Field oflnvention
[1] This invention relates to a lubricant composition comprising a copolymer,
a method for its production and its uses.
Technical Background
[2] One of the primary function of lubricants is to decrease friction.
Frequently, however, lubricating oils need additional properties to be used effectively. For example, lubricants used in large diesel engines, such as, for example, marine diesel engines, are often subjected to operating conditions requiring special considerations.
[3] Two-stroke marine engines are of crosshead design also named slow-speed engines, they are used for the largest, deep ocean going vessels and certain other industrial applications. Two-stroke Slow-speed engines are unique in size and method of operation. The output of these engines can be as high as 100,000 horsepower (84MW) with engine revolutions of 80 to about 200 revolutions per minute (rpm). Two-stroke Slow-speed marine engines have a high to very high power range (600 to 6000 kW per cylinder). These engines always consist of two separately lubricated parts, namely the piston/cylinder assembly lubricated with a highly viscous cylinder oil, generally of SAE 50 or 60 grade, and the crankshaft, crossheads, conrods, lubricated by a less viscous system oil, generally of SAE 30 grade. [4] The cylinders are lubricated on a total loss basis with the cylinder oil being injected separately into each cylinder by means of lubricators positioned around the cylinder liner. Oil is distributed to the lubricators by means of pumps, which are, in modern engine designs, actuated to apply the oil directly onto the rings to reduce oil wastage. The unique design of these engines creates the need for lubricants with enhanced rheological properties. Accordingly, lubricants used in a marine engine must protect the engine parts from corrosion which can reduce engine efficiency and lifetime. Also, the residual fuels commonly used in these diesel engines typically contain significant quantities of sulfur. During the combustion process, the sulfur oxide can combine with water to form sulfuric acid, the presence of which leads to corrosive wear. In particular, areas around the cylinder liners and piston rings can be corroded and worn by the acid. Therefore, it is important for marine engine to resist such corrosion and wear by being properly lubricated.

[5] To prevent corrosion, the lubricant is applied to the cylinder wall, typically
by a pulse lubricating system or by spraying the lubricant onto the piston's rings pack through an injector. The lubrication in a two-stroke marine engine differs significantly from any other type of engine. A defined volume per x stroke of lubricant is injected or sprayed on the piston's rings pack and spread most of the time horizontally by the sprayer or injector and also spread vertically by the piston rings when the piston is in its upward motion onto the cylinder liner.
[6] However, it has been seen that said system may not guarantee accessibility
of the lubricant over the entire cylinder liner surface because the lubricant is not
sufficiently well spread on the liner surface after its delivery. Further, the use of said
system for spraying lubricant over the liner surface underlines that although the
lubricant is not well spread, the property of well self-spreading of the lubricant is not
sufficient, This induces a large efficiency drop of the lubrication process and an
increase the corrosion of the corrosion process in marine engines.
[7] Thus, there is a need for a lubricant additive that will provide effective
corrosion resistance. Additionally, there is a need for a lubricant additive that will provide any rheology improvements, notably spreading and self-spreading rheology, in order to enhance lubricating efficacy and reduce the corrosion. The term "spreading rheology property" of the lubricant means the rheological property of the lubricant after its spreading on the cylinder liner surface.
SUMMARY
[8] We have found new copolymers that can modify the rheology, notably the
spreading and self-spreading rheology, of a marine lubricant to provide enhanced lubrication properties. In particular, marine engine lubricating oils comprising the copolymers of the disclosure as an additive, surprisingly allows increasing the spreading of the lubricant and its self-spreading on the liner surface after its delivery with respect to prior art oils, thereby leading to better lubrication and less engine cylinder wear and corrosion. It has been also shown that marine engine lubricating oils comprising the copolymers of the disclosure as an additive surprisingly allows increasing of the self-spreading of the lubricant on the liner surface.

[9] In a first aspect, the present disclosure provides the use of a lubricant
composition comprising a base oil and a copolymer of alkyl methacrylate monomers, wherein said alkyl methacrylate monomers comprise at least:
a. Monomers (A) selected from C6-C10 alkyl methacrylate monomers,
b. Monomers (B) selected from C10-C18 alkyl methacrylate monomers,
for increasing the spreading of the lubricant on the surface liner after its delivery.
[10] According to a favourite embodiment, monomers (B) comprise at least one
C12 alkyl methacrylate monomer.
[11] In a second aspect, the present disclosure provides the use of a lubricant
composition comprising a copolymer obtained by combining alkyl methacrylate monomers, wherein said alkyl methacrylate monomers comprise at least:
a. Monomers (A) selected from C6-C10 alkyl methacrylate monomers,
b. Monomers (B) selected from C10-C18 alkyl methacrylate monomers,
and a base oil,
for increasing the spreading of the lubricant on the surface liner after its delivery.
[12] According to a favourite embodiment, monomers (B) comprise at least one
C12 alkyl methacrylate monomer.
[13] Alternately, the present disclosure provides a method for increasing the
spreading of the lubricant on the surface liner after its delivery said method
comprising formulating the marine lubricant according to the first and the second
aspects. v
[14] In a third aspect, the present disclosure provides the use of a lubricant of
the first aspect and the second aspects for increasing the self-spreading of the lubricant on the liner surface after its delivery.
[15] Alternately, the present disclosure provides a method for increasing the
self-spreading of the lubricant on the surface liner after its delivery said method comprising formulating the marine lubricant according to the first and the second aspects.
[16] In a fourth aspect, the present disclosure provides the use of a lubricant of
the first aspect and the second aspects for increasing the spreading and the self-spreading of the lubricant on the liner surface after its delivery.
[17] Alternately, the present disclosure provides a method for increasing the
spreading and self-spreading of the lubricant on the surface liner after its delivery said

method comprising formulating the lubricant according to the first and the second
aspects.
[18] All publications referenced herein are incorporated by reference in their
entirety to the extent they are not inconsistent with the teachings presented herein.
DETAILED DESCRIPTION
[19] In the first aspect, the present disclosure provides the use of a lubricant
composition comprising a base oil and a copolymer of alkyl methacrylate monomers, wherein said alkyl methacrylate monomers comprise at least:
a. Monomers (A) selected from C6-C10 alkyl methacrylate monomers,
b. Monomers (B) selected from C10-C18 alkyl methacrylate monomers,
for increasing the spreading of the lubricant on the surface liner after its delivery.
Monomers (A) and (B) can be linear or branched.
[20] The copolymer used in the lubricant composition according to the
invention is prepared from a mixture of monomers that comprises at least two
monomers: one monomer (A) and one monomer (B), distinct from one another.
[21] According to a favourite embodiment, monomers (B) comprise at least one
C12 alkyl methacrylate monomer.
[22] Preferably, monomers (B) comprise 50 to 80% by weight of CI 2 alkyl
methacrylate as compared to the total weight of monomers (B), even more preferably
55 to 70% by weight.
[23] Advantageously, monomers (B) further comprise at least one C14 alkyl
methacrylate monomer.
[24] Preferably, monomers (B) comprise 15 to 40% by weight of C14 alkyl
methacrylate as compared to the total weight of monomers (B), even more preferably
20 to 30% by weight.
[25] Such copolymers can comprise units derived from other monomers. Other
monomers can be selected for example from C1-C5 alkyl methacrylates and C16-C24
alkyl methacrylates, cross-linking monomers, C1-C24 alkyl acrylates, styrene...
[26] Preferably, monomers (A) selected from C6-C10 alkyl methacrylate
monomers, and monomers (B) selected from CI 0-C 18 alkyl methacrylate monomers
represent at least 75% by weight of the total weight of monomers used to prepare the
copolymer, advantageously they represent at least 90%, even more preferably at least
95 %, or better 99% by weight.

