Description

The present invention relates to a midd le-pressure polymerization process for the

preparation of a liquid ethylene copolymer which com prises in polymerized form 20 to 60 wt% of ethylene; and at least 20 wt% of an acrylate, which is selected from C _j -C^ al kyl

(meth)acrylate, where a monomer mix com prising the ethylene and the acrylate is

polymerized at a pressu re of 50 to 400 bar and in the presence of at least 2 wt% of a chain transfer agent. The invention further relates to a liquid ethylene copolymer obtainable by the polymerization process; and to a lu bricant com prising the liquid ethylene copolymer obtainable by the polymerization process; and to a method for reducing friction between moving surfaces com prising the step of contacting the su rfaces with the lu bricant or with the ethylene copolymer. Com binations of preferred em bodiments with other preferred

embodiments are within the scope of the present invention.

Object was to find a polymerization process for the preparation of ethylene copolymers for lu bricants, which should overcome the drawbacks of the prior art. For exam ple the process shou ld be stable, wel l control led, reliable, scalable, or al low the production of the desired ethylene copolymer. The process should have a high space time yield, or a high acrylate content in the ethylene copolymer shou ld be achievable. The process shou ld avoid high pressure conditions which require special equipment and safety precautions. The process should al low the use of solvents and it shou ld al low the use of various monomers. The process can be made semi-batch, so the polymerization can progess and the product is free of remaining monomers. Preferably, several of thiese objects shou ld be achieved.

Fu rther objects were to find an ethylene copolymer obtainable by the polymerization process or to find a lu bricant comprising the liquid ethylene copolymer which shou ld overcome the d rawbacks of the prior art. For example the ethylene copolymers or the lu bricant com prising the ethylene copolymers should be liquid, shou ld have a low pou r point, a good miscibility with apolar base stocks, a good miscibility with polar base stocks, a good oxidation stability, a high viscosity index, a low friction coefficient, a low volatility, a high chemical stability, a high shear stability, a viscosity index, a low sludge, a high clean liness, a good thickening efficiency, a high hydrolytic stability, or good cold flow properties. Preferably, the ethylene copolymer or the lu bricant com prising the ethylene copolymers should provide a com bination of several of such advantages.

The object was solved by a middle-pressure polymerization process for the preparation of a liquid ethylene copolymer which com prises in polymerized form

- 20 to 60 wt% of ethylene; and

- at least 20 wt% of an acrylate, which is selected from C _j -C^ al kyl (meth)acrylate, where a monomer mix com prising the ethylene and the acrylate is polymerized at a pressure of 50 to 400 bar and in the presence of at least 2 wt% of a chain transfer agent.

The object was also solved by the liquid ethylene copolymer obtainable by the polymerization process; and by a lu bricant com prising the liquid ethylene copolymer obtainable by the polymerization process; and by a method for reducing friction between moving surfaces comprising the step of contacting the su rfaces with the lu bricant or with the ethylene copolymer.

The polymerization process may be a fed-batch process. Preferably, the polymerization process is a fed-batch process in which a reactor is partly fil led with the ethylene and a solvent, fol lowed by feeding of the acrylate, the chain transfer agent, and an initiator. The polymerization process may continue for at least 30 min, preferably at least 1 h, and in particu lar at least 2 h. The polymerization process may take 1 to 10 h, preferably 2-5 h.

The polymerization process may be carried out in stirred fed-batch autoclaves, hereinafter also referred to as semi-batch autoclaves.

The polymerization process may be carried out at a pressure in the range from 50 to 400 bar, preferably from 70 to 300 bar, and particularly 80 to 200 bar. I n another form the

polymerization process may be carried out at a pressu re of at least 20, 30, 40, 50, 60, 70, 80, or 90 bar. I n another form the polymerization process may be carried out at a pressu re of up to 120, 140, 160, 180, 200, 220, 240, 260, 280 or 300 bar. Conditions of this type wil l hereinafter also be referred to as midd le-pressu re. The pressu re can change during the polymerization.

The polymerization process may be carried out at a reaction temperature in the range of 50 to 200 ° C, preferably 70 to 140 ° C, and in particu lar 80 to 120 ° C.

The monomer mix may be polymerized in a polymerization solvent, such as in one or more hyd rocarbons or one or more ketone(s) which are liquid at room tem perature or mixtu res of hyd rocarbons (e.g. olefins or aromatic hydrocarbons such as toluene, ethyl benzene, ortho xylene, meta-xylene and para-xylene, also cycloaliphatic hydrocarbons such as cyclohexane and aliphatic C ₆ -C ₁₆ -hyd rocarbons, either branched or un branched, for exam ple n-heptane, n-octane, isooctane, n-decane, n-dodecane and in particu lar isododecane) , ketones (e.g. acetone, methyl isobutyl ketone, ethyl methyl ketone) . Preferred polymerization solvents are al phatic hyd rocarbons, such as cyclohexane.

The monomer mix com prises the ethylene and the acrylate and optional ly the chain transfer agent and optional ly a solvent. The monomer mix may com prise the ethylene and the acrylate and optional ly the further monomer in amou nts which are suitable to arrive at the desired monomer amou nts in the ethylene copolymer.

Usual ly, the monomer mix com prises at least 30 wt%, preferably at least 40 wt%, and in particu lar at least 50 wt% of ethylene, where the percentage is based on al l monomers present in the monomer mix. I n another form, the monomer mix comprises at least 30 - 90 wt%, preferably at least 40 - 80 wt%, and in particu lar at least 50 - 70 wt% of ethylene.

Usual ly, the monomer mix com prises at least 10 wt%, preferably at least 25 wt%, and in particular at least 35 wt% of acrylate, where the percentage is based on al l monomers present in the monomer mix. I n another form, the monomer feed com prises at least 10 - 70 wt%, preferably at least 20 - 60 wt%, and in particu lar at least 30 - 50 wt% of the acrylate.

The percentage of al l monomers (e.g. ethylene, the acrylate and the fu rther monomer) in the monomer mix usual ly su m u p to 100 %.

I n another form the monomer mix com prises at least 30 wt% (e.g. at least 35, 40, 45, 50, 55, or 60 wt%) ethylene and at least 20 wt% (e.g. at least 25, 30, 35, 40 wt%) of the acrylate.

I n another form the monomer mix com prises up to 90 wt% (e.g. up to 85, 80, 75, 70, or 65 wt%) ethylene and up to 70 wt% (e.g. up to 65, 60, 55, 50, 45, or 40 wt%) of the acrylate.

I n another form the monomer mix com prises 30 - 90 wt% ethylene, 10 - 70 wt% of the acrylate, and optional ly up to 20 wt% of further monomers, where the percentages of the monomers su m u p to 100%.

I n another form the monomer mix com prises 40 - 80 wt% ethylene, 20 - 60 wt% of the acrylate, and optional ly u p to 10 wt% of further monomers, where the percentages of the monomers su m u p to 100%.

The conversion of the ethylene is usual ly arou nd 15 - 70 wt%, preferably 25 - 55 wt% and in particu lar 30 - 45 wt%, based on the ethylene feed.

The percentage of the chain transfer agent can be based on the su m of the amou nts of monomers (e.g. ethylene, the acrylate, optional ly the fu rther monomers) and the chain transfer agent. For exam ple, a monomer feed of 15 kg/h ethylene and 3 kg/h acrylate and a feed of the chain transfer agent of 2 kg/h corresponds to the presence of 10 wt% of the chain transfer agent.

The monomer mix com prising the ethylene and the acrylate is polymerized in the presence of at least 2 wt%, preferably at least 4 wt%, and in particular at least 6 wt% of the chain transfer agent, e.g. in the polymerization zone. I n another form the monomer mix comprising the ethylene and the acrylate may be polymerized in the presence of at least 2.1 wt%, or at least 2.3 wt%, or at least 2.5 wt%, or at least 3.0 wt%, or at least 3.5 wt%, or at least 4.0 wt%, or at least 4.5 wt%, or at least 5.0 wt%, or at least 5.5 wt%, or at least 6.0 wt%, or at least 6.5 wt%, or at least 7.0 wt% of the chain transfer agent.

I n another form the monomer mix com prising the ethylene and the acrylate may be polymerized in the presence of up to 30 wt%, preferably up to 20 wt%, and in particular u p to 15 wt% of the chain transfer agent.

