New Additive Packages for Gasoline Fuels

Abstract

Novel compounds can be used as additive packages for improving the cleanliness of direct injection spark ignition (DISI) engines.

Claims

1: A method for controlling injector deposits in a direct injection spark ignition engine, the method comprising: adding an additive package to a fuel composition, wherein the additive package comprises a copolymer obtainable by: (I) copolymerizing (A) at least one ethylenically unsaturated dicarboxylic acid or a derivative thereof, (B) at least one α-olefin having from at least 12 up to and including 30 carbon atoms, (C) optionally, at least one further aliphatic or cycloaliphatic olefin which has at least 4 carbon atoms and is different than (B), and (D) optionally, one or more further copolymerizable monomers other than monomers (A), (B), and (C), selected from the group consisting of (Da) vinyl esters, (Db) vinyl ethers, (Dc) (meth)acrylic esters of alcohols having at least 5 carbon atoms, (Dd) allyl alcohols or ethers thereof, (De) N-vinyl compounds selected from the group consisting of vinyl compounds of heterocycles containing at least one nitrogen atom, N-vinylamides, and, N-vinyllactams, (Df) ethylenically unsaturated aromatics, (Dg) α,β-ethylenically unsaturated nitriles, (Dh) (meth)acrylamides, and (Di) allylamines, to obtain a first intermediate copolymer; (II) reacting the first intermediate copolymer obtainable from (I) with at least one amino compound of formula (I) ##STR00005## wherein R is H or a group —R.sup.1—X—H, wherein R.sup.1 is a divalent alkylene group comprising 2 to 6 carbon atoms, optionally interrupted by O, NH, and/or NR.sup.4 groups, and/or optionally bearing at least one further substituent, R.sup.2 and R.sup.3 are independently of another C.sub.1-to C.sub.20-alkyl, C.sub.6- to C.sub.10-aryl, C.sub.5- to C.sub.12-cycloalkyl, or C.sub.7- to C.sub.11-aralkyl, wherein R.sup.2 and R.sup.3 together with the nitrogen atom may form a cycloaliphatic or aromatic ring in which further hetero atoms may be incorporated, X is O, NH, or NR.sup.4, and R.sup.4 is C.sub.1- to C.sub.4-alkyl or C.sub.6- to C.sub.10-aryl, to obtain a second intermediate copolymer; and (III) optionally, partly or fully hydrolyzing anhydride functionalities present in the second intermediate copolymer obtained from (II), to obtain the copolymer.

2: The method according to claim 1, wherein monomer (A) is maleic anhydride.

3: The method according to claim 1, wherein no monomer (C) is present.

4: The method according to claim 1, wherein no monomer (D) is present.

5: The method according to claim 1, wherein R.sup.1 is selected from the group consisting of 1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, 2-methyl-1,2-propylene, 1,5-pentylene, 1,6-hexylene, 1-phenyl-1,2-propylene, and 2-hydroxy-1,3-propylene.

6: The method according to claim 1, wherein R.sup.2 and R.sup.3 are independently of another are C.sub.1-C.sub.4-alkyl.

7: The method according to claim 1, wherein R.sup.2 and R.sup.3 together are 1,4-butylene, 1,5-pentylene, 1,6-hexylene, or 3-oxa-1,5-pentylene.

8: The method according to claim 1, wherein X is NH.

9: The method according to claim 1, wherein the at least one amino compound of formula (I) comprises a mixture of compounds of formula (I), and wherein the mixture comprises compounds of formula (I) in which X is O and compounds of formula (I) in which X is NR.sup.4 or NH.

