JP6829601B2 - Lubricating composition - Google Patents

Description

The present invention relates to a lubricating composition for use in the crankcase of an engine to provide improved fuel economy.

Government regulation and market demand continue to emphasize fossil fuel savings in the transportation industry. There is an increasing demand for more fuel efficient vehicles to meet the goal of reducing CO ₂ emissions. Therefore, gradual improvements in fuel economy (FE) are of great importance in the automotive sector. Lubricants can play an important role in reducing the fuel consumption of vehicles, and there is a continuing need to improve the fuel economy of the lubricant compositions contained within internal combustion engines.

Various attempts have been made to improve the fuel economy of lubricating engine oils. One technique for improving fuel economy is to reduce the kinematic viscosity of a product and improve its viscosity index by combining reducing the viscosity of the base oil with the addition of a viscosity index improver, ie mulch. It is to grade. There are many viscosity modifiers and base oils that can be used, for example, to blend OW-20 formulations. However, it is not possible to achieve very high VI and acceptable volatility with conventional combinations of viscosity modifiers and base oils.

US-2010 / 0190671 relates to the use of comb-shaped polymers to reduce fuel consumption. In particular, the comb-shaped polymers disclosed herein are styrene monomers, alcohols having at least one repeating unit in the main chain, obtained from at least one polyolefin-based macromonomer, and 8 to 17 carbon atoms. Alkyl (meth) acrylate having 1 to 10 carbon atoms in the group, vinyl ester having 1 to 11 carbon atoms in the acyl group, vinyl ether having 1 to 10 carbon atoms in the alcohol group, alcohol It is selected from the group consisting of (di) alkyl fumarate having 1 to 10 carbon atoms in the group, (di) alkyl maleate having 1 to 10 carbon atoms in the alcohol group, and a mixture thereof. It contains at least one repeating unit obtained from at least one low molecular weight monomer, the degree of molar branching is in the range of 0.1 to 10 mol%, and the comb polymer is based on the total weight of the repeating unit of the comb polymer. Includes at least one repeating unit from at least one polyolefin-based macromonomer and at least one repeating unit from at least one low molecular weight monomer, for a total of at least 80% by weight.

US-2011 / 0124536 is (A) a lubricant base oil having a kinematic viscosity of 50 to 99.9% by mass, 1 or more and less than 5 mm ² / sec at 100 ° C. based on the total amount of the base oil, and 0. A lubricant base oil composed of 1 to 50% by mass, a lubricant base oil having a kinematic viscosity of 5 to 200 mm ² / sec at 100 ° C.; and (B) a weight average molecular weight of 10000 or more, and 0.8 × 10. A viscosity index improver having a weight average molecular weight ratio to PSSI of ⁴ or more; the composition comprises 0.1 to 50% by weight of the VI improver (B) based on the total amount of the composition. Relates to a lubricant composition having a kinematic viscosity at 100 ° C. of 3 to 15 mm ² / sec and a ratio of 150 ° C.-HTHS viscosity to 100 ° C.-HTHS viscosity of 0.50 or greater.

In WO-2009 / 130445, there is at least one type of monoester and 20% by weight or less of the additive, and at least one type of monoester, or a plurality of monoesters when more than one type is present. The mixture is disclosed as an engine lubricant having a kinematic viscosity at 100 ° C. of 3.3 or less, a viscosity index of at least 130, and a Noac evaporation loss of 15% by weight or less, especially an engine lubricant for use in a 4-stroke engine. There is.

US-2010 / 0190671 US-2011 / 0124536 WO-2009 / 130445

There is a need to provide a lubricating composition for use in the crankcase of an engine, where the composition provides high VI, low viscosity, and acceptable volatile properties, as well as improved fuel economy benefits.

According to the present invention
(I) Base oil containing at least one monoester or a mixture of multiple monoesters having a kinematic viscosity at 100 ° C. of 4 mm ² / sec or less, a viscosity index of at least 130, and a Noac evaporation loss of 20% by weight or less; And (ii) (a) one or more comb-shaped polymers;
(B) The following equation (1):

(In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² is a linear or branched hydrocarbon group having 16 or more carbon atoms).
Poly (meth) acrylate polymer having one or more (meth) acrylate structural units of 1-70 mol% represented by;
(C) Styrene-diene hydrogenated copolymer; and (d) Mixtures thereof;
Polymer viscosity index improver selected from;
Lubricating compositions for use within the crankcase of an engine are provided.

The lubricating compositions of the present invention provide high VI, low viscosity, and acceptable volatile properties, in addition to improved fuel economy.

The base oil comprises at least one monoester or a mixture of the monoesters, such monoester or the mixture of the monoesters at 100 ° C. of 4 mm ² / sec or less, preferably 3.3 mm ² / sec or less. It has kinematic viscosity (measured by ASTM-D445), a viscosity index of at least 130 (calculated by ASTM-D2270), and noac evaporation loss of 20% by weight or less, preferably 15% by weight or less (measured by ASTM-D5800).

Such monoesters or mixtures of monoesters are preferably in the lubricating composition at a total level of at least 10% by weight, more preferably at least 20% by weight, most preferably at least 30% by weight, based on the weight of the lubricating composition. Exists in. Such monoesters or mixtures of monoesters are preferably at a total level of at least one monoester of up to 75% by weight, more preferably up to 50% by weight, even more preferably up to 40% by weight. It is present in the lubricating composition.

Although not desired to be limited by theory, the present invention promotes the viscosity of lower base oil blends with low viscosity and low volatility monoesters or mixtures of monoesters with acceptable volatility. It is based on. The viscosity of this lower base oil blend means that more polymer viscosity index improvers are needed to achieve the required HTHS-150 viscosity (high temperature high shear viscosity at 150 ° C.) (according to ASTM-D4683). .. Higher levels of polymer VI improvers give a higher viscosity index (VI), and a lower HTHS-100 viscosity (high temperature high shear viscosity at 100 ° C.) (measured by ASTM-D6616) with respect to an equivalent HTHS-150 viscosity. In principle, the viscosity changes only slightly with temperature. Since the engine is operated at a temperature closer to 100 ° C than 150 ° C, the lubricant has a low viscosity under operating conditions, thus providing improved fuel economy. The addition of monoesters or mixtures of monoesters, and the lower viscosity of the base oil blends obtained, as well as the acceptable volatility, require more polymers no matter what polymer viscosity index improver is selected. Means that Therefore, the VI is higher and the HTHS-100 is lower than that of the corresponding formulation, which does not have a monoester or a mixture of multiple monoesters. Therefore, the inclusion of a monoester or a mixture of a plurality of monoesters promotes an improvement in fuel economy no matter what polymer viscosity index improver is selected.