I n another form the monomer mix com prising the ethylene and the acrylate may be polymerized in the presence of 4 to 18 wt%, preferably 6 to 15 wt%, and in particu lar 6 to 13 wt% of the chain transfer agent. I n another form the monomer mix com prising the ethylene and the acrylate may be polymerized in the presence of 3.0 to 12 wt%, preferably 3.5 to 10 wt%, and in particu lar 4.0 to 9 wt% of the chain transfer agent.

Suitable chain transfer agents (also named regulator) in the sense of this invention are regu lators which are terminating the growing of a polymer being incorporated as terminus of the polymer chain. Suitable regu lators are satu rated or u nsatu rated hydrocarbons, alcohols, thiols, ketones, aldehydes, amines, or hydrogen.

Among satu rated and u nsaturated hydrocarbons the chain transfer agents can be selected from pentane, hexane, cyclohexane, isododecane, propene, butene, pentene, cyclohexene, hexene, octene, decen and dodecen, and from aromatic hydrocarbonds such as toluol, xylol, trimethyl-benzene, ethyl benzene, diethyl benzene, triethyl benzene, mixtu res thereof.

Suitable ketones or aldehydes as chain transfer agents are aliphatic aldehydes or aliphatic ketones, such as regu lators of the formu la I I

or mixtu res thereof.

R _a and R _b are the same or different and are selected from

- hyd rogen;

- C _j -Cg-al kyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert- butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethyl propyl, isoamyl, n-hexyl, isohexyl, sec-hexyl; more preferably C ₁ -C ₄ -a I kyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl;

- C ₃ -C ₁₂ -cycloal kyl such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl; preference is given to cyclopentyl, cyclohexyl and cycloheptyl.

The R ^a and R ^b radicals may also be covalently bonded to one another to form a 4- to 13- mem-bered ring. For exam ple, R ^a and R ^b together may form the fol lowing al kylene

grou ps: -(CH ₂ ) ₄ -, -(CH ₂ ) ₅ -, -(CH ₂ ) ₆ -, -(CH ₂ ) ₇ -, -CH (CH ₃ ) -CH ₂ -CH ₂ -CH (CH ₃ ) - or -CH (CH ₃ ) -CH ₂ -

CH ₂ -CH ₂ -CH (CH ₃ ) -.

Preferred ketones as chain transfer agents are acetone, methylethyl ketone, diethyl ketone and diamyl ketone.

Preferred aldehydes as chain transfer agents are acetaldehyde, propionaldehyde, butanal and pentanal.

Among alcohols the chain transfer agents are selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol and pentanol. Among thiols the chain transfer agents maybe selected from mercaptoethanol to tetradecan- thiol. I n another form suitable thiols are organic thio compounds, such as primary, secondary, or tertiary aliphatic thiols, such as, ethanethiol, n-propanethiol, 2-propanethiol, n-butanethiol, tert-butanethiol, 2-butanethiol, 2-methyl-2-propanethiol, n-pentanethiol, 2-pentanethiol, 3- penta-nethiol, 2-methyl-2-butanethiol, 3-methyl-2-butanethiol, n-hexanethiol, 2-hexanethiol, 3-hexan-ethiol, 2-methyl-2-pentanethiol, 3-methyl-2-pentanethiol, 4-methyl-2-pentanethiol, 2-methyl-3-pentanethiol, 3-methyl-3-pentanethiol, 2-ethyl butanethiol, 2-ethyl-2-butanethiol, n-heptanethiol and its isomeric com pou nds, n-octanethiol and its isomeric com pou nds, n- nonanethiol and its isomeric com pou nds, n-decanethiol and its isomeric com pou nds, n- u ndecanethiol and its isomeric com pou nds, n-dodecanethiol and its isomeric com pou nds, n- tridecanethiol and its isomeric com pou nds, su bstituted thiols, such as 2-hyd roxyethanethiol, aromatic thiols, such as benzenethiol, ortho-, meta-, or para-methyl benzenethiol,

mercaptoal kanoic acid and derivatives thereof, such as 6-methyl heptyl 3-mercaptopropionate or 2-ethyl hexyl 2-mercaptoethanoate.

Among amines the chain transfer agents are selected from primary, secondary, or tertiary amines, such as dial kyl amines or trial kyl amines. Examples for amines are propyl amine, dipropyl amine, dibutyl amine, triethyl amine.

Preferred chain transfer agents are satu rated or unsatu rated hydrocarbons, aliphatic ketones, aliphatic aldehydes, or hydrogen, or mixtures thereof.

I n another preferred form the chain transfer agents are propene, butene, pentene,

propionaldehyde, methylethyl ketone, isododecane, or hydrogen, or mixtures thereof.

I n another preferred form the chain transfer agents are propionaldehyde, methyl ethyl ketone, or hydrogen, or mixtures thereof.

I n another preferred form the chain transfer agents are mixtures of propionaldehyde and/or methylethyl ketone and/or hydrogen.

I n another preferred form the chain transfer agents is propionaldehyde. I n another preferred form the chain transfer agents is a mixtrue of propionaldehyde and methylethyl ketone.

The chain transfer agents can be diluted with suitable solvents (e.g. hyd rocarbons) , preferably they are used without additional solvents.

The polymerization process is usual ly a free-radical polymerization, and usual ly initiated an initiator. Suitable initiators are organic peroxides, oxygen or azo com pou nds. Mixtures of a plurality of free-radical initiators are also suitable.

Suitable peroxides are didecanoyl peroxide, 2,5-dimethyl-2,5-di(2- ethyl hexanoyl peroxy) hexane, tert-amyl peroxypivalate, tert-amyl peroxy-2-ethyl hexanoate, dibenzoyl peroxide, tert-butyl peroxy-2-ethyl hexanoate, tert-butyl peroxydiethylacetate, tert- butyl peroxydiethylisobutyrate, l,4-di(tert-butyl peroxycarbonyl)cyclohexane as isomer mixture, tert-butyl perisononanoate, 1, 1 -d i (tert- buty I peroxy) -3, 3,5-tri methyl cyclohexane, 1, 1 -d i (tert-buty I peroxy) cyclohexane, methyl isobutyl ketone peroxide, tert-butyl peroxyisopropylcarbonate, 2,2-di (tert- buty I peroxy) buta ne or tert-butyl peroxacetate; tert-butyl peroxybenzoate, di-tert-amyl peroxide, dicu myl peroxide, the isomeric di-(tert-butyl peroxyisopropyl) benzenes, 2,5- dimethyl-2,5-di-tert-butyl peroxyhexane, tert-butyl cu myl peroxide, 2,5-dimethyl-2,5-di(tert- butyl peroxy) hex-3-yne, di-tert-butyl peroxide, 1,3-diisopropyl benzene monohyd roperoxide, cumene hydroperoxide or tert-butyl hydro-peroxide, or dimeric or trimeric ketone peroxides.

As azo compound azodicarboxylic esters, azodicarboxylic dinitriles are suitable, mention may be made by way of exam ple of azobisisobutyronitrile ("AI BN").

Preferred initiators are selected from the group consisting of di-tert-butyl peroxide, tert-amyl peroxypivalate, tert-butyl peroxypivalat, tert-butyl peroxyisononanoate, tert-butyl peroxy-2- ethyl-hexanoate, 2,2-di(tert-butyl peroxy) butane and mixtures thereof. Preferably tert-amyl peroxypivalate is used as initiator.

I nitiators, e.g. organic peroxides, are often admixed with solvents to make them easier to hand le. I n a preferred form the initiator is introduced in the form of a solution in one or more ketone(s) or hydrocarbons (especial ly olefins) which are liquid at room tem peratu re. The initiator are preferably fed in as a 0.1 - 50% strength by weight solution, preferably a 0.5 - 20% strength by weight solution, in one or more hyd rocarbons or one or more ketone(s) which are liquid at room temperatu re or mixtu res of hyd rocarbons (e.g. olefins or aromatic hyd rocarbons such as toluene, ethyl benzene, ortho-xylene, meta-xylene and para-xylene, also cycloaliphatic hydrocarbons such as cyclohexane and aliphatic C ₆ -C ₁₆ -hyd rocarbons, either branched or u n branched, for exam ple n-heptane, n-octane, isooctane, n-decane, n- dodecane and in particu lar isododecane) , ketones (e.g. acetone, methyl isobutyl ketone, ethyl methyl ketone) . I n cases where the solvents for the initiator are also fu nction as regu lators (e.g. ketones), then the amount of such regu lator is included for calculating the wt% of the regulator in the monomer feed.