[27] Preferably, the weight ratio of monomers (B) to monomers (A) in the
copolymer is about 99:1 to about 10:90.
[28] Advantageously, monomers (A) comprise at least 50% by weight of C8
alkyl methacrylate, as compared to the total weight of monomers (A), even more
preferably at least 75% by weight, even better at least 90% by weight, and even more
advantageously at least 99% by weight.
[29] According to a favourite variant, monomers (A) are branched, like for
example 2-ethyl hexyl methacrylate, isodecylmethacrylate.
[30] Advantageously, monomers (B) comprise a mixture of at least C10 alkyl
methacrylate, C12 alkyl methacrylate, C14 alkyl methacrylate, C16 alkyl methacrylate
and CI 8 alkyl methacrylate.
[31] More advantageously, monomers (B) comprise a mixture of at least:
- 0.1 to 2% by weight of C10 alkyl methacrylate as compared to the total weight of monomers (B),
- 50 to 80% by weight of C12 alkyl methacrylate as compared to the total weight of monomers (B),
- 15 to 40% by weight of C14 alkyl methacrylate as compared to the total weight of monomers (B),
- 2 to 12% by weight of C16 alkyl methacrylate as compared to the total weight of monomers (B) and
- 0.1 to 1% by weight of C18 alkyl methacrylate as compared to the total weight of monomers (B).
[32] Particularly, monomers (B) comprise a mixture of at least:
- 1 to 2% by weight of C10 alkyl methacrylate as compared to the total weight of monomers (B),
- 55 to 70% by weight of C12 alkyl methacrylate as compared to the total weight of monomers (B),
- 20 to 30% by weight of C14 alkyl methacrylate as compared to the total weight of monomers (B),
- 4 to 10% by weight of CI6 alkyl methacrylate as compared to the total weight of monomers (B) and
- 0.1 to 0.5%o by weight of CI 8 alkyl methacrylate as compared to the total weight of monomers (B).

[33] According to a favourite variant, monomers (B) are linear, like for example
n-ClO-aikyl methacrylate, n-Cll-alkyl methacrylate, lauryl methacrylate (n-C12-alkym methacrylate), n-C13-alkyl methacrylate, myristyl methacrylate (n-C14-alkyl methacrylate), n-C15-alkyl methacrylate, n-C16-alkyl methacrylate, n-C17-alkyl methacrylate, n-C18-alkyl methacrylate.
[34] The ratio of monomers in all aspects of the disclosure can be adjusted to
manipulate the characteristics of the copolymer as desired. For example, the
monomers can be present in ratios of C10-C18-alkyl methacrylate to C6-C10-alkyl
methacrylate of 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45,
60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5, and 99:1. Notably, the
monomers can be present in ratios of C10-Cl8-alkyl methacrylate to C8-alkyl
methacrylate of 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45,
60:40, 65:35, 70:30,75:25, 80:20, 85:15, 90:10, 95:5, and 99:1.
[35] In some embodiments of all aspects of the disclosure, the C8 alkyl
methacrylate is linear or branched C8 alkyl. In some favourite embodiments, the C8 alkyl methacrylate is 2-ethylhexyl methacrylate.
[36] According to an even more favourite embodiment, the copolymer is a
copolymer of 2-ethyl hexyl methacrylate and a mixture of monomers comprising C10 alkyl methacrylate, C12 alkyl methacrylate, C14 alkyl methacrylate, C16 alkyl methacrylate and C18 alkyl methacrylate.
[37] According to another favourite embodiment, the copolymer is a copolymer
of a mixture of monomers comprising C10 alkyl methacrylate, C12 alkyl methacrylate, C14 alkyl methacrylate, C16 alkyl methacrylate and C18 alkyl methacrylate and a C8 alkyl methacrylate, wherein the mass ratio of the mixture in the copolymer to C8 alkyl methacrylate monomers in the copolymer is about 99:1 to about 10:90 by weight.
[38] According to another favourite embodiment, the copolymer is a copolymer
of a mixture of monomers comprising at least, or even more preferably consisting of: a C8 alkyl methacrylate, a C12 alkyl methacrylate, a C14 alkyl methacrylate, and a CI6 alkyl methacrylate, and they are present in the mixture in weight ratio of:
- from 5 to 30 % C8 alkyl methacrylate,
- from 40 to 70 % C12 alkyl methacrylate,
- from 12 to 35 % C14 alkyl methacrylate,

- from 1 to 12 % C16 alkyl methacrylate,
- from 0.1 to 15 %, preferably from 0.5 to 10 %, even more preferably from 1 to 5 % other methacryiates,
by weight with regards to the total weight of the mixture.
[39] Typically, copolymers according to the disclosure have an average Root
Mean Square Radius of Gyration (Rg) as measured by Hydrodynamic Column
Chromatography-Multi Angle Light Scattering (HCC-MALS) from about 100 to
about 200 (run) Rg, from about 120 to about 190 (nm), from about 130 to 180, or from
about 140 to about 170 (run) Rg.
[40] In the second aspect, the present disclosure provides a lubricant
composition comprising a copolymer obtained by combining and polymerizing alkyl
methacrylate monomers, wherein said alkyl methacrylate monomers comprise at least:
a. Monomers (A) selected from C6-C10 alkyl methacrylate monomers,
b. Monomers (B) selected from C10-C18 alkyl methacrylate monomers,
for increasing the spreading of the lubricant on the surface liner after its delivery.
[41] Favourite embodiments according to the second aspect are identical to
those disclosed above for the first aspect.
[42] The copolymer may be synthesized by conventional methods for vinyl
addition polymerization known to those skilled in the art, such as, but not limited to,
solution polymerization, precipitation polymerization, and dispersion polymerizations,
including suspension polymerization and emulsion polymerization.
[43] In some embodiments, the polymer is formed by suspension
polymerization, wherein monomers that are insoluble in water or poorly soluble in water are suspended as droplets in water. The monomer droplet suspension is maintained by mechanical agitation and the addition of stabilizers. Surface active polymers such as cellulose ethers, poly(vinyl alcohol-co-vinyl acetate), polyvinyl pyrrolidone) and alkali metal salts of (meth)acrylic acid containing polymers and colloidal (water insoluble) inorganic powders such as tricalcium phosphate, hydroxyapatite, barium sulfate, kaolin, and magnesium silicates can be used as stabilizers. In addition, small amounts of surfactants such as sodium dodecylbenzene sulfonate can be used together with the stabilizer(s). Polymerization is initiated using an oil soluble initiator. Suitable initiators include peroxides such as benzoyl peroxide, peroxy esters such as tert-butylperoxy-2-ethylhexanoate, and azo compounds such as

