FUNCTIONAL POLYALKYL (METH)ACRYLATES WITH ENHANCED DEMULSIBILITY PERFORMANCE

Abstract

Polyalkyl(meth)acrylate (PAMA) polymers comprising a certain amount of hydroxyl-functionalized alkyl (meth)acrylates can be used for improving the demulsibility performance of high VI lubricating oil compositions. The lubricating oil compositions can be those which are based on apolar base oils, especially hydraulic fluid compositions. The polymers can be comprised in certain lubricating oil compositions.

Claims

1. A polyalkyl(meth)acrylate polymer, comprising: (a) 0% to 8% by weight of methyl (meth)acrylate; (b) 1.5% to 4.5% by weight of a hydroxyl-substituted C.sub.1-4 alkyl(meth)acrylate; and (c) 87.5% to 98.5% by weight of at least one C.sub.6-30 alkyl (meth)acrylate, wherein the polyalkyl(meth)acrylate polymer has a weight-average molecular weight M.sub.w in the range of 30,000 to 130,000 g/mol.

2. The polyalkyl(th)ac .sup.-late polymer according to claim 1, comprising: (a) 2% to 8% by weight, of methyl (meth)acrylate; (b) 1.9% to 4.0% by weight, of a hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate; and (c) 88.0% by weight to 96.1% by weight of at least one C.sub.6-30 alkyl (meth)acrylate.

3. The polyalkyl(meth)acrylate polymer according to claim 1, having a weight-average molecular weight M.sub.w in the range of 40,000 to 100,000 g/mol.

4. (canceled)

5. The polyalkyl(meth)acrylate polymer according to claim 1, having a weight-average molecular weight M.sub.w in the range of 50,000 and 70,000 g/mol.

6. An additive composition, comprising: (A) at least one apolar base oil selected from the group consisting of API Group II oils and API Group III oils and mixtures thereof, and (B) the polyalkyl(meth)acrylate polymer of claim 1.

7. The additive according to claim 6, wherein the polyalkyl(meth)acry late polymer (B) comprises: (a) 2% to 8% by weight, of methyl (meth)acrylate; (b) 1.9% to 4.0% by weight, of a hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate; and (c) 88.0% by weight to 96.1% by weight of at least one C.sub.6-30 alkyl (meth)acrylate.

8. The additive composition according to claim 6, wherein component (A) is present in an amount of 20% to 45% by weight and the polyalkyl(meth)acrylate polymer (B) is present in an amount of 55% to 80% by weight, based on a total weight of the composition.

9. The additive composition according to claim 6, wherein component (A) is present in an amount of 25% to 40% by weight and the polyalkyl(meth)acrylate polymer (B) is present in an amount f 60% to 75% by weight, based on a total weight of the composition.

10. A lubricating oil composition, comprising: (A) 84% to 97% by weight of at least one apolar base oil selected from the group consisting of API Group II oils and API Group III oils and mixtures thereof; (B) 3% to 16% by weight of the polyalkyl(meth)acrylate polymer of claim 1; and (C) optionally one or more further additives.

11. The lubricating oil composition according to claim 10, wherein the polyalkyl(meth)acrylate polymer (B) comprises: (a) 2% to 8% by weight, of methyl (meth)acrylate; (b) 1.9% to 4.0% by weight, of a hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate; and (c) 88.0% by weight to 96.1% by weight of at least one C.sub.6-30 alkyl (meth)acrylate.

12. The lubricating oil composition according to claim 10, wherein the one or more further additives (C) are present and are one or more selected from the group consisting of pour point depressants, dispersants, defoamers, detergents, demuisifiers, antioxidants, antiwear additives, extreme pressure additives, friction modifiers, anticorrosion additives, dyes and mixtures thereof.

13. (canceled)

14. A method of improving a VI and a demulsibility performance of a lubricating oil composition based on an apolar base oil, the method comprising: applying a polyalkyl(meth)acrylate polymer according to claim 1 to a lubricating oil composition in need thereof.

15. (canceled)

16. A method of improving a VI and a demulsibility performance of a lubricating oil composition based on an apolar base oil, the method comprising applying an additive composition according to claim 6 to a lubricating oil composition in need thereof.

17. The polyalkyl(meth)acrylate polymer according to claim 1, wherein the hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate comprises at least one selected from the group consisting of hydroxyethyl (meth)acrylate (HEMA) and hydroxypropyl (meth)acrylate (HPMA).