Viscoplex 3-201 comb polymer from Evonik Industries, and selected polymer viscosity index enhancements used in the present invention with optimized structures such as the Aclube V-5110 alkyl (meth) acrylate copolymer supplied by Sanyo Chemicals. The agent gives a higher VI due to the given increase in viscosity and therefore the benefits are higher with respect to these selected polymers.

Preferably, such at least one monoester is a reaction product of a monohydric alcohol with a monocarboxylic acid, and such monohydric alcohol is at least one saturated branched chain having carbon atoms between 16 and 36. Aliphatic monohydric alcohols, such monocarboxylic acids are at least one saturated linear aliphatic monocarboxylic acid having between 5 and 10 carbon atoms, preferably between 5 and 7 carbon atoms. If desired, a mixture of such alcohols and / or such acids can be used in the esterification reaction.

Alternatively, such at least one monoester is a reaction product of a monohydric alcohol with a monocarboxylic acid, and such monohydric alcohol is at least one saturated linear fat having between 5 and 7 carbon atoms. A group monohydric alcohol, such a monocarboxylic acid is at least one saturated branched chain aliphatic monocarboxylic acid having between 16 and 36 carbon atoms. If desired, a mixture of such alcohols and / or such acids can be used in the esterification reaction.

Mixtures of the plurality of monoesters described above can also be used.
In a preferred embodiment, the monoester used in the present invention is between such a branched chain alcohol having between 16 and 36 carbon atoms and between 5-10 and preferably between 5-7 as described above. A monoester which is a reaction product of such a linear acid having a carbon atom.

Branched chain monohydric alcohols can be obtained from any suitable source and can usually be selected from gerbet alcohols, oxo alcohols, aldol condensation-inducing alcohols, and mixtures thereof.

More particularly, branched chain monohydric alcohols are alcohols that are branched at the β position on the main carbon chain. Usually, such alcohols are 2-octadecanol-1,2-heptylundecanol-1, 2-octadodecanol-1, 2-nonyltridecanol-1, and 2-decyltetradecanol-2. , As well as a mixture of two or more such alcohols. Such alcohols are conveniently gerbet alcohols.

Preferably, the branched chain monohydric alcohol is at least one alcohol having between 16 and 28, more preferably between 20 and 24 carbon atoms.
Linear monocarboxylic acids can be obtained from any suitable source, such as pentanoic acid (valeric acid), hexanoic acid (caproic acid), heptanic acid (enanthic acid), octanoic acid (caprylic acid), decanoic acid (caprylic acid). Acid) and a mixture of two or more such acids.

Preferably, such at least one monoester has a kinematic viscosity (measured by ASTM-D445) at 100 ° C. of 3.0 mm ² / sec or less. Preferably, such at least one monoester has a viscosity index of at least 140 (measured by ASTM-2270). Preferably, such at least one monoester has a pour point of −30 ° C. or lower, more preferably −35 ° C. or lower, particularly −40 ° C. or lower (according to ASTM-D97). Preferably, such at least one monoester has a Noac evaporation loss (according to ASTM-D5800) of 17% by weight or less, more preferably 15.0% by weight or less.

Preferably, such at least one monoester has a flash point (by the Cleveland sealing method) of at least 200 ° C., more preferably at least 210 ° C., more particularly at least 220 ° C.

Preferably, such at least one monoester has a non-polarity index (NPI) described in EP-B-0792334 of at least 80, preferably at least 90.

Preferably, such at least one monoester has a low temperature crank simulation (CCS) kinematic viscosity (according to ASTM-D5293) at −35 ° C. below 6200 cPs.

Examples of monoesters or mixtures of monoesters suitable for use in the present invention include those disclosed in WO-2009 / 130445.
Examples of commercially available monoesters for use in the present invention include Priolube 1544, which is commercially available from Croda International Plc.

In the lubricating composition of the present invention, the base oil may contain one or more additional base oils in addition to the one or more monoesters or a mixture of the plurality of monoesters described above. The further base oil that can be used in the lubricating composition of the present invention is not particularly limited, and various ordinary mineral oils, synthetic oils, and naturally occurring esters such as vegetable oils can be conveniently used.

Conveniently, the base oil used in the present invention may contain a mixture of one or more mineral oils and / or one or more synthetic oils; thus, according to the present invention, the term "base oil" is used. It can refer to a mixture containing more than one base oil. Mineral oils include paraffinic, naphthenic, or mixed paraffinic / naphthenic type liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oils, which are further subjected to a hydrofinishing process and / or dewazing. Can be purified.

Suitable base oils for use in the lubricating oil compositions of the present invention are Group I-III mineral base oils (preferably Group III), Group IV polyα-olefins (PAOs), Group II-III Fisher Tropsch inductions. A base oil (preferably Group III), a Group V ester base oil, and mixtures thereof.

"Group I", "Group II", "Group III", and "Group IV", and "Group V" base oils are, in the present invention, US petroleums according to categories I, II, III, IV, and V. Lubricating oil base oil as defined by the Association (API). These API categories are defined in API Publication 1509, 15th Edition, Appendix E, April 2002.

A preferred base oil for use in the present invention in addition to a monoester or a mixture of a plurality of monoesters is a Fischer-Tropsch-induced base oil. Fischer-Tropsch-induced base oils are known in the art. The term "Fischer-Tropsch induction" means that the base oil is or is derived from a synthetic product of the Fischer-Tropsch process. The Fischer-Tropsch-induced base oil can also be referred to as GTL (Gas to Liquids) base oil. Suitable Fischer-Tropsch-induced base oils that can be conveniently used as the base oil in the lubricating composition of the present invention include, for example, EP-0776959, EP-0668342, WO-97 / 21788, WO-00 / 15736, WO-00. / 14188, WO-00 / 14187, WO-00 / 14183, WO-00 / 14179, WO-00 / 08115, WO-99 / 41332, EP-1029029, WO-01 / 18156, and WO-01 / 57166 It is disclosed.

Generally, the aromatic content of the Fischer-Tropsch-induced base oil, preferably preferably determined by ASTM-D4629, is usually less than 1% by weight, preferably less than 0.5% by weight, more preferably 0.1% by weight. Lower. Preferably, the base oil has a total paraffin content of at least 80% by weight, preferably at least 85, more preferably at least 90, even more preferably at least 95, most preferably at least 99% by weight. It preferably has a saturated content (measured by IP-368) of greater than 98% by weight. Preferably, the saturated content of the base oil is higher than 99% by weight, more preferably higher than 99.5% by weight. It further preferably has a maximum n-paraffin content of 0.5% by weight. The base oil also preferably has a content of 0 to less than 20% by weight, more preferably 0.5 to 10% by weight of the naphthenic compound.

