RU2678102C2 - Lubricant composition - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: present invention relates to a lubricating composition for use in an engine crankcase, comprising: (i) a base oil containing at least one monoester or a mixture of monoesters, where said monoester or mixture of monoesters is present from the total weight of the lubricating composition in an amount from at least 10 wt. % to 75 wt. % and has a kinematic viscosity at 100 °C of no more than 4 mm/s, a viscosity index of at least 130 and Noack evaporation loss of not more than 20 wt. %; wherein the base oil additionally contains Fischer-Tropsch-derived base oil, and (ii) polymer additives that increase viscosity index, which are present in an amount of dry polymer residue from 0.1 wt. % to 7 wt. %, by weight of the lubricating composition, selected from (a) one or more comb-shaped polymers; (b) a poly(meth)acrylate polymer containing from 1 to 70 mol. % of one or more (meth)acrylate structural fragments having formula (1) below, where Rrepresents a hydrogen atom or a methyl group, and Rrepresents a linear or branched hydrocarbon group containing at least 16 carbon atoms; (c) mixtures thereof, in which said at least one monoester is the reaction product of a monohydric alcohol and monocarboxylic acid, where said monohydroxy alcohol is at least one saturated branched aliphatic monohydric alcohol containing from 16 to 36 carbon atoms, and wherein said monocarboxylic acid is at least one saturated linear aliphatic monocarboxylic acid containing from 5 to 10 carbon atoms.(I).EFFECT: lubricating composition is used in an engine crankcase, in order to increase fuel efficiency.10 cl, 2 tbl

Description

FIELD OF THE INVENTION

The present invention relates to a lubricant composition for use in an engine crankcase in order to increase fuel economy.

State of the art

State regulations and market requirements continue to focus on the use of fossil fuels in the transport sector. There is a growing need for more fuel-efficient vehicles in order to meet the goals of reducing CO ₂ emissions. Therefore, any improvement in fuel efficiency (FC) is important in the automotive sector. Lubricants can play an important role in reducing fuel consumption of a vehicle, and there is a continuing need to improve fuel economy for lubricating compositions used in internal combustion engines.

Various attempts have been made to improve fuel economy for lubricating engine oils. One method to increase fuel economy is to reduce the kinematic viscosity and increase the viscosity index of products by combining a decrease in the viscosity of the base oil and adding additives to increase the viscosity index. A large number of viscosity modifiers and base oils are known, which can be used, for example, for oils of type 0W-20. However, it is not possible to achieve a very high viscosity index and acceptable volatility using well-known combinations of viscosity modifiers and base oils.

US 2010/0190671 relates to the use of comb polymers to reduce fuel consumption. In particular, the comb-shaped polymer described herein contains at least one repeating moiety derived from at least one polyolefin macromonomer and at least one repeating moiety derived from at least one low molecular weight monomer selected from the group consisting of styrene monomers containing from 8 to 17 carbon atoms, alkyl (meth) acrylates containing from 1 to 10 carbon atoms in the alcohol group, vinyl esters containing from 1 to 11 carbon atoms hydrogen in the acyl group, vinyl ethers containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl fumarates containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl maleates containing from 1 to 10 carbon atoms in the alcohol group, and mixtures thereof, where the molar degree of branching is in the range from 0.1 to 10 mol. %, and comb-like polymer in total contains at least 80 weight. %, based on the total weight of the repeating fragments of the comb-shaped polymer, at least one repeating fragment obtained from at least one polyolefin macromonomer, and at least one repeating fragment obtained from at least one low molecular weight monomer.