18. The additive composition according to claim 6, wherein the hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate is selected from the group consisting of hydroxyethyl (meth)acrylate (HEMA) and hydroxypropyl (meth)acrylate (HPMA).

19. The lubricating oil composition according to claim 10, wherein the hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate is selected from the group consisting of hydroxyethyl (meth)acrylate (HEMA) and hydroxypropyl (meth)acrylate (HPMA),

20. The lubricating oil composition according to claim 10, having a VI of from 150 to 250.

21. The lubricating oil composition according to claim 10, wherein the time to demulse of said lubricating oil composition is 9 minutes or less.

22. The polyalkyl(meth)acrylate polymer according to claim 1, wherein weight percent amounts of components (a), (b), and (c) add up to 100% of a total weight of the polyalkyl(meth)acrylate polymer.

23. The additive composition according to claim 6, wherein weight percent amounts of components (a), (b), and (c) add up to 100% of a total weight of the polyalkyl(meth)acrylate polymer.

24. The lubricating oil composition according to claim 10, wherein weight percent amounts of components (a), (b), and (c) add up to 100% of a total weight of the polyalkyl(meth)acrylate polymer.

25. The polyalkyl(meth)acrylate polymer according to claim 1, wherein the hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate is hydroxyethyl (meth)acrylate (HEMA).

Description

[0102] The invention has been illustrated by the following non-limiting examples.

[0103] Experimental Part

ABBREVIATIONS

[0104] KV kinematic viscosity measured according to ASTM D445 [0105] KV.sub.40 kinematic viscosity measured @40 C. to ASTM D445 [0106] KV.sub.100 kinematic viscosity measured @100 C. to ASTM D445 [0107] HEMA hydroxyethyl methacrylate [0108] HPMA hydroxypropyl methacrylate [0109] MMA methyl methacrylate [0110] NB 3020 Nexbase 3020, Group III base oil from Neste with a KV.sub.100 of 2.2 cSt [0111] NB 3043 Nexbase 3043, Group III base oil from Neste with a KV.sub.100 of 4.3 cSt [0112] NB 3080 Nexbase 3080, Group III base oil from Neste with a KV.sub.100 of 7.9 cSt [0113] 100R Group II base oil from Chevron with a KV.sub.100 of 4.1 cSt [0114] 220R Group II base oil from Chevron with a KV.sub.100 of 6.4 cSt [0115] Esso 100 Sentinel 619, Group I base oil obtained from Univar [0116] Esso 150 Sentinel 847, Group I base oil obtained from Univar [0117] Esso 600 Sentinel 876, Group I base oil obtained from Univar [0118] DDM dodecanethiol [0119] DPMA Methacrylate made from synthetic C.sub.12-15 mixture, 21% C.sub.12, 29% C.sub.13, 29% C.sub.14, 21% C.sub.15; 76% linear [0120] CEMA cetyl-eicosyl methacrylate, 52% C.sub.16, 31% C.sub.18, 13% C.sub.20, 4% others; all linear [0121] LMA lauryl methacrylate, 73% C.sub.12, 27% C.sub.14; all linear [0122] SMA stearyl methacrylate, 33% C.sub.16, 67% C.sub.18; all linear [0123] Sty styrene [0124] M.sub.w weight-average molecular weight [0125] PDI Polydispersity index [0126] Hitec 521 DI Package commercially available from Afton [0127] VPL 1-333 VISCOPLEX 1-333, pour point depressant commercially available from Evonik

[0128] Test Methods

[0129] The polymers according to the present invention and the comparative examples were characterized with respect to their molecular weight and PDI.

[0130] Molecular weights were determined by size exclusion chromatography (SEC) using commercially available polymethylmethacrylate (PMMA) standards. The determination is effected by gel permeation chromatography with THF as eluent (flow rate: 1 mL/min; injected volume: 100 l).

[0131] The additive compositions and lubricating oil compositions including the polyalkyl(meth)acrylate polymers according to the present invention and comparative examples were characterized with respect to kinematic viscosity at 40 C. (KV.sub.40) and 100 C. (KV.sub.100) to ASTM D445, the viscosity index (VI) to ASTM D2270 and demulsibility (time to demulse).

[0132] Samples for use in measuring viscosity index were formulated by adding an amount of a respective one of the compositions to apolar oils effective to provide a kinematic viscosity of about 46 mm.sup.2/s (cSt) at 40 C. The viscosity index of each of the samples was determined according to ASTM method D2270 by comparing the respective kinematic viscosities at 40 C. and 100 C. Results are set forth in Tables 4, 6 and 8 as VI.