10: An additive package, comprising: at least one detergent additive selected from the group consisting of a) polyisobutylene amine with M.sub.n 500 to 1500 g/mol, b) hydrocarbyl substituted primary amine with M.sub.n 140 to 255 g/mol, c) a Mannich reaction product resulting from a reaction of a substituted phenol or cresol with formaldehyde and a primary or secondary amine, d) an N-quaternary ammonium salt, and e) a reaction product of a hydrocarbyl-substituted acylating agent and a compound comprising at least one primary or secondary amine group; at least one further additive selected from the group consisting of carrier oils, cold flow improvers, lubricity improvers, corrosion inhibitors, demulsifiers, dehazers, antifoams, octane number improver, antioxidants, metal deactivators, and solvents; and at least one copolymer obtainable by: (I) copolymerizing (A) at least one ethylenically unsaturated dicarboxylic acid or a derivative thereof, (B) at least one α-olefin having from at least 12 up to and including 30 carbon atoms, (C) optionally, at least one further aliphatic or cycloaliphatic olefin which has at least 4 carbon atoms and is different than (B), and (D) optionally, one or more further copolymerizable monomers other than monomers (A), (B), and (C), selected from the group consisting of (Da) vinyl esters, (Db) vinyl ethers, (Dc) (meth)acrylic esters of alcohols having at least 5 carbon atoms, (Dd) allyl alcohols or ethers thereof, (De) N-vinyl compounds selected from the group consisting of vinyl compounds of heterocycles containing at least one nitrogen atom, N-vinylamides, and N-vinyllactams, (Df) ethylenically unsaturated aromatics, (Dg) α,β-ethylenically unsaturated nitriles, (Dh) (meth)acrylamides, and (Di) allylamines, to obtain a first intermediate copolymer; (II) reacting the first intermediate copolymer obtainable from (I) with at least one amino compound of formula (I) ##STR00006## wherein R is H or a group —R.sup.1—X—H, wherein R.sup.1 is a divalent alkylene group comprising 2 to 6 carbon atoms, optionally interrupted by O, N—H, and/or NR.sup.4 groups, and/or optionally bearing at least one further substituent, R.sup.2 and R.sup.3 are independently of another C.sub.1- to C.sub.20-alkyl, C.sub.6- to C.sub.10-aryl, C.sub.5- to C.sub.12-cycloalkyl, or C.sub.7- to C.sub.11-aralkyl, wherein R.sup.2 and R.sup.3 together with the nitrogen atom may form a cycloaliphatic or aromatic ring in which further hetero atoms may be incorporated, X is O, NH, or NR.sup.4, and R.sup.4 is C.sub.1- to C.sub.4-alkyl or C.sub.6- to C.sub.10-aryl, to obtain a second intermediate copolymer; and (III) optionally, partly or fully hydrolyzing anhydride functionalities present in the second intermediate copolymer obtained from (II), to obtain the copolymer.

11: A gasoline fuel, comprising at least one additive package according to claim 10.

12: A method of operating a spark ignition engine, the method comprising: introducing into a combustion chamber of a spark ignition engine the gasoline fuel according to claim 11.

13: The method according to claim 1, wherein monomer (A) is an anhydride of a dicarboxylic acid.

14: The method according to claim 1, wherein in the formula (I), R.sup.1 is selected from the group consisting of alkyl, alkyloxy, aryl, hydroxy, amino, and mono- or dialkylated amino group.

15: The method according to claim 1, wherein in the formula (I), R.sup.4 is methyl.

16: The method according to claim 12, wherein the spark ignition engine is a direct injection spark ignition engine.

Description

EXAMPLES

[0277] Methods and Reagents:

[0278] 3-(Dimethylamino)propylamine (DMAPA), CAS 109-55-7

[0279] 1,3,5-Tris[3-(dimethylamino)propyl]hexahydro-1,3,5-triazine, CAS 15875-13-5

[0280] Kerocom® PIBA (65% by weight solution of polyisobutylene amine based on high-reactivity polyisobutene (after hydroformylation and amination), M.sub.n=1000, in an aliphatic hydrocarbon mixture), according to DE 10314809 A1.

[0281] N,N-Dimethylethanolamine (DMEOA), CAS 108-01-0

[0282] All from BASF SE.

[0283] Hydrosol® A200 ND from DHC Solvent Chemie GmbH.

[0284] Nalco® 5406: Corrosion inhibitor based on dimer fatty acid from Baker Hughes.

[0285] Determination of total base nitrogen according to DIN EN 13716:2001.

[0286] Solid content was determined using a Mettler Toledo, HB43-S, Halogen moisture analyser. Solvent was evaporated at 140° C. for 30 minutes.

[0287] Determination of M.sub.n, M.sub.w and polydispersity D by gel permeation chromatography (GPC).

