ACRYLATE-OLEFIN COPOLYMERS AS HIGH VISCOSITY BASE FLUIDS

Abstract

The invention relates to acrylate-olefin copolymers and to a method for preparing these polymers. The present invention is also directed to lubricant compositions comprising these copolymers, and to the use of these copolymers as a lubricant additive or a synthetic base fluid in a lubricating oil composition, preferably in a gear oil composition, a transmission oil composition, a hydraulic oil composition, an engine oil composition, a marine oil composition, an industrial lubricating oil composition or in grease.

Claims

1. A copolymer comprising: a) from 65 to 90% by weight, based on the total weight of the copolymer, of monomer units derived from at least one acrylate of Formula (I), ##STR00005## wherein R.sub.1 means a linear or branched alkyl group having from 6 to 12 carbon atoms, b) from 10 to 35% by weight, based on the total weight of the copolymer, of monomer units derived from at least one non-functionalized alpha-olefin of formula (II), ##STR00006## wherein R.sub.2 means a linear alkyl group having from 6 to 16 carbon atoms, and c) from 0 to 10% by weight of monomer units derived from at least one monomer selected from the list consisting of methacrylamides, fumarates, maleates or a mixture thereof, based on the total weight of the copolymer, and wherein the copolymer has a kinematic viscosity from 80 to 600 cSt at 100° C. according to ASTM D 445, and wherein the copolymer comprises from 0 to 22% by weight of monomer units derived from monomers with linear alkyl group having more than 8 carbon atoms, based on the total weight of the copolymer.

2. The copolymer according to claim 1, wherein the copolymer comprises from 0 to 20% by weight, of monomer units derived from monomers with linear alkyl group having more than 8 carbon atoms, based on the total weight of the copolymer.

3. The copolymer according to claim 1, wherein the copolymer has a kinematic viscosity from 100 to 500 cSt at 100° C. according to ASTM D 445.

4. The copolymer according to claim 1, wherein the copolymer comprises 10 to 30% by weight, preferably from 10 to 25% by weight, of monomer units b) derived from the non-functionalized alpha-olefin of Formula (II), based on the total weight of the copolymer.

5. The copolymer according to claim 1, wherein the non-functionalized alpha-olefin b) of Formula (II) is selected from the group consisting of decene, dodecene, tetradecene, hexadecene or a mixture thereof.

6. The copolymer according to claim 1, wherein R.sub.1 in the acrylate of Formula (I) is a linear or branched alkyl group having from 6 to 10 carbon atoms.

7. The copolymer according to claim 1, wherein the copolymer comprises 0 to 7% by weight, of monomer units derived from monomer c), based on the total weight of the copolymer.

8. The copolymer according to claim 1, wherein the total amount of monomer units derived from monomers a) and b) in the copolymer sums up to 90% by weight, based on the total weight of the copolymer.

9. The copolymer according to claim 1, wherein the total amount of monomer units derived from monomers a), b) and c) in the copolymer sums up to 90% by weight, based on the total weight of the copolymer.

10. The copolymer according to claim 1, wherein the copolymer has a weight average molecular weight from 5,000 to 30,000 g/mol according to DIN 55672-1.

11. The copolymer according to claim 1, wherein the copolymer has a PDI from 1 to 4.

12. The copolymer according to claim 1, wherein the copolymer has a COC flashpoint above 250° C. according to ASTM D92.

13. The method for the preparation of a copolymer as defined in claim 1, wherein the method comprises the steps of: i) providing a monomer composition, and ii) initiating radical polymerization in the monomer composition to obtain the copolymer.

14. The lubricant composition comprising one or more base oil and at least one copolymer according to claim 1.

15. A lubricant additive comprising the copolymer as defined in claim 1.

16. The copolymer according to claim 1, wherein the copolymer has a kinematic viscosity from 150 to 400 cSt at 100° C. according to ASTM D 445.

17. A synthetic base fluid comprising the copolymer as defined in claim 1.

18. The copolymer according to claim 1, wherein the copolymer has a PDI from 1.5 to 3.5.

19. The copolymer according to claim 1, wherein the copolymer has a weight average molecular weight from 8,000 to 20,000 g/mol according to DIN 55672-1.

20. The copolymer according to claim 1, wherein the total amount of monomer units derived from monomers a), b) and c) in the copolymer sums up to 100% by weight, based on the total weight of the copolymer.

Description

DETAILED DESCRIPTION

[0018] Copolymer According to the Invention

[0019] The present invention relates to a copolymer comprising: [0020] a) 65 to 90% by weight, based on the total weight of the copolymer, of monomer units derived from at least one acrylate of Formula (I),

##STR00001## [0021] wherein R.sub.1 means a linear or branched alkyl group having from 6 to 12 carbon atoms, [0022] b) 10 to 35% by weight, based on the total weight of the copolymer, of monomer units derived from at least one non-functionalized alpha-olefin of Formula (II),

##STR00002## [0023] wherein R.sub.2 means a linear alkyl group having from 6 to 16 carbon atoms, [0024] c) 0 to 10% by weight of monomer units derived from at least one monomer selected from the list consisting of methacrylamides, fumarates, maleates or a mixture thereof, based on the total weight of the copolymer, and
wherein the copolymer has a kinematic viscosity at 100° C. from 80 to 600 cSt according to ASTM D 445, and
wherein the copolymer comprises from 0 to 22% by weight of monomer units derived from monomers with linear alkyl group having more than 8 carbon atoms, based on the total weight of the copolymer.

[0025] According to one aspect of the invention, it is preferred that the copolymer comprises 0 to 20% by weight, more preferably 0 to 18% by weight, of monomer units derived from monomers with linear alkyl group having more than 8 carbon atoms, based on the total weight of the copolymer.

[0026] According to another aspect of the invention, it is preferred that the copolymer has a kinematic viscosity at 100° C. from 100 to 500 cSt according to ASTM D 445, more preferably from 150 to 400 cSt according to ASTM D 445, more preferably from 150 to 350 cSt according to ASTM D 445.

[0027] According to another preferred aspect of the invention, the total content of monomer units derived from monomers a) and b) in the copolymer of the invention sums up to 90% by weight, more preferably sums up to 95% by weight, even more preferably sums up to 98% by weight, most preferably sums up to 100% by weight, based on the total weight of the copolymer.

