USE OF HYDROPHOBICALLY MODIFIED POLYALKANOLAMINES AS WAX INHIBITORS, POUR POINT DEPRESSANT AND ADDITIVE FOR LUBRICANTS

Abstract

Use of hydrophobically modified polyalkanolamines obtainable by condensing at least one trialkanolamine and optionally further condensable monomers and reacting at least one of the terminal OH groups with suitable reactants capable of reacting with OH groups and comprising long chain hydrocarbon groups as wax inhibitor, pour point depressant and additive for lubricants.

Claims

1-20. (canceled)

21. A method of preventing wax deposits on surfaces in contact with crude oil, mineral oil and/or mineral oil products, comprising adding at least one hydrophobically modified, branched polyalkanolamine (III) to the crude oil, mineral oil and/or mineral oil products, wherein the at least one hydrophobically modified, branched polyalkanolamines (III) is obtained by the following process (A) condensing at least one trialkanolamine of the general formula N(R.sup.1OH).sub.3 (Ia) thereby obtaining branched polyalkanolamines (II) comprising terminal OH groups, wherein the R.sup.1 moieties are each independently divalent, linear or branched aliphatic hydrocarbon moieties having from 2 to 6 carbon atoms, and (B) reacting at least one of the terminal OH groups with a reagent R.sup.6X (IV), wherein R.sup.6 is an aliphatic, linear or branched, saturated or unsaturated hydrocarbon group having 8 to 100 carbon atoms and X is a functional group capable of reacting with OH-groups.

22. The method according to claim 21, wherein (Ia) is at least one trialkanolamine selected from the group consisting of triethanolamine, triisopropanolamine and tributan-2-olamine.

23. The method according to claim 21, wherein besides the trialkanolamines (Ia) at least one additional monomer selected from monomers (Ib) and (Ic) is used in course of step (A), wherein (Ib) are dialkanolamines having the general formula R.sup.2N(R.sup.1OH).sub.2 (Ib), wherein R.sup.2 is hydrogen and/or linear or branched aliphatic, cycloaliphatic and/or aromatic hydrocarbon radicals having from 1 to 30 carbon atoms, and (Ic) are monomers different from (Ia) and (Ib) and having at least two hydroxyl and/or amino groups may be used for the polycondensation.

24. The method according to claim 21, wherein the amount of trialkanolamines (Ia) is at least 50% by weight relating to all monomers used for the polycondensation.

25. The method according to claim 21, wherein in stage (B) at least 50% of the terminal OH groups are reacted with a reagent R.sup.6X (IV).

26. The method according to claim 21, wherein R.sup.6 has 10 to 32 carbon atoms.

27. The method according to claim 21, wherein the reactant R.sup.6X (IV) is a carboxylic acid or an activated carboxylic acid derivative.

28. The method according to claim 21, wherein the hydrophobically modified, branched polyalkanolamines (III) are added as formulation in a suitable solvent.

29. The method according to claim 21, wherein the groups R.sup.6 comprise linear, aliphatic saturated hydrocarbon groups R.sup.6a.

30. The method according to claim 21, wherein at least 50% of the groups R.sup.6 are linear, aliphatic saturated hydrocarbon groups R.sup.6a.

31. The method according to claim 21, wherein the formulation used additionally comprises at least one wax dispersant.

32. The method according to claim 21, wherein the amount added is 50 to 1500 ppm of the hydrophobically modified, branched polyalkanolamines (III) based on the crude oil, mineral oil and/or mineral oil products

33. The method according to claim 31, wherein the oil is crude oil.

34. The method according to claim 33, wherein a formulation comprising a hydrophobically modified, branched polyalkanolamine (III) and a suitable solvent is injected into a crude oil pipeline.

35. The method according to claim 33, wherein a formulation comprising a hydrophobically modified, branched polyalkanolamine (III) and a suitable solvent is injected into a production well.

