers.

Process B): in a continuous high-pressure autoclave, ethylene, vinyl acetate and propylene were copolymerized with addition of a 10% by weight solution of bis(2-ethylhexyl)peroxodicarbonate as an initiator and the molecular weight regulator specified in table 1. The polymer formed was removed from the reaction mixture and then freed of residual monomers.

For comparison, an ethylene vinyl-acetate copolymer (Ex. 24), a terpolymer of ethylene, vinyl acetate and propene according to EP 0 190 553 (Ex. 25), a terpolymer of ethylene, vinyl acetate and 4-methylpentene-1 according to EP 0 807 642 (Ex. 26), and a terpolymer of ethylene, vinyl acetate and isobutylene (Ex. 27) were employed.

The vinyl acetate content was determined by means of pyrolysis of the polymer which had been freed of residual monomers at 150° C./100 mbar. To this end, 100 mg of the polymer are dissociated thermally with 200 mg of pure polyethylene in a pyrolysis flask at 450° C. in a closed system under reduced pressure for 5 minutes, and the dissociation gases are collected in a 250 ml round-bottom flask. The acetic acid dissociation product is reacted with an NaI/KIO₃ solution, and the iodine released is titrated with Na₂S₂O₃ solution.

The total number of methyl groups in the polymer which do not stem from vinyl esters is determined by means of ¹H NMR spectroscopy at a measurement frequency of 500 MHz on 10 to 15% solutions in C₂D₂Cl₄ at 300 K. The integral of the methylprotons between about 0.7 and 0.9 ppm is determined as a ratio relative to that of the methylene and methine protons between about 0.9 and 1.9 ppm. A correction of the number of the methyl groups for the structural units which are derived from the moderator used and overlap with the signals of the main polymer chain is effected on the basis of the methine proton of the moderator which appears separately (for example, methyl ethyl ketone and propanal exhibit multiplets at 2.4 and 2.5 ppm).

The content of methyl groups which derive from propene is determined by means of ¹³C NMR spectroscopy at a measurement frequency of 125 MHz on likewise 10 to 15% solutions in C₂D₂Cl₄ at 300 K. The integral of the methyl groups derived from propene between 19.3 and 20.2 ppm is determined as a ratio relative to that of the aliphatic hydrocarbons of the polymer backbone between 22 and 44 ppm. Advantageously, ¹H and ¹³C NMR measurement is performed on the same sample.

The number of chain ends is determined by subtracting the number of methyl groups derived from propene, determined by means of ¹³C NMR, from the total number of methyl groups, determined by means of ¹H NMR. The two values should be treated as dimensionless numbers.

To assess the cold flowability of concentrates which contain inventive additives, the abovementioned active substances were homogenized at 35% strength in a relatively high-boiling aromatic solvent (Solvent Naphtha) with stirring at 60° C. The pour point of the resulting concentrate was subsequently determined.

TABLE 1
Characterization of the polymers
		Vinyl acetate in	Propene-CH3
	Polymerization	the polymer	per 100 aliph.	Number of		V140	Pour point
Polymer	process/moderator	[mol %]	CH2	chain ends	Total G	[mPas]	[° C.]
P1	A/PA	13.5	3.0	6.2	16.5	155	−27
P2	B/PA	13.4	2.6	4.7	16.0	182	−33
P3	B/PA	13.6	3.0	4.9	16.6	140	−39
P4	B/PA	12.2	3.1	5.2	15.3	115	−36
P5	B/PA	13.4	1.8	4.1	15.2	143	−27
P6	B/PA	14.9	1.6	4.6	16.5	148	−30
P7	B/PA	14.0	2.2	3.8	16.2	95	−21
P8	B/PA	13.8	2.8	3.9	16.6	90	−27
P9	B/PA	14.4	3.4	3.6	17.8	88	−30
P10	B/PA	13.5	2.3	3.4	15.8	103	−18
P11	B/PA	13.3	2.6	4.2	15.9	156	−27
P12	B/PA	13.8	3.1	4.4	16.9	147	−33
P13	B/PA	14.1	3.6	4.8	17.7	99	−36
P14	A/MEK	13.5	2.9	4.3	16.4	175	−24
P15	A/MEK	13.5	2.0	5.4	15.5	155	−18
P16	A/MEK	14.4	2.8	4.8	17.2	153	−21
P17	A/MEK	14.0	2.2	5.2	16.2	157	−27
P18	B/PA	14.3	2.2	3.6	16.5	97	−21
P19	B/PA	14.0	2.9	3.2	16.9	154	−24
P20	B/MPK	14.9	1.2	5.3	16.1	104	−18
P21	B/PA	13.7	4.2	5.8	17.9	138	−48
(comp.)
P22	B/PA	16.2	2.5	5.8	18.6	138	−42
(comp.)
P23	B/PA	13.6	2.7	6.7	17.3	133	−39
(comp.)
P24	A/MEK	13.3	—	4.6	13.3	125	−9
(comp.)
P25	B/—	12.8	12.0	6.9	18.9	145	−21
(comp.)
P26	B/PA	12.5	4.6 mol % of 4-	n.a.	n.a.	115	−24
(comp.)			MP-1
P27	B/PA	13.1	4.3 mol % of	n.a.	n.a.	122	−27
(comp.)			DIB
PA = propionaldehyde;
MEK = methyl ethyl ketone;
MPK = methyl propyl ketone