[0028] According to another preferred aspect of the invention, the total content of monomer units derived from monomers a), b) and c) in the copolymer of the invention sums up to 90% by weight, more preferably sums up to 95% by weight, even more preferably sums up to 98% by weight, most preferably sums up to 100% by weight, based on the total weight of the copolymer.

[0029] The acrylate a) of Formula (I) refers to esters of acrylic acid with straight chain or branched alcohols having 6 to 12 carbon atoms, preferably 6 to 10 carbon atoms, more preferably 8 to 10 carbons. The term encompasses individual acrylic esters with an alcohol of a particular length, and likewise mixtures of acrylic esters with alcohols of different lengths.

[0030] According to one aspect of the invention, it is preferred that R.sup.1 in the acrylate monomer of Formula (I) is a linear or branched alkyl group having from 6 to 10 carbon atoms, more preferably linear or branched alkyl group having 8 to 10 carbon atoms. Particularly preferred acrylates a) of Formula (I) are 2-ethylhexyl acrylate, 2-propylheptyl acrylate, n-octylacrylate or a mixture thereof.

[0031] According to the present invention, it is preferred that the copolymer of the invention comprises 70 to 90% by weight, more preferably 75 to 90% by weight, of monomer units derived from the acrylate monomer a) of Formula (I), based on the total weight of the copolymer.

[0032] According to the present invention, it is preferred that the copolymer of the invention comprises 10 to 30% by weight, more preferably 10 to 25% by weight, of monomer units derived from the non-functionalized alpha-olefin b) of Formula (II), based on the total weight of the copolymer. Particularly preferred non-functionalized alpha-olefins b) of Formula (II) are selected from the group consisting of decene, dodecene, tetradecene, hexadecene or a mixture thereof.

[0033] According to a preferred aspect of the present invention, the copolymer has a weight-average molecular weight from 5,000 to 30,000 g/mol, preferably from 7,000 to 25,000 g/mol, even more preferably from 8,000 to 20,000 g/mol according to DIN 55672-1.

[0034] In the present invention, the weight-average molecular weights (Mw) or number-average molecular weights (M.sub.n) of the copolymers were determined by gel permeation chromatography (GPC) using PMMA calibration standards according to DIN 55672-1 using the following measurement conditions:

[0035] Eluent: tetrahydrofuran (THF)

[0036] Operation temperature: 35° C.

[0037] Columns: the column set consists of four columns: two columns SDV 106 Å, one column SDV 104 Å and one column SDV 103 Å (PSS Standards Service GmbH, Mainz, Germany), all with the size of 300×8 mm and an average particle size of 10 μm Flow rate: 1 mL/min

[0038] Injected volume: 100 μL

[0039] Instrument: Agilent 1100 series consisting of an autosampler, pump and column oven Detection device: a refractive index detector from Agilent 1100 series.

[0040] Preferably, the copolymers of the invention have a very low degree of cross-linking and a narrow molecular weight distribution, which further contribute to their shear resistance. The low degree of crosslinking and the narrow molecular weight are reflected in the polydispersity index of the copolymers. Preferably, the polydispersity index (PDI) of the copolymers according to the invention is in the range of 1.0 to 4.0, more preferably 1.5 to 3.5. A polydispersity index in the range of 1.0 to 3.5 is considered optimal for most industrial applications with regard to the shear resistance of the copolymers. The polydispersity index is defined as the ratio of weight-average molecular weight to number-average molecular weight (Mw/Mn).

[0041] According to a preferred aspect of the present invention, the copolymer of the invention has a COC flashpoint above 250° C. according to ASTM D92.

[0042] The copolymers of the invention optionally comprise monomer units derived from monomer c), which is selected from the list consisting of methacrylamides, fumarates, maleates or a mixture thereof. Preferably, the amount of monomer units derived from monomer c) in the resulting copolymer of the invention is from 0 to 10% by weight, preferably from 0 to 7% by weight, more preferably from 0 to 5% by weight, even more preferably from 0 to 3% by weight, based on the total weight of the copolymer. Particularly preferred monomers c) are di-2-ethylhexyl maleate, N-3-dimethylamino propyl methacrylamide di-2-ethylhexyl fumarate, or a mixture thereof.

[0043] It has been surprisingly observed that the incorporation of monomer units c) in the copolymer allows a full conversion of the non-functionalized alpha-olefins b) and thus no final distillation step is needed at the end of the copolymerization.

[0044] According to a preferred aspect of the present invention, on top of monomer units derived from monomers a), b) and optionally c), the acrylate-olefin copolymer of the invention further comprises 0 to 10% by weight, more preferably 0 to 6% by weight, based on the total weight of the copolymer, of monomer units derived from at least one monomer d) selected from alkyl (meth)acrylates, vinyl esters or a mixture thereof. Particularly preferred monomers d) are lauryl methacrylate (LMA), stearyl methacrylate (SMA) or vinyl laurate (VLA).

[0045] According to another preferred aspect of the present invention, the total content of monomer units of monomers a), b) c) and d) sums up to 95% by weight, more preferably 98% by weight, even more preferably 100% by weight,

[0046] According to another preferred aspect of the invention, when the copolymer consists of monomer units derived from monomers a), b), optionally c) and optionally d), the copolymer comprises 0 to 22% by weight, more preferably 0 to 20% by weight, even more preferably 0 to 18% by weight, of monomer units derived from monomers a), b), c) and d) with linear alkyl group having more than 8 carbon atoms, based on the total weight of the copolymer.

[0047] According to the invention, the copolymer is a statistical copolymer, with a sequential distribution of the monomer units derived from monomers a) and b) and optionally monomers c) and d).

