Use of comb polymers for reducing fuel consumption

Abstract

The present invention relates to the use of comb polymers comprising, in the main chain, repeat units which are derived from polyolefin-based macromonomers, and repeat units which are derived from low molecular weight monomers selected from the group consisting of styrene monomers having 8 to 17 carbon atoms, alkyl (meth)acrylates having 1 to 10 carbon atoms in the alcohol group, vinyl esters having 1 to 11 carbon atoms in the acyl group, vinyl ethers having 1 to 10 carbon atoms in the alcohol group, (di)alkyl fumarates having 1 to 10 carbon atoms in the alcohol group, (di)alkyl maleates having 1 to 10 carbon atoms in the alcohol group and mixtures of these monomers, where the molar degree of branching is in the range of 0.1 to 10 mol % and the comb polymer comprises a total of at least 80% by weight, based on the weight of the repeat units, of repeat units which are derived from polyolefin-based macromonomers and repeat units which are derived from low molecular weight monomers selected from the group consisting of styrene monomers having 8 to 17 carbon atoms, alkyl (meth)acrylates having 1 to 10 carbon atoms in the alcohol group, vinyl esters having 1 to 11 carbon atoms in the acyl group, vinyl ethers having 1 to 10 carbon atoms in the alcohol group, (di)alkyl fumarates having 1 to 10 carbon atoms in the alcohol group, (di)alkyl maleates having 1 to 10 carbon atoms in the alcohol group and mixtures of these monomers, for reducing the fuel consumption of vehicles.

Claims

1. An additive for reducing fuel consumption of a vehicle, comprising a comb polymer of repeat units comprising: 11-23 wt % of a hydrogenated polybutadiene macromonomer, 65-84 wt % of n-butyl methacrylate, and up to 13 wt % of styrene, wherein the hydrogenated polybutadiene macromonomer is copolymerizable with the n-butyl methacrylate and styrene, wt % is based on the total weight of the comb polymer, and wherein the comb polymer comprises a main chain and a side chain, the main chain comprises copolymerized units of methacrylates and styrene, a molar degree of branching of the comb polymer is 0.3-0.5 mol %, a weight average molecular weight of the comb polymer is from 312,000 to 374,000 g/mol, and a glass transition temperature of the main chain of the comb polymer is in the range of 0 to 90° C.

2. The additive according to claim 1, wherein the comb polymer comprises: 8-15 wt % of the hydrogenated polybutadiene macromonomer, 68-84 wt % of n-butyl methacrylate, styrene up to 13 wt %, and further comprises up to 5 wt % of an alkyl methacrylate mixture having 12 to 14 carbon atoms in the alkyl groups.

3. The additive according to claim 1, wherein the content of styrene is from 5 to 13% by weight.

4. A lubricant oil formulation comprising the additive according to claim 1.

5. The lubricant oil formulation according to claim 4, further comprising at least one base oil selected from the group consisting of API group I, II, III, IV and group V.

6. The lubricant oil formulation according to claim 4, further comprising at least one additional additive.

7. The lubricant oil formulation according to claim 6, wherein the additive is at least one selected from the group consisting of a viscosity index improver, a pour point improver, a dispersant, a detergent, a defoamer, a corrosion inhibitor, an antioxidant, an antiwear additive, an extreme pressure additive and a friction modifier.

8. The lubricant oil formulation according to claim 4, wherein a difference between a high-temperature high-shear viscosity at 100° C. and 150° C. of the lubricant is from 2.5 to 4 mPA.Math.s according to ASTM D 4683.

9. The additive of claim 2, wherein the comb polymer consists of: 8-15 wt % of the hydrogenated polybutadiene macromonomer, 68-84 wt % of n-butyl methacrylate, up to 13 wt % of styrene, and up to 5 wt % of the alkyl methacrylate mixture having 12 to 14 carbon atoms in the alkyl groups.

10. The additive of claim 9, wherein the comb polymer consists of: 11 wt % of a hydrogenated polybutadiene macromonomer having a Mn of 4,800 g/mol, 84 wt % of n-butyl methacrylate, and 5 wt % of an alkyl methacrylate mixture having 12 to 14 carbon atoms in the alkyl groups.