2,2'-azobis(2-methylbutyronitrile). At the completion of the polymerization, solid
polymer product can be separated from the reaction medium by filtration and washed
with water, acid, base, or solvent to remove unreacted monomer or free stabilizer.
[44] In other embodiments the polymer is formed by emulsion polymerization,
one or more monomers are dispersed in an aqueous phase and polymerization is
initiated using a water soluble initiator. The monomers are typically water insoluble or
very poorly soluble in water, and a surfactant or soap is used to stabilize the monomer
droplets in the aqueous phase. Polymerization occurs in the swollen micelles and latex
particles. Other ingredients that might be present in an emulsion polymerization
include chain transfer agents such as mercaptans (e.g. dodecyl mercaptan) to control
molecular weight, electrolytes to control pH, and small amounts of organic solvent,
preferably water soluble organic solvents, including but not limited acetone, 2-
butanone, methanol, ethanol, and isopropanol, to adjust the polarity of the aqueous
phase. Suitable initiators include alkali metal or ammonium salts of persulfate such as
ammonium persulfate, water-soluble azo compounds such as 2,2'-azobis(2-
aminopropane)dihydrochloride, and redox systems such as Fe(ll) and cumene
hydroperoxide, and tert-butyl hydroperoxide-Fe(II)-sodium ascorbatc. Suitable
surfactants include anionic surfactants such as fatty acid soaps (e.g. sodium or
potassium stearate), sulfates and sulfonates (e.g. sodium dodecyl 20 benzene
sulfonate), sulfosuccinates (e.g. dioctyl sodium sulfosuccinate); non-ionic surfactants
such as octylphenol ethoxylates and linear and branched alcohol ethoxylates; cationic
surfactants such as cetyl trimethyl ammonium chloride; and amphoteric surfactants.
Anionic surfactants and combinations of anionic surfactants and non-ionic surfactants
are most commonly used. Polymeric stabilizers such as poly(vinyl alcohol-co-vinyl
acetate) can also be used as surfactants. The solid polymer product free of the aqueous
medium can be obtained by a number of processes including
destabilization/coagulation of the final emulsion followed by filtration, solvent
precipitation of the polymer from latex, or spray drying of the latex.
[45] The polymer can be isolated by conventional methods known to those
skilled in the art, such as, but not limited to, solvent exchange, evaporation of solvent, spray drying and freeze-drying.
[46] The characteristics of the copolymer obtained by combining alkyl
methacrylate monomers, wherein said alkyl methacrylate monomers comprise at least:

a. Monomers (A) selected from C6-C10 alkyl methacrylate monomers,
b. Monomers (B) selected from C10-C18 alkyl methacrylate monomers,
in a mixture and co-polymerizing can be manipulated by controlling the additional
reagents added to the polymerization mixture. These reagents include, but are not limited to, initiator systems and surfactants.
[47] The type and amount of initiator system used in the polymerization
mixture can influence the properties of the resulting copolymer. An initiator system can be a single initiator compound (e.g., a persulfate salt) or a mixture of two or more components (e.g., hydrogen peroxide and sodium ascorbate). In some examples, the initiator system can include an oxidant, a reductant, and optionally a metal salt. The oxidant can be a persulfate, such as, for example, ammonium persulfate, or a peroxide, such as, for example, hydrogen peroxide (H2O2) or tert-butyl hydroperoxide (TBHP). A desirable copolymer may be obtained, for example, when the polymerization mixture includes tert-butyl hydroperoxide in about 0.01 to about 0.06 mass percent of all monomers in the mixture. In other examples, the mixture may include tert-butyl hydroperoxide in about 0.01 to about 0.03 mass percent of the monomers in the mixture. In some examples, the mixture further comprises tert-butyl hydroperoxide in about 0.013 mass percent of the monomers in the mixture. Useful initiators for the copolymers of the present disclosure include any conventional initiator, including any conventional redox initiator,
[48] In some embodiments the reductant of the redox initiator system can be
ascorbic acid or a salt thereof. For example, the polymerization mixture can include sodium ascorbate in about 0.04 to about 0.1 mass percent of the monomers in the mixture. In other examples, the sodium ascorbate may be present in about 0.08 to about 0.1 mass percent of the monomers in the mixture. In some embodiments, the polymerization mixture includes sodium ascorbate in about 0.098 mass percent of the monomers in the mixture.
[49] The initiator system may also include a metal salt. The metal may be any
suitable transition metal, such as, for example, iron. In some embodiments, the metal salt of the initiator system can be ferrous sulfate (FeS04). In some embodiments, the metal salt is present in the polymerization mixture in about 0.0005 to about 0.1 mass percent of the monomers in the mixture. In some examples, the metal salt is added to the polymerization mixture as a solution.

[50] The copolymer may also be under the fonn of a mixture further including a
surfactant. In some embodiments, the surfactant may contain a sulfonate group. For example, the surfactant may include a dialkyl sulfosuccinate, such as, for example, dioctyl sulfosuccinate sodium salt. In some examples, the surfactant may be Aerosol® OT.
[51] The copolymer can be a random copolymer, a block copolymer, or mixture
thereof. In some embodiments, the copolymer is a substantially random copolymer (e.g., greater than 90, 95, 98, or 99 mass percent). In other examples, the copolymer is partially a random copolymer and partially a block copolymer. In these examples the weight percent ratio of random copolymer to block copolymer is generally 90:10, 80:20, 70: 30, 60:40, 50:50, 40:60, 30:70, 20:80 or 10:90. The copolymer may also be a substantially block copolymer (e.g., greater than 90, 95,98, or 99 weight percent). In other examples, the copolymer can contain additional monomers in addition to the monomers (A) selected from C6-C10 alkyl methacrylate monomers, and monomers (B) selected from C1Q-C18 alkyl methacrylate monomers. These additional monomers can be present in an amount less than 25 weight percent, preferably less than 10 weight percent. In some embodiments, the additional monomers are present in an amount from about 0.5 to 10 weight percent, or about 1 to 10 weight percent or about 1 to 5 weight percent or about 5 to 10 weight percent. In other embodiments, the additional monomers are present in an amount less than about 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 or about 0.5 weight percent. The additional monomers can include, for example, Cl-C5 alkyl methacrylates and C16-C24 alkyl methacrylates, cross-linking monomers, C1-C24 alkyl acrylates, styrene, and other similar monomers.
[52] The copolymer may also be crosslinked. That is, the copolymer can
contain monomeric units that connect one or more of the backbone chains of the polymer. In some examples, the copolymer contains crosslinked monomeric units present in up to about 5% by weight of the copolymer.
[53] The crosslinked copolymer may be obtained by the addition of a
crosslinking agent. In some embodiments, the crosslinking agent is a diacrylate or dimethacrylate crosslinking agent, such as, for example, 1,6-hexanediol dimethacrylate. In some examples, the mixture includes a crosslinking agent in up to about 0.005 mass percent of the monomers in the mixture.