[0133] Samples for use in measuring demulsibility were formulated by adding an amount of a respective one of the compositions to apolar oils effective to provide a kinematic viscosity of about 46 mm.sup.2/s (cSt) at 40 C. The demulsibility of each of the samples was characterized by the method of ASTM D 1401 Standard Test Method for Water Separability of Petroleum Oils and Synthetic Fluids. 40 mL of fluid are mixed with 40 mL of water at 54 C. Time given is the time until no more than 3 mL of emulsion are left. Test is stopped after 30 minutes as less than 30 minutes is required for hydraulic fluids according to ISO 11158. Results are set forth below in Tables 4, 6 and 8 as the respective time to demulse given in minutes.

[0134] Polymer Synthesis

[0135] Example for a Product with 3.5% HEMA and 8% MMA (Example 2)

[0136] A round-bottom flask equipped with a glass stir rod, nitrogen inlet, reflux condenser and thermometer was charged with 218.07 g of Group III oil supplied by Neste, 511.2 g C.sub.12/C.sub.14-methacrylate, 20.2 g hydroxyethylmethacrylate (HEMA), 46.2 g methyl methacrylate and 3.75 g chain transfer agent (DDM). The mixture was heated up to 110 C. while stirring and nitrogen bubbling for inertion. Then 3-stage feed for 3 hours feed of a mixture consisting of 1.44 g tert-butyl-perhexanoate and 4.33 g Group III oil supplied by Neste was started. After the feed end the mixture was stirred for an additional 60 minutes. After addition of 1.16 g tert-butyl-perhexanoate the mixture was stirred for an additional 60 minutes.

[0137] All other polyalkyl(meth)acrylate polymers were prepared by radical polymerization in oil as described in the synthesis procedure of Example 2. Group II and III dilution oils were used in the examples with respect to their future use in Group II or III formulations. As the dilution oil of the polymer will be only a minor part of a final formulation, dilution oils from other base oil classes as group I, IV and V are possible.

[0138] Modifications of the procedure are noted in Table 1. The monomer components will add up to 100%. The amounts of DDM and dilution oil are given relative to the total amount of monomers.

TABLE-US-00003 TABLE 1 Compositions of reaction mixtures used for preparation of the polyalkyl(meth)acrylate polymers according to the present invention Monomers Reaction Dilution Polymer used conditions oil Example HEMA HPMA MMA LMA SMA DDM NB 3020 100R # [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] 1 2.5 5.0 92.5 0.65 28 2 3.5 8.0 88.5 0.65 28 3 2.3 5.5 92.2 0.65 28 4 3.5 3.0 93.5 0.65 28 5 4.5 6.0 89.5 0.65 28 6 3.0 97.0 0.65 28 7 3.0 2.0 95.0 0.65 28 8 1.9 8.0 90.1 0.65 28 9 1.9 5.0 93.1 0.65 28 10 3.0 97.0 0.30 28 11 3.0 5.0 92.0 0.30 28 12 3.0 5.0 92.0 1.20 28 13 3.0 5.0 92.0 0.40 28 14 3.0 71.8 25.2 0.55 31 15 3.0 7.0 66.6 23.4 0.55 31 16 2.5 5.0 92.5 0.70 28 17 4.0 5.0 91.0 0.65 28 18 2.5 5.0 92.5 0.30 34 19 4.0 5.0 91.0 0.30 34 20 3.0 5.0 92.0 0.65 28 21 100.0 0.75 28 (Comp.) 22 10.0 90.0 0.75 28 (Comp.) 23 5.0 10.0 85.0 0.60 28 (Comp.) 24 5.0 95.0 0.60 28 (Comp.) 25 1.0 8.0 91.0 0.65 28 (Comp.) 26 1.0 3.0 96.0 0.65 28 (Comp.) 27 3.0 10.0 87.0 0.65 28 (Comp.) 28 6.0 6.0 88.0 0.30 28 (Comp.) 29 5.0 70.3 24.7 0.55 31 (Comp.) 30 5.0 5.0 66.6 23.4 0.55 31 (Comp.)

[0139] The polymers prepared according to the present invention comprise defined amounts of hydroxy-functionalized alkyl(meth)acrylates.

[0140] The net compositions of the resulting polyalkyl(meth)acrylate polymers and their characteristic weight-average molecular weights M.sub.w as well as their polydispersity indices are given in the following Table 2.