11. A lubricant oil formulation comprising: the additive according to claim 2; and at least one base oil selected from the group consisting of API group I, II, III, IV and group V; wherein a difference between a high-temperature high-shear viscosity at 100° C. and 150° C. of the lubricant is from 2.5 to 4 mPA.Math.s according to ASTM D 4683.

12. A lubricant oil formulation comprising: the additive according to claim 9; and at least one base oil selected from the group consisting of API group I, II, III, IV and group V; wherein a difference between a high-temperature high-shear viscosity at 100° C. and 150° C. of the lubricant is from 2.5 to 4 mPA.Math.s according to ASTM D 4683.

13. A lubricant oil formulation comprising: the additive according to claim 10; and at least one base oil selected from the group consisting of API group I, II, III, IV and group V; wherein a difference between a high-temperature high-shear viscosity at 100° C. and 150° C. of the lubricant is from 2.5 to 4 mPA.Math.s according to ASTM D 4683.

Description

SYNTHESES OF THE COMB POLYMERS

Examples 1 to 5 and Comparative Examples 1 to 3

(1) An apparatus comprising a 4-neck flask and precision glass sabre stirrer is initially charged with a 600 g mixture of a mixture of low molecular weight monomers and macromonomer whose composition is stated in Table 1, and a 400 g mixture of Shell Risella 907 gas oil and 35 g of 100N oil (65%/35%). After heating to 115° C. under nitrogen, 1.2 g of 2,2-bis-tert-butylperoxybutane are added and the temperature is maintained. 3 h and 6 h after the first addition of initiator, another 1.2 g of 2,2-bis-tert-butylperoxybutane is supplied in each case and the mixture is stirred at 115° C. overnight. The next day, the mixture is diluted from 60% to 40% solids with 500 g of 150N oil. 1500 g of a 40% solution of comb polymer in mineral oil are obtained.

(2) TABLE-US-00002 TABLE 1 Monomer mixture Net polymer Gross composition [wt %] composition [wt %] Example 1 hPBD.sub.MM4800 nBMA Sty LMA 28.0 58.0 .sup. 14.0 0 26 59 15 0 Example 2 hPBD.sub.MM4800 nBMA Sty LMA 25.0 64.0 .sup. 11.0 0 23 65 12 0 Example 3 hPBD.sub.MM4800 nBMA Sty LMA 16.0 67.0 12 5 15 68 12 5 Example 4 hPBD.sub.MM4800 nBMA Sty LMA 12.0 71.0 12 5 11 71 13 5 Example 5 hPBD.sub.MM4800 nBMA Sty LMA 12.0 83.0  0 5 11 84 0 5 Example 6 hPBD.sub.MM4800 nBMA Sty MMA 42.sup.  18.sup.  40 0 40.8 18.4 40.9 0 Comparative hPBD.sub.MM4800 nBMA Sty LMA Example 1 42.0 12.0  3 43  41 12 3 44 Comparative hPBD.sub.MM4800 nBMA MMA LMA Example 2 20.0 20.0 15 45  18.4 20.4 15.3 45.9 Comparative hPBD.sub.MM4800 nBMA MMA LMA Example 3 20.0 20.0  8 52  18.4 20.4 8.2 53 In Table 1: hPBD.sub.MM4800: hydrogenated polybutadiene from CrayValley (Paris) with M.sub.n = 4800 g/mol, T.sub.M = −25° C. and f.sub.MM in the range of 90-95% (macromonomer) nBMA: n-butyl methacrylate Sty: styrene LMA: alkyl methacrylate mixture having 12 to 14 carbon atoms in the alcohol radicals MMA: methyl methacrylate

(3) The macromonomer functionality f.sub.MM of the macromonomer was derived from the GPC curves of the comb polymers themselves, as detailed in WO 2007/025837.

(4) The molecular weights and the polydispersity index PDI were determined by means of GPC, as detailed in WO 2007/025837.