Preferable Copolymers of the Invention

[0048] According to a preferred aspect of the invention, the copolymer comprises: [0049] a) 65 to 90% by weight, more preferably 70 to 90% by weight, even more preferably 75 to 90% by weight, based on the total weight of the copolymer, of monomer units derived from at least one acrylate of Formula (I),

##STR00003## [0050] wherein R.sub.1 means a linear or branched alkyl group having from 8 to 10 carbon atoms, [0051] b) 10 to 35% by weight, more preferably 10 to 30% by weight, even more preferably 10 to 25% by weight, based on the total weight of the copolymer, of monomer units derived from at least one non-functionalized alpha-olefin of Formula (II),

##STR00004## [0052] wherein R.sub.2 means a linear alkyl group having from 8 to 12 carbon atoms, [0053] c) 0 to 10% by weight, more preferably 0 to 5% by weight, even more preferably 0 to 3% by weight, of monomer units derived from at least one monomer selected from the list consisting of methacrylamides, fumarates, maleates or a mixture thereof, based on the total weight of the copolymer, and
wherein the copolymer has a kinematic viscosity at 100° C. from 80 to 600 cSt according to ASTM D 445, and
wherein the copolymer comprises from 0 to 22% by weight, preferably 0 to 18% by weight, of monomer units derived from monomers with linear alkyl group having more than 8 carbon atoms, based on the total weight of the copolymer.

[0054] According to a preferred embodiment, the total content of monomer units of monomers a), b) and c) sums up to 95% by weight, more preferably 98% by weight, even more preferably 100% by weight, based on the total weight of the copolymer.

[0055] According to a preferred embodiment, the copolymer further comprises 0 to 10% by weight, more preferably 0 to 6% by weight, based on the total weight of the copolymer, of monomer units derived from at least one monomer d) selected from alkyl (meth)acrylates, vinyl ester or a mixture thereof. Particularly preferred monomers d) are lauryl methacrylate (LMA), stearyl methacrylate (SMA) or vinyl laurate (VLA).

[0056] According to a preferred embodiment, the total content of monomer units of monomers a), b), c) and d) sums up to 95% by weight, more preferably 98% by weight, even more preferably 100% by weight,

Method for Preparing the Copolymer According to the Invention

[0057] According to the present invention, the above-mentioned polymers are prepared following the method comprising the steps of: [0058] i) providing a monomer composition as described above; and [0059] ii) initiating radical polymerization in the monomer composition.

[0060] Standard free-radical polymerization is detailed, inter alia, in Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition. In general, a polymerization initiator and optionally a chain transfer agent are used for this purpose.

[0061] The polymerization can be conducted under standard pressure, reduced pressure or elevated pressure.

[0062] For the radical copolymerization of olefins with acrylates, the polymerization temperature is critical. In general, the copolymerization temperature is in the range from 140 to 180° C., preferably from 150 to 170° C.

[0063] The polymerization step ii) may be performed with or without dilution in oil. Preferably, the polymerization step (ii) is made without dilution oil or any solvent.

[0064] Preferably, step (ii) comprises the addition of a radical initiator. Preferably, the radical initiator is selected from di-tert-butyl peroxide or dicumyl peroxide. Preferably, the total amount of radical initiator relative to the total weight of the monomer mixture is 0.01 to 5% by weight, more preferably 0.1 to 1% by weight. Preferably, the total amount of radical initiator is added continuously over the course of the copolymerization reaction (ii).

[0065] Preferably, the copolymerization step (ii) is made by feeding the acrylate monomers a), and optionally the monomers c) or any other comonomers, together with the initiator to the non-functionalized alpha-olefin monomers b). Preferably, the total reaction time of the radical polymerization is 2 to 5 hours, more preferably 3 hours.

[0066] In another preferred aspect of the invention, a third step iii) is optionally performed, corresponding to a distillation step to remove the unreacted alpha-olefin monomer b).

[0067] Preferably, residual unreacted alpha-olefin monomer b) is removed by distillation at 150° C. and pressures as low as 5 mbar using a rotary evaporator. Advantageously, no distillation step iii) is needed when the copolymer of the invention comprises monomer units derived from monomer c). It has been surprisingly observed that small amounts of monomers c) (below 10% by weight, more preferably below 5% by weight, based on the total weight of the copolymer) enhance the conversion of the olefins during copolymerization (lower than 1% by weight residual unreacted alpha-olefin b)), so that no distillation step iii) is needed.

Lubricating Oil Compositions

[0068] As indicated above, the present invention also relates to a lubricating oil composition comprising at least one base oil and at least one copolymer as defined in the present invention.

[0069] The base oils correspond to lubricant base oils, mineral, synthetic or natural, animal or vegetable oils suited to their use/chosen depending on the intended use.

[0070] The base oils used in formulating the lubricating oil compositions according to the present invention include, for example, conventional base stocks selected from API (American Petroleum Institute) base stock categories known as Group I, Group II, Group III, Group IV and Group V. The Group I and II base stocks are mineral oil materials (such as paraffinic and naphthenic oils) having a viscosity index (or VI) of less than 120. Group I is further differentiated from Group II in that the latter contains greater than 90% saturated materials and the former contains less than 90% saturated material (that is more than 10% unsaturated material). Group III is considered the highest level of mineral base oil with a VI of greater than or equal to 120 and a saturates level greater than or equal to 90%. Preferably the base oil included in the lubricating oil composition of the present invention is selected from the group consisting of API Group II and III base oils. Most preferably, the lubricant composition comprises an API Group III base oil. Group IV base oils are polyalphaolefins (PAO). Group V base oils are esters and any other base oils not included in Group I to IV base oils. These base oils can be used individually or as a mixture.

[0071] In a preferred embodiment of the invention, the lubricating oil composition comprises from 0.1 to 99.9% by weight, preferably from 1 to 95% by weight, of at least one base oil and from 0.1 to 99.9% by weight, preferably from 5% to 99% by weight, of at least one copolymer according to the present invention, based on the total weight of the lubricating composition.

[0072] The lubricating oil compositions according to the present invention may also comprise any other additional additives suitable for use in the formulations. These additives include additional viscosity index improvers, pour point depressants, dispersants, demulsifiers, defoamers, lubricity additives, friction modifiers, antioxidants, detergents, dyes, corrosion inhibitors and/or odorants.

Applications for the Copolymer of the Invention

[0073] The invention also relates to the use of the copolymer according to the present invention as a lubricant additive or a synthetic base fluid in a lubricating oil composition, preferably in a gear oil composition, a transmission oil composition, a hydraulic oil composition, an engine oil composition, a marine oil composition, an industrial lubricating oil composition or in grease.