The amou nt of the initiator depends on the chemical natu re of the initiator and can by adjusted by routine experiments. Typical ly, the initiator is present in 0,001 to 0,1 wt%, preferably 0,01 to 0,05 wt% based on the weight of the monomer feed.

The initiators em ployed herein can be introduced into the polymerization zone in any suitable man ner, for example, by dissolving the initiator in a suitable solvent and injecting the initiator solution directly into the polymerization zone. Alternatively, the initiator may be injected into the feed stream, prior to introduce-tion thereof into the polymerization zone. I n the autoclave the initiator can be fed either in one point in the midd le or twice: first in the u pper part of the reactor and the second time either in the middle or in the bottom of the reactor. I n addition three or more injections are possible.

The polymerization process may be followed by postpolymerization chemical reactions, such as a hydrogenation. The hyd rogenation may be a homogeneous or heterogenous catalytic hyd rogenation. Usual ly, the hydrogenation is achieved with molecular hydrogen in the presence of a transition metal catalyst (e.g. based on RH, Co, Ni, Pd, or Pt), which may be dissolved in solvents or supported on inorganic supports.

The ethylene copolymer is liquid, which usually means that it is liquid at room temperature, e.g. at 25 ° C.

The ethylene copolymers are usually not crystalline, so that in general no crystallization commencement temperature, T _cc , is measurable at T > 15° C with differential scanning calorimetry. Usually, a melt flow index cannot be determined with ethylene copolymers.

The ethylene copolymer may have a pour point below 25 ° C, preferably below 20 ° C, and in particular below 15 ° C. In another form the ethylene copolymer may have a pour point below 10 ° C, preferably below 5 ° C, and in particular below 0 ° C. The pour point may be determined according to ASTM D 97.

In one form the ethylene copolymer is considered liquid when its pour point is below 25 ° C, preferably below 20 ° C, and in particular below 15 ° C.

The ethylene copolymer may be clear liquid at room temperature, e.g. at 25 ° C. Typically, in a clear liquid no turbidity is visible.

The ethylene copolymer may have a cloud point of below 25 ° C, preferably below 20 ° C, and in particular below 15 ° C. The cloud point may be determined according to ISO 3015.

The ethylene copolymer may be miscible with a polyalphaolefine having a kinematic viscosity at 100 ° C of about 6 cSt. This miscibility may be determined in a weight ratio of 50:50 at room temperature, e.g. 25 ° C for 24 h.

The ethylene copolymer may have a viscosity index of at least 100, preferably at least 120, and in particular of at least 180. The viscosity index may be determined according to ASTM D2270.

The ethylene copolymer may have a kinematic viscosity at 40° C from 200 to 30 000 m m ² /s (cSt), preferably from 500 to 10 000 m m ² /s, and in particular from 1000 to 5000 mm ² /s. The kinematic viscosity may be determined according to ASTM D445.

In another form the ethylene copolymer may have a kinematic viscosity at 40° C from 700 to 4000 mm ² /s (cSt), preferably from 1000 to 3000 mm ² /s, and in particular from 1200 to 2500 mm ² /s.

In another form the ethylene copolymer may have a kinematic viscosity at 40° C from 5000 to 50 000 mm ² /s (cSt), preferably from 10 000 to 35 000 mm ² /s, and in particular from 15 000 to 30 000 mm ² /s. The ethylene copolymer may have a kinematic viscosity at 100° C from 10 to 5000 m m ² /s (cSt), preferably from 30 to 3000 m m ² /s, and in particular from 50 to 2000 mm ² /s

In another form the ethylene copolymer may have a kinematic viscosity at 100° C from 50 to 500 mm ² /s (cSt), preferably from 80 to 350 mm ² /s, and in particular from 100 to 200 mm ² /s.

In another form the ethylene copolymer may have a kinematic viscosity at 100° C from 200 to 3000 mm ² /s (cSt), preferably from 700 to 2500 mm ² /s, and in particular from 800 to 2100 mm ² /s.

The ethylene copolymer has usually a weight-average molecular weight M _w in the range up to 35 000 g/mol, preferably up to 30 000 g/mol, and in particular up to 25 000 g/mol. In another form the ethylene copolymer has usually a weight-average molecular weight M _w in the range from 1000 to 30 000 g/mol, preferably from 1500 to 25 000 g/mol, and in particular from 3000 to 25000 g/mol.

In another form the ethylene copolymer has usually a weight-average molecular weight M _w in the range from 1 000 to 25 000 g/mol, preferably from 2 000 to 20 000 g/mol, and in particular from 3000 to 15 000 g/mol.

In another form the ethylene copolymer has usually a weight-average molecular weight M _w in the range from 8 000 to 35 000 g/mol, preferably from 10 000 to 30 000 g/mol, and in particular from 12 000 to 25 000 g/mol.

The ethylene copolymer has usually a number-average molecular weight M _n in the range up to 12000 g/mol, preferably up to 10000 g/mol, and in particular up to 7000 g/mol. In another form the ethylene copolymer has usually a number-average molecular weight M _n in the range from 1000 to 12000 g/mol, preferably from 1200 to 9000 g/mol, and in particular from 1500 to 7000 g/mol. The Mw and Mn may be determined by GPC on calibrated columns.

In another form the ethylene copolymer has usually a number-average molecular weight M _n in the range from 1000 to 10000 g/mol, preferably from 1500 to 8000 g/mol, and in particular from 1700 to 5000 g/mol.

In another form the ethylene copolymer has usually a number-average molecular weight M _n in the range from 2000 to 15 000 g/mol, preferably from 3500 to 10 000 g/mol, and in particular from 4000 to 7000 g/mol.

The ethylene copolymer has usually a polydispersity (M _w /M _n ) of at least 1, preferably in the range from 1.3 to 5, more preferably from 1.5 to 4, and most preferably from 1.8 to 3.8.

In another form the ethylene copolymer has usually a polydispersity in the range from 1.3 to 3.5, more preferably from 1.5 to 3.3, and most preferably from 1.9 to 3.0. I n another form the ethylene copolymer has usual ly a polydispersity in the range from 2.7 to 4.5, more preferably from 3.0 to 4.0, and most preferably from 3.2 to 3.8.

The liquid ethylene copolymer comprises in polymerized form 20 to 60 wt%, preferably 25 to 55 wt%, and in particu lar 30 to 50 wt% of ethylene.

I n another form the liquid ethylene copolymer com prises in polymerized form at least 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80 mol% of ethylene. I n another form the liquid ethylene copolymer com prises in polymerized form 35 to 95 mol% , preferably 45 to 40 mol%, and in particular 55 to 88 mol% of ethylene. I n another form the liquid ethylene copolymer comprises in polymerized form 60 to 95 mol%, preferably 65 to 40 mol%, and in particu lar 70 to 88 mol% of ethylene.

The liquid ethylene copolymer comprises in polymerized form at least 20 wt%, preferably at least 40 wt%, and in particular at least 50 wt% of the acrylate. The ethylene copolymer may com prise in polymerized form 30 to 80 wt%, preferably 40 to 75 wt%, and in particu lar 50 to 75 wt% of the acrylate. I n another form the liquid ethylene copolymer com prises in

polymerized form at least 20, 25, 30, 35, 40, 45, 50, or 55 wt% of the acrylate. I n another form the liquid ethylene copolymer comprises in polymerized form less than 80, 75, 70, 65, 60, 55, or 50 wt% of the acrylate.

I n another form the liquid ethylene copolymer may comprise in polymerized form at least 5 mol%, preferably at least 10 mol%, and in particular at least 15 mol% of the acrylate. I n another form the liquid ethylene copolymer may com prise in polymerized form at least 5, 10, 15, 20, 25, 30, or 35 mol% of the acrylate. I n another form the liquid ethylene copolymer may com prise in polymerized form less than 20, 25, 30, 35, 40, or 45 mol% of the acrylate. I n another form the ethylene copolymer may comprise in polymerized form 5 to 50 mol%, preferably 10 to 45 mol%, and in particular 15 to 40 mol% of the acrylate.

The wt% or the mol% of the monomers, which are present in polymerized form in the ethylene copolymer, usual ly refers to the total amount of monomers which are present in polymerized form in the ethylene copolymer. Other compou nds, such as radical starters or chain transfer agents, may be incorporated in the ethylene copolymer, but they are usual ly not considered for this calculation.