36. The method according to claim 34, wherein the injection is effected on an offshore platform.

37. A method comprising adding a pour point depressant to crude oil, mineral oil and/or mineral oil products, wherein the pour point depressant is at least one hydrophobically modified, branched polyalkanolamine (III) obtained by the following process (A) condensing at least one trialkanolamine of the general formula N(R.sup.1OH).sub.3 (Ia) thereby, obtaining branched polyalkanolamines (II) comprising terminal OH groups, wherein the R.sup.1 moieties are each independently divalent, linear or branched aliphatic hydrocarbon moieties having from 2 to 6 carbon atoms, and (B) reacting at least one of the terminal OH groups with a reagent R.sup.6X (IV), wherein R.sup.6 is an aliphatic, linear or branched, saturated or unsaturated hydrocarbon group having 8 to 100 carbon atoms and X is a functional group capable of reacting with OH-groups.

38. A method of making a lubricating oil composition comprising mixing at least (a) one base oil component, (b) at least one hydrophobically modified polyalkanolamine (III), and (c) additives; wherein the at least one hydrophobically modified polyalkanolamine (III) is obtained by the following process (A) condensing at least one trialkanolamine of the general formula N(R.sup.1OH).sub.3 (Ia) thereby obtaining branched polyalkanolamines (II) comprising terminal OH groups, wherein the R=moieties are each independently divalent, linear or branched aliphatic hydrocarbon moieties having from 2 to 6 carbon atoms, and (B) reacting at least one of the terminal OH groups with a reagent R.sup.6X (IV), wherein R.sup.6 is an aliphatic, linear or branched, saturated or unsaturated hydrocarbon group having 8 to 100 carbon atoms and X is a functional group capable of reacting with OH-groups.

39. The method according to claim 38, wherein the lubricating oil composition comprises (a) 0.1 to 30% by wt. of the at least one hydrophobically modified polyalkanolamine (III), (b) 70 to 99.9% by wt. base oil, and (c) 0.05 to 20% by wt. of additives.

40. The method according to claim 38, wherein the lubricating oil composition comprises at least one additive selected from the group consisting of antioxidants, oxidation inhibitors, corrosion inhibitors, friction modifiers, metal passivators, rust inhibitors, anti-foamants, viscosity index enhancers, additional pour-point depressants, dispersants, detergents, further extreme-pressure agents and/or anti-wear agents.

Description

ANALYTICAL METHODS

Molecular Weight

[0169] The number average molecular weights and the weight average molecular weights of the samples were determined by gel permeation chromatography using a refractometer as the detector. The mobile phase used was hexafluoroisopropanol (HFIP), the standard employed for determining the molecular weight being polymethylmethacrylate (PMMA).

OH-Number

[0170] The OH number was determined in accordance the below reported procedure:

[0171] 0.5 g of the target polymer was weighted in a glass Erlenmeyer equipped with a magnetic stirrer. The exact amount of polymer was noted. Then, 5 mL of a solution of acetic anhydride at 2,433 mol/L in pyridine was added. When the polymer was solved, the Erlenmeyer was heat at 135 C. during 1 h on a heating plate. 10 mL of distilled water was added with a measuring cylinder and heat for 10 more minutes, then 10 mL of ethanol were added followed by 50 mL of a mixture of toluene/ethanol 1/1. 3-4 drops of phenolphthalein were added and the solution was titrated with a solution of KOH in ethanol at 0.1 mol/L. The OH number (OH #) is given by the following formula:

[00001]$\mathrm{OH}.Math.\#=\frac{\left(\mathrm{mL}.Math..Math.\mathrm{blank}-\mathrm{mL}.Math..Math.\mathrm{sample}\right).Math.\left(N_{\mathrm{KOH}}\right).Math.\left(56,1\right)}{\mathrm{sample}.Math..Math.\mathrm{weight}}$

[0172] 56.1 corresponds to the molar mass of KOH (g/mol).

[0173] N.sub.KOH is the concentration of the KOH solution (mol/L).

[0174] mL sample is the volume of KOH used to titrate the solution (mL).