Generally, Fischer-Tropsch-induced base oils or base oil blends are 1 to 30 mm ² / sec (cSt), preferably 1 to 25 mm ² / sec (cSt), more preferably 2 mm ² / sec to 12 mm ² / sec. It has a range of kinematic viscosities at 100 ° C. (measured by ASTM-D7042). Preferably, the Fischer-Tropsch-induced base oil has a kinematic viscosity at 100 ° C. of at least 2.5 mm ² / sec, more preferably at least 3.0 mm ² / sec (measured by ASTM-D7042). In one aspect of the present invention, the Fischer-Tropsch derived base oil, up to 5.0 mm ² / sec, preferably up to 4.5 mm ² / s, 4.2 mm 100 ° C. for ² / sec and more preferably at the highest Has kinematic viscosity in (eg, "GTL4"). In another aspect of the invention, the Fischer-Tropsch-induced base oil has kinematic viscosities of up to 8.5 mm ² / sec, preferably up to 8 mm ² / sec at 100 ° C. (eg, "GTL8").

In addition, Fischer-Tropsch-induced base oils typically have kinematic viscosities of 10-100 mm ² / sec (cSt), preferably 15-50 mm ² / sec at 40 ° C. (measured by ASTM-D7042).

The Fischer-Tropsch-induced base oil also has a pour point (measured according to ASTM-D5950), preferably lower than −30 ° C., more preferably lower than −40 ° C., and most preferably lower than −45 ° C.

The flash point (measured by ASTM-D92) of the Fischer-Tropsch-induced base oil is preferably higher than 120 ° C, more preferably further higher than 140 ° C.
The Fischer-Tropsch-induced base oil preferably has a viscosity index in the range of 100-200 (according to ASTM-D2270). Preferably, the Fischer-Tropsch-induced base oil has a viscosity index of at least 125, preferably 130. Further, the viscosity index is lower than 180, preferably lower than 150.

If the Fischer-Tropsch-induced base oil contains a blend of two or more Fischer-Tropsch-induced base oils, the above values apply to the blend of two or more Fischer-Tropsch-induced base oils.

The lubricating oil composition preferably contains 80% by weight or more of Fischer-Tropsch-induced base oil.
Synthetic oils include hydrocarbons such as olefin oligomers (polyα-olefin base oils: including PAO), dibasic acid esters, polyol esters, polyalkylene glycols (PAGs), alkylnaphthalene, and dewaxed isomerates. Oil is mentioned.

Polyα-olefin base oils (PAOs) and their production are well known in the art. Preferred poly alpha-olefin base oils that may be used in the lubricating compositions of the present invention, linear _C 2 _{-C 32,} preferably may be derived from _C 6 _{-C 16} alpha-olefin. Particularly preferred feedstocks for such polyα-olefins are 1-octene, 1-decene, 1-dodecene, and 1-tetradecene.

From the viewpoint of the high cost of producing PAO, it is strongly oriented to use Fischer-Tropsch-induced base oil rather than PAO base oil. Thus, preferably, the base oil is more than 50% by weight, preferably more than 60% by weight, more preferably more than 70% by weight, even more preferably more than 80% by weight, and most preferably more than 90% by weight. Contains a large amount of Fischer-Tropsch-induced base oil. In a particularly preferred embodiment, 5% by weight or less, preferably 2% by weight or less of the base oil is not a Fischer-Tropsch-induced base oil. It is even more preferred that 100% by weight of the base oil be based on one or more Fischer-Tropsch-induced base oils.

The total amount of the base oil contained in the lubricating composition of the present invention is preferably in the range of 60 to 99% by weight, more preferably in the range of 65 to 90% by weight, and most preferably in the range of 60 to 90% by weight, based on the total weight of the lubricating composition. It is in the range of 70 to 85% by weight.

Generally, the base oil (or base oil blend) used according to the present invention has a kinematic viscosity (according to ASTM-D445) at 100 ° C., which is higher than 2.5 cSt and lower than 5.6 cSt. According to a preferred embodiment of the invention, the base oil has a kinematic viscosity (according to ASTM-D445) at 100 ° C. between 2.7 and 4.5 cSt. When the base oil contains a blend of two or more base oils, the blend preferably has a kinematic viscosity at 100 ° C. between 2.7 and 4.5 cSt.

Another essential component of the lubricating composition of the present invention is one or more polymer viscosity index improvers. The lubricating composition according to the present invention is preferably 0.1% by weight to 7% by weight, more preferably 0.25% by weight to 5% by weight, still more preferably 0.5% by weight, based on the weight of the total lubricating composition. Contains one or more polymer viscosity index improvers in an amount of ~ 4% by weight solid polymer.

Preferably, the polymer viscosity index improver has a ratio of weight average molecular weight to 10000 or more weight average molecular weight, and 0.8 × 10 ⁴ or more PSSI.
Polymer VI improvers suitable for use in the present invention are
(A) One or more comb-shaped polymers;
(B) The following equation (1):

(In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² is a linear or branched hydrocarbon group having 16 or more carbon atoms).
Poly (meth) acrylate polymer having one or more (meth) acrylate structural units of 1-70 mol% represented by;
(C) Styrene-diene hydrogenated copolymer; and (d) Mixtures thereof;
Is selected from.

In a preferred embodiment of the present invention, the polymer VI improver is a comb polymer. Preferred comb polymers for use in the present invention include at least one repeating unit obtained from at least one polyolefin-based macromonomer in the main chain, and a styrene monomer having 8 to 17 carbon atoms, an alcohol group. Alkyl (meth) acrylate having 1 to 10 carbon atoms in it, vinyl ester having 1 to 11 carbon atoms in an acyl group, vinyl ether having 1 to 10 carbon atoms in an alcohol group, alcohol group At least selected from the group consisting of (di) alkyl polymers having 1 to 10 carbon atoms in them, (di) alkyl polymers having 1 to 10 carbon atoms in alcohol groups, and mixtures thereof. It contains at least one repeating unit obtained from one low molecular weight monomer, the degree of molar branching is in the range of 0.1 to 10 mol%, and the comb polymer is based on the total weight of the repeating units of the comb polymer. At least one repeating unit obtained from at least one polyolefin-based macromonomer, and at least one low molecular weight, totaling at least 80% by weight (or in other forms relative to the total weight of the comb polymer). Contains at least one repeating unit obtained from the monomer.