Usual ly, the sum of the wt% of ethylene and the acrylate (e.g. the polar and the u npolar acrylate) and optional ly the fu rther monomer is u p to 100 wt%, preferably 80 to 100 wt%, in particular 95 to 100 wt%. I n another form the sum of the wt% of ethylene and the acrylate is 100 wt%. Usual ly, the su m of the mol% of ethylene and the acrylate (e.g. the polar and the u npolar acrylate) and optional ly the fu rther monomer is u p to 100 mol%, preferably 80 to 100 mol%, in particu lar 95 to 100 mol%. I n another form the su m of the wt% of ethylene and the acrylate is 100 mol%.

The wt% or the mol% of ethylene and the acrylate (and optional ly the fu rther monomers) in the ethylene copolymer may be determined by H-N M R. In one form the ethylene copolymer comprises in polymerized form

- 25 to 55 wt% of ethylene, and

- at least 40 wt% of the acrylate, such as 40 to 75 wt%, and in particular 50 to 75 wt%.

In another form the ethylene copolymer comprises in polymerized form

- 30 to 50 wt% of ethylene, and

- at least 50 wt% of the acrylate, such as 50 to 75 wt%.

In another form the ethylene copolymer comprises in polymerized form

- 25 to 55 wt% of ethylene,

- at least 20 wt% of the polar acrylate, and

- at least 15 wt% of the unpolar acrylate.

In another form the ethylene copolymer comprises in polymerized form

- 20 to 60 wt% of ethylene,

- 20 to 50 wt% of the polar acrylate, and

- 15 to 40 wt% of the unpolar acrylate.

In another form the ethylene copolymer comprises in polymerized form

- 30 to 50 wt% of ethylene,

- 25 to 50 wt% of the polar acrylate, and

- 20 to 40 wt% of the unpolar acrylate.

In another form the ethylene copolymer comprises in polymerized form

- 25 to 55 wt% of ethylene,

- at least 20 wt% of the polar acrylate which is selected from C _j- alkyl (meth)acrylate, and

- at least 15 wt% of the unpolar acrylate which is selected from C _6- C ₂₂ alkyl (meth)acrylate.

In another form the ethylene copolymer comprises in polymerized form

- 30 to 50 wt% of ethylene,

- 20 to 50 wt% of the polar acrylate which is selected from C _j- alkyl (meth)acrylate, and

- 15 to 40 wt% of the unpolar acrylate which is selected from C _6- C ₂₂ alkyl (meth)acrylate.

In another form the ethylene copolymer comprises in polymerized form

- 25 to 55 wt% of ethylene,

- at least 20 wt% of the polar acrylate which is selected from C ₃ _C ₄ alkyl (meth)acrylate, and

- at least 15 wt% of the unpolar acrylate which is selected from C _8- C ₁₄ alkyl (meth)acrylate.

In another form the ethylene copolymer comprises in polymerized form

- 30 to 50 wt% of ethylene,

- 20 to 50 wt% of the polar acrylate which is selected from C _3- C ₄ alkyl (meth)acrylate, and

- 15 to 40 wt% of the unpolar acrylate which is selected from C _8- C ₁₂ alkyl (meth)acrylate. The acrylate is selected from C _! -C ₂₂ alkyl (meth)acrylate, preferably from C _j -0 ₂₂ al kyl acrylate. The acrylate may comprise at least one (meth)acrylate, such as one, two or th ree (meth) -acrylates. The acrylate is preferably selected from C ₂ -C ₂₀ al kyl (meth)acrylate, and in particular from selected from C ₃ -C ₁₈ al kyl (meth)acrylate. I n another form the acrylate is preferably selected from C ₂ -C ₂₀ al kyl acrylate, and in particu lar from selected from C ₃ -C ₁₈ al kyl acrylate.

The term“(meth)acrylate” refers to esters or acrylic acid, methacrylic acid, or mixtures thereof. Preferably, the acrylate is selected from C _j -0 ₂₂ al kyl acrylate, in particular from C ₃ - C ₁₈ al kyl acrylates.

The C ₄ - C ₂₂ al kyl grou p of the C _j -0 ₂₂ al kyl (meth)acrylate (preferably of the the C _j -0 ₂₂ al kyl acrylate) may be satu rated or unsatu rated (preferably satu rated) , branched, cyclic or linear (preferably linear or branched) or mixtu res thereof, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pen-tyl, isopentyl, sec-pentyl, neopentyl, 1,2- dimethyl-propyl, isoamyl, n-hexyl, isohexyl, sec-hexyl, cyclo-hexyl, n-heptyl, n-octyl, isooctyl, 2-ethyl-hexyl, n-nonyl, 2— propyl hepty I , n-decyl, u n-decyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, 2-buty loctyl , 2-pen-tyl nonyl, 2-hexyldecyl, isohexyl, isoheptyl, isooctyl, isononyl, isodecyl, isou ndecyl, isododecyl, isotridecyl,

isotetradecyl, isopentadecyl, isohexadecyl, isoheptadecyl, isooctadecyl, and mixtu res thereof.

The acrylate may comprise a polar acrylate and an unpolar acrylate. Preferably, the acrylate comprises

- a polar acrylate selected from C _j -Cs al kyl (meth)acrylate (preferably C _j -Cs al kyl acrylate) , and

- an u n polar acrylate selected from C ₆ -C ₂₂ al kyl (meth)acrylate (preferably C ₆ -C ₂₂ al kyl acrylate) .

The polar acrylate may be methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl

(meth)acrylate, or n-butyl (meth)acrylate, wherein n-butyl acrylate is preferred.

The u npolar acrylate may be preferably selected from C ₈ -C ₁₈ al kyl (meth)acrylate, and in particu lar from C ₈ -C ₁₂ al kyl (meth)acrylate.

Exam ples of the u n polar acrylate are (meth)acrylates of n-octyl, isooctyl, 2-ethyl hexyl, n- nonyl, 2— propyl hepty I , n-decyl, u n-decyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, 2 - butyl octyl , 2-pentyl nonyl, 2-hexyldecyl, isohexyl, isoheptyl, isooctyl, isononyl, isodecyl, isoundecyl, isododecyl, isotridecyl, isotetradecyl, isopentadecyl, isohexadecyl, isoheptadecyl, isooctadecyl and mixtu res thereof.

More preferably, the polar acrylate is selected from C ₃ _C ₄ al kyl (meth)acrylate, and the u npolar acrylate selected from C ₈ -C ₂₂ al kyl (meth)acrylate.

I n particular, the polar acrylate is selected from C ₃ _C ₄ al kyl acrylate, and the u npolar acrylate selected from C ₈ -C ₂₂ al kyl acrylate. The weight ratio of the u n polar acrylate to the polar acrylate may be from 10:90 to 70:30, preferably from 20:80 to 65:35, and in particu lar from 30:70 to 60:40.

The ethylene copolymer may com prise in polymerized form further monomers beside ethylene and the acrylate, such as u p to 10 wt%, preferably u p to 4 wt%, and in particular up to 2 wt% of al l monomers. Preferably, the ethylene copolymer is free of further monomers beside the ethylene and the acrylate. I n another form the ethylene copolymer may com prise less than 2 wt%, preferably less than 1 wt%, and in particu lar less than 0.3 wt% further monomers. I n another form the ethylene copolymer may comprise in polymerized form less than 2 mol%, preferably less than 1 mol%, and in particular less than 0.5 mol% further monomers.

Exam ples for further monomers are

- vinyl aromatic compounds, such as styrene, al pha-methyl styrene, vinyl toluene or p-(tert- butyl) styrene;

- acrylamide and methacrylamide;

- maleic acid and the imides and C _j to C ₁₄ -a I kyl or di al kyl esters thereof;

- fumaric acid and the imides and C _j to C ₁₄ -a I kyl or di al kyl esters thereof;

- itaconic acid and the imides and C _j to C ₁₀ -a I kyl esters thereof;

- acrylonitrile and methacrylonitrile;

- acrylates and methacrylates with fu nctionalized chain such as dimethylaminoethyl

methacrylate, dimethylaminopropyl methacrylate, diethylaminoethyl methacrylate, diethylaminopropyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminoethyl acrylate, diethylaminopropyl acrylate, tert-butylaminoethyl methacrylate, glycidyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, 2- morpholinoethyl methacrylate, hydroxyethyl methacrylate, hyd roxypropyl methacrylate;

- acrylamide derivatives such as as N,N-dimethylaminopropyl methacrylamide, N , N -d i- methylaminopropyl acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide;

- vinyl derivatives such as vinylimidazol, vinyl pyrrolidone, vinylformamide, vinylethers,

propylvinylether, butylvinylether and cyclohexylvinylether.