The test oils used were current oils from European refineries. The CFPP value was determined to EN 116 and the cloud point to ISO 3015.

TABLE 2
Characterization of the test oils:
The test oils used were current oils from European refineries. The CFPP
value was determined to EN 116 and the cloud point to ISO 3015
	Test oil 1	Test oil 2	Test oil 3	Test oil 4
Distillation
IBP [° C.]	200	194	188	171
20% [° C.]	251	249	232	218
90% [° C.]	342	341	323	324
FBP [° C.]	357	355	355	351
Cloud Point [° C.]	−4.2	−5.6	−18	−5.4
CFPP [° C.]	−6	−7	−20	−8
Density @15° C. [g/cm3]	0.8433	0.840	0.852	0.831

TABLE 3
Testing as a cold flow improver in test oil 1.
	Dosage rate
Example	Polymer	100 ppm	200 ppm	300 ppm
1	P1	−7	−10	−18
2	P2	−11	−14	−17
3	P3	−10	−18	−20
4	P4	−11	−19	−21
5	P7	−11	−20	−21
6	P8	−11	−16	−21
7	P9	−7	−12	−18
8	P10	−12	−22	−21
9	P11	−10	−17	−21
10	P12	−9	−17	−20
11	P13	−11	−19	−21
12	P14	−10	−19	−19
13	P15	−11	−18	−21
14	P16	−12	−20	−22
15	P17	−10	−18	−19
16	P18	−12	−19	−21
17	P19	−11	−20	−22
18	P20	−10	−17	−20
19	P21 (comp.)	−9	−10	−10
20	P22 (comp.)	−7	−7	−8
21	P23 (comp.)	−7	−8	−8
22	P24 (comp.)	−11	−17	−19
23	P25 (comp.)	−7	−10	−11
24	P26 (comp.)	−8	−10	−13

The effectiveness of the inventive terpolymers in test oil 2 was determined in combination of 75% by weight of the inventive polymers with 25% by weight of an ethylene copolymer with 24% by weight of vinyl acetate and a melt viscosity measured at 140° C. of 280 mPas.

TABLE 4
Testing as a cold flow improver in test oil 2
	Dosage rate
Example	Polymer	100 ppm	200 ppm	300 ppm
25	P1	−9	−14	−18
26	P2	−11	−19	−21
27	P4	−10	−15	−21
28	P5	−11	−19	−20
29	P6	−10	−17	−20
30	P7	−11	−19	−21
31	P8	−11	−18	−21
32	P9	−10	−16	−20
33	P16	−10	−16	−20
34	P17	−11	−17	−20
35	P20	−10	−14	−20
36	P21 (comp.)	−10	−12	−15
37	P22 (comp.)	−11	−12	−15
38	P23 (comp.)	−11	−11	−13
39	P24 (comp.)	−10	−18	−20
40	P25 (comp.)	−10	−11	−15
41	P27 (comp.)	−11	−13	−17

The effectiveness of the inventive terpolymers was determined in test oils 3 and 4 in a combination of 85% by weight of the inventive polymers with 15% by weight of a condensate of alkylphenol and formaldehyde having a mean molecular weight of 12 000 g/mol.