Preferably, the comb-type polymer used in the present invention has repeating units derived from 8 to 30% by weight of polyolefin-based macromonomer, and the degree of molar branching of the comb-type polymer is 0.3% to 1.1%. Is the range of.

The term "comb-shaped polymer" as used in the present invention means that relatively long side chains are attached to a polymer backbone, often also known as the backbone. Comb-shaped polymers for use in the present invention have at least one repeating unit derived from a polyolefin-based macromonomer. The actual ratio is clear from the degree of molar branching. The term "main chain" as used in the present invention does not necessarily mean that the chain length of the main chain is longer than that of the side chain. Rather, the term relates to the composition of this chain. The side chains have a very high proportion of olefin repeat units, especially units derived from alkenes or alkazienes such as ethylene, propylene, n-butene, isobutene, butadiene, isoprene, while the main chain has a relatively large proportion. Includes the polar unsaturated monomers detailed above.

The term "repeating unit" is known to those of skill in the art. The comb-shaped polymer can be obtained by a process involving free radical polymerization of macromonomers and low molecular weight monomers (double bonds are cleaved to form covalent bonds). Therefore, the repeating unit is generated from the monomer used. However, comb-type polymers can also be produced by polymer-related reactions and graft copolymerization. In this case, the converted repeating unit of the main chain is counted as the repeating unit derived from the polyolefin-based macromonomer. The same applies to the production of comb-shaped polymer by graft polymerization.

Further details of the method for making comb polymers can be found in US-2010 / 0190671 and US-2008 / 0194443, both of which are incorporated herein by reference.

Preferred comb polymers for use in the present invention contain repeating units derived from polyolefin-based macromonomers. These repeating units contain at least one group derived from polyolefin. Examples of suitable _polyolefins, C 2 _{-C 10} alkenes, such as ethylene, propylene, n- butene, isobutene, norbornene, and / or _C 4 _{-C 10} alkadienes, such as butadiene, isoprene, and the like norbornadiene.

The repeating unit derived from the polyolefin-based macromonomer is preferably at least 70% by weight, more preferably at least 80% by weight, and most preferably at least 90% by weight based on the weight of the repeating unit derived from the polyolefin-based macromonomer. Contains weight% of alkenes and / or groups derived from alkadiene.

Polyolefin-based groups may also be present in hydrogenated form. In addition to the groups derived from alkenes and / or alkazienes, the repeating units derived from polyolefin-based macromonomers can contain additional groups. These include, among others, small proportion copolymerizable monomers such as alkyl (meth) acrylates, styrene monomers, fumarates, maleates, vinyl esters, and / or vinyl ethers. The proportion of these groups relative to copolymerizable monomers is preferably up to 30% by weight, more preferably up to 15% by weight, based on the weight of the repeating units derived from the polyolefin-based macromonomers. .. Repeating units derived from polyolefin-based macromonomers may include starting and / or terminal groups resulting from the production of repeating units provided by functionalization or derived from polyolefin-based macromonomers. it can. The proportion of these initiating and / or end groups is preferably up to 30% by weight, more preferably up to 15% by weight, based on the weight of the repeating unit derived from the polyolefin-based macromonomer.

The number average molecular weight of the repeating units derived from the polyolefin-based macromonomer is preferably 500-50000 g / mol, more preferably 700-10000 g / mol, even more preferably 1500-4900 g / mol, most preferably 2000-. It is in the range of 3000 g / mol.

The melting point of the repeating unit derived from the polyolefin-based macromonomer is preferably −10 ° C. or lower, more preferably −20 ° C. or lower, and even more preferably −40 ° C. or lower as measured by DSC. Most preferably, the DSC melting point cannot be measured for repeating units derived from polyolefin-based macromonomers.

In addition to repeating units derived from polyolefin-based macromonomers, comb-shaped polymers useful in the present invention are styrene monomers with 8-17 carbon atoms, alkyls with 1-10 carbon atoms in alcohol groups. (Meta) acrylate, vinyl ester having 1 to 11 carbon atoms in the acyl group, vinyl ether having 1 to 10 carbon atoms in the alcohol group, didi having 1 to 10 carbon atoms in the alcohol group. It contains (alkyl) fumarate, (di) alkyl maleates having 1 to 10 carbon atoms in the alcohol group, and repeating units obtained from low molecular weight monomers selected from the group consisting of mixtures of these monomers.

The molecular weight of the low molecular weight repeating unit or low molecular weight monomer is preferably up to 400 g / mol, more preferably up to 200 g / mol, and most preferably up to 150 g / mol.

Examples of styrene monomers having 8 to 17 carbon atoms are styrene, substituted styrenes having alkyl substituents in the side chains, such as α-methylstyrene, and α-ethylstyrene, substituteds having alkyl substituents on the ring. Styrene, such as vinyltorene, p-methylstyrene, halogenated styrene, such as monochlorostyrene, dichlorostyrene, tribromostyrene, and tetrabromostyrene.

The term "(meth) acrylate" includes acrylates and methacrylates, as well as mixtures of acrylates and methacrylates. Alkyl (meth) acrylates having 1 to 10 carbon atoms in the alcohol group include (meth) acrylates derived from saturated alcohols, such as methyl (meth) acrylate, ethyl (meth) acrylate, and n-propyl (meth). ) Acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate , 2-tert-Butylheptyl (meth) acrylate, octyl (meth) acrylate, 3-isopropylheptyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate; (meth) acrylate derived from unsaturated alcohol , For example 2-propynyl (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, oleyl (meth) acrylate; cycloalkyl (meth) acrylate, for example cyclopentyl (meth) acrylate, and 3-vinylcyclohexyl (meth). Acrylate can be mentioned.

Preferred alkyl (meth) acrylates contain 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms in the alcohol group. Here, the alcohol group may be linear or branched.
Examples of vinyl esters having 1 to 11 carbon atoms in the acyl group include vinyl formate, vinyl acetate, vinyl propionate, and vinyl butyrate. Preferred vinyl esters contain 2-9, more preferably 2-5 carbon atoms in the acyl group. The acyl group may be linear or branched.

Examples of vinyl ethers having 1 to 10 carbon atoms in an alcohol group include vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, and vinyl butyl ether. Preferred vinyl ethers contain 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms in the alcohol group. The alcohol group may be linear or branched.