Other suitable further monomers are C ₂ 4-C ₄₀ al kyl (meth)acrylates, which are preferably branched, such as (meth)acrylates of 2-decyl-tetradecanol, 2-dodecyl-hexadecanol, tetradecyl-octadecanol.

Other suitable further monomers are polyolefin-based macromonomers, preferably the macromonomers according to WO 2018/024563, such as macromonomers of the fol lowing formu la (I I I)

wherein R ¹ to R ⁵ are each independently selected from the group consisting of H, C _j -C^- Al kyl, C _j -C _j o-Al kyloxy and C ₈ -C ₃₅₀₀ -Polyisobutyl and C ₈ -C3 ₅₀₀ -Polyisobutenyl,

R is a 2 to 10 carbon atoms comprising al kylene grou p,

R ⁶ is hyd rogen or methyl,

R ⁷ is hyd rogen, methyl or COOR ⁸ ,

R ⁸ is hyd rogen or C ₁ -C ₂₀ -al kyl, and

n is a positive integer from 1 to 50,

with the provisio that at least of of the residues R ¹ to R ⁵ is a C ₈ -C ₃₅₀₀ -polyisobutyl or C ₈ -C ₃₅₀₀ - polyisobutenyl.

I n another form the further monomers are non-ionic monomers.

I n another form the ethylene copolymer may be free of further monomers which are

vinylester of the formula (I) in polymerized form

where R ^c , R ^d , and R ^e are each independently H or C ₁ -C ₄ -al kyl, and R ^f is C _j -C^ al kyl. A suitable vinyl ester of the formula (I) is vinyl acetate. I n another form the ethylene copolymer com prises less than 2 mol%, less than 1.5 mol%, less than 1.0 mol%, less than 0.5 mol% or less than 0.1 mol% of the vinylester of the formu la (I) , such as vinyl acetate. I n another form the ethylene copolymer may be free of vinyl derivatives such as vinylester.

I n another form the ethylene copolymer may com prise less than 5 wt%, preferably less than 1 wt%, and in particu lar less than 0.5 of an al kyl methacrylate in polymerized form (for example the ethylene copolymer is free of al kyl methacrylates) and the acrylate is selected from - C ₂₂ al kyl acrylate.

I n another form the ethylene copolymer may be free of fu rther monomers in polymerized form, which comprise a functional group, such as a fu nctional grou p selected from

carboxylic acid, su lfonic acid, phosphonic acid, amino, amide, imide, hyd roxyl, and cyano. I n another form the ethylene copolymer may com prise less than 5 wt%, preferably less than 1 wt%, and in particu lar less than 0.5 wt% fu rther monomers in polymerized form, which com prise a functional grou p. I n another form the ethylene copolymer may comprise in polymerized form less than 2 mol%, preferably less than 1 mol%, and in particu lar less than 0.5 mol% further monomers in polymerized form, which com prise a fu nctional group.

I n another form the ethylene copolymer may be free of fu rther monomers which are vinylester of the formula (I) in polymerized form, and of fu rther monomers in polymerized form, which com prise fu nctional grou ps.

I n another form the ethylene copolymer is free of fu rther monomers in polymerized form, which com prise an ionic group (e.g. anionic, cationic, or zwitter ionic) , such as a carboxylic acid, sulfonic acid, or phosphonic acid. In another form the ethylene copolymer may comprise less than 5 wt%, preferably less than 1 wt%, and in particular less than 0.5 wt% further monomers in polymerized form, which comprise an ionic group.

In another form the ethylene copolymer is free of further monomers in polymerized form, which comprise an acidic group, such as maleic acid, fumaric acid, itaconic acid, acrylic acid, and methacrylic acid. In another form the ethylene copolymer may comprise less than 5 wt%, preferably less than 1 wt%, and in particular less than 0.5 wt% further monomers in polymerized form, which comprise an acidic group, such as maleic acid, fumaric acid, itaconic acid, acrylic acid, and methacrylic acid. In another form the ethylene copolymer is free of acrylic acid and/or methacrylic acid in polymerized form. In another form the ethylene copolymer may comprise less than 5 wt%, preferably less than 1 wt%, and in particular less than 0.5 wt% of acrylic acid and/or methacrylic acid in polymerized form.

In another form the ethylene copolymer is free of further monomers in polymerized form, which comprise a hydroxyl group, such as hydroxyalkyl (meth)acrylates. In another form the ethylene copolymer may comprise less than 5 wt%, preferably less than 1 wt%, and in particular less than 0.5 wt% further monomers in polymerized form, which comprise a hydroxyl group, such as hydroxyalkyl (meth)acrylates. In another form the ethylene copolymer may be free of esters of unsaturated carboxylic acids in polymerized form containing at least one free hydroxyl group located in the part of the molecule derived from the alcohol.

The lubricant usually further comprises

- a base oil selected from mineral oils, polyalphaolefins, polymerized and interpolymerized olefins, alkyl naphthalenes, alkylene oxide polymers, silicone oils, phosphate ester and carboxylic acid ester; and/or

- a lubricant additive.

In one form the lubricant further comprises a base oil selected from mineral oils, polyalpha olefins, polymerized and interpolymerized olefins, alkyl naphthalenes, alkylene oxide polymers, silicone oils, phosphate ester and carboxylic acid ester. In another form the lubricant usually further comprises a lubricant additive.

In one form the lubribant may comprise at least 10 wt%, preferably at least 30 wt% and in particular at least 60 wt% of the ethylene copolymer.

In another form the lubricant may comprise 10 - 99 wt%, preferably 30 - 95 wt% and in particular at least 60 - 95 wt% of the ethylene copolymer.

In another form the lubricant may comprise 1 -90 wt%, preferably 5 -50 wt% and in particular 20 - 50 wt% of the base oil.

In another form the lubricant may comprise at least 0.1 wt%, preferably at least 0.5 wt% and in particular at least 1 wt% of the ethylene copolymer. I n another form the lu bricant may com prise 0.1 - 20 wt%, preferably 0.1 - 150 wt% and in particu lar at least 0.1 - 10 wt% of the ethylene copolymer.

I n another form the lubricant may com prise 30 - 99.9 wt%, preferably 50 - 99 wt% and in particu lar 70 - 95 wt% of the base oil.

The lu bricant may com prise up to 20 wt%, preferably u p to 15 wt% and in particu lar up to 10 wt% of the lu bricant additive.

I n another form the lu bricant may com prise 0.1 - 20 wt%, preferably 0.1 - 15 wt% and in particu lar at least 0.1 - 10 wt% of the lu bricant additive.

Lubricants usual ly refers to composition which are capable of reducing friction between su rfaces (preferably metal surfaces) , such as su rfaces of mechanical devices. A mechanical device may be a mechanism consisting of a device that works on mechanical principles. Suitable mechanical device are bearings, gears, joints and guidances. The mechanical device may be operated at temperatures in the range of -30 C to 80 ° C.

Lu bricants are usual ly specifical ly formu lated for virtual ly every type of machine and manufacturing process. The type and concentration of base oils and/or lu bricant additives used for these lubricants may be selected based on the requirements of the machinery or process being lu bricated, the quality required by the builders and the users of the machinery, and the government regu lation. Typical ly, each lubricant has a u nique set of performance requirements. I n addition to proper lu brication of the machine or process, these requirements may include maintenance of the quality of the lu bricant itself, as wel l as the effect of the lu bricant’s use and disposal on energy use, the quality of the environ ment, and on the health of the user.

Typical lu bricants are automotive lubricants (e.g. gasoline engine oils, diesel engine oils, gas engine oils, gas turbine oils, automatic transmission fluids, gear oils) and industrial lu bricants (e.g. industrial gear oils, pneumatic tool lu bricating oil, high tem peratu re oil, gas compressor oil, hydraulic fluids, metalworking fluids) .