TABLE-US-00004 TABLE 2 Net compositions of polyalkyl(meth)acrylate polymers prepared according to the present invention (monomer components add up to 100%), their molecular weight and PDI Polymer Exam- HEMA HPMA MMA LMA SMA M.sub.w ple [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] [g/mol] PDI 1 2.5 5.0 92.5 56100 2.1 2 3.5 8.0 88.5 59800 2.1 3 2.3 5.5 92.2 58100 2.1 4 3.5 3.0 93.5 58700 2.1 5 4.5 6.0 89.5 59100 2.1 6 3.0 97.0 56400 2.1 7 3.0 2.0 95.0 56000 2.0 8 1.9 8.0 90.1 58900 2.0 9 1.9 5.0 93.1 56100 2.1 10 3.0 97.0 125000 2.6 11 3.0 5.0 92.0 118000 2.6 12 3.0 5.0 92.0 32100 1.9 13 3.0 5.0 92.0 92100 2.3 14 3.0 71.8 25.2 69700 2.2 15 3.0 7.0 66.6 23.4 71300 2.2 16 2.5 5.0 92.5 55900 2.1 17 4.0 5.0 91.0 58800 2.0 18 2.5 5.0 92.5 117000 2.5 19 4.0 5.0 91.0 124000 2.6 20 3.0 5.0 92.0 59100 2.1 21 100.0 48800 2.0 (Comp.) 22 10.0 90.0 49400 2.1 (Comp.) 23 5.0 10.0 85.0 64800 2.2 (Comp.) 24 5.0 95.0 62300 2.1 (Comp.) 25 1.0 8.0 91.0 55000 2.2 (Comp.) 26 1.0 3.0 96.0 54500 2.2 (Comp.) 27 3.0 10.0 87.0 59500 2.1 (Comp.) 28 6.0 6.0 88.0 138000 2.7 (Comp.) 29 5.0 70.3 24.7 69200 2.1 (Comp.) 30 5.0 5.0 66.6 23.4 71100 2.2 (Comp.)

[0141] Polymer Examples 1 to 20 are working examples and comprise the hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate (HEMA or HPMA) and methyl methacrylate in amounts specified in the present invention.

[0142] Polymer Examples 21 to 30 are comparative examples and comprise the hydroxyl-substituted C.sub.1-4 alkyl (meth)acrylate (HEMA or HPMA) and/or methyl methacrylate in amounts which are outside the ranges as specified in the present invention.

[0143] To demonstrate the effect of the polyalkyl(methacrylate) polymers according to the present invention on the demulsibility performance of lubricating compositions, different formulation examples were prepared.

FORMULATION EXAMPLES A

[0144] The following Table 3 shows the composition of Formulations A1-A20, each comprising one of the polyalkyl(meth)acrylates as presented in Table 2 and a base oil, which were formulated to a KV.sub.40 of about 46 mm.sup.2/s. As apolar base oil was used a mixture of NB 3043 (Group III base oil with a KV.sub.100 of 4.3 cSt) and NB 3080 (Group III base oil with a KV.sub.100 of 7.9 cSt).

[0145] Formulations A1 to A11 are working examples and comprise the polyalkyl(meth)acrylates according to the present invention (Polymer Examples 1-20).

[0146] Formulations A12 to A20 are comparative examples as they comprise polyalkyl(meth)acrylates which compositions are outside the ranges as disclosed and claimed in the present invention (Polymer Examples 21-30).

TABLE-US-00005 TABLE 3 Additive compositions A prepared according to the present invention Product Oils Formulation Polymer Treat rate NB 3043 NB 3080 # # [%] [%] [%] A1 Example 1 8.8 48.0 43.2 A2 Example 2 9.0 42.8 48.2 A3 Example 3 8.9 45.1 46.0 A4 Example 6 8.9 45.1 46.0 A5 Example 7 8.9 45.1 46.0 A6 Example 8 8.3 43.0 48.7 A7 Example 9 8.9 46.1 45.0 A8 Example 14 8.2 44.0 47.8 A9 Example 15 7.7 39.4 52.9 A10 Example 16 9.2 47.0 43.8 A11 Example 20 8.7 47.0 44.3 A12*.sup.) Example 21 10.4 52.6 37.0 (Comp.) A13*.sup.) Example 22 9.4 46.6 44.0 (Comp.) A14*.sup.) Example 23 8.5 40.5 51.0 (Comp.) A15*.sup.) Example 24 8.7 48.3 43.0 (Comp.) A16*.sup.) Example 25 9.6 48.3 42.1 (Comp.) A17*.sup.) Example 26 9.6 51.2 39.2 (Comp.) A18*.sup.) Example 27 8.7 42.0 49.3 (Comp.) A19*.sup.) Example 29 8.4 41.3 50.2 (Comp.) A20*.sup.) Example 30 8.3 40.2 51.5 (Comp.) *.sup.)= comparative examples

[0147] The PAMA VI improvers according to the present invention consist mainly of comparably apolar methacrylates such as LMA to generate an oil soluble polymer.