[54] Example copolymers are shown in Table 1. For each example, Table 1
shows the ratio of the mixture of methacrylate monomer (e.g. a mixture of monomers comprising CIO alkyl methacrylate, C12 alkyl methacrylate, C14 alkyl methacrylate, CI6 alkyl methacrylate and C18 alkyl methacrylate) to C8 alkyl methacrylate monomer (e.g., 2-ethylhexyl methacrylate), the amount of acetone, the components of the redox initiator system, the surfactant used, the molecular weight, Rg and viscosity of each example copolymer.
[55] For example, a method of making a copolymer as described above is
disclosed. The method includes the polymerization of monomers (A) selected from C6-C10 alkyl methacrylate monomers, and monomers (B) selected from C10-C18 alkyl methacrylate monomers, advantageously polymerization of a mixture of monomers comprising CIO alkyl methacrylate, CI2 alkyl methacrylate, C14 alkyl methacrylate, C16 alkyl methacrylate and C18 alkyl methacrylate, and a C8 alkyl methacrylate monomer, wherein the mass ratio of monomers (B) to monomers (A) in the copolymer is about 99:1 to about 10:90 by weight (e.g., 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15,90:10,95:5,99:1).
[56] The method includes: combining monomers (A) selected from C6-C10
alkyl methacrylate monomers, and monomers (B) selected from C10-C18 alkyl methacrylate monomers, advantageously combining a mixture of monomers comprising C10 alkyl methacrylate, C12 alkyl methacrylate, C14 alkyl methacrylate, C16 alkyl methacrylate and CI 8 alkyl methacrylate, and C8 alkyl methacrylate monomers in a ratio of about 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10,95:5, 99:1 and initiating the polymerization of the monomers to provide a copolymer.
[57] For example, the ratio of monomers and the initiator, or initiator system,
can be selected as described above. The method may include further components to provide a copolymer with desirable properties. For example, the method may also include a surfactant, such as, for example, Aerosol® OT, or a crosslinker, such as, for example, 1,6-hexanediol dimethacrylate.
[58] Polymerization can occur in an aqueous mixture or a mixture that
comprises both aqueous and organic solvents. For example, the polymerization mixture can include a mixture of water and acetone. In some embodiments the

polymerization mixture may require an organic solvent. Often it will be desirable to include an organic solvent when C10-C18 alkyl methacrylates are in the polymerization mixture. Organic solvents for use in such polymerization reactions are known and routinely selectable by those of ordinary skill in the field of polymer synthesis. Suitable organic solvents include, for example and without limitation, acetone, 2-butanone, methanol, ethanol, and isopropanol.
[59] According to the first and the second aspects of the present invention, the
quantity of copolymer in the lubricant composition of the invention is from 0.01% to
10% by weight relative to the total weight of the lubricant composition, preferably
from 0.01% to 5%, more preferably from 0.01% to 4%, further preferably from 0.01%
to 3%. This quantity is to be construed as quantity of polymer dry matter. The
copolymer used in the present invention is sometimes contained in dilution in a
synthetic or mineral oil (most often a Group 1 oil according to the API classification).
[60] Generally, the oils also called "base oils" used for formulating lubricant
composition according to the present invention may be oils of mineral, synthetic or plant origin as well as their mixtures. The mineral or synthetic oils generally used in the application belong to one of the classes defined in the API classification as summarized below:
[61] These mineral oils of Group 1 may be obtained by distillation of selected
naphthenic or paraffinic crude oils followed by purification of these distillates by methods such as solvent extraction, solvent or catalytic dewaxing, hydrotreating or hydrogenation.

[62] The oils of Groups 2 and 3 are obtained by more severe purification
methods, for example a combination of hydrotreating, hydrocracking, hydrogenation and catalytic dewaxing.Examples of synthetic bases of Groups 4 and 5 include poly-alpha olefins, polybutenes, polyisobutenes, alkylbeivzenes.
[63] These base oils may be used alone or as a mixture. A mineral oil may be
combined with a synthetic oil.
[64] The lubricant compositions of the invention have a viscosity grade of S AE-
20, SAE-30, SAE-40, SAE-50 or SAE-60 according to the SAEJ300 classification.
Grade 20 oils have a kinematic viscosity at 100° C. of between 5.6 and 9.3 mm /s.
Grade 30 oils have a kinematic viscosity at 100° C of between 9.3 and 12.5 mm2/s.
Grade 40 oils have a kinematic viscosity at 100° C- of between 12.5 and 16.3 mm2/s.
Grade 50 oils have a kinematic viscosity at 100° C- of between 16.3 and 21.9 mm2/s.
Grade 60 oils have a kinematic viscosity at 100° C. of between 21.9 and 26.1 mm2/s.
[65] Preferably, the lubricant composition according to the first aspect and the
second aspect is a cylinder lubricant.
[66] The cylinder oils for two-stroke diesel marine engines have a viscosimetric
grade SAE-40 to SAE-60, generally preferentially SAE-50 equivalent to a kinematic viscosity at 100° C comprised between 16.3 and 21.9 mm2/s. Typically, a conventional formulation of cylinder lubricant for two-stroke marine diesel engines is of grade SAE 40 to SAE 60, preferentially SAE 50 (according to the SAE J300 classification) and comprises at least 50% by weight of a lubricating base oil of mineral and/or synthetic origin, adapted to the use in a marine engine, for example of the API Group 1 class. Their viscosity index (VI) is comprised between 80 and 120; their sulfur content is greater than 0.03% and their saturated substance content is less than 90%.
[67] The system oils for two-stroke diesel marine engines have a viscosimetric
grade SAE-20 to SAE-40, generally preferentially SAE-30 equivalent to a kinematic viscosity at 100° C comprised between 9.3 and 12.5 mm2/s.
[68] These viscosities may be obtained by mixing additives and base oils for
example containing mineral bases of Group 1 such as Neutral Solvent (for example 150 NS, 500 NS or 600 NS) bases and brightstock. Any other combination of mineral, synthetic bases or bases of plant origin, having, as a mixture with the additives, a viscosity compatible with the chosen SAE grade, may be used.