Examples for lu bricants are axel lubrication, mediu m and heavy duty engine oils, industrial engine oils, marine engine oils, automotive engine oils, crankshaft oils, compressor oils, refrigerator oils, hyd rocarbon compressor oils, very low-temperature lubricating oils and fats, high temperature lubricating oils and fats, wire rope lubricants, textile machine oils, refrigerator oils, aviation and aerospace lubricants, aviation tu rbine oils, transmission oils, gas tu rbine oils, spind le oils, spin oils, traction fluids, transmission oils, plastic transmission oils, passenger car transmission oils, truck transmission oils, industrial transmission oils, industrial gear oils, insu lating oils, instru ment oils, brake fluids, transmission liquids, shock absorber oils, heat distribution mediu m oils, transformer oils, fats, chain oils, minimu m quantity lu bricants for metalworking operations, oil to the warm and cold working, oil for water-based metalworking liquids, oil for neat oil metalworking fluids, oil for semi-synthetic metalworking fluids, oil for synthetic metalworking fluids, dril ling detergents for the soil exploration, hydraulic oils, in biodegradable lubricants or lubricating greases or waxes, chain saw oils, release agents, molding fluids, gun, pistol and rifle lubricants or watch lubricants and food grade approved lubricants.

The lubricant has usually may have a kinematic viscosity at 40° C of at least 10, 50, 100, 150, 200, 300, 400, 500, 600, 900, 1400, or 2000 mm ² /s. In another form the lubricant has usually may have a kinematic viscosity at 40° C from 200 to 30000 mm ² /s (cSt), preferably from 500 to 10000 mm ² /s, and in particular from 1000 to 5000 mm ² /s.

The lubricant has usually may have a kinematic viscosity at 100° C of at least 2, 3, 5, 10, 20, 30, 40, or 50 mm ² /s. In another form the lubricant may have a kinematic viscosity at 100° C from 10 to 5000 mm ² /s (cSt), preferably from 30 to 3000 mm ² /s, and in particular from 50 to 2000 mm ² /s

The lubricant may have a viscosity index of at least 50, 75, 100, 120, 140, 150, 160, 170, 180, 190 or 200.

The lubricant is usually a lubricating liquid, lubricating oil or lubricating grease.

The base oil may selected from the group consisting of mineral oils (Group I, II or III oils), polyalphaolefins (Group IV oils), polymerized and interpolymerized olefins, alkyl

naphthalenes, alkylene oxide polymers, silicone oils, phosphate esters and carboxylic acid esters (Group V oils). Preferably, the base oil is selected from Group I, Group II, Group III base oils according to the definition of the API, or mixtures thereof. Definitions for the base oils are the same as those found in the American Petroleum Institute (API) publication "Engine Oil Licensing and Certification System", Industry Services Department, Fourteenth Edition, December 1996, Addendum 1, December 1998. Said publication categorizes base oils as follows: a) Group I base oils contain less than 90 percent saturates (ASTM D 2007) and/or greater than 0.03 percent sulfur (ASTM D 2622) and have a viscosity index (ASTM D 2270) greater than or equal to 80 and less than 120.

b) Group II base oils contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120.

c) Group III base oils contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120. d) Group IV base oils contain polyalphaolefins. Polyalphaolefins (PAO) include known PAO materials which typically comprise relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include but are not limited to C2 to about C32 alphaolefins with the C8 to about C16 alphaolefins, such as 1-octene, 1-decene, 1- dodecene and the like being preferred. The preferred polyalphaolefins are poly- 1- octene, poly-l-decene, and poly-l-dode-cene. e) Group V base oils contain any base oils not described by Groups I to IV. Exam ples of

Group V base oils include al kyl naphthalenes, al kylene oxide polymers, silicone oils, and phosphate esters.

Synthetic base oils include hydrocarbon oils and halo-su bstituted hyd rocarbon oils such as pol-ymerized and interpolymerized olefins (e.g., polypropylenes, propylene-isobutylene copolymers, ch lorinated polybutylenes, poly(l-hexenes) , poly(l-octenes), poly(l-decenes)) ; al kyl benzenes (e.g., dodecyl benzenes, tetradecyl benzenes, dinonyl benzenes, d i (2 - ethyl hexy benzenes) ; poly-phenyls (e.g., biphenyls, terphenyls, al kylated polyphenols); and al kylated diphenyl ethers and al kylated diphenyl su lfides and derivative, analogs and homologs thereof.

Al kylene oxide polymers and interpolymers and derivatives thereof where the terminal hyd roxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic base oils. These are exemplified by polyoxyal kylene polymers prepared by polymeriza-tion of ethylene oxide or propylene oxide, and the al kyl and aryl ethers of polyoxyal kylene poly-mers (e.g., methyl-polyiso-propylene glycol ether having a molecular weight of 1000 or diphenyl ether of polyethylene glycol having a molecu lar weight of 1000 to 1500); and mono- and polycar-boxylic esters thereof, for exam ple, the acetic acid esters, mixed C3-C8 fatty acid esters and C13 oxo acid diester of tetraethylene glycol.

Silicon-based oils such as the polyal kyl-, polyaryl-, polyal koxy- or polyaryloxysilicone oils and sili-cate oils comprise another useful class of synthetic base oils; such base oils include tetraethyl silicate, tetraisopropyl silicate, tetra-(2- ethyl hexyl) si I icate, tetra-(4-methyl-2- ethyl he-xy I) silicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-methyl-2- ethyl hexy disiloxane, poly(methyl) siloxanes and poly(methyl phenyl)siloxanes. Other synthetic base oils include liquid esters of phosphorous-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decyl phosphonic acid) and polymeric tetrahyd rofu rans.

Suitable lubricant additives may be selected from viscosity index im provers, polymeric thickeners, antioxidants, corrosion in hibitors, detergents, dispersants, anti-foam agents, dyes, wear protection additives, extreme pressu re additives (EP additives) , anti-wear additives (AW additives), friction modifiers, metal deactivators, pou r point depressants.

The viscosity index improvers include high molecular weight polymers that increase the relative viscosity of an oil at high temperatures more than they do at low temperatures.

Viscosity index improvers include polyacrylates, polymethacrylates, al kyl methacrylates, vinyl pyrrolidone/me-thacrylate copolymers, poly vinyl pyrrolidones, polybutenes, olefin copolymers such as an ethylene-propylene copolymer or a styrene-butadiene copolymer or polyal kene such as PI B, styrene/acrylate copolymers and polyethers, and combinations thereof. The most com mon VI improvers are methacrylate polymers and copolymers, acrylate polymers, olefin polymers and copolymers, and styrenebutadiene copolymers. Other examples of the viscosity index im prover include polymethacrylate, polyisobutylene, al pha- olefin polymers, al pha-olefin copolymers (e.g., an ethylenepropylene copolymer) , polyal kylstyrene, phenol condensates, naphthalene condensates, a styrenebutadiene copolymer and the like. Of these, polymethacrylate having a num ber average molecu lar weight of 10000 to 300000, and al pha-olefin polymers or al pha-olefin copolymers having a num ber average molecu lar weight of 1000 to 30000, particu larly ethylene- al pha-olefin copolymers having a nu mber average molecu lar weight of 1000 to 10000 are preferred. The viscosity index increasing agents can be added and used individual ly or in the form of mixtu res, conveniently in an amou nt within the range of from > 0.05 to < 20.0 % by weight, in relation to the weight of the base stock.

Suitable (polymeric) thickeners include, but are not limited to, polyisobutenes (PI B) , oligomeric co-polymers (OCPs) , polymethacrylates (PMAs) , copolymers of styrene and butadiene, or high viscosity esters (com plex esters) .

Antioxidants include phenolic antioxidants such as hindered phenolic antioxidants or non- phenolic oxidation in hibitors.

Useful phenolic antioxidants include hindered phenols. These phenolic antioxidants may be ash less (metal-free) phenolic compou nds or neutral or basic metal salts of certain phenolic compounds. Typical phenolic antioxidant compou nds are the hindered phenolics which are the ones which contain a sterical ly hindered hydroxyl grou p, and these include those derivatives of dihydroxy aryl compounds in which the hydroxyl grou ps are in the o- or _/ ex position to each other. Typical phenolic antioxidants include the hindered phenols su bstituted with al kyl grou ps having 6 carbon atoms or more and the al kylene coupled derivatives of these hindered phenols. Exam ples of phenolic materials of this type 2 -t- butyl - 4-heptyl phenol; 2-t-buty I -4-octy I phenol; 2-t-butyl-4-dodecyl phenol; 2,6-d i-t— butyl -4- heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl phenol; and 2- methyl-6-t-butyl-4-dodecyl phenol. Other usefu l hindered mono-phenolic antioxidants may include for example hindered 2,6-di-al kyl- phenolic propionic ester derivatives. Bis-phenolic antioxidants may also be used in combination with the present invention. Examples of ortho- cou pled phenols include: 2,2'-bis(4-heptyl-6-t-butyl-phenol) ; 2,2'-bis(4- octyl -6-t-butyl- phenol) ; and 2,2'-bis(4-dodecyl-6-t-butyl-phenol) . Para-cou pled bisphenols include for example 4,4'- bis(2,6-d i-t- butyl phenol) and 4,4'- methylene-bis(2,6-di-t-butyl phenol) .