[0148] In solution most polymers form of a spherical coil. The superior VI performance of PAMAs is a result of the change in hydrodynamic radius of the coil with temperature. The highly polar backbone is poorly solved at low temperatures which results in a relatively small polymer coil. With inreasing temperatures the solvency of the oil increases, the backbone is better dissolved and the coil gets bigger. This change in hydrodynamic radius correlates with the thickening contribution of the polymer. In order to increase this effect and to shift it into the desired temperature window the polarity of the polymer can be adjusted. Polar monomers like MMA, BMA and also HEMA will reduce the solubility of the backbone and therefore contribute to a more contracted polymer backbone.

[0149] As the VI effect gets more pronounced polar monomers reduce the amount of polymer required to reach a certain VI (viscosity index) level, i.e. they reduce the treat rate of the VI improver. Table 3 shows that the treat rates of the polymers comprising small amounts of polar monomers have a lower treat rate (Formulations A1 to A11: treat rate is between 7.7 and 9.2%) than very apolar PAMA like e.g. Formulation A12 which comprises Polymer Example 21.

[0150] A lower VI improver treat rate is highly desired as it is much more expensive than mineral oil. State of the art are therefore PAMAs with increased backbone polarity. As can be seen in the comparison of the formulations A12 and A13, the even 10% of the polar monomer MMA reduces the treat rate by 10%. The effect is further increased in the final application as more contracted polymers will be also less vulnerable to shear forces which allows the use of higher molecular weight polymers which will further reduce the treat rate.

[0151] The high-polarity backbones also have several drawbacks which limit the applicability of this approach. For hydraulic fluids the main challenge is the influence on the demulsibility performance according to standards such as ISO 11158. A more polar backbone will result in a more surfactant-like chemical structure of the polymer with pronounced polar and apolar parts. These polymers are able to stabilize water in oil emulsions and water will not separate from the oil.

[0152] Demulsifiers can be used to overcome this effect sometimes, but these polar components have other unwanted side-effects as their activity is not limited to the water/oil interface.

[0153] No demulsifiers are used in the examples according to the present invention as the demulsibility performance is controlled via the polymer composition.

[0154] The effect of the different polyalkyl(meth)acrylates on the demulsibility is presented in Table 4 as the Time to Demulse. Additionally, KV.sub.100 and viscosity index (VI) of the formulations are also given.

TABLE-US-00006 TABLE 4 Formulation properties of the additive compositions A prepared according to the present invention demonstrating the effect of monomer composition on the demulsification performance Formulation Properties Formulation KV.sub.40 KV.sub.100 Time to Demulse # [cSt] [cSt] VI [min] A1 46.7 9.1 180 2.0 A2 46.6 9.1 182 6.7 A3 46.5 9.1 182 4.0 A4 46.4 9.0 180 4.7 A5 46.1 9.0 180 4.7 A6 46.2 9.0 180 2.3 A7 46.2 9.0 180 3.1 A8 46.8 9.1 181 <5 A9 46.3 9.0 180 <5 A10 46.7 9.1 182 4.4 A11 46.2 9.0 181 8.2 A12*.sup.) 46.4 9.0 178 9.6 A13*.sup.) 46.5 9.0 179 >30 A14*.sup.) 46.0 8.9 178 >30 A15*.sup.) 46.3 9.1 181 >30 A16*.sup.) 47.0 9.2 182 >30 A17*.sup.) 46.5 9.1 181 >30 A18*.sup.) 46.2 9.0 181 >30 A19*.sup.) 46.2 9.0 181 20.0 A20*.sup.) 46.1 9.0 181 >30 *.sup.)= comparative examples

[0155] Hydroxy-functionalized monomers can be considered as an extreme case of a polar monomer unit as hydrogen bonding will contribute massively to contraction of the polymers in apolar oils. For this reason, monomers such as HEMA and HPMA are expected to have a strong negative effect on demulsification performance. This effect can be observed both at high and low concentrations of these hydroxy-functionalized monomers, but surprisingly there is a certain range of rather low concentrations in which even the opposite effect can be observed in apolar base oils from groups II and III.