[69] The quantity of base oil in the lubricant composition of the invention is
from 30% to 90% by weight relative to the total weight of the lubricant composition,
preferably from 40% to 90%, more preferably from 50% to 90%.
[70] In one embodiment of the invention, the lubricant composition has a Base
Number (BN) determined according to the standard ASTM D-2896 of at most 50, preferably at most 40, advantageously at most 30 milligrams of potassium hydroxide per gram of the lubricating composition, in particular ranging from 10 to 40, preferably 15 to 40 milligrams of potassium hydroxide per gram of the lubricant composition.
[71] In another embodiment of the invention, the lubricant composition has a
BN determined according to the standard ASTM D-2896 of at least 50, preferably at
least 60, more preferably at least 70, advantageously 70 to 100.
[72] It is optionally possible to substitute the above-described base oils in full or
in part by one or more thickening additives whose role is to increase both the hot and cold viscosity of the composition, or by additives improving the viscosity index (VI). The lubricant composition of the invention may comprise at least one optional additive, chosen in particular from among those frequently used by persons skilled in the art.
[73] In one embodiment, the lubricant of the first aspect and the second aspect
further comprises an optional additive chosen amongst a neutral detergent, an
overbased detergent, an anti-wear additive, an oil soluble fatty amine, a polymer, a
dispersing additive,, an anti-foaming additive or a mixture thereof.
[74] Detergents are typically anionic compounds containing a long lipophilic
hydrocarbon chain and a hydrophilic head, wherein the associated cation is typically a metal cation of an alkali metal or alkaline earth metal. The detergents are preferably selected from alkali metal salts or alkaline earth metal (particularly preferably calcium, magnesium, sodium or barium) salts of carboxylic acids, sulphonates, salicylates, naphthenates, as well as the salts of phenates. These metal salts may contain the metal in an approximately stoichiometric amount relative to the anion group(s) of the detergent. In this case, one refers to non-overbased or "neutral" detergents, although they also contribute to a certain basicity. These "neutral" detergents typically have a BN measured according to ASTM D2896, of less than 150 mg KOH/g, or less than 100 mg KOH/g, or less than 80 mg KOH/g of detergent. This

type of so-called neutral detergent may contribute in part to the BN of lubricating
compositions. For example, neutral detergents are used such as carboxylates,
sulphonates, salicylates, phenates, naphthenates of the alkali and alkaline earth metals,
for example calcium, sodium, magnesium, barium. When the metal is in excess
(amount greater than the stoichiometric amount relative to the anion groups(s) of the
detergent), then these are so-called overbased detergents. Their BN is high, higher
than 150 mg KOH/g of detergent, typically from 200 to 700 mg KOH/g of detergent,
preferably from 250 to 450 mg KOH/g of detergent. The metal in excess providing the
character of an overbased detergent is in the form of insoluble metal salts in oil, for
example carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate. In
one overbased detergent, the metals of these insoluble salts may be the same as, or
different from, those of the oil soluble detergents. They arc preferably selected from
calcium, magnesium, sodium or barium. The overbased detergents are thus in the form
of micelles composed of insoluble metal salts that are maintained in suspension in the
lubricating composition by the detergents in the form of soluble metal salts in the oil.
These micelles may contain one or more types of insoluble metal salts, stabilised by
one or more types of detergent. The overbased detergents comprising a single type of
detergent-soluble metal salt are generally named according to the nature of the
hydrophobic chain of the latter detergent. Thus, they will be called a phenate,
salicylate, sulphonate, naphthenate type when the detergent is respectively a phenate,
salicylate, sulphonate or naphthenate. The overbased detergents are called mixed type
if the micelles comprise several types of detergents, which are different from one
another by the nature of their hydrophobic chain. The overbased detergent and the
neutral detergent may be selected from carboxylates, sulphonates, salicylates,
naphthenates, phenates and mixed detergents combining at least two of these types of
detergents. The overbased detergent and the neutral detergent include compounds
based on metals selected from calcium, magnesium, sodium or barium, preferably
calcium or magnesium. The overbased detergent may be overbased by metal insoluble
salts selected from the group of carbonates of alkali and alkaline earth metals,
preferably calcium carbonate. The lubricating composition may comprise at least one
overbased detergent and at least a neutral detergent as defined above.
[75] Polymers are typically polymers having a low molecular weight of from
2000 to 50 000 dalton (Mn). The polymers are selected amongst PIB (of from 2000

Dalton), polyacrylates or polymetacrylates (of from 30 000 Dalton), distinct from the copolymer based on monomers A and B, olefin copolymers, olefin and alpha-olefm copolymers, EPDM, polybutenes, poly alpha-olefin having a high molecular weight (viscosity 100°C > 150), hydrogenated or non-hydrogenated styrene-olefin copolymers.
[76] Anti-wear additives protect the surfaces from friction by forming a
protective film adsorbed on these surfaces. The most commonly used is zinc dithiophosphate or DTPZn. Also in this category, there are various phosphorus, sulphur, nitrogen, chlorine and boron compounds. There are a wide variety of anti-wear additives, but the most widely used category is that of the sulphur phospho additives such as metal alkylthiophosphates, especially zinc aikylthiophosphates, more specifically, zinc dialkyl dithiophosphates or DTPZn. The preferred compounds are those of the formula Zn((SP(S)(ORi)(OR2))2, wherein Rj and R2 are alkyl groups, preferably having 1 to 18 carbon atoms. The DTPZn is typically present at levels of about 0.1 to 2% by weight relative to the total weight of the lubricating composition. The amine phosphates, polysulphides, including sulphurised olefins, are also widely used anti-wear additives. One also optionally finds nitrogen and sulphur type anti-wear and extreme pressure additives in lubricating compositions, such as, for example, metal dithiocarbamates, particularly molybdenum dithiocarbamate. Glycerol esters are also anti-wear additives. Mention may be made of mono-, di- and trioleates, monopalmitates and monomyristates. In one embodiment, the content of anti-wear additives ranges from 0.01 to 6%, preferably from 0.1 to 4% by weight relative to the total weight of the lubricating composition.
[77] Dispersants are well known additives used in the formulation of lubricating
compositions, in particular for application in the marine field. Their primary role is to maintain in suspension the particles that are initially present or appear in the lubricant during its use in the engine. They prevent their agglomeration by playing on steric hindrance. They may also have a synergistic effect on neutralisation. Dispersants used as lubricant additives typically contain a polar group, associated with a relatively long hydrocarbon chain, generally containing 50 to 400 carbon atoms. The polar group typically contains at least one nitrogen, oxygen, or phosphorus clement. Compounds derived from succinic acid are particularly useful as dispersants in lubricating additives. Also used are, in particular, succinimides obtained by condensation of