[0175] mL blank is obtained by the titration of a solution made in the same conditions but with no polymers (mL).

[0176] Sample weight is the mass of polymer weighted (g).

[0177] The result is given in mg KOH/g.

Acid Number

[0178] The OH number was determined in accordance with the below reported procedure:

[0179] 0.5 g of the target polymer was weighted in a glass Erlenmeyer equipped with a magnetic stirrer. The exact amount of polymer was noted. Then, 50 mL of a mixture of toluene/ethanol 1/1 was added. 3-4 drops of phenolphthalein were added and the solution was titrated with a solution of KOH in ethanol at 0.1 mol/L. The acid number (SZ #) is given by the following formula:

[00002]$\mathrm{SZ}.Math.\#=\frac{\left(\mathrm{mL}.Math..Math.\mathrm{sample}\right).Math.\left(N_{\mathrm{KOH}}\right).Math.\left(56,1\right)}{\mathrm{sample}.Math..Math.\mathrm{weight}}$

[0180] 56.1 corresponds to the molar mass of KOH (g/mol).

[0181] N.sub.KOH is the concentration of the KOH solution (mol/L).

[0182] mL sample is the volume of KOH used to titrate the solution (mL).

[0183] mL blank is obtained by the titration of a solution made in the same conditions but with no polymers (mL).

[0184] Sample weight is the mass of polymer weighted (g).

[0185] The result is given in mgKOH/g.

Dynamic Viscosity

[0186] The dynamic viscosity was measured using an Anton Paar viscometer MCR51 (Kegel Platte GP50-1) at 23 C. 1/100 sec.sup.1.

Preparation of Unmodified Polyalkanolamines

Example 1

Synthesis of Polytriethanolamine

[0187] A four-neck flask equipped with stirrer, distillation bridge, gas inlet tube, and internal thermometer was charged with 2500 g triethanolamine (TEA) and 70.8 g of aqueous H.sub.3PO.sub.2 (50% by weight) and the mixture so obtained was heated under nitrogen to 200 C. The reaction mixture was stirred at 200 C. for a period of 25 hours, during which the condensate formed in the reaction is removed by means of a moderate stream of N.sub.2 as stripping gas via the distillation bridge. Towards the end of the reaction time indicated, the temperature was lowered to 140 C. and residual low molecular weight products were removed under a pressure of 100 hPa. The reaction mixture was cooled to ambient temperature and polytriethanolamine was obtained.

[0188] M.sub.n=2,100 g/mol

[0189] M.sub.w=31,800 g/mol

[0190] M.sub.w/M.sub.n=15.1

[0191] OH number: 274 mg KOH/g

[0192] Dynamic viscosity at 23 C.: 10,270 mPa.Math.s 1/100 sec

Example 2

Synthesis of Polytriisopropanolamine

[0193] A four-neck flask equipped with stirrer, distillation bridge, gas inlet tube, and internal thermometer was charged with 2500 g triisopropanolamine (TIPA) and 30.0 g of aqueous H.sub.3PO.sub.2 (50% by weight) and the mixture so obtained was heated under nitrogen to 200 C. The reaction mixture was stirred at 200 C. over a period of 10 hours, during which the condensate formed in the reaction is removed by means of a moderate stream of N.sub.2 as stripping gas via the distillation bridge. Towards the end of the reaction time indicated, the temperature was lowered to 140 C. and residual low molecular weight products were removed under a pressure of 100 hPa.

[0194] The reaction mixture was cooled to ambient temperature and polytrisopropanolamine polyol was obtained.