(5) TABLE-US-00003 TABLE 1 M.sub.w [g/mol] PDI f.sub.branch Example 1 191 000 3.5 1.0% Example 2 325 000 4.2 0.8% Example 3 352 000 3.7 0.5% Example 4 312 000 3.5 0.4% Example 5 374 000 4.5 0.4% Example 6 193 000 4.0 1.6% Comparative Example 1 2.9% Comparative Example 2 662 000 6.7 0.8% Comparative Example 3 599 000 5.1 0.9%
Evaluation of the Comb Polymers
A) In 0W-20 Base Oil with DI Package Based on API Group I/III Oil:

(6) The resulting comb polymer additives were characterized by means of measurements of the kinematic viscosities at 40° C. and 100° C. (KV.sub.40 and KV.sub.100) to ASTM D445, by means of the CCS viscosity determined to ASTM D5292 and by means of the high-temperature high-shear viscosity HTHS.sub.100 measured at 100° C. to ASTM D4683, of a solution of high-temperature high-shear viscosity HTHS.sub.150=2.6 mPas set at 150° C. (ASTM D 4683) in a DI package-containing 0W-20 base oil (KV40=23.45 mm.sup.2/s, KV100 4.92 mm.sup.2/s, VI=138).

(7) It is shown clearly that the inventive comb polymers have a significantly lower KV.sub.40 (and likewise lower KV.sub.100) and a lower high-temperature high-shear viscosity HTHS.sub.100 at 100° C. and the polymers detailed in the publication EP 0699694. Similar results are also obtained in relation to the CCS viscosity at −35° C. The results of the evaluation detailed are shown in Table 2.

(8) For comparison, commercially available VI improvers were additionally examined. For this purpose, motor oil formulations were produced with commercially available Infineum SV200 (an HSD star polymer) and Viscoplex® 6-950 (linear PAMA from RohMax Additives GmbH). These results are likewise shown in Table 2.

(9) TABLE-US-00004 TABLE 2 KV.sub.40 KV.sub.100 HTHS.sub.100 CCS-35 Polymer according to [mm.sup.2/s] [mm.sup.2/s] [mPas] [mPas] Example 1 27.9 6.52 4.96 4832 Example 2 27.5 6.51 4.83 4807 Example 3 27.3 6.56 4.82 5028 Example 4 26.4 6.30 4.63 4387 Example 5 26.2 6.34 4.68 4741 Comparative Example 1 39.0 8.14 5.40 5989 Comparative Example 2 35.3 8.73 5.20 5678 Comparative Example 3 39.7 9.19 5.37 5854 Infineum SV200 36.8 7.70 4.95 5350 Viscoplex ® 6-950 37.0 8.64 5.01 5590

(10) In addition, the shear stabilities of the lubricant oil compositions which comprised the comb polymers of Examples 1 to 5 were examined. For this purpose, PSSI measurements were performed to DIN 51382 (30 cycles of a Bosch pump), and all lubricant oils achieved an excellent PSSI value of 0, i.e. the products exhibited no decline in KV.sub.100 whatsoever. As a result of this, it is surprisingly possible to provide a lubricant oil composition which to remain relatively close to the in the specifications detailed above for the viscosity values at high temperature, for example 100° C., without the values in use being lower than these values.

(11) To examine the compatibility of the comb polymers with pour point improvers, further tests were performed. To this end, lubricant oil compositions which comprised a commercially available pour point improver (Viscoplex® 1-247) in a concentration of 0.37% by weight were prepared. In this case, the pour point (PP) was measured to ASTM D97, as were dynamic viscosity DV and yield stress YS to MRV-TP1 (ASTM D4684). The results are detailed in Table 3.

(12) TABLE-US-00005 TABLE 3 MRV-TP1 MRV-TP1 PP YS-40 DV-40 Polymer according to [° C.] [Pa] [mPa] Example 3 −48 <35 20 900 Example 4 −42 <35 16 030 Example 5 −42 <35 18 140

(13) The results show that lubricant oil compositions which the present comb polymers in combination with pour points depressants, especially based on PAMA, have outstanding low-temperature properties (target: <−40° C./<35 Pa/<=60 000 mPas).

(14) B) In 0W-20 Base Oil Based on API Group III Oil:

(15) A 0W-20 base oil of KV40=27.24 mm.sup.2/s, KV100=5.390 mm.sup.2/s and VI=136 was prepared from 11.2% HiTEC® 1192 (Afton Chemical), 8.8% Nexbase® 3030, 80% Nexbase® 3043 (Neste Oil). Thereafter, as in A), the viscometry of examples and comparative examples in formulations of HTHS.sub.150=2.6 mPas was analysed.

