CORROSION INHIBITORS FOR FUELS AND LUBRICANTS

Abstract

The present invention relates to novel uses of corrosion inhibitors in fuels and lubricants.

Claims

1-12. (canceled)

13. A corrosion inhibitor, comprising a reaction product that is essentially free of acid groups and is obtained by reacting: a polyisobutene (A), having a number-average molecular weight M.sub.n of 200 to 10,000, with a maleic acid derivative (B) comprising at least one selected from the group consisting of a monoalkyl ester, a dialkyl ester and an anhydride, in a stoichiometric ratio of more than one equivalent of (B) per a total of terminal - and -double bonds, determined by .sup.13C NMR, in (A), where a bismaleation level, calculated as 100%[(wt-% (BM PIBSA)/(wt-% (BM PIBSA)+wt-% (PIBSA))], wherein PIBSA represents monomaleated polyisobutene and BM PIBSA represents polymaleated polyisobutene, is at least 11%, with the proviso that when (B) comprises the monoalkyl ester and/or the dialkyl ester, more than 90% of the ester groups present are conserved in the reaction product and/or when (B) comprises the anhydride, more than 90% of the anhydride groups present are conserved in the reaction product.

14. The corrosion inhibitor of claim 13, wherein (A) has a number-average molecular weight M.sub.n of 500 to 2,500.

15. The corrosion inhibitor of claim 13, wherein (B) comprises maleic anhydride.

16. The corrosion inhibitor of claim 13, wherein the reaction product has a bismaleation level of up to 40%.

17. The corrosion inhibitor of claim 13, wherein the reaction product comprises no more than 30% by weight of unreacted (A).

18. A method of reducing corrosion on a nonferrous metal surface, the method comprising contacting the nonferrous metal surface with the corrosion inhibitor of claim 13 or a composition comprising the corrosion inhibitor.

19. A gasoline fuel, comprising the corrosion inhibitor of claim 13.

20. The gasoline fuel of claim 19, having a sodium and/or potassium content of at least 0.1 ppm by weight.

21. The gasoline fuel of claim 19, having a magnesium and/or calcium content of at least 0.1 ppm by weight.

22. The gasoline fuel of claim 19, having a zinc content of at least 0.1 ppm by weight.

23. A lubricant, comprising the corrosion inhibitor of claim 13.

Description

EXAMPLES

[0213] GPC Analysis

[0214] Unless stated otherwise, the mass-average molecular weight M.sub.w and number-average molecular weight M.sub.n of the polymers was measured by means of gel permeation chromatography (GPC). GPC separation was effected by means of two PLge Mixed B columns (Agilent) in tetrahydrofuran at 35 C. Calibration was effected by means of a narrow-distribution polystyrene standard (from PSS, Germany) having a molecular weight of 162-50 400 Da. Hexylbenzene was used as a marker for low molecular weight.

Synthesis Example 1

[0215] 524 g (0.54 mol) of a polyisobutene having a number-average molar mass M.sub.n of 1000 g/mol and a content of -double bonds of 87% were initially charged together with 87 g (0.89 mol) of maleic anhydride in a 1 L autoclave equipped with a stirrer and thermometer. The mixture was converted under nitrogen at 210 C. over the course of 8 hours, in the course of which the pressure rose to 3 bar. The reaction mixture was cooled down to room temperature, transferred to a round-bottom flask with the aid of 1 L of toluene and filtered. Solvent and maleic anhydride were removed on a rotary evaporator at 190 C. at 1 mbar. 580 g of a dark brown, oily and viscous product were obtained.

[0216] In order to ascertain the hydrolysis number, the product was dissolved in toluene to give a 50% solution. The hydrolysis number of the product was measured by reaction of 10 mL of the solution obtained with excess potassium hydroxide, followed by back-titration of the potassium hydroxide residue with hydrochloric acid. The hydrolysis number was found to be 120 mg KOH/g.

[0217] 10 mL of the solution were then eluted through a silica gel column in order to determine the content of unfunctionalized polyisobutene. All the polyisobutene that had reacted with maleic anhydride was retained on the column, and polyisobutene was eluted with hexane. According to this, the reaction mixture comprised 13.4% by weight of unfunctionalized polyisobutene.

[0218] According to the above measurements, the reaction mixture comprised, as well as 13.4% by weight of unfunctionalized polyisobutene, monofunctionalized and difunctionalized polyisobutenesuccinic anhydride, which, assuming that no other by-products were present, gives a bismaleation level of 40.3%.

Synthesis Examples 2 and 3

[0219] In an analogous manner to synthesis example 1, by altering the maleic anhydride:polyisobutene stoichiometry, reaction mixtures with a bismaleation level of 10% or 25.9% (11.9% by weight of unfunctionalized polyisobutene) were obtained.

USE EXAMPLES

[0220] 1) Calcium Compatibility Test:

[0221] 100 mL of motor oil (Shell Helix, FIGS. 1a and 1b, far left beaker, with a Ca content of 1500 ppm, Mg content of 1100 ppm and Zn content of 1300 ppm) were heated to 70 C. in the beaker and then 1 mL of corrosion inhibitor was added. Should the solution still be clear, a further 1 mL of inhibitor is added. If the solution turns cloudy, the test is considered to have been failed (e.g. FIG. 1a, right-hand beaker). FIG. 1a shows, in the middle, the oil to which 2 mL of product from synthesis example 3 has been added, which remains clear. In the right-hand beaker, 1 mL of dimer fatty acid (dimeric oleic acid; CAS: 61788-89-4, 40% in Solvent Naphtha) was used. Distinctly visible turbidity is apparent.

[0222] FIG. 1b shows, on the right, the oil to which 2 mL of product from synthesis example 1 has been added, which remains clear.

[0223] 2) Steel Corrosion Test to ASTM D 665 B (Gasoline)

[0224] The fuel used was conventional E0 CEC RF-12-09 gasoline fuel from Haltermann (batch number 1878), which was additized with 490 mg/kg of an additive package composed of polyisobuteneamine (PIBA) and carrier oil (polyether). The corrosion inhibitors specified in the table which follows were added to the formulation in the amounts specified (based on active component) and subjected to a corrosion test to ASTM D 665 B in saltwater.

[0225] Dimer fatty acid as corrosion inhibitor (dimeric oleic acid; CAS: 61788-89-4, 40% in Solvent Naphtha) was used as a comparison.

TABLE-US-00001 Dosage Assessment Corrosion Bismaleation [mg/kg] according to Formulation inhibitor level active NACE E0 base fuel E Formulation 1** Dimer fatty 4/4 B++/B++ acid Formulation 2** Example 1 40.3 10/10 A/A Formulation 3** Example 2 10% 16/8 A/C Formulation 4** Example 3 25.9% 10 B+ **PIBA-containing base package with polyether carrier oil at 490 mg/kg

[0226] The assessment was made as follows:

[0227] A 100% rust-free

[0228] B++0.1% or less of the total surface area rusted

[0229] B+0.1% to 5% of the total surface area rusted

[0230] B 5% to 25% of the total surface area rusted

[0231] C 25% to 50% of the total surface area rusted

[0232] D 50% to 75% of the total surface area rusted

[0233] E 75% to 100% of the total surface area rusted