[0195] M.sub.n=2,550 g/mol

[0196] M.sub.w=6,180 g/mol

[0197] M.sub.w/M.sub.n=2.4

[0198] OH number: 498 mg KOH/g

[0199] Dynamic viscosity at 23 C.: 10,200 mPa.Math.s 1/100 sec

Synthesis of Modified Polyalkanolamines

Example 3

[0200] Esterification of Polytriethanolamine with Stearic Acid

[0201] 65.4 g of PolyTEA, synthesized according to the procedure described in example 1, and 90.9 g of stearic acid were placed in 250 mL flask equipped with stirrer, distillation bridge, gas inlet tube, and internal thermometer. Then 0.016 g of Titan (IV) butoxide were added to the reaction flask, which was heated by means of an oil bad up to 140 C. under nitrogen atmosphere. The reaction mixture was kept for 2 hours at 140 C. under nitrogen stream and under stirring. Thereafter the pressure was reduced stepwise to 100 hPa. The reaction was followed by measuring the acid numbers. The reaction mixture was stirred under vacuum at 140 C. until the acid number dropped to 4 mgKOH/g.

[0202] A solid yellowish polymer mass was obtained with the following analytics:

[0203] Acid number: 4 mg KOH/g

[0204] OH number: 3 mg KOH/g

Example 4

[0205] Esterification of Polytrisopropanolamine with Stearic Acid

[0206] 40.0 g of PolyTIPA, synthesized according to the procedure described in example 2, and 101 g of stearic acid were placed in 250 mL flask equipped with stirrer, distillation bridge, gas inlet tube, and internal thermometer. Then 0.028 g of Titan (IV) butoxide were added to the reaction flask, which was heated by means of an oil bad up to 140 C. under nitrogen atmosphere. The reaction mixture was kept for 4 hours at 140 C. under Nitrogen stream and under stirring.

[0207] Thereafter, the pressure was stepwise reduced to 100 hPa. The reaction was followed by measuring the acid numbers. The reaction mixture was stirred under vacuum at 140 C. until the acid number dropped to 4 mgKOH/g.

[0208] A solid yellowish polymer mass was obtained with the following analytics:

[0209] Acid number: 3 mgKOH/g

[0210] OH number: 0 mgKOH/g

Wax Inhibition

[0211] The cold finger deposition test was utilized to determine the wax inhibition properties of the modified polyalkanolamines. The wax inhibition was determined by exposing the crude oil to a cold metal finger surface in the presence and absence of the inhibitor. The amount and type of wax deposited on the cold metal finger was used to determine waxing tendency.

[0212] For the tests, a crude oil from the Landau oilfield in south-west Germany (Wintershall Holding GmbH) having an API gravity of 37 and a pour point of 21 C. was used.

[0213] The test was started by conditioning the oil sample by heating to 80 C. and holding for 30 minutes to remove thermal history. A water bath on the cold finger apparatus was adjusted so that the oil temperature is maintained at 30 C. The cold finger was maintained at 15 C. and the cold finger was inserted into oil sample. The test was run for 6 hours. The cold finger was removed the wax deposit was removed with a previous weighed paper towel. The wax deposit was weighed.

[0214] The wax test was repeated in the presence and absence of the modified polyalkanolamines. The amount of copolymers used was 1000 ppm (added as solution of 10% copolymer in Solvesso 150 (mixture of aromatic hydrocarbons (aromatic content >99%), distillation range 182-207 C.) with respect to crude oil. The percent efficacy was calculated on the performance of paraffin inhibitor as compared to the baseline (i.e. the measurement without wax inhibitor).

[0215] Each test was performed twice and the average of the two tests calculated. The results are summarized in the following table 1.

TABLE-US-00001 TABLE 1 Summary of the wax deposition tests Polymers Conc./ Oil Wax deposit/g % Example No. used ppm Batch No.* Average (test1; test2) Inhibition Comparative example 1 1 2.69 (2.81; 2.56) 0 Example 5 Example 3 1000 1 1.91 (1.81; 2.01) 29 Comparative example 2 2 3.21 (3.15; 3.27) 0 Example 6 Example 4 1000 2 2.65 (2.51; 2.78) 18 (*Although oil of the same source was used, different batches may have slightly different properties. Therefore, a comparative example was performed for each of the batches)

[0216] The tests show that a significant wax inhibition effect is achieved by the use of the modified polyalkanolamines.