[0156] As can be seen from Table 4, Formulation A12 using Polymer Example 21 as polymer product shows average demulsification performance (time to demulse=9.6 minutes), while excellent results are obtained with polymers containing 1.5-4.5% HEMA and not more than 9% MMA. Poor results are for example obtained with formulations A16 (using Polymer Example 25) and A17 (using Polymer Example 26) with an amount of HEMA of only 1% by weight (time to demulse>30 minutes).

[0157] They demonstrate that the demulsifying effect is induced by a certain amount of hydroxyl functions. As described before, a high backbone polarity induced by polar monomers is desirable. If HEMA is used according to this invention, it can be combined with MMA to improve the performance of the polymer as VI improver. Comparison of the formulations comprising one of the two high MMA polymers, Formulation A2 (3.5% HEMA and 8% MMA) and Formulation A6 (1.9% HEMA and 8% MMA) with formulations comprising polymer Example 25 (1% HEMA and 8% MMA), Formulation 16, and polymer Example 27 (3% HEMA and 10% MMA), Formulation A18, shows that only a careful balance of MMA and HEMA will lead to optimum results. Formulations A2 (with polymer Example 2) and A6 (with polymer Example 8) both show very low times to demulse of 2.0 and 2.3 minutes, whereas formulations A16 (with polymer Example 25) and A18 (with polymer Example 27) both show times to demulse of >30 minutes which equals a failure in the test procedure.

FORMULATION EXAMPLES B

[0158] To demonstrate the superior effect of the polyalkyl(meth)acrylates according to the present invention on API Group II and/or Group III oils in contrast to Group I oils, lubricating oil compositions B with different oil mixtures are prepared. Details are outlined in the following Table 5.

TABLE-US-00007 TABLE 5 Lubricating oil compositions B according to the present invention, prepared with different base oil mixtures Group I Oils Group III Oils Other components Product Esso Esso Esso Group II Oils NB NB Hitec VPL Formulation Polymer Treat rate 100 150 600 100R 220R 3043 3080 521 1-333 # Example # [wt %] [wt %] [wt %] [wt %] [wt %] [wt %] [wt %] [wt %] [wt %] [wt %] B1 1 8.8 48.0 43.2 B2 1 11.0 47.0 42.0 B3*.sup.) 14 10.5 76.0 13.5 B4 14 8.2 44.0 47.8 B5*.sup.) 14 10.3 58.0 31.7 B6*.sup.) 15 9.9 73.2 16.9 B7 15 7.7 39.4 52.9 B8 16 9.2 47.0 43.8 B9 16 9.0 35.0 54.9 0.9 0.2 *.sup.)= comparative examples

[0159] Formulations B1 to B9 comprise one of the Polymer Examples in accordance with the present invention and either API Group I base oil (Formulations B3 and B6, which are comparative examples), Group II base oils (Formulations B2 and B9), Group III base oils (Formulations B1, B4, B7 and B8) or mixtures of Group I and Group III base oils (Formulation B5). Formulation B9 does additionally comprise a DI package (Hitec 521) and a PAMA pour point depressant (VPL 1-333) in order to show the applicability of the present invention to a typical state of the art hydraulic formulation.

[0160] Table 6 compares the demulsification performance of the polymers, which are prepared in accordance with the present invention, in different base oils, formulated to a KV.sub.40 of 46 mm.sup.2/s.

TABLE-US-00008 TABLE 6 Formulation properties of lubricating oil compositions B according to the present invention, prepared with different oil mixtures Formulation Properties Formulation KV.sub.40 KV.sub.100 Time to Demulse # [mm.sup.2/s] [mm.sup.2/s] VI [min] B1 46.7 9.1 180 2.0 B2 46.5 9.1 180 0.5 B3*.sup.) 46.0 9.0 180 >30 B4 46.8 9.1 181 <5 B5*.sup.) 46.4 9.1 181 >30 B6*.sup.) 45.9 9.0 180 >30 B7 46.3 9.0 180 <5 B8 46.7 9.1 182 4.4 B9 49.3 9.0 165 4.8 *.sup.)= comparative examples

[0161] Table 6 clearly shows that while excellent values are obtained in the apolar Group II and Group III base oils (see Formulations B1, B2, B4, B7, B8 and B9 with Time to Demulse<5 minutes), a very poor performance is observed in Group I formulations (see Formulations B3 and B6 with Time to Demulse>30 minutes). Also mixtures of Group I and Group III base oils do not show an improvement (see Formulation B5 with Time to Demulse>30 minutes). Formulation B9 represents a fully formulated oil, comprising additionally a DI package and a PAMA pour point depressant. Despite the polar nature of the DI package components, their influence on the demulsification properties of the formulation with HEMA-containing PAMA seems to be minimal.