(16) In this 0W-20 too, it was found that the inventive comb polymers have a significantly lower KV.sub.40 (and likewise lower KV.sub.100) and a lower high-temperature high-shear viscosity HTHS.sub.100 than Viscoplex® 6-950. Similarly results are also obtained with regard to the CCS viscosity at −35° C. The results of the evaluation detailed are shown in Table 4.

(17) TABLE-US-00006 TABLE 4 KV.sub.40 KV.sub.100 HTHS.sub.100 CCS-35 Polymer according to [mm.sup.2/s] [mm.sup.2/s] [mPas] [mPas] Example 3 30.82 6.623 4.98 5784 Example 5 30.49 6.595 4.85 5648 Viscoplex ® 6-950 41.54 10.06 5.52 6336

(18) The 0W-20 formulations too, in the presence of a commercially available pour point improver based on PAMA (Viscoplex® 1-247 in a concentration of approx. 0.37% by weight) give excellent MRV-TP1 low-temperature properties. The results are shown in Table 5 (target: <35 Pa or <=60 000 mPas).

(19) TABLE-US-00007 TABLE 5 MRV-TP1 MRV-TP1 YS-40 DV-40 Polymer according to [Pa] [mPa] Example 3 <35 14 350 Example 5 <35 14 710
C) In 5W-30 Base Oil with DI Package Based on API Group III Oil:

(20) Finally, a third series of measurements was performed in a DI package-containing 5W-30 base oil (KV40=38.76 mm.sup.2/s, KV100=6.938 mm.sup.2/s and VI=140). Deviating from SAE J300, which required “only” HTHS.sub.150=2.9 mPas for a 5W-30 formulation, the 5W-30 formulations were adjusted to HTHS.sub.150=3.5 mPas in a manner customary for European engine manufacturers (for example Mercedes-Benz operating fluid specifications MB229.1 and MB228.3 for factory fillings).

(21) In the 5W-30 formulations too, it was found that the inventive comb polymers have a significantly lower KV.sub.40 (and likewise lower KV.sub.100) and a lower high-temperature high-shear viscosity HTHS.sub.100 than Viscoplex® 6-950. The results of the evaluation detailed are compiled in Table 6.

(22) TABLE-US-00008 TABLE 6 KV.sub.40 KV.sub.100 HTHS.sub.100 CCS-30 Polymer according to [mm.sup.2/s] [mm.sup.2/s] [mPas] [mPas] Example 3 46.19 9.502 6.76 6032 Example 5 46.04 10.200  6.49 5929 Viscoplex ® 6-950 71.69 15.29 7.63 6830

(23) The 5W-30 formulations too, in the presence of a commercially available pour point improver based on PAMA (Viscoplex® 1-247 in a concentration of approx. 0.37% by weight) give excellent MRV-TP1 low-temperature properties. The results are shown in Table 7 (target: <35 Pa or <=60 000 mPas).

(24) TABLE-US-00009 TABLE 7 MRV-TP1 MRV-TP1 YS-35 DV-35 Polymer according to [Pa] [mPa] Example 3 <35 18 010 Example 5 <35 17 350
D) Examination of Fuel Saving with the “RohMax Test”

(25) Using the RohMax test detailed above, the fuel saving with various polymers was examined. To determine the measurement accuracy of the examination, a run with a 15W-40 oil (CEC reference motor oil RL 191) was carried out at the start and at the end of the test series. The determination of the fuel saving was carried out with the polymers detailed in Table 8, for which 5W-30 formulations were produced according to the examples adduced under point C). The results achieved are likewise stated in Table 8.

(26) TABLE-US-00010 TABLE 8 Consumption Polymer according to Formulation [g] Example 5 5W-30 658.77 Example 6 5W-30 659.09 VISCOPLEX ® 6-950 5W-30 664.21 — 15W-40 675.03 (before the test runs) — 15W-40 675.09 (after the test runs)

(27) The tests show excellent repeatability, as is evident from the comparative runs with the 15W-40 reference oil. This repeatability, which is well below 0.1 g, was achieved especially through careful control of the temperature conditions.

(28) In addition, it was found that, in the case of use of inventive comb polymers, a surprisingly high fuel saving compared to VISCOPLEX® 6-950 can be achieved. Moreover, a comparison of Example 5 with Example 6 shows that, using the comb polymers detailed in claim 3, a further, significant reduction in fuel consumption occurs.