[0288] Method A: Eluent THF+0.1% trifluoroacetic acid, column temperature 35° C., flow velocity 1 mL/min, sample concentration 2 mg/mL in eluent, sample injection volume 100 μL, sample solutions were filtrated over Chromafil Xtra PTFE (0.20 μm) prior to injection, guard column Plgel (length 5 cm, diameter 7.5 mm), main column PLgel MIXED-B (length 30 cm, diameter 7.5 mm), detector DRI Agilent 1100 series, calibration was done with polystyrene standards with M=580 to M=6870000 from Polymer Laboratories and hexylbenzene (M=162). Samples were dissolved in the eluent.

[0289] Method B: Eluent THF+0.035 mol/I diethanolamine, column temperature 35° C., flow velocity 1 mL/min, sample concentration 2 mg/mL in eluent, sample injection volume 100 μL, sample solutions were filtrated over Chromafil Xtra PTFE (0.20 μm) prior to injection, column PLgel MIXED-E (length 30 cm, diameter 7.5 mm), detector DRI Agilent 1100 series, calibration was done with polystyrene standards with M=266 to M=50400 from Polymer Laboratories. Samples were dissolved in the eluent.

Comparative Example 1: Deposit Control Additive 5 from EP 1293553, Condensation Product of Tall Oil Fatty Acid and DMAPA

Example A

[0290] A 4 L glass reactor was equipped with a mechanical stirrer and a reflux condenser. A mixture of C20-C24 alpha olefin (958 g, average molecular weight 296 g/mol) and o-xylene (1288 g) was added and heated to 150° C. under stirring and nitrogen. To the reactor maleic anhydride (317 g) and di-tert butyl peroxide (13 g) were added over 5 h. After the addition finished, the mixture was stirred one additional hour and then cooled down to room temperature.

[0291] GPC (Method A, evaluation limit 610 g/mol): M.sub.n 2430 g/mol, M.sub.w 4600 g/mol, D 1.9.

Example B

[0292] A 4 L glass reactor was equipped with a mechanical stirrer and a reflux condenser. C20-C24 alpha olefin (924 g, average molecular weight 296 g/mol) was added and heated to 140° C. under stirring and nitrogen. To the reactor maleic anhydride (306 g) and di-tert butyl peroxide (13 g) were added over 6 h. After the addition finished, the mixture was stirred for one additional hour, diluted with o-xylene (1242 g) and then cooled down to room temperature.

[0293] GPC (Method A, evaluation limit 307 g/mol): M.sub.n 3730 g/mol, M.sub.w 14700 g/mol, D 3.9.

Example C

[0294] A 4 L glass reactor was equipped with a mechanical stirrer and a reflux condenser. A mixture of C20-C24 alpha olefin (466 g, average molecular weight 296 g/mol) and C12 alpha olefin (605 g) was added and heated to 150° C. under stirring and nitrogen. To the reactor maleic anhydride (500 g) and di-tert butyl peroxide (16 g) in C12 alpha olefin (49 g) were added over 6 h. After the addition finished, the mixture was stirred for one additional hour, diluted with o-xylene (1635 g) and then cooled down to room temperature.

[0295] GPC (Method A, evaluation limit 307 g/mol): M.sub.n 2780 g/mol, M.sub.w 8630 g/mol, D 3.1.

Example D

[0296] A 4 L glass reactor was equipped with a mechanical stirrer and a reflux condenser. A mixture of C20-C24 alpha olefin (1157 g, average molecular weight 296 g/mol) and o-xylene (1555 g) was added and heated to 150° C. under stirring and nitrogen. To the reactor maleic anhydride (383 g) and di-tert butyl peroxide (16 g) were added over 3 h. After the addition finished, the mixture was stirred for one additional hour and then cooled down to room temperature.

[0297] GPC (Method A, evaluation limit 307 g/mol): M.sub.n 1730 g/mol, M.sub.w 4750 g/mol, D 2.7.

Example E

[0298] A 4 L glass reactor was equipped with a mechanical stirrer and a reflux condenser. A mixture of C20-C24 alpha olefin (462 g, average molecular weight 296 g/mol), polyisobutene with an average molecular weight of 1000 g/mol (Glissopal® 1000 from BASF) (669 g), and o-xylene (134 g) was added and heated to 150° C. under stirring and nitrogen. To the reactor maleic anhydride (219 g) and di-tert butyl peroxide (28 g) were added over 4 h and 4.5 h, respectively. After the addition finished, the mixture was stirred for one additional hour, diluted with o-xylene (1242 g) and then cooled down to room temperature.