FORMULATION EXAMPLES C

[0162] A superior effect of the polyalkyl(meth)acrylates according to the present invention on API Group II and/or Group III oil formulations can also be shown with regard to different treat rates. Therefore, lubricating oil compositions C are prepared.

TABLE-US-00009 TABLE 7 Lubricating oil compositions C according to the present invention with different treat rates Polymer Product Polymer Oils Formulation Polymer Treat rate treat rate NB 3020 NB 3043 NB 3080 # Example # [wt %] [wt %] [wt %] [wt %] [wt %] C1 10 4.8 3.5 40.2 55.0 C2 11 5.1 3.7 40.0 54.9 C3 11 7.3 5.3 54.7 38.0 C4 11 9.8 7.1 74.2 16.0 C5 11 4.1 3.0 75.0 20.9 C6 12 14.5 10.4 52.0 33.5 C7 12 22.3 16.1 5.0 72.7 C8 12 11.8 8.5 84.2 4.0 C9 13 6.0 4.3 39.0 55.0 C10 13 8.6 6.2 54.9 36.5 C11 13 4.8 3.5 74.2 21.0 C12 1 8.8 6.3 48.0 43.2 C13 1 13.0 9.4 65.0 22.0 C14 1 17.2 12.4 39.8 43.0 C15 1 7.1 5.1 78.9 14.0 C16 1 11.5 8.3 13.0 75.5 C17*.sup.) Ex 28 5.2 3.7 35.0 59.8 (Comp.) *.sup.)= comparative examples

[0163] Table 8 compares formulation examples C with different treat rates of the polymers according to the present invention due to different viscosity, VI and time to demulse.

[0164] The different compositions are formulated to a KV.sub.40 of 32 mm.sup.2/s, 46 mm.sup.2/s or 68 mm.sup.2/s which relates to the most important ISO viscosity classes for hydraulic fluids.

TABLE-US-00010 TABLE 8 Formulation properties of lubricating oil compositions C according to the present invention with different treat rates Formulation Properties Formulation KV.sub.40 KV.sub.100 Time to Demulse # [cSt] [cSt] VI [min] C1 46.2 9.0 180 8.3 C2 46.2 9.0 182 9.0 C3 46.8 9.7 199 8.2 C4 46.7 10.4 219 4.6 C5 32.6 6.9 180 5.0 C6 46.6 9.1 180 4.1 C7 46.6 9.7 200 13.8 C8 32.4 6.9 181 8.0 C9 46.4 9.1 181 13.7 C10 46.6 9.7 199 11.4 C11 32.5 6.9 180 7.2 C12 46.7 9.1 180 2.0 C13 46.8 9.7 200 3.2 C14 46.4 10.4 220 6.0 C15 32.4 6.9 181 1.5 C16 68.3 12.2 179 7.1 C17*.sup.) 46.2 9.0 180 >30 *.sup.)= comparative examples

[0165] As expected, very high polymer treat rates as with the low molecular weight Polymer Example 12 (Formulations C6, C7 and C8) show longer, but still good times for demulsification.

[0166] Surprisingly, also lower treat rates of the high molecular weight Polymer Examples 10, 11 and 13 (Formulations C1-C5 and C9-C11) show a similar effect, and demulsification performance even improves if more polymer is added to reach a higher VI. Counterbalancing the lower polymer treat rate by a higher HEMA content as shown with Formulation C17 (using Polymer Example 28) is not possible (time to demulse>30 minutes). This indicates that the origin of the effect can be found in the balance between polar and apolar parts within the polymeric chain.

[0167] To further show the importance of a careful balance of MMA and HEMA in PAMA polymers to receive a high VI compared to excellent demulsibilty performance of lubricanting oil compositions, the following examples were prepared in accordance with state of the art literature.

[0168] Example (a) corresponds to Example 1 as disclosed in EP 0 569 639 A1 and was prepared following the protocol disclosed therein (see page 8, lines 35-54).

[0169] Example (b) corresponds to Example 3 as disclosed in EP 0 569 639 A1 and was prepared following the protocol disclosed therein (see page 9, lines 13-32).

[0170] Example (c) corresponds to Example 1 as disclosed in U.S. Pat. No. 5,851,967 and was prepared following the protocol disclosed therein (see columns 5 and 6).

