POLY(METH)ACRYLATE COPOLYMERS WITH BRANCHED C17 ALKYL CHAINS AND THEIR USE IN LUBRICANT OIL COMPOSITIONS

Abstract

The presently claimed invention is directed to poly(meth)acrylate copolymers containing alkyl(meth)acrylate comonomer with branched C17 alkyl group. The invention is further related to lubricating oil compositions comprising poly(meth)acrylate copolymers containing alkyl(meth) acrylate comonomer with branched C17 alkyl group as viscosity index improving component.

Claims

1.-15. (canceled)

16. A poly(meth)acrylate copolymer that is obtained by polymerizing a mixture comprising: (A) C17 alkyl (meth)acrylate, where C17 alkyl chain is branched with a mean degree of branching between 2.0 and 4.0, (B) methyl methacrylate and/or methyl acrylate, and (C) alkyl methacrylate and/or alkyl acrylate with a linear or branched C2 to C30 alkyl chain.

17. The copolymer of claim 16, wherein the C17 alkyl chain is branched with a mean degree of branching between 2.8 and 3.7.

18. The copolymer of claim 16, wherein the copolymer has a weight average molecular weight M.sub.W of from 10,000 to 800,000 determined by gel permeation chromatography according to DIN 55672-1.

19. The copolymer of claim 16, wherein the amount of comonomer (A) is from 5 to 80 wt.-%, based on the total weight of the poly(meth)acrylate copolymer.

20. The copolymer of claim 16, wherein the amount of comonomer (B) is from 5 to 40 wt.-%, based on the total weight of the poly(meth)acrylate copolymer.

21. The copolymer of claim 16, wherein the amount of comonomer (C) is from 15 to 80 wt.-%, based on the total weight of the poly(meth)acrylate copolymer.

22. The copolymer of claim 16, wherein the linear or branched C2 to C30 alkyl chain is selected from the group consisting of ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, 2-propyl heptyl, nonyl, decyl, stearyl, lauryl, octadecyl, heptadecyl, nonadecyl, eicosyl, henicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, hexacosyl, octacosyl, nonacosyl, triacontyl and behenyl.

23. A concentrate composition for use in lubricating oils comprising: (i) diluent, and (ii) from 30 to 70 wt.-% of the poly(meth)acrylate copolymer according to claim 16.

24. A lubricating oil composition comprising: (a) a base oil, (b) the poly(meth)acrylate copolymer according to claim 16, and (c) additives

25. The lubricating oil composition of claim 24, comprising 0.1 to 30 wt.-% of the poly(meth)acrylate copolymer according to claim 16, 70 to 99.9 wt.-% base oil, and 0.05 to 20 wt.-% of additives.

26. The lubricating oil composition of claim 24 wherein the additives comprise 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 anti-wear agents.

27. The lubricating oil composition of claim 24, having shear stability index as measured according to ASTM D7109 and as calculated by ASTM D6022 of less than 50.

28. The lubricating oil composition of claim 24, having high temperature high shear viscosity at 100 C. from 4.00 to 6.00 mPas, as measured according to ASTM D5481.

29. An automatic transmission fluid, a manual transmission fluid, an hydraulic fluid, a grease, a gear fluid, a metal-working fluid, a crankcase engine oil or shock absorber fluid comprising the lubricating oil composition of claim 24.

30. A method for improving the shear stability of a lubricating oil, wherein said method comprises adding the poly(meth)acrylate copolymer according to claim 16 to a lubricating oil composition comprising a base oil and additives.

Description

EXAMPLES

[0179] 1. Methods Measurement of the relative weight average molecular weight and molecular weight distribution of polymers was determined based on GPC measurements using polystyrene standards according to DIN 55672-1.

[0180] The kinematic viscosity at 100 C. was determined according to ASTM D445.

[0181] High temperature high shear viscosity (HTHS) at 100 C. and 150 C., respectively, were determined according to ASTM D5481.

[0182] Viscosity index (VI) was determined according to ASTM D2270.

[0183] Shear stability was determined based on the shear stability index (SSI) which was measured according to ASTM D7109 (30 pass) and calculating shear stability index (SSI) by ASTM method D6022.

[0184] 2. Polymerization of Methacrylates

[0185] 54 g branched C17 alkyl methacrylate (C17MA) having a branching degree of 3.1 (prepared and determined as described in WO 09/124979 A1), 45 g methyl methacrylate (MMA), 81 g linear stearyl methacrylate (SMA) and 242 mg dodecyl mercaptane as 10% Nexbase 3030 solution were mixed in 325 g Nexbase 3030 base oil from Neste Oil in 1 L 4-neck flask. The mixture was heated up to 95 C. resulting in a colorless, clear solution. A solution of 0.13 g tert-butylperoctoate in 6 g Nexbase 3030 was prepared and continuously fed to the flask with a rate of 0.0413 ml/min. After 3 hours 1,486 ml of this solution were fed to the product mixture within 30 min. The prepared polymer solution was stirred without any further initiator feed at 95 C. for 90 min. The solution was allowed to cool down to room temperature forming a colorless, viscous liquid.

[0186] The kinematic viscosity of 557.3 mm.sup.2/s (cSt) was determined using Brookfield viscometer at 100 C. (KV100).