The term "(di) ester" as used herein means that in particular a mixture of monoesters, diesters, and multiple esters of fumaric acid and / or maleic acid can be used. Examples of the (di) alkyl fumarate having 1 to 10 carbon atoms in the alcohol group include monomethyl fumarate, dimethyl fumarate, monoethyl fumarate, diethyl fumarate, methyl ethyl fumarate, monobutyl fumarate, and dibutyl. Examples include fumarate, dipentyl fumarate, and dihexyl fumarate. A preferred (di) alkyl fumarate contains 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms in the alcohol group. The alcohol group may be linear or branched.

Di (alkyl) maleates having 1 to 10 carbon atoms in the alcohol group include monomethyl maleate, dimethyl maleate, monoethyl maleate, diethyl maleate, methyl ethyl maleate, monobutyl maleate, and dibutyl maleate. Ate is mentioned. A preferred (di) alkyl maleate contains 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms in the alcohol group. Here, the alcohol group may be linear or branched.

In addition to the repeating units detailed above, the comb-shaped polymers useful in the present invention may include additional repeating units derived from additional comonomer, the proportion of which is the weight of the repeating unit. As a reference, the maximum is 20% by weight, preferably the maximum is 10% by weight, and more preferably the maximum is 5% by weight.

These are also alkyl (meth) acrylates having 11 to 30 carbon atoms in the alcohol group, especially undecyl (meth) acrylate, 5-methylundecyl (meth) acrylate, dodecyl (meth) acrylate, 2-methyldodecyl. (Meta) acrylate, tridecyl (meth) acrylate, 5-methyltridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, 2-methylhexadecyl (meth) acrylate, heptadecyl (Meta) acrylate, 5-isopropylheptadecyl (meth) acrylate, 4-tert-butyl octadecyl (meth) acrylate, 5-ethyl octadecyl (meth) acrylate, 3-isopropyl octadecyl (meth) acrylate, octadecyl (meth) acrylate, Derived from nonadesyl (meth) acrylates, eicosyl (meth) acrylates, cetyl eicosyl (meth) acrylates, stearyl eicosyl (meth) acrylates, docosyl (meth) acrylates, and / or eicosyl tetratoriacontyl (meth) acrylates Also includes repeating units.

They are also derived from dispersed oxygen and nitrogen functionalized monomers such as those listed in paragraphs [0036]-[0059] of US-2010 / 0190671 (included herein by reference). Also includes repeating units.

The comb-shaped polymer suitable for use in the present invention is preferably 0.1 to 10 mol%, more preferably 0.3 to 6 mol%, still more preferably 0.3 to 1.1 mol%, particularly. It has a degree of molar branching in the range of 0.4 to 1.0 mol%, most preferably 0.4 to 0.6 mol%.

The molar branch degree (f _branch ) of the comb polymer is expressed by the formula:

(During the ceremony,
A is the number of repeating units of the type derived from polyolefin-based macromonomers;
B is a styrene monomer having 8 to 17 carbon atoms, an alkyl (meth) acrylate having 1 to 10 carbon atoms in an alcohol group, and a vinyl ester having 1 to 11 carbon atoms in an acyl group. Vinyl ether having 1 to 10 carbon atoms in the alcohol group, (di) alkyl fumarate having 1 to 10 carbon atoms in the alcohol group, and 1 to 10 carbon atoms in the alcohol group (di) ) The number of repeating units of the type derived from low molecular weight monomers selected from the group consisting of alkylmalates and mixtures of these monomers;
n _a is the number of repeating units derived from the a-type polyolefin-based macromonomer in the comb polymer molecule;
n _b is a b-type styrene monomer having 8 to 17 carbon atoms in a comb-shaped polymer molecule, an alkyl (meth) acrylate having 1 to 10 carbon atoms in an alcohol group, and 1 to 11 acyl groups. Vinyl ester having a carbon atom, vinyl ether having 1 to 10 carbon atoms in an alcohol group, (di) alkyl fumarate having 1 to 10 carbon atoms in an alcohol group, 1 to 10 carbon atoms in an alcohol group The number of repeating units derived from low molecular weight monomers selected from the group consisting of (di) alkyl maleates with, and mixtures of these monomers).
Calculated by.

When the comb polymer is produced by copolymerization of low molecular weight monomers and high molecular weight monomers, the degree of molar branching is due to the ratio of the monomers commonly used. For this calculation, the number average molecular weight of macromonomers can be used in the present invention.

When the comb-shaped polymer is obtained by a polymer-related reaction or graft copolymerization, the degree of molar branching is determined by a known method for determining the conversion rate.
At least 80% by weight, preferably at least 90% by weight, a styrene monomer having 8 to 17 carbon atoms, an alkyl (meth) acrylate having 1 to 10 carbon atoms in an alcohol group, and 1 to 1 in an acyl group. Vinyl ester having 11 carbon atoms, vinyl ether having 1 to 10 carbon atoms in the alcohol group, (di) alkyl fumarate having 1 to 10 carbon atoms in the alcohol group, 1 in the alcohol group Low molecular weight repeating units derived from monomers selected from the group consisting of (di) alkylmalates having 10 carbon atoms and mixtures of these monomers, and repetitions derived from polyolefin-based macromonomers. The unit ratio is based on the weight of the repeating unit. In addition to repeating units, polymers generally also include initiating and terminal groups that can be formed by initiation and termination reactions. In one embodiment of the invention, at least 80% by weight, preferably at least 90% by weight, a styrene monomer having 8 to 17 carbon atoms, an alkyl (meth) having 1 to 10 carbon atoms in an alcohol group. An acrylate, a vinyl ester having 1 to 11 carbon atoms in an acyl group, a vinyl ether having 1 to 10 carbon atoms in an alcohol group, and a (di) alkyl having 1 to 10 carbon atoms in an alcohol group. Fumarate, a (di) alkyl maleate having 1 to 10 carbon atoms in an alcohol group, and a low molecular weight repeating unit derived from a monomer selected from the group consisting of a mixture of these monomers, and a polyolefin base. The description of repeating units derived from macromonomers in is based on the weight of the comb polymer.

The comb polymer preferred for use in the present invention has 8-30% by weight, more preferably 10-26% by weight of repeating units derived from polyolefin-based macromonomers relative to the total weight of the repeating units.

The comb-shaped polymer preferable to be used in the present invention is 500,000 to 1,000,000 g / mol, more preferably 100,000 to 500,000 g / mol, and most preferably 150,000 to 450,000 g / mol. Those having a weight average molecular weight Mw in the range of are mentioned.

The number average molecular weight Mn may preferably be in the range of 20,000 to 800,000 g / mol, more preferably 40,000 to 200,000 g / mol, and most preferably 50,000 to 150,000 g / mol. ..