succinic anhydrides and amines, succinic esters obtained by condensation of succinic
anhydrides and alcohols or polyols. These compounds can then be treated with
various compounds including sulphur, oxygen, formaldehyde, carboxylic acids and
boron-containing compounds or zinc in order to produce, for example, borated
succinimides or zinc-blocked succinimides. Mannich bases, obtained by
polycondensation of phenols substituted with alkyl groups, formaldehyde and primary
or secondary amines, are also compounds that are used as dispersants in lubricants. In
one embodiment of the invention, the dispersant content may be greater than or equal
to 0.1%, preferably 0.5 to 2%, advantageously from I to 1.5% by weight relative to
the total weight of the lubricating composition. It is possible to use a dispersant from
the PIB succinimide family, e.g. boronated or zinc-blocked.
[78] Other optional additives may be chosen from defoamers, for example,
polar polymers such as polydimethylsiloxanes, polyacrylates. They may also be
chosen from antioxidant and/or anti-rust additives, for example organometallic
detergents or thiadiazoles. These additives are known to persons skilled in the art.
These additives are generally present in a weight content of 0.1 to 5% based on the
total weight of the lubricating composition.
[79] In one embodiment, the lubricant composition according to the invention
may further comprise an oil soluble fatty amine.
[80] The fatty amine is of a general formula (1):
R1-[(NR2)-R3]J1-NR4R5, (I)
wherein,
• Ri represents a saturated or unsaturated, linear or branched, hydrocarbon group comprising at least 12 carbon atoms, and optionally at least one heteroatom chosen amongst nitrogen, sulfur or oxygen,
• R2, R4 and R5 represent independently a hydrogen atom or a saturated or unsaturated, linear or branched, hydrocarbon group comprising optionally at least one heteroatom chosen amongst nitrogen, sulfur or oxygen,
• R3 represents a saturated or unsaturated, linear or branched, hydrocarbon group comprising at least 1 carbon atom, and optionally at least one heteroatom chosen amongst nitrogen, sulfur or oxygen, preferably oxygen,

• n is an integer, n is superior or equal to 1, preferably comprised
between 1 and 10, more preferably between 1 and 6, notably chosen
amongst 1,2 or 3.
[81] Preferably, the fatty amine is of a general formula (I), wherein:
• Ri represents a saturated or unsaturated, linear or branched, hydrocarbon group comprising between 12 and 22 carbon atoms, preferably between 14 and 22 carbon atoms, and optionally at least one heteroatom chosen amongst nitrogen, sulfur or oxygen, and/or
• R2, R4 and R5 represent independently a hydrogen atom; a saturated or unsaturated, linear or branched, hydrocarbon group comprising between 12 and 22 carbon atoms, preferably between 14 and 22 carbon atoms, more preferably between 16 and 22 carbon atoms; a (R^-O^-H group wherein R^ represents a saturated, linear or branched, hydrocarbon group comprising at least 2 carbon atoms, preferably between 2 and 6 carbon atoms, more preferably between 2 and 4 carbon atoms, and p is superior or equal to 1, preferably comprised between 1 and 6, more preferably comprised between 1 and 4; a (R7-N)p-H2 group wherein R7 represents a saturated, linear or branched, hydrocarbon group comprising at least 2 carbon atoms, preferably between 2 and 6 carbon atoms, more preferably between 2 and 4 carbon atoms, and p is superior or equal to 1, preferably comprised between 1 and 6, more preferably comprised between 1 and 4, and/or
• R3 represents a saturated or unsaturated, linear or branched, alkyl group comprising between 2 and 6 carbon atoms, preferably between 2 and 4 carbon atoms.
[82] In one embodiment, the fatty amine of general formula (I) represents of
from 0.5 to 10%, preferably of from 0.5 to 8% by weight with respect to the total
weight of the lubricant composition.
1 [83] The optional additives such as defined above contained in the lubricant
compositions of the present invention can be incorporated in the lubricant composition as separate additives, in particular through separate addition thereof in the base oils.

However, they may also be integrated in a concentrate of additives for marine
lubricant compositions.
[84] Advantageously, the lubricant composition comprises:
from 50 to 90 % of at least one base oil,
from 0,01 to 10 % of at least one copolymer based on Monomers (A) and Monomers (B) as above defined
the percentages being defined by weight of component as compared to the total
weight of the composition.
[85] Even more advantageously, the lubricant composition comprises:
from 70 to 90 % of at least one base oil
from 0,01 to 5 % of at least one copolymer based on Monomers (A) and Monomers (B) as above defined,
the percentages being defined by weight of component as compared to the total weight of the composition.
[86] In a third aspect, the present disclosure provides the use of a lubricant of
the first aspect and the second aspect for increasing the self-spreading of the lubricant on the liner surface after its delivery.
[87] In one embodiment, the use of a lubricant of the first and the second
aspects is for increasing the spreading and the self-spreading of the lubricant on the liner surface after its delivery.
[88] Alternately, the present disclosure provides a method for increasing the
spreading of the lubricant on the surface liner after its delivery said method comprising formulating the marine lubricant according to the first and the second aspects.
[89] Alternately, the present disclosure provides a method for increasing the
self-spreading of the lubricant on the surface liner after its delivery said method comprising formulating the marine lubricant according to the first and the second aspects.
[90] Alternately, the present disclosure provides a method for increasing the
spreading and self-spreading of the lubricant on the surface liner after its delivery said method comprising formulating the lubricant according to the first and the second aspects.

[91] In one embodiment, the increasing of the spreading of the lubricant on the
surface liner after its delivery results from the enhancement of the rheology properties of the lubricant, notably the spreading rheology properties of the lubricant. The term "spreading rheology properties" of the lubricant means the rheological properties of the lubricant after its spreading on the cylinder liner surface.
[92] In one embodiment, the increasing of the self-spreading of the lubricant on
the surface liner after its delivery results from the enhancement of the rheology
properties of the lubricant, notably the self-spreading rheology properties of the
lubricant. The term "self-spreading rheology properties" of the lubricant means the
rheological properties of the lubricant after its spreading on the cylinder liner surface.
[93] In an embodiment the polymers have a molecular weight superior than
20000 D.
[94] In an embodiment the polymers have a bimodal molecular weight
distribution.
[95] Copolymers having a molecular weight (Mw), average root mean square
radius of gyration (Rg) and viscosity correlation in a certain range are particularly suitable as an oil additive to enhance the performance of oil as a lubricant while maintaining the ability to handle and pump the oil. A preferred correlation of a bimodal Mw, Rg and viscosity values for one embodiment of the copolymers disclosed herein is represented by the following formula:
Performance X = U39.69418+(2.54756* Peak 1 Mw)-(0.91396* Peak 1 Rg)-(66.18535* Peak 2 Mw)-(0.23020* Viscosity+1.18947E-003* Peak 1 Rg) * (Viscosity),
[96] where the units for Mw is 106 g/mol, Rg is nm, and Viscosity is mPa-s, as
set forth in Table 1. A performance X value between 500 and 900, more preferably between 550 and 800, and most preferably between 600 and 750 is indicative of a copolymer having properties that are particularly suitable to enhance the performance of oil as a lubricant, notably the spreading and/or the self-spreading of the lubricant.
Definitions
[97] As used herein, C10-C18 alkyl methacrylate is a mixture of C10 alkyl
methacrylate, C12 alkyl methacrylate (CAS 142-90-5), C14 alkyl methacrylate (CAS