TABLE 5
Testing as a cold flow improver in test oil 3
	Dosage rate
Example	Polymer	25 ppm	50 ppm	100 ppm
42	P2	−33	−35	−36
43	P6	−33	−34	−37
44	P7	−34	−33	−36
45	P8	−34	−35	−38
46	P14	−33	−34	−35
47	P16	−34	−34	−35
48	P17	−32	−33	−35
49	P19	−35	−38	−39
50	P25 (comp.)	−25	−27	−28
51	P27 (comp.)	−29	−31	−32

TABLE 6
Testing as a cold flow improver in test oil 4
	Dosage rate
Example	Polymer	300 ppm	400 ppm	500 ppm
52	P4	−12	−12	−18
53	P5	−12	−18	−19
54	P6	−12	−19	−20
55	P7	−19	−19	−19
56	P8	−17	−20	−18
57	P11	−12	−19	−19
58	P12	−12	−18	−18
59	P13	−12	−15	−18
60	P15	−12	−14	−16
61	P16	−12	−17	−19
62	P22 (comp.)	−11	−12	−12
63	P23 (comp.)	−11	−11	−12
64	P26 (comp.)	−11	−13	−15

The experiments show that the inventive additives, with regard to the improvement in the cold flowability and especially the lowering of the CFPP of middle distillates are superior to the prior art additives. At the same time, their concentrates are usable at relatively low temperatures as corresponding copolymers of ethylene and vinyl esters.

Claims

1. A polymer of ethylene, at least one ethylenically unsaturated ester and propene, which comprises: a) from 12.0 to 16.0 mol % of structural units derived from at least one ethylenically unsaturated ester,b) from 1.0 to 4.0 methyl groups derived from propene per 100 aliphatic carbon atoms, andc) fewer than 6.5 methyl groups stemming from chain ends per 100 CH2 groups.

2. The polymer as claimed in claim 1, in which the ethylenically unsaturated ester is the vinyl ester of a carboxylic acid having from 2 to 12 carbon atoms.

3. The polymer of claim 1, in which the ethylenically unsaturated ester is vinyl acetate.

4. The polymer as claimed in claim 3, in which the polymer comprises between 28.0 and 36.0% by weight of the vinyl acetate.

5. The polymer of claim 1, in which a sum G of molar content of unsaturated ester a) and the number of methyl groups derived from propene per 100 aliphatic carbon atoms of the polymer b), according to the formula G=[mol % of unsaturated ester]+[propene-CH3]

6. The polymer of claim 1, which further comprises structural units derived from at least one moderator having a carbonyl group.

7. The polymer as claimed in claim 6, which further comprises from 0.5 to 7.0% by weight of at least one structural unit derived from a moderator comprising carbonyl groups.

8. A process for preparing the polymer of claim 1, by reacting a mixture of ethylene, propene and the at least one ethylenically unsaturated ester under elevated pressure and elevated temperature in the presence of a free radical-forming initiator, and in which the molecular weight is adjusted by a moderator comprising carbonyl groups.

9. The process as claimed in claim 8, in which a high-pressure bulk polymerization is performed at the elevated pressure of at least 100 MPa.

10. The process as claimed in claim 8, in which a high-pressure bulk polymerization is performed at a peak temperature below 220° C.

11. A composition comprising at least one polymer as claimed in claim 1 and at least one further ethylene copolymer.

12. The composition as claimed in claim 11, wherein the total comonomer content of the further ethylene copolymer is at least two mol % lower than that of the at least one polymer.

13. A composition comprising at least one polymer as claimed in claim 1 and at least one oil-soluble polar nitrogen compound.

14. A composition comprising at least one polymer as claimed in claim 1 and at least one alkylphenol-aldehyde resin.

15. A composition comprising at least one polymer as claimed in claim 1 and at least one comb polymer.

16. The composition comprising at least one polymer as claimed in claim 1, and at least one polyoxyalkylene compound.

17. (canceled)

18. A free-flowing additive concentrate having an intrinsic pour point of −10° C. or lower for improving the flowability of middle distillates, said concentrate containing 20-40% by weight of at least one terpolymer as claimed in claim 1 and 60-80% by weight of at least one solvent.

19. A process for improving the cold flow properties of a fuel oil, by adding to the fuel oil a formulation containing at least 20% by weight of at least one terpolymer as claimed in claim 1 at a temperature of 0° C. or lower.

20. A fuel oil comprising a middle distillate and at least one polymer as claimed in claim 1.

21. The composition of claim 1, further comprising at least one component selected from the group consisting of a further ethylene copolymer, an oil-soluble polar nitrogen compound, an alkylphenol-aldehyde resin, a comb polymer, a polyoxyalkylene compound, and mixtures thereof.