Preferably, the comb polymer used in the present invention has a polydisperse index Mw / Mn in the range of 1-5, more preferably 2.5-4.5. The number average and weight average molecular weight can be determined by a known process such as gas permeation chromatography (GPC).

In certain embodiments of the invention, the preferred comb polymer has a low proportion of olefinic double bonds. The iodine value is preferably 0.2 g or less per 1 g of the comb-shaped polymer, and more preferably 0.1 g or less per 1 g of the comb-shaped polymer. This ratio can be determined according to DIN-53241 after removing the carrier oil and low molecular weight residual monomers at 180 ° C. under reduced pressure for 24 hours.

In a preferred embodiment of the invention, the lubricating composition comprises a comb polymer having repeating units derived from n-butyl methacrylate and / or n-butyl acrylate. Preferably, the proportion of repeating units derived from n-butyl methacrylate and / or n-butyl acrylate is at least 50% by weight, more preferably at least 60% by weight, based on the total weight of the repeating units.

In a preferred embodiment of the invention, the comb polymer has repeating units derived from styrene. The proportion of repeating units derived from styrene is preferably in the range of 0.1 to 30% by weight, more preferably 5 to 25% by weight.

In a preferred embodiment of the invention, the comb polymer is preferably in the range of 0.1% to 15% by weight, more preferably in the range of 1 to 10% by weight, in an amount of 11 to 30 elements in the alkyl group. It has a repeating unit derived from an alkyl (meth) acrylate having a carbon atom.

In a preferred embodiment of the invention, the comb polymer has repeating units derived from styrene and repeating units derived from n-butyl methacrylate. The weight ratio of the styrene repeating unit to the n-butyl methacrylate repeating unit is preferably in the range of 1: 1 to 1: 9, more preferably 1: 2 to 1: 8.

In another preferred embodiment, the comb polymer is a repeating unit derived from methyl methacrylate, preferably in a weight ratio of 1: 1 to 0: 100, more preferably 3: 7 to 0: 100, and n-butyl. It has repeating units derived from methacrylate.

A commercially available comb polymer suitable for use in the present invention is available from Evonik Industries under the trade name Viscoplex 3-201.
In another embodiment, the polymer viscosity index improver is prepared by the following formula (1).

It is selected from those having one or more (meth) acrylate structural units of 1 to 70 mol% represented by.
In formula (1), R ¹ is a hydrogen or methyl group, and R ² is a linear or linear compound having 16 or more carbon atoms, preferably 18 or more carbon atoms, more preferably 20 or more carbon atoms. It is a branched hydrocarbon group, more preferably a branched hydrocarbon group having 20 or more carbon atoms.

The poly (meth) acrylate viscosity index improver may be either a non-dispersible type or a dispersible type, but the latter is more preferable.
In the poly (meth) acrylate viscosity index improver, the ratio of the (meth) acrylate structural unit represented by the formula (1) is preferably 1 to 70 mol%, more preferably 60 mol% or less, still more preferably 50. It is mol% or less, particularly preferably 40 mol% or less, particularly 30 mol% or less; preferably 3 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more.

Such a poly (meth) acrylate VI improver may preferably be a copolymer of one or more monomers represented by the formula (2) and a monomer other than that represented by the formula (2).

In formula (2), R ¹ is a hydrogen or methyl group and R ² is a linear or branched hydrocarbon group having 16 or more carbon atoms.
Any monomer can be combined with the monomer of the formula (2), and for example, the monomer represented by the following formula (3) is preferable.

The copolymers of formulas (2) and (3) are non-dispersible type poly (meth) acrylate VI improvers.
In formula (3), R ³ is a hydrogen or methyl group and R ⁴ is a linear or branched hydrocarbon group having 1 to 15 carbon atoms.

As the other monomer to be combined with the monomer of the formula (2), one or more kinds of monomers represented by the formula 4 or the formula 5 are preferable.

In formula (4), R ⁵ is a hydrogen or methyl group, R ⁶ is an alkylene group having 1 to 18 carbon atoms, and E ¹ is 1 to 2 nitrogen atoms and 0 to 2 nitrogen atoms. It is an amine or heterocyclic residue having an oxygen atom and indicates 0 or 1.

In formula 5, R ⁷ is a hydrogen or methyl group and E ² represents an amine or heterocyclic residue having 1-2 nitrogen atoms and 0-2 oxygen atoms.
Copolymers of monomers having formulas (2), (4), and (5) constitute dispersible type poly (meth) acrylate VI improvers. This dispersible type poly (meth) acrylate VI improver can further contain the monomer of the formula (3) as a constituent monomer.

Specific examples of R ⁶ an alkylene group in the formula (4), ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, and octadecylene (These alkylene groups may be either linear or branched).

The group represented by E ¹ in the formula (4) and the group represented by E ² in the formula (5) are independently dimethylamino, diethylamino, dipropylamino, dibutylamino, aniline, toluidino, xylidino, It may be an acetylamino, benzoylamino, morpholino, pyrrolyl, pyrrolino, pyridyl, methylpyridyl, pyrrolidinyl, piperidinyl, quinonyl, pyrrolidonyl, pyrrolidono, imidazolino, or pyradino group.

Preferred examples of the monomers having formulas (4) and (5) are dimethylaminomethylmethacrylate, diethylaminomethylmethacrylate, dimethylaminoethylmethacrylate, diethylaminoethylmethacrylate, 2-methyl-5-vinylpyridine, morpholinomethylmethacrylate, morpholinoethyl. Methyl methacrylate, N-vinylpyrrolidone, and mixtures thereof can be mentioned.

The copolymerization molar ratio with respect to the copolymer of the monomers having the formulas 2 and 3 to 5 is not particularly limited, and the monomer of the formula 2: the monomer of the formulas 3 to 5 is preferably 10:90 to 40:60.

The VI improver can be produced, for example, by radically solvent-polymerizing a mixture of the monomers of the formulas (1) and (3) to (5) in the presence of a polymerization initiator such as benzoyl peroxide.

As used in the present invention, "PSSI" means a permanent shear stability index of a polymer calculated from data measured according to ASTM-D6278-02 with reference to ASTM-D6022-01.

The PSSI of such a poly (meth) acrylate VI improver is preferably 35 or less, more preferably 30 or less, even more preferably 25 or less; preferably 5 or more, more preferably 10 or more, still more preferably less than 20. , Especially 20 or more.