2549-53-3), C16 alkyl methacrylate (CAS 2495-27-4) and C18 alkyl methacrylate.
For example, this mixture comprises of about- 0.1 to 2% by weight of CIO alkyl
methacrylate, 50 to 80% by weight of C12 alkyl methacrylate, 15 to 40% by weight of
C14 alkyl methacrylate, 2 to 12% by weight of C16 alkyl methacrylate and 0.1 to 1 %
by weight of C18 alkyl methacrylate as compared to the total weight of the mixture,
such as commercially available methacrylic ester 13.0 (Evonik trade name:
VISIOMER® Terra C13.0-MA).
[98] As used herein, the term "about" refers to the given value ± 10 % of the
value.
[99] As used herein, the term "C8 alkyl" refers to a group comprised of eight
saturated carbon atoms connected in a linear or branched configuration. Examples of
linear C8 alkyl groups include n-octyl. Examples of branched Cgalkyl groups include,
but are not limited, to 2-ethylhexyl.
[ 100] As used herein, the expression "comprised between x and y", wherein x
and y are numerical values, means that the value may be x, or y or may be any value
from x to y.
[101] It is noted that any embodiment disclosed herein can be combined with any
other embodiment with the result being subject matter in accordance with the
invention.
[102] It is noted that, unless used differently, "%" means percent by weight.
Figures:
[103] Figure 1: variation of the spreadability of different lubricant compositions
versus the number of cycles.
Curve (-□-) represents the evolution of the spreadability of a first composition
according to the invention (composition C3). Curve (-A-) represents the evolution of
the spreadability of a second composition according to the invention (Composition
C4). Curve (-0-) represent the evolution of the spreadability of a reference lubricant
composition (Composition R).
Examples
[104] C10-C18 alkyl methacrylate as used in Examples 1 and 2 was provided as
methacrylic ester 13.0, which is commercially available as VISIOMER Terra C13,0-
MA from Evonik Industries.

Example t
[105] To a 4-neck 2000 mL flask equipped with an overhead stirrer, a condenser, a thermocouple and a subsurface nitrogen purge was added 645.5 g of water and 8.7 g of Aerosol® OT. The stirring was turned up to 200 rpm and the subsurface nitrogen purge was started. To the reaction mixture was then added 270.0 g of C10-C18 alkyl methacryiate, 30.0 g of 2-ethylhexyl methacrylate and 129.9 g of acetone. The reaction was heated up to 43 °C by using a temperature controlled water batch set at 45 °C. Once the reaction reached 43 °C, 0.04 g of t-butyl hydroperoxide in 7.5g of water was added. After 5 minutes, 0.29 g of sodium ascorbate dissolved in 7.5 g of water and 0.60 g of a 0.25% solution of iron sulfate hexahydrate was added. The nitrogen purge was then changed to a nitrogen blanket. The reaction was held an additional 5 hours, cooled to room temperature and isolated.
Example 2
[106] To a 4-neck 2000 mL flask equipped with an overhead stirrer, a condenser, a thermocouple and a subsurface nitrogen purge was added 645.5 g of water and 8.7 g of Aerosol® OT. The stirring was turned up to 200 rpm and the subsurface nitrogen purge was started. To the reaction mixture was then added 240.0 g of C10-C18 alkyl methacrylate, 60.0 g of 2-ethylhexyl methacrylate and 129.9 g of acetone. The reaction was heated up to 43 °C by using a temperature controlled water batch set at 45 °C. Once the reaction reached 43 °C, 0.04 g of t-butyl hydroperoxide in 7.5g of water was added. After 5 minutes, 0.29 g of sodium ascorbate dissolved in 7.5 g of water and 0.60 g of a 0.25% solution of iron sulfate hexahydrate was added. The nitrogen purge was then changed to a nitrogen blanket. The reaction was held an additional 5 hours, cooled to room temperature and isolated.
Preparation of a test lubricant composition comprising 5% Solids Solution of Copolymer in Oil
[107] To a 4-neck lOOOmL flask equipped with an overhead stirrer, a Barrett
distillation trap with a condenser and a thermocouple was added an amount of the emulsion of any of Examples 1 and 2 to give 20.0 g of polymer. Neutral Solvent 600 was then added to bring the total up to 400.0 g, followed by 150.0 g of toluene. The stirring was turned up to 200 rpm and the mixture was brought up to reflux. As water condensed in the Barrett trap it was drained off. Once the water stopped overflowing,

the contents of the reactor were brought up to 130 °C to distill of a majority of the toluene. The remaining material was transferred to a lOOOmL single neck round bottom and concentrated at vacuum with a bath at 60 °C until the material reached a constant weight. [108] The test lubricant was submitted to the above disclosed finger pull test.
Method for Determining Molecular Weight and Radius of Gyration
[109] The Molecular Weight and Radius of Gyration of the polymer samples,
supplied at 5% solids in base oil, was determined by the procedure outlined below:
[110] Eluant: HPLC Grade Tetrahydrofuran stabilized with 0.01% Butylated
Hydroxytoluene
[111] Column: Phenogel Guard Column 100A lOum 300mm x 7.8mm.
[112] Flow Rate: 0.50 ml/min.
[113] Detectors: Wyatt Dawn Heleos-II MultiAngle Light Scattering (MALS) at
663nm and room temperature and Wyatt Optilab T-rEX Refractive Index Detector at
658nmand40°C
[114] Pump/Autosampler: Agilent 1100 Isocratic HPLC Pump and Autosampler
[115] Column Compartment: 40 °C.
[116] Standards: There were no standards directly correlated with the analysis,
but the Heleos-II MALS calibration constant was established with Toluene and the
Optilab T-rEX calibration constant was established with NaCl in water. The 17 angles
on the Heleos-II were normalized with a narrow range polystyrene standard at 28,500
daltons Molecular Weight and the detector delay volume was adjusted with the same
standard.
[117] Sample Preparation: The samples were prepared by gravimetricalty
diluting about 8.0 mg of sample with about 5.0 g of tetrahyrofuran. The actual
concentration of polymer in mg/ml was calculated based on the density of
tetrahydrofuran (0.889 g/ml) and the percentage solids in the sample solutions (5.0%).
[118] Injection: 50 ul.
[119] Run time: 20 minutes.
[120] Software: Wyatt Astra Version 6.1.4.25.
[121] Calculations: The Astra software provides several choices of formalisms
and exponent order to fit the data. All samples were fit with a 2nd order Berry. The

angles used were adjusted to give the best fit, using a minimum of 13 angles and up to the maximum of 17. The dn/dc was calculated from the refractive index data assuming 100% recovery. The software reported the average Molecular Weight as Mw and the average Root Mean Square Radius of Gyration as Rg. The results are shown in Table I.
1 Percentage of monomer as a mass percent of the total amount of monomer
1 Parts per hundred based on the total amount of monomer
LMA = C10-C18alkylmethacry[ate;2-EHMA = 2-ethylhexyl methacrylate.
Example lubricant compositions
[123] Lubricant compositions CI, C2, C3 and C4 have been prepared with the
following compounds:
- lubricating base oil 1: Group I Mineral oils or brightstock of density between 895 and 915 kg/m3,
- lubricating base oil 2: Group I mineral oils, in particular called 600R viscosity at 40 ° C of 120 cSt measured according to ASTM D7279,
- detergent package 1 comprising an anti-foaming agent,
- detergent package 2,
- fatty amine,
- polymer from example 2.
[124] The compositions CI, C2, C3 and C4 are disclosed in Table 2. The
percentages disclosed in Table 2 correspond to weight percent.