Experimental Part

[0074] The invention is further illustrated in detail hereinafter with reference to examples and comparative examples, without any intention to limit the scope of the present invention. All percentages in relation to monomers or base fluids given in the tables below are weight percentages (wt %).

Abbreviations

[0075] BF-26 Brookfield viscosity measured at −26° C.
BF-30 Brookfield viscosity measured at −26° C.
BV bulk viscosity
BV40 bulk viscosity @40° C. in accordance with ASTM D445
BV100 bulk viscosity @100° C. in accordance with ASTM D445
cSt centistokes
cP centipoise
DBPO di-tert-butyl peroxide
DCP dicumyl peroxide
Dec decene
DEHF di-2-ethylhexyl fumarate
DEHM di-2-ethylhexyl maleate
DMAPMAM N-3-dimethylamino propyl methacrylamide
DoDec dodecene
EHA 2-ethylhexyl acrylate
EHMA 2-ethylhexyl methacrylate
HA hexyl acrylate
HexDec hexadecene
Hitec® 2030 defoamer commercially available from Afton
Hitec® 307 DI Package commercially available from Afton
Hitec® 3250 DI Package commercially available from Afton
IDA iso-decyl acrylate
IDMA iso-decyl methacrylate
Ini initiator
ITDA iso-tridecyl acrylate, commercially available from Aldrich
KV kinematic viscosity measured according to ASTM D445
KV.sub.40 kinematic viscosity measured @40° C. to ASTM D445
KV.sub.100 kinematic viscosity measured @100° C. to ASTM D445
LA lauryl acrylate, dodecylacrylate
LMA lauryl methacrylate, 73% C12, 27% C14, all linear
Mn number-average molecular weight
MO methyloleate
Mw weight-average molecular weight
n.m. not measured
nOA n-octylacrylate
NB3080 Nexbase® 3080; Group III base oil from Neste with a KV100 of 7.9 cSt
PAO100 polyalphaolefin base oil with a KV100 of 100 cSt from Chevron Phillips
PAO4 polyalphaolefin base oil with a KV100 of 4 cSt
PAO6 polyalphaolefin base oil with a KV100 of 6 cSt
PAO8 INEOS Durasyn 168 polyalphaolefin base oil with a KV.sub.100 of 7.8 cSt
PAO8 I INEOS Durasyn 128polyalphaolefin base oil with a KV.sub.100 of 7.8 cSt
PDI polydispersity index
PHA 2-propylheptyl acrylate
PP pour point
Priolube 3970 ester base fluid available from Croda
RC9420 DI package commercially available from Rheinchemie
ReMo Residual Monomer content
SMA stearyl methacrylate, 35% C16, 65% C18, all linear
SL KRL20 shear loss after 20 hours KRL measurement determined at 100° C.
SL KRL100 shear loss after 100 hours KRL measurement determined at 100° C.
TetDec tetradecene
VI viscosity index
VLA vinyl laurate
VPL 1-180 Evonik VISCOPLEX® 1-180, pour point depressant
VPL 1-300 Evonik VISCOPLEX® 1-300, pour point depressant
Yubase 4 Group III base oil from SK Lubricants with a KV.sub.100 of 4 cSt

Test Methods

KV ASTM D445

VI ASTM D2270

PP ASTM D5950

Copper Corrosion ASTM D130

Steel Corrosion DIN ISO 7120

TOST ASTM D2893

RPVOT ASTM D2272

Foam ASTM D892

KRL CEC L-45-A-99

BF ASTM D2983

COC ASTM D92

[0076] In the present invention, the bulk viscosity (BV) of the product (product obtained from polymerization reaction) corresponds to the kinematic viscosity (KV) of the resulting product of the polymerization measured in accordance with ASTM D 445. Thus, the bulk viscosity of the polymers, BV40 and BV100 as shown in Tables 1, 2, 3 and 4 below, were measured as kinematic viscosity at 40° C. and 100° C., respectively, in accordance with ASTM D445.

Examples

Synthesis 1: Pure Acrylate (Ex.39*)

[0077] 1.62 g of DBPO (0.6 wt % relative to the amount of acrylate) dissolved in 270.0 g EHA was slowly fed to 30.0 g of PAO8 under nitrogen at 160° C. for 3 hours. After stirring for another hour, the resulting clear and colorless polymer solution was cooled down and used in the further experiments without further purification.

Synthesis 2: (Meth)Acrylate/Olefin Copolymer with Distillation Step (Ex.8)

[0078] 3.6 g of DBPO (0.3 wt % relative to the monomer in the feed) dissolved in 1200 g EHA was slowly fed to 300 g (0.33 molar equivalents relative to the (meth)acrylate) of 1-Decene under nitrogen at 160° C. for 3 hours. After stirring for another hour, the resulting clear and colorless polymer was cooled down. Subsequently, the residual decene was removed by distillation at 150° C. and pressures as low as 5 mbar using a rotary evaporator.

Synthesis 3: Acrylate/Olefin Copolymer without Distillation Step (Ex.54)

[0079] 0.77 g of DBPO (0.3 wt % relative to the monomer in the feed) dissolved in 249.3 g EHA and 5.7 g DEHF was slowly fed to 45.0 g of 1-Tetradecene under nitrogen at 160° C. for 3 hours. After stirring for another hour, the resulting clear and colorless polymer was cooled down and used without further purification.

[0080] Examples 1 to 28 were prepared in the same way as Synthesis 2, except that except that the amounts of reactants or other reaction conditions were changed as listed in Table 1. The alpha-olefin monomers are always first charged to the reactor and the (meth)acrylate monomers and the initiator are fed over a set period of time.

[0081] Examples 38 to 43 were prepared in the same way as Synthesis 1, except that the amounts of reactants or other reaction conditions were changed as listed in Table 3.

[0082] Examples 44 to 61 were prepared in the same way as Synthesis 3, except that the amounts of reactants or other reaction conditions were changed as listed in Table 4.