The weight average molecular weight (Mw) of the poly (meth) acrylate VI improver is preferably 10,000 or more, more preferably 50,000 or more, even more preferably 100,000 or more, even more preferably 150,000 or more, and most preferably 200,000 or more. It is preferably 1,000,000 or less, more preferably 700,000 or less, even more preferably 600,000 or less, and particularly preferably 500,000 or less.

The ratio of the weight average molecular weight to the number average molecular weight of the poly (meth) acrylate VI improver is preferably 0.5 to 5.0, more preferably 1.0 to 3.5, and even more preferably 1.5 to 3. Especially 1.7 to 2.5.

The ratio of the weight average molecular weight to the PSSI of the poly (meth) acrylate VI improver is preferably 0.8 × 10 ⁴ or more, more preferably 1 × 10 ⁴ or more, still more preferably 2 × 10 ⁴ or more, preferably even more is 2.5 × 10 ⁴ or more.

Examples of poly (meth) acrylate viscosity index improvers suitable for use in the present invention include those disclosed and exemplified in US-2011 / 0124536.

Commercially available poly (meth) acrylate polymers suitable for use in the present invention are available from Sanyo Chemicals under the trade name Aclube 5110.
Another suitable polymer viscosity index improver for use in the present invention is a styrene-diene hydrogenated copolymer.

Examples of commercially available styrene-diene hydrogenated copolymers suitable for use in the present invention are available from Infineum under the trade name Infineum SV600.
In a preferred embodiment of the present invention, the weight ratio of one or more polymer viscosity index improvers to one or more monoesters or a mixture of a plurality of monoesters is in the range of 1: 8 to 1:40, more preferably. It is in the range of 1: 10 to 1:30.

Usually, the lubricating compositions of the present invention are used in SAE-J300 viscosity grades 0W-16, 0W-20, 0W-30, 0W-40, 5W-20, 5W-30, and 5W-40, but not necessarily. Not limited to these. This is because these are grades aimed at fuel economy. As new SAE-J300 viscosity grades with lower viscosities than the current 0W-16 have been published, the present invention will also be well applicable to these new lower viscosity grades. It is believed that the present invention can also be used with higher viscosity grades.

Lubricating compositions according to the invention preferably have a Noac volatility (according to ASTM-D5800) of less than 15% by weight. Typically, the Noac volatility of the composition (according to ASTM-D5800) is between 1 and 15% by weight.

The lubricating composition in the present invention is an antioxidant, an abrasion resistant additive, a dispersant, a cleaning agent, a hyperbasified cleaning agent, an extreme pressure additive, a friction modifier, a viscosity index improver, a flow point lowering agent, and a metal-free material. It further comprises one or more additives such as kinetic agents, corrosion inhibitors, demulsifiers, defoamers, seal compatible agents, and additive diluent base oils.

Those skilled in the art are familiar with the above and other additives and will not be discussed in more detail here. Specific examples of such additives are described, for example, in Kirk-Othmer Encyclopedia of Chemical Technology, 3rd Edition, vol.14, p.477-526.

Antioxidants that can be conveniently used include, for example, phenylnaphthylamines disclosed in WO-2007 / 045629 and EP-1058720B1 (eg, "IRGANOX L-06" available from Ciba Specialty Chemicals) and diphenylamines (eg, "eg," IRGANOX L-06 "). "IRGANOX L-57") available from Ciba Specialty Chemicals, phenolic antioxidants, etc. The teachings of WO-2007 / 045629 and EP-1058720B1 are incorporated herein by reference.

Abrasion resistant additives that can be conveniently used include zinc-containing compounds such as zinc dithiophosphate compounds selected from zinc dialkyl, diaryl, and / or alkylaryl dithiophosphate, molybdenum-containing compounds, boron-containing compounds, and substitutions. Alternatively, ashless abrasion resistant additives such as unsubstituted thiophosphate and salts thereof can be mentioned.

Examples of such molybdenum-containing compounds can conveniently include molybdenum dithiocarbamate, such as the trinuclear molybdenum compound described in WO-98 / 26030, molybdenum sulfide, and molybdenum dithiophosphate.

Boron-containing compounds that can be conveniently used include borate esters, boron-containing fatty amines, boron-containing epoxides, volates of alkali metals (or mixed forms of alkali metals or alkaline earth metals), and boron-containing hyperbasified metal salts. Can be mentioned.

The dispersant used is preferably an ashless dispersant. Preferable examples of ashless dispersants are polybutylene succinimide polyamines and Mannich base type dispersants.
The cleaning agent used is preferably a superbasic cleaning agent or a cleaning agent mixture containing, for example, salicylate, sulfonate, and / or phenate type cleaning agents.

Examples of other types of viscosity index improvers that can be conveniently used in the lubricating compositions of the present invention are styrene-butadiene star copolymers, styrene-isoprene star copolymers, and crystalline and non-crystalline types. Examples include polymethacrylate copolymers and ethylene-propylene copolymers (also known as olefin copolymers). Dispersants-viscosity index improvers can be used in the lubricating compositions of the present invention.

Preferably, the composition comprises at least 0.1% by weight of a pour point depressant. As an example, alkylated naphthalenes and phenolic polymers, polymethacrylates, maleate / fumarate copolymer esters can be conveniently used as effective pour point depressants. Preferably, a pour point depressant of 0.3% by weight or less is used.

Further, a compound such as alkenyl succinic acid or an ester moiety thereof, a benzotriazole-based compound, and a thiodiazole-based compound can be conveniently used as a corrosion inhibitor in the lubricating composition of the present invention.

Compounds such as polysiloxane, dimethylpolycyclohexane, and polyacrylate can be conveniently used as antifoaming agents in the lubricating compositions of the present invention.
Compounds that can be conveniently used as seal-fixing or seal-compatible agents in the lubricating compositions of the present invention include, for example, commercially available aromatic esters.

The lubricating composition of the present invention comprises a base oil containing one or more monoesters or a mixture of a plurality of monoesters, and a polymer viscosity index improver, optionally by mixing with one or more additives. It can be conveniently manufactured.

The above-mentioned additives are usually in an amount in the range of 0.01-35.0% by weight based on the total weight of the lubricating composition, preferably 0.05 to 25.0% by weight based on the total weight of the lubricating composition. %, More preferably in an amount in the range of 1.0 to 20.0% by weight.

Preferably, the composition comprises at least 9.0% by weight, preferably at least 10.0% by weight, more preferably at least 11.0% by weight of abrasion resistant additives, metal cleaners, ashless dispersants, and oxidations. Includes additive packages containing inhibitors.