[0187] GPC analysis (polystyrene standard): detector: DRI Agilent 1100 UV Agilent 1100 VWD [254 nm], eluent: tetrahydrofuran+0.1% trifluoroacetic acid eluent, flow rate: 1 ml/min), concentration: 2 mg/ml, column: PL gel MIXED-B

[0188] M.sub.n=128 000 g/mol, M.sub.w=384 000 g/mol, PDI=3.0;

[0189] Polymers containing C17MA, MMA, and SMA were prepared as above with varying C17MA and SMA content, tert-butylperoctoate and dodecylmercaptane amount. The reaction temperature, solvent, and polymer concentration were kept constant. The viscosity of the solutions at 100 C. was measured (KV100) and the polymers analyzed by GPC. The characteristics of the resultant polymers are summarized in Table 1 and Table 2.

TABLE-US-00001 TABLE 1 polymer C17MA/ MMA/ SMA/ KV100/ M.sub.w # [g] [g] [g] [mm.sup.2/s] [g/mol] PDI P1 45 45 90 1020 490 000 3.3 P2 18 45 117 2008 680 000 3.6 P3* 0 45 135 1930 511 000 3.7 *= outside the scope of the presently claimed invention

TABLE-US-00002 TABLE 2 polymer C17MA/ MMA/ SMA/ KV100 M.sub.w # [g] [g] [g] [mm.sup.2/s] [g/mol] PDI P4 63 45 72 1302 429 000 4.2 P5 63 45 72 1659 475 000 4.3 P6 36 45 99 626 407 000 3.1 P7 36 45 99 1023 536 000 3.3

[0190] 3. Preparation of Motor Oil Blends

[0191] The copolymers P1 to P7 as prepared above were used for obtaining lubricating oil compositions B1 to B7.

[0192] As the base oil component in the lubricating oil compositions B1 to B7, a Group III base oil was added. As further commercially available passenger car motor oil additive package Infineum V 534 was included.

[0193] The amounts of the components in blends B1 to B7 were as follows: [0194] copolymer P1 to P7: 3.5-5.0 wt.-% [0195] Base oil component: 81.9-83.4 wt.-% [0196] Additive: 13.1 wt.-%

[0197] Rheology behavior and other performance characteristics of lubricating oil compositions B1 to B7 were measured. Table 3 shows that increasing C17MA content in the PMA polymer decreases the SSI, and increase the shear stability of the polymer and the corresponding formulation. Table 4 shows that polymers with higher C17MA content and comparable molecular weight result in higher VI in the oil formulation.

TABLE-US-00003 TABLE 3 blend treat rate KV 100 HTHS 150 HTHS 100 SSI (30) # [wt. %] [mm.sup.2/s] (blend) [mPas] [mPas] [] B1* P1 3.85 8.25 2.63 5.54 40 B2 P2 3.5 8.47 2.64 5.46 44 B3 P3 4.0 8.72 2.62 5.58 45 *= outside the scope of the presently claimed invention

TABLE-US-00004 TABLE 4 blend treat rate KV 100 HTHS 150 HTHS 100 # [wt. %] [mm.sup.2/s] (blend) [mPas] [mPas] VI B4 P4 4.0 8.58 2.63 5.59 210 B5 P5 4.2 8.72 2.64 5.59 213 B6 P6 4.5 8.17 2.63 5.52 202 B7 P7 4.0 8.64 2.59 5.46 208

[0198] 4. Polymerization of Guerbet 20 Methacrylate Having a Branching Degree of 1:

[0199] 135 g branched C20 alkyl methacrylate (C20MA) having a branching degree of 1.45 g methyl methacrylate (MMA), and 60 mg dodecyl mercaptane as 10% Nexbase 3030 solution were mixed in 325 g Nexbase 3030 from Neste Oil base oil in 1 L 4-neck flask. The mixture was heated up to 95 C. resulting in a colorless, clear solution. A solution of 0.13 g tert-butylperoctoate in 6 g Nexbase 3030 is prepared and continuously fed to the flask with a rate of 0.0413 ml/min. After 3 hours 1,486 ml of this solution is fed to the product mixture within 30 min. The prepared polymer solution is then stirred without any further initiator feed at 95 C. for 90 min. The solution is allowed to cool down to room temperature forming a colorless, viscous liquid.

[0200] The kinematic viscosity of 659 mm.sup.2/s (cSt) has been determined using Brookfield viscometer at 100 C. (KV100).

[0201] GPC analysis (polystyrene standard): detector: DRI Agilent 1100 UV Agilent 1100 VWD [254 nm], eluent: tetrahydrofuran+0.1% trifluoracetic acid eluent, flow rate: 1 ml/min), concentration: 2 mg/ml, column: PLgel MIXED-B

[0202] M.sub.n=109 000 g/mol, M.sub.w=446 000 g/mol, PDI=4.1;

[0203] Preparation of Motor Oil Blends

[0204] The copolymer has been used for obtaining lubricating oil composition.

[0205] As the base oil component, Group III has been added. As further commercially available passenger car motor oil additive package Infineum V 534 has been included.

[0206] Shear stability of the blend has been measured. An SSI of 51 was obtained.

[0207] Compared to the motor oil blends with the polymer of example 2 with a branching degree of 3.1 it can be seen that the shear stability index (table 3, last column) of the polymer with a branching degree of 1 is remarkable higher.

[0208] The higher branching degree resulted in a decrease of SSI which is related to an increase of shear stability.