[0083] As the molar ratio in the reaction is not representative for the final composition, the final ratio of olefin in the polymer after distillation is given in weight % (olefin inc.). This ratio was determined gravimetrically under the assumption that the conversion of the (meth)acrylate is either complete or its boiling point is too high to be removed by the distillation. For example, Example 8 has a residual content of EHA of less than 0.01 wt % before the distillation step.

[0084] For some examples up to 3 polymers with similar viscosities were blended. For the blending process, the products were stirred together at 80° C. for an hour. The blends are listed in Table 2 (see examples 29 to 37). The amount of incorporated olefin was calculated from the values determined for the separate components. The other values such as molecular weight or viscosity were measured on the blend.

[0085] A good high viscosity base fluid needs to combine several properties. An important criterion for high-performance gear oils is the low temperature performance. Aside from a low dependency of the viscosity on the temperature, which is also reflected in the VI, it is important that the polymers do not show strong intermolecular interactions, leading to bad low temperature performance.

[0086] The polymers according to this invention have a favorable combination of viscosity, viscosity index and shear stability as exemplified with Example 5, 6 or 8. In contrast, it can be observed that the acrylate-olefin copolymer comparative example 7*, which comprises 22.6% by weight of linear side chains with more than 8 carbon atoms, has a good VI (236) but as shown in the lubricant formulation thereof (example F-21*), does not perform well at low temperature (BF-26=192,000 cP). In contrast, the acrylate-olefin copolymer inventive example 50 with only 15% by weight linear side chain with more than 8 carbon atoms combines both high VI (220) and as shown in the lubricant formulation thereof (example F-28) performs very well under even more severe low temperature conditions (BF-30=102,000 cP) (BF-30 instead of BF-26 for comparative example F-21*).

[0087] Surprisingly even longer side chains such as in inventive examples 48 (C12 side chain) or 51 (C14 side chain) perform on the same level as example 50 (C10 side chain) because the total amount of monomer units derived from monomers with linear alkyl group having more than 8 carbon atoms in total in the copolymer, is lower than 22% by weight, based on the total weight of the copolymer. The long linear side chains (more than 8 carbon atoms) can be any monomer units of the copolymer (any monomers a), b), c), d) or other comonomers) as shown in comparative example 13* which has 81% by weight of linear side chains of more than 8 carbon atoms due to a high content of laurylacrylate. As shown in comparative formulation F-38*, the high content of long linear side chains having more than 8 carbon atoms in the acrylate monomer units results in extremely poor low temperature performance (PP of −18° C.) despite a high VI (195), thus no good combination of high VI and good low temperature performance is achieved. The quantity of these sidechains is provided as “>C8 SC” in Tables 1 to 4.

[0088] While polymethacrylates are known as excellent VI improvers, they are surprisingly outperformed in the lower molecular weight range by their acrylate counterparts. This is exemplified in Table 5, where F-2 and F-3* are based on very similar polymers (based on EHA for inventive example 29 and EHMA for comparative example 20*), but a much higher VI of the EHA based polymer (inventive example 29) results in a higher VI of the final formulation and a better low temperature viscosity.

[0089] F-2 performs on a similar level as the PAO100 base formulation F-1*. Compared to pure polyolefins, the polar ester functions in the acrylate-olefin copolymer of the invention are beneficial for the overall compatibility of different formulation components (to allow the direct comparison with PAO100 the formulations in Table 4 were prepared without further additives). Different to PAOs, which have to be prepared by cationic or coordination polymerization methods, the radical polymerization process used for the preparation of the acrylate-olefin copolymers of the invention provides easy access to higher viscous products with good shear stability level in a commercially attractive way.

TABLE-US-00001 TABLE 1 Methacrylate-olefin copolymers or acrylate-olefin copolymers Olefin >C8 Ini Olefin inc Mw Mn BV100 BV40 SC Ex# (M)A Olefin [wt %] T[° C.] [eq] [wt %] [g/mol] [g/mol] PDI [cSt] [cSt] VI [wt %] Ex. 1 EHA Dec 0.10 150 2.00 34.7 6,410 3,450 1.9  87.9 n.m. n.m. 0.0 Ex. 2 EHA Dec 0.04 150 2.00 30.5 7,680 3,860 2.0 117.2 n.m. n.m. 0.0 Ex. 3 EHA Dec 0.05 150 2.00 29.7 8,090 4,020 2.0 128.1 n.m. n.m. 0.0 Ex. 4 EHA Dec 0.07 150 1.00 25.4 10,500 4,750 2.2 188.7 2479 196 0.0 Ex. 5 EHA Dec 0.07 150 0.60 20.7 14,900 5,770 2.6 306.3 4372 214 0.0 Ex. 6 EHA Dec 0.07 150 0.40 18.6 19,500 6,390 3.1 445.8 6573 233 0.0 Ex. 7* EHA DoDec 0.07 150 0.42 22.6 18,500 5,650 3.3 304.8 3551 236 22.6 Ex. 8 EHA Dec 0.30 160 0.33 18.2 15,600 5,980 2.6 299.7 4148 216 0.0 Ex. 9 HexA Dec 0.09 160 0.54 26.7 14,400 5,750 2.5 145.5 1425 214 0.0 Ex. 10 HexA Dec 0.08 160 0.54 26.2 14,300 6,260 2.3 160.1 1672 212 0.0 Ex. 11 HexA Dec 0.08 160 0.54 26.1 15,800 6,430 2.5 175.4 1809 218 0.0 Ex. 12* iTDA Dec 0.05 150 0.54 19.4 15,100 6,440 2.3 258.6 4107 194 0.0 Ex. 13* LA Dec 0.14 150 0.46 18.6 15,100 7,100 2.1  99.08 783.7 222 81.4 Ex. 14 PHA Dec 0.07 150 0.43 18.1 16,000 6,660 2.4 269.7 3221 226 0.0 Ex. 15 PHA Dec 0.08 150 0.43 17.9 15,400 6,580 2.3 259.8 3145 222 0.0 Ex. 16 nOA Dec 0.10 160 0.71 22.8 14,000 6,450 2.2 132.8 1294 210 0.0 Ex. 17 nOA Dec 0.10 160 0.61 23.4 14,700 6,570 2.2 138.3 1336 213 0.0 Ex. 18* EHMA Dec 0.10 155 2.00 25.8 11,200 3,570 3.2 452.6 12200 178 0.0 Ex. 19* EHMA Dec 0.30 155 2.00 31.3 6,210 2,720 2.3 143.8 2640 150 0.0 Ex. 20* EHMA Dec 0.50 155 2.00 32.7 5,430 2,550 2.1 110.9 1899 143 0.0 Ex. 21* IDMA Dec 0.80 150 2.00 31.2 6,550 2,920 2.2 129.5 n.m. n.m. 0.0 Ex. 22* IDMA Dec 0.65 150 2.00 29.0 7,750 3,250 2.4 184.6 n.m. n.m. 0.0 Ex. 23* IDMA Dec 0.10 155 2.00 21.5 12,200 3,790 3.2 n.m. n.m. n.m. 0.0 Ex. 24* IDMA Dec 0.07 155 2.00 n.m. 13,500 4,050 3.3 n.m. n.m. n.m. 0.0 Ex. 25* LMA Dec 0.12 150 1.50 18.2 n.m. n.m. n.m. 490.2 n.m. n.m. 81.8 Ex. 26* LMA Dec 0.13 150 1.50 17.6 n.m. n.m. n.m. 442.0 n.m. n.m. 82.4 Ex. 27* LMA Dec 0.20 155 2.00 23.7 10,700 4,000 2.7 131.7 n.m. n.m. 85.3 Ex. 28* LMA Dec 0.12 155 2.00 n.m. 13,700 4,260 3.2 182.3 n.m. n.m. 85 *means comparative examples