Non-phenolic oxidation in hibitors which may be used include aromatic amine antioxidants and these may be used either as such or in com bination with phenolics. Typical examples of non-phenolic antioxidants include: al kylated and non-al kylated aromatic amines such as aromatic monoamines of the formula R ⁸ R ⁹ R ¹⁰ N, where R ⁸ is an aliphatic, aromatic or su bstituted aromatic grou p, R ⁹ is an aromatic or a substituted aromatic grou p, and R ¹⁰ is H, al kyl, aryl or R ⁿ S(0) _x R ¹² , where R ¹¹ is an al kylene, al kenylene, or aral kylene grou p, R ¹² is a higher al kyl grou p, or an al kenyl, aryl, or al karyl grou p, and x is 0, 1 or 2. The aliphatic grou p R ⁸ may contain from 1 to about 20 carbon atoms, and preferably contains from about 6 to 12 carbon atoms. The aliphatic grou p is a satu rated aliphatic grou p. Preferably, both R ⁸ and R ⁹ are aromatic or substituted aromatic groups, and the aromatic group may be a fused ring aromatic grou p such as naphthyl. Aromatic grou ps R ⁸ and R ⁹ may be joined together with other groups such as S. Typical aromatic amines antioxidants have al kyl su bstituent grou ps of at least about 6 carbon atoms. Examples of aliphatic grou ps include hexyl, heptyl, octyl, nonyl, and decyl. General ly, the aliphatic grou ps wil l not contain more than about 14 carbon atoms. The general types of amine antioxidants useful in the present com positions include

diphenylamines, phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of two or more aromatic amines are also usefu l. Polymeric amine antioxidants can also be used. Particular exam ples of aromatic amine antioxidants usefu l in the present invention include:

r,r'-dioctyldiphenylamine; t-octyl phenyl-al pha- naphthylamine; phenyl-al phanaphthylamine; and p-octyl phenyl-al pha-naphthylamine. Sulfu rized al kyl phenols and al kali or al kaline earth metal salts thereof also are useful antioxidants.

Corrosion inhibitors may include various oxygen-, nitrogen-, su lfu r-, and phosphorus- containing materials, and may include metal-containing compou nds (salts, organometal lics, etc.) and non metal-containing or ash less materials. Corrosion in hibitors may include, but are not limited to, additive types such as, for exam ple, hydrocarbyl-, aryl-, al kyl-, arylal kyl-, and al kylaryl- versions of detergents (neutral, overbased) , su lfonates, phenates, salicylates, alcoholates, carboxylates, salixarates, phosphites, phosphates, thiophosphates, amines, amine salts, amine phosphoric acid salts, amine su lfonic acid salts, al koxylated amines, etheramines, polyether-amines, amides, imides, azoles, diazoles, triazoles, benzotriazoles, benzothiadoles, mercapto-benzothiazoles, tolyltriazoles (TTZ-type), heterocyclic amines, heterocyclic su lfides, thiazoles, thiadiazoles, mercaptothiadiazoles, dimercaptothiadiazoles (DMTD-type) , imidazoles, benzimidazoles, dithiobenzimidazoles, imidazolines, oxazolines, Mannich reactions products, glycidyl ethers, an hyd rides, carbamates, thiocarbamates, dithiocarbamates, polyglycols, etc., or mixtu res thereof.

Detergents include cleaning agents that ad here to dirt particles, preventing them from attaching to critical surfaces. Detergents may also ad here to the metal su rface itself to keep it clean and prevent corrosion from occurring. Detergents include calcium al kylsalicylates, calciu m al kyl phe-nates and calciu m al karylsu lfonates with alternate metal ions used such as magnesium, barium, or sodium. Exam ples of the cleaning and dispersing agents which can be used include metal-based detergents such as the neutral and basic al kaline earth metal su l phonates, al kaline earth metal phenates and al kaline earth metal salicylates

al kenylsuccinimide and al kenylsuccinimide esters and their borohydrides, phenates, salienius com plex detergents and ashless dispersing agents which have been modified with su l phu r compounds. These agents can be added and used individually or in the form of mixtu res, conveniently in an amou nt within the range of from > 0.01 to < 1.0 % by weight in relation to the weight of the base stock; these can also be high total base nu mber (TBN) , low TBN, or mixtu res of high/low TBN.

Dispersants are lubricant additives that hel p to prevent sludge, varnish and other deposits from forming on critical surfaces. The dispersant may be a succinimide dispersant (for exam ple

N-su bstituted long chain al kenyl succinimides) , a Mannich dispersant, an ester-containing dispersant, a condensation product of a fatty hydrocarbyl monocarboxylic acylating agent with an amine or ammonia, an alkyl amino phenol dispersant, a hydrocarbyl-amine dispersant, a polyether dispersant or a polyetheramine dispersant. In one embodiment, the succinimide dispersant includes a polyisobutylene-substituted succinimide, wherein the polyisobutylene from which the dispersant is derived may have a number average molecular weight of about 400 to about 5000, or of about 950 to about 1600. In one embodiment, the dispersant includes a borated dispersant. Typically, the borated dispersant includes a succinimide dispersant including a polyisobutylene succinimide, wherein the polyisobutylene from which the dispersant is derived may have a number average molecular weight of about 400 to about 5000. Borated dispersants are described in more detail above within the extreme pressure agent description.

Anti-foam agents may be selected from silicones, polyacrylates, and the like. The amount of anti-foam agent in the lubricant compositions described herein may range from > 0.001 wt.- % to< 0.1 wt.-% based on the total weight of the formulation. As a further example, an anti foam agent may be present in an amount from about 0.004 wt.-% to about 0.008 wt.-%.

Suitable extreme pressure agent is a sulfur-containing compound. In one embodiment, the sulfur-containing compound may be a sulfurised olefin, a polysulfide, or mixtures thereof. Examples of the sulfurised olefin include a sulfurised olefin derived from propylene, iso butylene, pentene; an organic sulfide and/or polysulfide including benzy Idisu Ifide; bis- (chlorobenzyl) disulfide; dibutyl tetrasulfide; di-tertiary butyl polysulfide; and sulfurised methyl ester of oleic acid, a sulfurised al kyl phenol , a sulfurised dipentene, a sulfurised terpene, a sulfurised Diels-Alder adduct, an alkyl sulphenyl N'N- dialkyl dithiocarbamates; or mixtures thereof. In one embodiment, the sulfurised olefin includes a sulfurised olefin derived from propylene, isobutylene, pentene or mixtures thereof. In one embodiment the extreme pressure additive sulfur-containing compound includes a dimercaptothiadiazole or derivative, or mixtures thereof. Examples of the dimercaptothiadiazole include compounds such as 2,5-dimercapto-l,3,4-thiadiazole or a hydrocarbyl-substituted 2,5-dimercapto-l,3,4- thiadiazole, or oligomers thereof. The oligomers of hydrocarbyl-substituted 2,5-dimercapto- 1,3,4-thiadiazole typically form by forming a sulfur-sulfur bond between 2,5-dimercapto- 1,3,4-thiadiazole units to form derivatives or oligomers of two or more of said thiadiazole units. Suitable 2,5-dimercapto-l,3,4-thiadiazole derived compounds include for example

2.5-bis(tert-nonyldithio) -1,3,4-thiadiazole or 2-tert-nonyldithio-5-mercapto-l,3,4-thiadiazole. The number of carbon atoms on the hydrocar-byl substituents of the hydrocarbyl-substituted

2.5-dimercapto-l,3,4-thiadiazole typically include 1 to 30, or 2 to 20, or 3 to 16. Extreme pressure additives include compounds containing boron and/or sulfur and/or phosphorus. The extreme pressure agent may be present in the lubricant compositions at 0 wt.-% to about 20 wt.-%, or at about 0.05 wt.-% to about 10.0 wt.-%, or at about 0.1 wt.-% to about 8 wt.-% of the lubricant composition.