[0299] GPC (Method A, evaluation limit 307 g/mol): M.sub.n 2040 g/mol, M.sub.w 6040 g/mol, D 3.0.

Example 1

[0300] 500 g (0.63 mol) of Example A was mixed with DMAPA (65.4 g, 0.64 mol) and heated to 150° C. for 18 h. Liberated water was removed using a Dean-Stark trap. Imide formation was confirmed by ATR-IR (attenuated total reflection, 1699 cm.sup.−1 for C═O absorption). Xylene was removed by distillation. Quantitative gas chromatography of the product thus obtained showed residual DMAPA content of 3%.

Example 2

[0301] 400 g (0.50 mol) of Example A were mixed with DMAPA (40.3 g, 0.394 mol) and heated to 155° C. for 14 h. Liberated water was removed using a Dean-Stark trap. Imide formation was confirmed by ATR-IR (1699 cm.sup.−1 for C═O absorption). Xylene was removed by distillation. Liquid chromatography of the product thus obtained showed residual DMAPA content of <30 ppm.

[0302] GPC (Method B, evaluation limit 261 g/mol): M.sub.n 1970 g/mol, M.sub.w 5390 g/mol, D 2.7.

Example 3

[0303] 567 g (0.72 mol) of Example B were mixed with DMAPA (71.5 g, 0.7 mol) and heated to 155° C. for 14 h. Liberated water was removed using a Dean-Stark trap. Imide formation was confirmed by ATR-IR (1699 cm.sup.−1 for C═O absorption). Liquid chromatography of the product thus obtained showed residual DMAPA content of 0.018%. Solid content 57.7%, total base nitrogen 68.4 mg KOH/g.

Example 4

[0304] 567 g (0.72 mol) of Example D were mixed with DMAPA (71.5 g, 0.70 mol) and heated to 155° C. for 5 h. Liberated water was removed using a Dean-Stark trap. Imide formation was confirmed by ATR-IR (1699 cm.sup.−1 for C═O absorption). Liquid chromatography of the product thus obtained showed residual DMAPA content of 0.16%. Solid content 53.7%, total base nitrogen 67.2 mg KOH/g.

Example 5

[0305] 578 g (0.90 mol) of Example C were mixed with DMAPA (92.0 g, 0.90 mol) and heated to 155° C. for 5 h. Liberated water was removed using a Dean-Stark trap. Imide formation was confirmed by ATR-IR (1699 cm.sup.−1 for C═O absorption). Liquid chromatography of the product thus obtained showed residual DMAPA content of 0.23%. Solid content 57.3%, total base nitrogen 82.7 mg KOH/g.

Example 6

[0306] 309 g (0.25 mol) of Example E were mixed with DMAPA (25.6 g, 0.25 mol) and heated to 155° C. for 5 h. Liberated water was removed using a Dean-Stark trap. Imide formation was confirmed by ATR-IR (1699 cm.sup.−1 for C═O absorption). Liquid chromatography of the product thus obtained showed residual DMAPA content of <0.005%.

Example 7

[0307] 567 g (0.72 mol) of Example B were mixed with DMAPA (35.8 g, 0.35 mol) and DMEOA (31.2 g, 0.35 mol) and heated to 135-155° C. for 4 h. Liberated water was removed using a Dean-Stark trap. Liquid chromatography of the product thus obtained showed residual DMAPA content of <0.005%. %. Solid content 53.9%, total base nitrogen 54.9 mg KOH/g.

Example 8

[0308] 567 g (0.72 mol) of Example D were mixed with DMAPA (35.8 g, 0.35 mol) and DMEOA (31.2 g, 0.35 mol) and heated to 135-155° C. for 3 h. Liberated water was removed using a Dean-Stark trap. Liquid chromatography of the product thus obtained showed residual DMAPA content of <0.005%. %. Solid content 49.6%, total base nitrogen 58.5 mg KOH/g.

Example 9

[0309] 578 g (0.90 mol) of Example C were mixed with DMAPA (46.0 g, 0.45 mol) and DMEOA (40.1 g, 0.45 mol) and heated to 131-148° C. for 3 h. Liberated water was removed using a Dean-Stark trap. Liquid chromatography of the product thus obtained showed residual DMAPA content of <0.005%. %. Solid content 53.4%, total base nitrogen 71.6 mg KOH/g.