TABLE-US-00002 TABLE 2 Blends of copolymers from Table 1 Olefin >C8 Comp. 1 Comp. 2 Comp. 3 inc Mw Mn BV100 BV40 SC Ex# [wt %] [wt %] [wt %] [wt %] [g/mol] [g/mol] PDI [cSt] [cSt] VI [wt %] Ex. 29 50% 50% n.m. 32.6 n.m. n.m. n.m. 99.9 1,137 178 0.0 Ex. 1 Ex. 2 Ex. 30 64% 36% n.m. 28.3  8,940 4,260 2.1 146.9 1,800 190 0.0 Ex. 3 Ex. 4 Ex. 31 34% 32% 34% 26.3 15,000 6,470 2.3 160.6 1,653 214 0.0 Ex. 9 Ex. 10 Ex. 11 Ex. 32 50% 50% n.m. 18.0 n.m. n.m. n.m. 263.3 3,176 224 0.0 Ex. 14 Ex. 15 Ex. 33 38% 62% n.m. 23.2 n.m. n.m. n.m. 135.4 1,315 212 0.0 Ex. 16 Ex. 17 Ex. 34* 51% 49% n.m. 30.1 n.m. n.m. n.m. 147.0 2,753 150 0.0 Ex. 21 Ex. 22 Ex. 35* 36% 64% n.m. n.m. n.m. n.m. n.m. 450.7 11,740 181 0.0 Ex.23 Ex. 24 Ex. 36* 50% 50% n.m. 17.9 23,900 5,940 4.0 468.1 8,699 213 82.1 Ex. 25 Ex. 26 Ex. 37* 64% 36% n.m. n.m. n.m. n.m. n.m. 146.8 1,979 180 85 Ex. 27 Ex. 28 *means comparative examples

TABLE-US-00003 TABLE 3 Pure polyacrylates >C10 Solvent Ini ReMo Mw Mn BV100 BV40 SC Ex# (M)A Solvent [wt %] Ini [wt %] T [° C.] [wt %] [g/mol] [g/mol] PDI [cSt] [cSt] VI [wt %] Ex. 38* EHA Yubase 20 DBPO 0.5 160 0.04 9590 5020 1.9 67.4 712 168 0.0 4 Ex. 39* EHA PAO8 10 DBPO 0.6 160 0.02 16400 6970 2.4 210.3 2942 195 0.0 Ex. 40* PHA PAO8 85 DCP 0.5 150 0.01 14100 7270 1.9 145.8 1671 197 0.0 Ex. 41* IDA Nexbase 75 DCP 0.5 150 n.m. 15400 7490 2.1 83.0 975 166 0.0 3080 Ex. 42* LA Nexbase 70 DCP 0.5 150 n.m. 15600 8530 1.8 43.0 314 192 100.0 3080 Ex. 43* ITDA Nexbase 75 DCP 0.5 150 n.m. 14700 7270 2.0 95.9 1320 157 0.0 3080 *means comparative examples

TABLE-US-00004 TABLE 4 Acrylate-olefin copolymers comprising monomer units of monomer c) Como- >C8 EHA PHA Olefin DEHF Como- nomer Ini Mw Mn BV100 BV40 SC Ex# [wt %] [wt %] Olefin [wt %] [wt %] nomer [wt %] [%] [g/mol] [g/mol] PDI [cSt] [cSt] VI [wt %] Ex. 44 83.1 TetDec 15 DMAPMAM 1.9 0.3 18,200 6,130 3.0 299.7 4,148 216 15.0 Ex. 45 80 TetDec 15 DMAPMAM 5 0.3 16,600 5,380 3.1 273.0 3,988 206 15.0 Ex. 46 83.1 TetDec 15 DEHM 1.9 0.3 19,800 6,310 3.1 300.5 4,043 219 15.0 Ex. 47 80 TetDec 15 5 0.3 16,200 5,820 2.8 283.9 3,823 216 15.0 Ex. 48 80 TetDec 15 5 0.3 17,100 6,030 2.8 301.8 4,125 218 15.0 Ex. 49 80 Dec 15 5 0.3 15,400 5,880 2.6 301.1 4,138 217 0.0 Ex. 50 80 DoDec 15 5 0.3 16,600 6,000 2.8 303.6 4,103 220 15.0 Ex. 51 80 HexDec 15 5 0.3 18,300 6,130 3.0 301.9 3,986 222 15.0 Ex. 52 83.1 TetDec 15 1.9 0.3 14,600 5,890 2.5 203.8 2,538 206 15.0 Ex. 53 79.5 Dec 15 5 DMAPMAM 0.5 0.15 15,300 5,880 2.6 280.5 3,878 213 15.0 Ex. 54 83.1 Tetdec 15 1.9 0.3 19,000 6,030 3.2 317.5 3,098 211 0.0 Ex. 55 70 10 Tetdec 15 5 0.3 17,600 6,110 2.9 284.9 3,806 217 15.0 Ex. 56 40 40 Tetdec 15 5 0.3 16,100 5,940 2.7 239.8 4,498 217 15.0 Ex. 57 80 Dec 15 VLA 5 0.3 19,800 6,530 3.0 339.0 n.m. n.m. 5.0 Ex. 58 80 Dec 15 SMA 5 0.3 18,400 6,330 2.9 307.8 n.m. n.m. 5.0 Ex. 59 80 Dec 15 LMA 5 0.3 18,400 6,180 3.0 321.6 n.m. n.m. 5.0 Ex. 60 85 Dec 14 MO 1 0.7 18,600 6,190 3.0 330.9 n.m. n.m. 0.0 Ex. 61 80 TetDec 15 5 0.3 17,800 6,160 2.9 322.9 4,295 225 15.0