Examples of anti-wear additives include organo borates, organo phosphites such as didodecyl phosphite, organic sulfur-containing compounds such as sulfurized sperm oil or sulfurized terpenes, zinc dialkyl dithiophosphates, zinc diaryl dithiophosphates,

phosphosulfurized hydrocarbons and any combinations thereof. Friction modifiers may include metal-containing com pou nds or materials as wel l as ash less com pou nds or materials, or mixtu res thereof. Metal-containing friction modifiers include metal salts or metal-ligand com plexes where the metals may include al kali, al kaline earth, or transition grou p metals. Such metal-containing friction modifiers may also have low-ash characteristics. Transition metals may include Mo, Sb, Sn, Fe, Cu, Zn, and others. Ligands may include hydrocarbyl derivative of alcohols, polyols, glycerols, partial ester glycerols, thiols, carboxylates, carbamates, thiocarbamates, dithiocarbamates, phosphates,

thiophosphates, dithiophosphates, amides, imides, amines, thiazoles, thiadiazoles, dithiazoles, diazoles, triazoles, and other polar molecu lar functional grou ps containing effective amounts of 0, N, S, or P, individual ly or in combination. I n particu lar, Mo- containing compounds can be particu larly effective such as for example Mo- dithiocarbamates, Mo(DTC) , Mo-dithiophosphates, Mo(DTP) , Mo-amines, Mo (Am) , Mo- alcoholates, Mo- alcohol-amides, and the like.

Ash less friction modifiers may also include lubricant materials that contain effective amou nts of polar groups, for exam ple, hyd roxyl-containing hydrocarbyl base oils, glycerides, partial glycerides, glyceride derivatives, and the like. Polar grou ps in friction modifiers may include hyd rocarbyl grou ps containing effective amounts of 0, N , S, or P, individual ly or in com bination. Other friction modifiers that may be particu larly effective include, for exam ple, salts (both ash-containing and ashless derivatives) of fatty acids, fatty alcohols, fatty amides, fatty esters, hyd roxyl-containing carboxylates, and comparable synthetic long-chain hyd rocarbyl acids, alcohols, amides, esters, hydroxy carboxylates, and the like. I n some instances, fatty organic acids, fatty amines, and su lfurized fatty acids may be used as suitable friction modifiers. Examples of friction modifiers include fatty acid esters and amides, organo molybdenu m compou nds, molybdenu m dial kylthiocarbamates and

molybdenu m dial kyl dithiophosphates.

Suitable metal deactivators include benzotriazoles and derivatives thereof, for exam ple 4- or

5-al kyl benzotriazoles (e.g. triazole) and derivatives thereof, 4,5,6,7-tetrahyd robenzotriazole and 5,5'-methylenebisbenzotriazole; Man nich bases of benzotriazole or triazole, e.g. l- [bis(2- ethyl -hexyl) aminomethyl) triazole and l- [bis(2- ethyl hexyl) aminomethyl) benzotriazole; and al koxyal-kyl benzotriazoles such as l-(nonyloxymethyl) benzotriazole, l-(l-butoxyethyl) benzotriazole and l-(l-cyclohexyloxybutyl) triazole, and combinations thereof. Additional non-limiting examples of the one or more metal deactivators include 1,2,4-triazoles and derivatives thereof, for exam ple 3 -a I ky I (o r a ry I) - 1 , 2,4-triazoles, and Man nich bases of 1,2,4- triazoles, such as l-[bis(2-ethyl h exy I) aminomethyl-1, 2,4-triazole; al koxyal kyl-1, 2,4- triazoles such as l-(l-butoxyethyl) -l, 2,4-triazole; and acylated 3-amino-l, 2,4-triazoles, imidazole derivatives, for exam ple 4,4'-methylenebis(2-u ndecyl-5-methylimidazole) and bis[(N-methyl)imidazol-2-yl]car-binol octyl ether, and com binations thereof. Fu rther non limiting exam ples of the one or more metal deactivators include sulfu r-containing

heterocyclic com pou nds, for exam ple 2-mercapto-benzothiazole, 2,5-dimercapto-l, 3,4-thia- diazole and derivatives thereof; and 3,5- bis [d i (2- ethyl hexyl) aminomethyl] -l, 3,4- thiadiazolin-2-one, and combinations thereof. Even fu rther non-limiting examples of the one or more metal deactivators include amino com pou nds, for exam ple

salicylidenepropylenediamine, salicylami-noguanidine and salts thereof, and combinations thereof. The one or more metal deactivators are not particularly limited in amou nt in the com position but are typical ly present in an amount of from about 0.01 to about 0.1, from about 0.05 to about 0.01, or from about 0.07 to about 0.1, wt.-% based on the weight of the com position. Alternatively, the one or more metal deactivators may be present in amounts of less than about 0.1, of less than about 0.7, or less than about 0.5, wt.-% based on the weight of the composition.

Pour point depressants (PPD) include polymethacrylates, al kylated naphthalene

derivatives, and com binations thereof. Com mon ly used additives such as al kylaromatic polymers and polymethacrylates are also useful for this pu rpose. Typical ly, the treat rates range from > 0.001 wt.-% to < 1.0 wt.-%, in relation to the weight of the base stock.

Demulsifiers include trial kyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtu res thereof.

The invention fu rther relates to a method for reducing friction between moving su rfaces (e.g. metal surfaces) com prising the step of contacting the su rfaces with the lu bricant or with the ethylene copolymer.

The friction may be determined by measu ring the friction coefficient at 25% slide rol l ratio (SRR) using mini-traction machine (MTM) measu rements at 70 ° C and 1 GPa.

The ethylene copolymer according to the invention may be used for many pu rposes in lu bricants, e.g. for increasing the viscosity index of the lu bricant, for thickening of the lu bricant, for im proving the coefficient of friction of the lu bricant, for reducing wear, or as a base stock for the lubricant.

Examples

N BA: N-butyl acrylate,

EHA: 2-Ethyl hexyl acrylate, commercial ly available from BASF SE.

LA: Lau ryl acrylate (60:40 mixtu re of C ₁₂ :C ₁₄ al kyl acrylates)

Preparation of copolymers

I n an autoclave 720 g cyclohexane was initial ly added, and then ethylene (“E”) was fed u nder a pressu re of 60 bar. The mixtu re was heated u nder stirring to 100 ° C and further ethylene were added at a pressure of 100 bar. Feed 1 (26,6 g tert-butyl peroxypivalate and 53 g cyclohexane) and Feed 2 (400 g acrylate and 80 g propionaldehyde) were fed to the reaction mixtu re during two hours. The reaction mixtu re cooled down and the cyclohexane was d esti I led off u nder vacuu m. Detailed reaction conditions are su mmarized in Table 1.

Table 1: Reaction conditions

Characterization of the liquid ethylene copolymers

The molecular weight number distribution Mn and the molecular weight weight distribution Mw were determined via GPC. The polydispersity was calculated as PD = (Mw/M n). The GPC analysis was made with a Rl detector, a PLgel MIXED-B column (column temperature 35 ° C) and THF with 0,1% trifluor acetic acid as elution medium. The calibration was done with very narrow distributed polystyrene standards from the Polymer Laboratories with a molecular weights M = from 580 until 6.870.000 g/mol.

The Cloud Point CP was determined according to ISO 3015. The Pour Point PP was determined according to ASTM D 97.

The results demonstrated that all ethylene copolymers were liquid at room temperature and had a pour point below 25 ° C.

The results further indicate that all ethylene copolymers tend to have good low temperature characteristics.

The amounts of monomomers which are present in polymerized form in the polymer was determined by H-NMR and shown in Table 2.

Table 2: Analytical data of copolymers

Viscosity and appearance of the liquid ethylene copolymers

The Kinematic Viscosity at 40° C (V40) and at 100 ° C (V100) were determined according to ASTM D 445 . The Viscosity Index (VI) was determined according to ASTM D 2270.

The results demonstrated that the ethylene copolymers have a desired high kinematic viscosity, as well as a desired high viscosity index.

Table 3: Viscosity data

Miscibility with polyalphaolefins

The liquid ethylene copolymers were mixed with polyalphaolefine having a kinematic viscosity at 100 ° C of about 6 cSt in a weight ratio of 50:50 at room temperature and mixed at room temperature by rolling for 12 hours. The mixtures' appearance was observed after homogenization and again after 24 hours. The copolymer is deemed compatible with the polyalphaolefine when no phase separation was observed after 24 hours.

The results demonstrated that the ethylene copolymers are miscible with very unpolar low viscosity polyalphaolefines (typically based on poly(l-decen)).

Table 4: Miscibility with PAO-6 (50:50 vol%)