Measure of the spreadability of the lubricant compositions
[126] The value of the spreadability of several lubricant oil compositions is
determined by submitting a drop of each composition to a repeated ring movement at a given temperature, surface roughness and radial load and by determining the surface occupied by the drop at the end of the experiment.
Materials:
Compositions according to the invention:
[127] The compositions according to the invention are Composition C3 and
Composition C4 disclosed in Table 2.
Reference composition:
[128] Composition R: lubricating oil commercially available as TALUS1A
HR70® from TOTAL.
Additive:
[129] Fluorescein, commercially available from Sigma Aldrich.
Protocol:
[130] The spreadability of the oil compositions is determined by using a Liner
Guardian Test Rig.

[131] The Liber Average Roughness of the support has been determined by
dividing the surface of the support in elemental quadrangles thus defining a matrix. The roughness of each quadrangle of the matrix has been then determined by using a rugosimeter. The average value for the Roughness of the support has been calculated.
[132] The radial load value has been determined by positioning a strain gauge on
the structure supporting the ring.
The strain gauge was calibrated before the experiments by using weights of known
value.
[133] The temperature of the liner is set by using electrical resistances and was
measured at two different locations (at opposite ends of the structure). The Liner temperature considered is the average value.
[134] Temperature and radial load value are controlled all along the experiments
by a Lab VIEW program in order to ensure that the operational conditions would remain constant. The Experimenter could thus check the variables value at any time and, if necessary, make any adjustment to the apparatus so that radial load and temperature would remain constant at the required value. The radial load can be adjusted by actuating a valve situated on the strain gauge.
[135] Test parameters are disclosed in Table 3.

[137] In order to enhance the visibility of the oil compositions under black light,
fluorescein is added to each oil compositions in a content of 0,10% by weight, based on the total oil composition weight.
[138] At the end of the trails, images of the oil compositions spreading profiles
are collected by using a dark (UV) light of at most 490 nm and a high-resolution camera.
[139] Collected images are then analysed with MATLAB® image processing
tools. The script developed acts on the following sequence:
a) Area detection and contour definition,
b) having the best fit parameters, it was possible to determine the area of each profile; the script would convert the area in pixels to cm2,
c) the output stored was the area of the oil composition drop in cm .
[140] The spreadability of each composition is finally obtained by dividing the
area occupied by the drop by the weight of the drop introduced.
[141] Images are collected after 1,3 and 5 cycles.
Results:
[142] The variation of the spreadability of the compositions C3, C4 and R after
several cycles is represented on Figure 1.
[143] Curve (-□-) relates to composition C3. Curve (-A-) relates to composition
C14 and curve (-0-) relates to composition R.
[144] After 1 cycle, the highest value of the spreadability is observed for
composition C4 with about 2.40 cm /mg.
Spreadability of compositions C3 and R is similar and of about respectively 1.40 cm2/mg and 1.37 cm2/mg.
[145] After 3 cycles, the highest value of spreadability is still observed for
composition C4 with about 2.96 cm2/mg.

Spreadability of compositions C3 and R is similar and of about respectively 1.90 cm2/mg and 1.82 cm2/mg.
[146] After 5 cycles, the highest value of spreadability is still observed for
composition C4 with about 2.96 cm2/mg.
Spreadability of composition C3 is about 2.51 cm2/mg and spreadability of composition R is about 1.88 cm2/mg.
[147] We observed that that lubricant compositions according to the invention
have an improved value of spreadability after 3 and 5 cycles when compared to the reference lubricant composition.

1. The use of a lubricant composition comprising;
- a copolymer of alkyl methacrylate monomers, wherein said alkyl
methacrylate monomers comprise at least:
a. Monomers (A) selected from C6-C10 alkyl methacrylate monomers,
b. Monomers (B) selected from C10-C18 alkyl methacrylate monomers,
a base oil,
for increasing the spreading of the lubricant on the liner surface after its delivery.
2. The use of a lubricant composition comprising:
- a copolymer obtained by combining at least
a. Monomers (A) selected from C6-C10 alkyl methacrylate monomers,
b. Monomers (B) selected from C10-C18 alkyl methacrylate monomers,
in a mixture and co-polymerizing the monomers, and
a base oil,
for increasing the spreading of the lubricant on the liner surface after its
delivery.
3. The use according to claim 1 or 2, wherein monomers (A) and monomers (B) represent at least 75% by weight of the total weight of monomers used to prepare the copolymer, advantageously they represent at least 90%, even more preferably at least 95 %, or better 99% by weight.
4. The use according to any of claims 1 to 3, wherein the weight ratio of monomers (B) to monomers (A) in the copolymer is about 99:1 to about 10:90.
5. The lubricant composition according to any of claims 1 to 4, wherein monomers (A) are branched, preferably monomers A are 2-ethyl hexyl methacrylate.
6. The use according to any of claims 1 to 5, wherein monomers (B) are linear, preferably monomers (B) are a mixture of CIO alkyl methacrylate, C12 alkyl

methacrylate, C14 aikyl methacrylate, C16 alkyl mcthacrylate aad C18 alkyl methacrylate.
7. The use according to any of claims 1 to 6, wherein the copolymer is a copolymer of a mixture of CIO alkyl methacrylate, C12 alkyl methacrylate, C14 alkyl methacrylate, C16 alkyl methacrylate and C18 alkyl methacrylate, and a C8 alkyl methacrylate.
8. The use according to any of claims 1 to 7, wherein the mass ratio of the monomers (B) to monomers (A) is from about 90:10 to about 80:20.
9. The use according to any claims 1 to 8, wherein the quantity of copolymer is from 0.01% to 10% by weight relative to the total weight of the lubricant composition.
10. The use according to any claims 1 to 9, wherein the lubricant further comprises an optional additive chosen amongst a neutral detergent, an overbased detergent, an anti-wear additive, a fatty amine soluble in lubricant, a polymer, a dispersing additive, an anti-foaming additive or a mixture thereof.
11. The use according to any claims 1 to 10, wherein the lubricant composition is a marine lubricant having a BN determined according to the standard ASTM D-2896 of at most 50 milligrams of potassium hydroxide per gram of the lubricant composition.

12. The use according to any claims 1 to 10, wherein the lubricant composition is a marine lubricant having a BN determined according to the standard ASTM D-2896 of at least 50 milligrams of potassium hydroxide per gram of the lubricant composition.
13. The use according to any of claims 1 to 12, for two-stroke marine engines.
14. The use according to any of claims 1 to 13 for further increasing the self-spreading of the lubricant on the cylinder liner surface after its delivery.
15. The use of a lubricant composition as defined in any of claims 1 to 13 for increasing the self-spreading of the lubricant on the cylinder liner surface after its delivery.