TABLE-US-00005 TABLE 5 Lubricant formulations with 100 cSt high viscosity base fluids Form. Ex. F-1* F-2 F-3* PAO100 22.3 [wt %] Ex. 29 [wt %] 31.5 Ex. 20* [wt %] 29.8 PAO4 [wt %] 77.7 68.5 70.2 KV40 [cSt] 46.0 46.1 45.9 KV100 [cSt] 8.4 8.5 8.1 VI 162 164 151 BF-40 [cP] 11,000 12,200 14,000 PP [° C.] −66 −66 −66 *means comparative examples

[0090] Examples of formulations with EHA homopolymers can be found in Tables 6 and 7. For process reasons the pure acrylates shown in Table 3 were prepared as solutions in oil, so that no bulk properties are available for these polymers. In order not to influence the comparison of the copolymers, the oil used for the polymerization was the same which was later used in the formulations. As can be seen the mentioned EHA homopolymers (comparative examples 38* and 39*) provide lower VIs in the formulation and show poorer low temperature performance. As shown in Table 8, the comparative polyacrylate examples with longer side chains as the EHA homopolymers also do not perform as good as the inventive acrylate-olefin copolymers of the invention.

TABLE-US-00006 TABLE 6 Lubricant formulations with 150 cSt high viscosity base fluids Form. Ex. F-4* F-5 F-6* F-7* F-8* Ex. 38* 35.2 [wt %] Ex. 30 28.5 [wt %] Ex. 19* 28.2 [wt %] Ex. 34* 25.2 [wt %] Ex. 37* 23.1 [wt %] VPL 1-300 0.3 0.3 0.3 0.3 0.3 [wt %] Yubase 4 64.5 71.2 71.5 74.5 76.6 [%] KV40 [cSt] 49.7 48.6 49.2 46.2 46.7 KV100 [cSt] 8.9 8.9 8.6 8.2 8.8 VI 161 166 152 153 172 BF-40 [cP] 90,000 55,000 83,000 77,000 solid PP [° C.] −42 −39 −42 −39 −39 *means comparative examples

TABLE-US-00007 TABLE 7 Lubricant formulations with 450 cSt high viscosity base fluids Form. Ex. F-9* F-10 F-11* F-12* F-13* F-14 F-15* F-16* Ex. 39* 55.0 55.1 [wt %] Ex. 6 47.0 47.4 [wt %] Ex. 18* 45.0 43.6 [wt %] Ex. 35* 43.0 42.1 [wt %] RC9420 2.0 2.0 2.0 2.0 [wt %] Hitec 307 2.7 2.7 2.7 2.7 [wt %] VPL 1-180 0.7 0.7 0.7 0.7 [wt %] NB3080 41.6 43.4 53.1 54.6 [wt %] PAO8 43.0 51.0 53.0 55.0 [wt %] KV40 [cSt] 312.9 320.3 325.3 318.9 314.9 326.5 312.6 312.7 KV100 [cSt] 36.4 39.5 34.5 34.5 36.3 39.6 33.4 33.8 VI 164 176 150 153 163 174 149 152 BF-26 [cP] 74,000 49,000 74,000 77,000 n.m. n.m. n.m. n.m. PP [° C.] −39 −45 −42 −45 −36 −39 n.m. −39 *means comparative examples

TABLE-US-00008 TABLE 8 Lubricant formulations with pure polyacrylate high viscosity base fluids Form. Ex. F-17* F-18* F-190* F-20* Ex. 40* [wt %] 62.4 Ex. 41* [wt %] 67.5 Ex. 42* [wt %] 96.6 Ex. 43* [wt %] 62.0 Viscoplex 1-180 0.7 0.7 0.7 0.7 [wt %] Hitec 307 [wt %] 2.7 2.7 2.7 2.7 Nexbase 3080 29.1 34.6 [wt %] PAO8 [wt %] 34.9 KV40 [cSt] 328.1 314.5 315.5 313.6 KV100 [cSt] 38.1 35.2 42.9 33.1 VI 166 158 193 147 BF-26 [cP] 81,000 220,000 solid 212,000 PP [° C.] −45 −39 −6 −36 *means comparative examples

TABLE-US-00009 TABLE 9 Residual monomers of the polymers (all amounts in wt %) described in Table 4 Residual monomers Ex# EHA PHA Olefin DEHF Comonomer Ex. 44 0.12% 0.87% 0.01% Ex. 45 0.26% 1.09% 0.03% Ex. 46 0.07% 0.32% 0.57% Ex. 47 0.13% 0.33% 0.16% Ex. 48 0.08% 0.35% 0.11% Ex. 49 0.06% 0.58% 0.07% Ex. 50 0.05% 0.40% 0.05% Ex. 51 0.04% 0.25% 0.10% Ex. 52 0.14% 0.47% 0.04% Ex. 53 0.11% 0.72% 0.12% 0.00% Ex. 54 0.07% 0.37% 0.05% Ex. 55 0.07% 0.07% 0.38% 0.0% Ex. 56 0.03% 0.10% 0.36% 0.08% Ex. 57 0.02% 0.57% n.m. Ex. 58 0.04% 0.75% n.m. Ex. 59 0.04% 0.71% n.m. Ex. 60 0.02% 0.48% 0.53% Ex. 61 0.06% 0.03% 0.08%

[0091] High-performance lubricants also need to fulfill many requirements. Especially excellent low temperature properties, high flashpoints and good ageing behavior are directly influenced by the choice of high viscosity base fluids.