[0171] Example (d) corresponds to Example 2 as disclosed in U.S. Pat. No. 5,851,967 and was prepared following the protocol disclosed therein (see columns 5 and 6).

[0172] Example (e) corresponds to Example 1 as disclosed in U.S. Pat. No. 6,409,778 and was prepared following the protocol disclosed therein (see columns 5 and 6).

[0173] Example (f) corresponds to Polymer C disclosed under Example 6 of EP 0569639 A1 (see page 11). It was prepared following the protocol given under Example 1 of EP 0569639 A1 (see page 8).

[0174] Therein, a paraffinic oil base stock, a 100N oil, was used as solvent.

[0175] The weight-average molecular weight of the resulting polymer (f) is 140.000 g/mol and the PDI is 2.87.

TABLE-US-00011 TABLE 9 PAMA polymers prepared according to the protocols disclosed in the state of the art documents (the monomer components will add up to 100%). Monomers C.sub.10 DPMA CEMA SMA HEMA HPMA MMA AMA* C.sub.12-15 C.sub.16/18/20 C.sub.16/18 Sty # Example [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] [wt. %] (a) Example 1 of 5 10 55 30 EP 0569639A1 (b) Example 3 of 5 5 85 5 EP 0569639A1 (c) Example 1 of 4.0 26.5 39.3 30.2 U.S. Pat. No. 5,851,967 (d) Example 2 of 3.1 26.7 39.7 30.5 U.S. Pat. No. 5,851,967 (e) Example 1 of 6.0 79.3 14.7 U.S. Pat. No. 6,409,778 (f) Example 6-C of 4.0 8.0 88.0 EP 0569639A1 *= C.sub.10 alkyl methacrylate (isodecyl methacrylate)

[0176] The following Table 10 shows the composition of Formulations (a1) to (f2), each comprising one of the polyalkyl(meth)acrylates as presented in Table 5 and a base oil, which were formulated to a KV.sub.40 of about 46 mm.sup.2/s. As apolar base oil was used a mixture of NB 3043 (Group III base oil with a KV.sub.100 of 4.3 cSt) and NB 3080 (Group III base oil with a KV.sub.100 of 7.9 cSt).

TABLE-US-00012 TABLE 10 Additive compositions prepared by using the polymers presented in Table 9 Product Oils Formulation Polymer Treat rate NB 3043 NB 3080 # # [%] [%] [%] (a1) (a) 3.7 22.5 73.8 (b1) (b) A formulation was not possible as polymer (b1) could not be dissolved. (c1) (c) 3.5 37.0 59.5 (d1) (d) 3.7 38.0 58.3 (e1) (e) 16.7 42.3 41.0 (f1) (f) 7.2 34.8 58.0

[0177] The effect of the different polyalkyl(meth)acrylates on the demulsibility is presented in Table 11 as the Time to Demuls. Additionally, KV.sub.100 and viscosity index (VI) of the formulations are also given.

TABLE-US-00013 TABLE 11 Formulation properties of the additive compositions as presented in Table 10 Formulation Properties Formulation KV.sub.40 KV.sub.100 Time to Demulse # [cSt] [cSt] VI [min] (a1) 46.2 9.1 181 >30 (b1) (c1) 46.6 9.1 181 >30 (d1) 46.4 9.0 180 >30 (e1) 46.5 9.1 180 >30 (f1) 45.9 9.0 181 >30

[0178] Polymer (a) contains too much HPMA and MMA and provides therefore a very poor demulsibility performance. Polymer (b) is incompatible with the oil mixture which may be attributed to the formation of gel-like polymer during the polymerization procedure. Group III base oils react more sensitive to such poorly soluble crosslinked polymer chains than Group I base oils which are better solvents.

[0179] Formulation (a1) containing polymer (a) which is produced in a similar way was already hazy, but due to the higher molecular weight the required treat rate in the formulation was significantly lower and the haze did not settle. Hydroxy-functional methacrylates are known to contain a certain amount of dimethacrylates produced via esterification of the free hydroxy function. These dimethacrylates favor the formation of gelled polymers.

[0180] Despite an amount of HPMA in the range as claimed in this invention formulations (c1) and (d1) showed no sign of phase separation in the demulsibility test which can probably be attributed to the poor balance of the composition with regard to the polar monomers HPMA and styrene.

[0181] Whilst the oil compatibility of polymer (e) is excellent, the HEMA content is too high to reach a good demulsibility performance.

[0182] Formulation (f1) containing polymer (f) also showed a very poor demulsibility performance which can be correlated to the relatively high molecular weight.