The lubricating composition according to the present invention may be a so-called "low SAPS" (SAPS = sulfate ash, phosphorus, and sulfur), "medium SAPS", or "standard SAPS" formulation.
For passenger car motor oil (PCMO) engine oil, the above range is:
Sulfate ash content of 0.5% by weight or less, 0.8% by weight or less, and 1.5% by weight or less, respectively (according to ASTM-D874);
-Liquid content of 0.05% by weight or less, 0.08% by weight or less, and usually 0.1% by weight or less (according to ASTM-D5185); and-0.2% by weight or less and 0.3% by weight, respectively. Below, and usually 0.5% by weight or less, sulfur content (according to ASTM-D5185);
Means.

For diesel engine oils for heavy vehicles, the above range is:
Sulfate ash content of 1% by weight or less, 1% by weight or less, and 2% by weight or less, respectively (according to ASTM-D874);
Phosphorus content of 0.08 wt% or less (low SAPS) and 0.12 wt% (medium SAPS), respectively (according to ASTM-D5185); and 0.3 wt% or less (low SAPS), and 0, respectively. .4% by weight or less (medium SAPS) sulfur content (according to ASTM-D5185);
Means.

In other embodiments, the present invention provides the use of an engine with a lubricating composition according to the present invention as an engine oil in the crankcase of an engine to improve fuel economy. Examples of engine oils include diesel engine oils for large vehicles, motor engine oils for passenger vehicles, and other types of engine oils.

Hereinafter, the present invention will be described with reference to the following examples, but these are not intended to limit the scope of the present invention in any way.
GTL base oils and monoesters (Priolube 1544 commercially available from Croda International Plc.), Additive packages and polymer viscosity index improvers (commercially available combs from Evonik Industries) using conventional lubricant manufacturing methods. Lubricating compositions with the formulations shown in Table 1 by mixing with the type polymer Viscoplex 3-201 or the poly (meth) acrylate polymer Aclube V-5110 commercially available from Sanyo Chemicals (Example 1). ~ 4) was prepared.

Lubricating compositions (Examples 5 to 12) having the formulations shown in Table 2 were prepared using a usual lubricant manufacturing method. The monoester used in Examples 8, 9, 11 and 12 was Sample 2 of WO-2009 / 130445. The polymer viscosity index improvers used in Examples 6-12 were Viscoplex 3-201 (comb polymer from Evonik Industries), Aclube 5110 (poly (meth) acrylate polymer from Sanyo Chemicals), and Infineum SV277 (from Infineum). (Styrene-diene hydrogenated copolymer).

In order to show the improved fuel economy of the lubricating composition of the present invention, Examples 5 to 9 were subjected to various test methods shown in Table 2 below.

Discussion:
From Table 2, it can be seen that with respect to the given HTHS-150 (2.6), the addition of the polymer VI improver increases VI and decreases HTHS-100.

By selecting a comb polymer (eg Viscoplex 3-210) or a poly (meth) acrylate polymer with optimal structure (eg Aclube 5110), the VI will be higher and the HTHS-100 will be lower. This shows improved fuel economy (as is clear from Comparative Examples 7 and 10).

With the addition of monoesters (Examples 4 and 5 and Examples 7 and 8), VI is further increased and HTHS-100 is decreased. This shows improved fuel economy (as is apparent from comparing Example 8 with Comparative Example 7).

Since the engine is operated at a temperature closer to 100 ° C than 150 ° C, the lubricant is less viscous under operating conditions and thus provides improved fuel economy.

Claims (13)

(I) Base oil containing at least one monoester or a mixture of multiple monoesters having a kinematic viscosity at 100 ° C. of 4 mm ² / sec or less, a viscosity index of at least 130, and a Noac evaporation loss of 20% by weight or less; And (ii) (a) one or more comb-shaped polymers;
(B) The following equation (1):

(In the formula, R ¹ is a hydrogen atom or a methyl group, and R ² is a linear or branched hydrocarbon group having 16 or more carbon atoms).
Poly (meth) acrylate polymer having one or more (meth) acrylate structural units of 1-70 mol% represented by;
(C) Styrene-diene hydrogenated copolymer; and (d) Mixtures thereof;
Polymer viscosity index improver selected from;
Including
The at least one monoester is a reaction product of a monohydric alcohol and a monocarboxylic acid, and the monohydric alcohol is at least one saturated branched aliphatic aliphatic monohydric alcohol having 16 to 36 carbon atoms. There, at least one of Ri saturated linear aliphatic monocarboxylic acids der, base oil further comprises a Fischer-Tropsch derived base oil, engine crankcase with the carbon atom between monocarboxylic acids of 5 to 10 Lubricating composition for use within. The lubricating composition according to claim 1, wherein the monoester or a mixture of a plurality of monoesters has a kinematic viscosity at 100 ° C. of 3.3 mm ² / sec or less. The lubricating composition according to claim 1 or 2, wherein the monoester or a mixture of the plurality of monoesters has a Noac evaporation loss of 15% by weight or less. The lubricating composition according to any one of claims 1 to 3, wherein at least one monoester or a mixture of a plurality of monoesters is present at a total level of at least 10% by weight based on the weight of the lubricating composition. The lubricating composition according to any one of claims 1 to 4, wherein at least one monoester or a mixture of a plurality of monoesters is present at a total level of up to 75% by weight based on the weight of the lubricating composition. .. The lubricating composition according to any one of claims 1 to 5, wherein the polymer viscosity index improver is a comb-shaped polymer. The lubricating composition according to any one of claims 1 to 6, wherein the polymer viscosity index improver is present in a solid polymer amount of 0.1% by weight to 7% by weight based on the weight of the lubricating composition. The lubricating composition according to any one of claims 1 to 7, wherein the at least one monoester or a mixture of a plurality of monoesters has a non-polarity index of at least 90. The lubricating composition according to any one of claims 1 to 8, wherein the at least one type of monoester or a mixture of a plurality of monoesters has a pour point of −30 ° C. or lower. At least one monoester or a mixture of multiple monoesters has a kinematic viscosity of 3.0 cSt or less at 100 ° C. and / or a viscosity index of at least 140 and / or a pour point of -35 ° C. or less, and / or 15. The lubricating composition according to any one of claims 1 to 9, which has a Noac evaporation loss of 0.0% by weight or less. The lubricating composition according to any one of claims 1 to 10, wherein the alcohol is branched at the β-position on the main carbon chain and contains an alcohol containing 20 carbon atoms. The lubricating composition according to any one of claims 1 to 11, wherein the acid is enanthic acid and / or valeric acid. Use of the lubricating composition according to any one of claims 1 to 12 in the crankcase of an engine to improve fuel economy.