[0092] In Table 10 below, it is shown that the inventive acrylate-olefin copolymers of the invention have high flashpoints, which fulfills the requirements for gear oil applications.

[0093] The effect of different PAO viscosity grades is shown in Table 11 below (PAO4, PAO 6, PAO8). Lower grades such as PAO4 allow the use of higher amount of acrylate-olefin copolymer of the invention, which improves VI and low temperature performance of the resulting formulations even further. For inventive formulation F-23, further performance parameters are provided which are important for industrial gear oil formulations. The strong performance in the TOST and RPVOT test shows the good stability towards severe thermo-oxidative stress. The low foaming tendency and low corrosiveness of the formulation underline the suitability of the acrylate-olefin copolymers of the invention in gear oil formulations.

TABLE-US-00010 TABLE 10 Flashpoint of some high viscosity base fluids Example COC [° C.] Ex. 53 256 Ex. 61 271 Ex. 5 260

TABLE-US-00011 TABLE 11 320 cSt lubricant formulations with base oils of different viscosity Form. Ex. F-21 F-22 F-23 F-24 F-25 Ex. 7* [wt %] 51.2 Ex. 5 [wt %] 51.6 63.3 57.5 51.9 Hitec 3250 [wt %] 2.0 2.0 2.0 2.0 2.0 PAO4 [wt %] 34.7 PAO6 [wt %] 40.5 PAO8 [wt %] 46.8 46.4 43.6 Priolube 3970 [wt %] 2.5 Hitec 3250 [wt %] 2.0 2.0 2.0 2.0 2.0 Hitec 2030 [wt %] (**) 0.02 0.02 0.02 KV40 [cSt] 321.9 319.8 326.1 318.4 316.7 KV100 [cSt] 40.3 38.9 41.83 39.87 38.66 VI 179 173 184 178 173 BF-26 [cP] 192,000 50,000 50,000 n.m. n.m. BF-30 [cP] n.m. n.m. 81,000 82,000 88,000 Copper Corrosion n.m. n.m. 1b n.m. n.m. Steel Corrosion n.m. n.m. free of n.m. n.m. rust TOST KV100 increase [%] n.m. n.m. 6 n.m. n.m. RPVOT [min] n.m. n.m. 292 n.m. n.m. Foam after Sequence I n.m. n.m. 20 n.m. n.m. [mL] Foam after Sequence II n.m. n.m. 10 n.m. n.m. [mL] Foam after Sequence III n.m. n.m. 20 n.m. n.m. [mL] PP [° C.] −51 −48 −48 −48 −51 SL KRL20 100° C. [%] 1.5 0.6 n.m. n.m. n.m. SL KRL100 100° C. [%] n.m. n.m. 3.6 2.5 n.m. *means comparative example (**) added on top

[0094] Performance of the polymers without the distillation step is shown in Tables 12 and 13 below and is on a similar level as the distilled samples (Table 1). Care needs to be taken with regard to the comparison of different formulations in PAO8 as two different samples were used. While “PAO8” has excellent low temperature properties, “PAO8 I” shows slightly inferior low temperature properties at an improved VI level.

TABLE-US-00012 TABLE 12 320 cSt lubricant formulations with different high viscosity base fluids Form. Ex F-26 F-27 F-28 F-29 F-30 F-31 F-32 F-33 F-34 F-35 Ex. 5 53.2 [wt %] Ex. 49 54.2 [wt %] Ex. 50 54.0 [wt %] Ex. 51 53.0 [wt %] Ex. 54 52.4 [wt %] Ex. 46 52.6 [wt %] Ex. 44 52.6 [wt %] Ex. 45 53.6 [wt %] Ex. 47 54.4 [wt %] Ex. 48 53.4 [wt %] Hitec 3250 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 [wt %] PAO8 I 44.8 43.8 44.0 45.0 45.6 45.4 45.5 44.4 43.4 44.4 [wt %] KV40 [cSt] 318.8 320.2 322.1 317.7 317.7 316.6 321.1 323.9 322.5 323.3 KV100 [cStl 39.3 38.6 39.1 39.1 39.2 39.2 38.9 37.7 39.3 39.6 VI 175 172 173 175 176 176 173 178 174 175 BF-30 [cP] 89k 116k 102k 102k 96k 97k 114k 124k 102k 93k PP [° C.] −39 −39 −39 −39 −39 −39 −39 −36 −39 −39 SL KRL100 6.3 2.4 3.1 4.7 5.0 5.7 4.8 2.8 3.4 4.3 100° C. [%] “k” means thousands (10.sup.3) e.g. BF-30 [cP] 89k cP = 89,000 cP

TABLE-US-00013 TABLE 13 320 cSt lubricant formulations with different high viscosity base fluids Form. Ex. F-36 F-37* F-38* F-39 F-40 F-41 F-42 Ex. 31 60.0 [wt %] Ex12* 50.0 [wt %] Ex13* 71.8 [wt %] Ex. 32 53.8 [wt %] Ex. 33 63.5 [wt %] Ex. 52 57.7 [wt %] Ex. 8 52.1 [wt %] Hitec 3250 2.0 2.0 2.0 2.0 2.0 2.0 2.0 [wt %] PAO8 38.0 48.0 26.2 44.2 34.5 40.3 45.9 [wt %] KV40 [cSt] 323.0 322.0 323.2 323.6 322.8 322.8 319.6 KV100 [cSt] 41.1 36.6 44.2 39.5 41.7 38.7 38.1 VI 182 162 195 174 185 171 170 BF-30 [cP] 95,000 140,000 solid 96,000 84,000 104,000 104,000 PP [° C.] −48 −42 −18 −45 −48 −48 −45 SL KRL20 2.7 n.m. 1.6 5.2 2.2 3.6 3.5 100° C. [%]