Example 10

[0310] 309 g (0.25 mol) of Example E were mixed with DMAPA (12.8, 0.125 mol) and DMEOA (11.1 g, 0.125 mol) and heated to 138-150° C. for 3 h. Liberated water was removed using a Dean-Stark trap. Liquid chromatography of the product thus obtained showed residual DMAPA content of <0.005%.

[0311] Determination of Injector Cleanliness with a Direct Injection Spark Ignition Engine.

[0312] According to an internal BASF test procedure, a loaded commercially available four-cylinder direct injection spark ignition engine (1.6 liters cylinder capacity) was run with a commercially available gasoline fuel (according to DIN EN 228) containing 7 volume % of oxygen-containing components, during 50 hours.

[0313] In run 1 the fuel did not contain any additive In run 2 the fuel contained 160 ppm by weight of the component of Example 2.

[0314] In both runs, the “FR” value was determined. FR is a parameter generated by engine steering, corresponding to the time of the process of injection of the fuel into the combustion chamber. If FR increases during a run, this indicates injection nozzles deposit formation, and the FR value increases with the deposit formation. If FR is kept constant or slightly decreases during a run, this indicates that the injection nozzles stay free of deposits.

[0315] The following table shows the FR results of runs 1 and 2:

TABLE-US-00001 Run 1 (for comparison) at the beginning: 0% at the end +6.39% Run 2 (according to  at the beginning 0% at the end −2.55% the invention)

[0316] These results demonstrate a keep clean performance of example 2.

[0317] In run 3 the fuel did not contain any additive. At the beginning of the 50 minutes dirty-up phase the FR value was 1.60% and at the end 1.71% indicating injector deposit formation. A SEM picture taken at this stage confirmed deposit formation in the external as well as in the internal injector holes (FIG. 1). In run 4 (clean-up, duration 20 minutes) the fuel contained 40 ppm by weight of the component of Example 2. The injectors from the dirty-up phase after run 3 were used. At the end of the clean-up phase the FR value was −3.74%. A SEM picture taken at this stage (FIG. 2) showed the removal of major parts of the deposits in the internal as well as in the external injector holes compared to the picture taken after the dirty-up.

[0318] These results demonstrate a clean-up performance of the compound according to Example 2.

[0319] Example 2 was also tested in a preliminary version of the upcoming CEC DISI detergency test (TDG-F-113). The test engine is a VW EA111 1,4L TSI engine with 125 kW. The test procedure is a steady state test at an engine speed of 2000 rpm and a constant torque of 56 Nm. Nozzle coking is measured as change of injection timing. Due to nozzle coking, the hole diameter of the injector holes is reduced, and the injection time adjusted by the Engine Control Unit (ECU) accordingly. The injection time in milliseconds is a direct readout from the ECU via ECU control software. Test duration is 48 h. As base fuel without performance additives a EO gasoline fuel compliant to DIN EN 228 from Haltermann Carless (DISI TF Low Sulphur, Batch GJ0203T456, Orig. Batch 4) with the following properties was used:

TABLE-US-00002 Limits Feature Units Results Minimum Maximum Method RON (*.sup.1) 98.8 98.0 — DIN EN ISO 51642014-10 MON (*.sup.1) 87.8 87.0 — DIN EN ISO 5163:2014-10 Density at 15° C. kg/m3 748.4 745.0 760.0 ASTM D4052:2018 DVPE kPa 62.3 60.0 65.0 DIN EN 13016-1:2018-06 Appearance — clear and bright — — Visual Distillation IBP ° C. 32.0 25.0 35.0 DIN EN ISO 3405:2011-04 Dist. 10% v/v ° C. 50.5 45.0 55.0 DIN EN ISO 3405:2011-04 Dist. 50% v/v ° C. 103.9 95.0 110.0 DIN EN ISO 3405:2011-04 Dist. 90% v/v ° C. 177.4 160.0 180.0 DIN EN ISO 3405:2011-04 Dist. 70 deg C. % (V) 27.7 22.0 50.0 DIN EN ISO 3405:2011-04 Dist. 100 deg C. % (V) 47.3 46.0 71.0 DIN EN ISO 3405:2011-04 Dist. 150 deg C. % (V) 80.0 75.0 — DIN EN ISO 3405:2011-04 Distillation FBP ° C. 199.1 190.0 210.0 DIN EN ISO 3405:2011-04 Dist. Residue % (V) 0.7 — 2.0 DIN EN ISO 3405:2011-04 Oxidation Stabilit (*.sup.1) min. >1200 480 — DIN EN ISO 7536:1996-08 Solvent Washed Gum mg <1.0 — 4.0 DIN EN ISO 6246:2017-07 per 100 mL Aromatics % (V) 33.2 35.0 DIN EN ISO 22854:2016 Olefins % (V) 12.9 10.0 14.0 DIN EN ISO 22854:2016 Saturates % (V) 53.8 DIN EN ISO 22854:2016 Benzene % (V) 0.33 — 1.00 DIN EN ISO 22854:2016 Corrosion-Copper — 1A max. 1 — — DIN EN ISO 2160:1999-04 Oxygenates % (V) 0.1 — 0.2 DIN EN ISO 22854:2016 Hydrogen % w 13.19 ASTM D3343:2016 Carbon % w 86.81 ASTM D3343:2016 C:H Ratio (H = 1) 6.58 ASTM D3343:2016 H:C Ratio (C = 1) 0.152 ASTM D3343:2016 Net Heating Value MJ/kg 42.824 ASTM D3338:2009 Net Heating Value Btu/lb 18410 ASTM D3338:2009 Lead mg/l <2.5 — 5.0 ASTM D3237:2017 Sulfur mg/kg 4.3 — 10.0 DIN EN ISO 20846:2012-01 Phosphorus (*.sup.1) g/l <0.0002 0.0013 ASTM D3231:2013 Manganese (*.sup.1) mg/kg <0.5 2.0 DIN EN 16136:2015-04 Al (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES B (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Ba (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Ca (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Cr (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Cu (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Fe (*.sup.1) mg/kg 0.1 — 5.0 ICP-OES Mg (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Mo (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Ni (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Si (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES Zn (*.sup.1) mg/kg <0.1 — 0.1 ICP-OES (*.sup.1) tested by subcontractor (*.sup.2) not accredited (*.sup.3) modified

[0320] Test results are summarized in Table 1.

TABLE-US-00003 TABLE 1 Relative SEM change of picture of Injection injector tip Test Time after test Base run (base fuel without +8.16% FIG. 3 performance additives) Base fuel additized with −0.05% FIG. 4 81 mg/kg Example 2 Base fuel additized with +5.50% FIG. 5 81 mg/kg Comparative Example 1 (DCA 5 from EP1293553) Base fuel additized with 125 +2.53% FIG. 6 mg/kg Kerocom PIBA ®

[0321] The test results and the pictures show a keep-clean performance of Example 2. They show a performance benefit over Comparative Example 1 and Kerocom PIBA®, the latter one being designed to prevent intake valve deposit formation in port fuel injection engines.

[0322] Determination of Storage Stability of a Fully Formulated Gasoline Performance Package

[0323] Two gasoline performance packages were formulated according to the following table. 1,3,5-Tris[3-(dimethylamino)propyl]hexahydro-1,3,5-triazine is Deposit Control Additive 1 from EP 1293553. The carrier fluid used is a propoxylated, butoxylated tridecanol derived from trimer-butene (after hydroformylation and hydrogenation). Clear formulations were obtained in both cases.

TABLE-US-00004 Formulation 2 Formulation 1 [wt %] [wt %] (Comparative) Kerocom PIBA* 35.54 35.54 Carrier fluid** 21.42 21.42 Nalco 5406  2.00  2.00 Example 2  8.01 0   Triazine*** 0    8.01 Hydrosol A200 ND**** 33.03 33.03 Sum 100    100    *Kerocom (R) PIBA (65% by weight solution of polyisobutylene amine based on high-reactivity polyisobutene (after hydroformylation and amination), Mn = 1000, in an aliphatic hydro-car-bon mixture) **propoxylated, butoxylated tridecanol derived from trimerbutene (after hydroformylation and hydrogenation) ***1,3,5-Tris[3-(dimethylamino)propyl]hexahydro-1,3,5-triazine ****solvent

[0324] Both formulations were stored at 40° C. to evaluate their storage stability. In case of comparative Formulation 2 the formation of a dark deposit was observed after 5 weeks, whereas inventive Formulation 1 was still clear after 7 weeks. Thus, Formulation 1 according to the invention showed improved storage stability compared to comparative Formulation 2 containing Deposit Control Additive 1 from EP 1293553.