US 2011/0124536 relates to a lubricating composition containing (A) a lubricating base oil, consisting, based on the total amount of the specified base oil, from 50-99.9 mass. % lubricating base oil having a kinematic viscosity at 100 ° C of not less than 1 and less than 5 mm ² / s, and 0.1-50 mass. % lubricating base oil having a kinematic viscosity at 100 ° C from 5 to 200 mm ² / s, and (B) an additive that increases the viscosity index, having a weight average molecular weight of at least 10,000, and a weight average molecular weight to PSSI ratio of at least 0.8 × 10 ⁴ , where the specified composition contains 0.1-50 mass. % of the specified viscosity index increasing agent (B) relative to the total amount of the composition, and where the specified composition has a kinematic viscosity at 100 ° C of 3 to 15 mm ² / s, and the HTHS viscosity ratio (viscosity at high temperature and high shear force) at 150 ° С and HTHS viscosity at 100 ° С not less than 0.50.

WO 2009/130445 describes motor lubricants, in particular engine lubricants used in four-stroke engines, containing at least one monoester and not more than 20 weight. % additives where at least one monoester or a mixture of these monoesters, if more than one monoester is present, has a kinematic viscosity at 100 ° C. of not more than 3.3, a viscosity index of at least 130, and evaporation losses determined by the Noack method , no more than 15 weight. %

There is a need to develop lubricant compositions for use in an engine crankcase that have a high viscosity index, low viscosity and acceptable volatility characteristics, as well as provide improved fuel economy.

Disclosure of invention

The present invention describes a lubricating composition for use in an engine crankcase, comprising:

(i) a base oil containing at least one monoester or mixture of monoesters, wherein said monoester or mixture of monoesters has a kinematic viscosity at 100 ° C. of not more than 4 mm ² / s, a viscosity index of at least 130, and evaporation losses determined by Noack method, not more than 20 weight. %; and

(ii) polymer viscosity index improvers selected from

(a) one or more comb-like polymers;

(b) a poly (meth) acrylate polymer containing from 1 to 70 mol. % of one or more (meth) acrylate structural fragments having the formula (I) below

where R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched hydrocarbon group containing at least 16 carbon atoms;

(c) styrene-diene hydrogenated copolymers; and

(d) mixtures thereof.

The lubricating composition of the present invention has a high viscosity index, low viscosity and acceptable volatility characteristics, and also provide improved fuel economy

The implementation of the invention

The specified base oil contains at least one monoester or mixture of monoesters, where the specified monoester or mixture of monoesters has a kinematic viscosity at 100 ° C (measured according to ASTM D445) of not more than 4 mm ² / s, preferably not more than 3.3 mm ² / s, a viscosity index of at least 130 (calculated according to ASTM D2270), and evaporation losses determined by the Noack method (measured according to ASTM D5800) not more than 20 weight. %, preferably not more than 15 weight. %

The specified monoester or a mixture of these monoesters is preferably present in the lubricating composition in a total amount of at least 10 weight. %, more preferably at least 20 weight. %, most preferably at least 30 weight. %, based on the total weight of the lubricating composition. The specified monoester or a mixture of these monoesters is preferably present in the lubricating composition in a total amount of not more than 75 weight. %, more preferably not more than 50 weight. %, and even more preferably not more than 40 weight. %

Without reference to any theory, the present invention relies on the fact that a monoester or a mixture of monoesters having low viscosity and low volatility reduces the viscosity of a base oil blend having acceptable volatility. This reduced viscosity of the base oil blend means that a higher viscosity index polymer is required to achieve the target HTHS 150 viscosity (oil viscosity at high temperature and high shear stress at 150 ° C) (according to ATSM D4683). The increased amount of polymer additive that increases the viscosity index provides a higher viscosity index (VI) and lower HTHS 100 viscosity (oil viscosity at high temperature and high shear stress at 100 ° C) (measured according to ASTM D6616) at the same HTHS 150 viscosity . In fact, the viscosity will change less with temperature. Since the engine operates at a temperature closer to 100 ° C than to 150 ° C, the lubricant will be less dense under engine operating conditions and thereby provide improved fuel economy. The addition of a monoester or a mixture of monoesters and a lower viscosity of the resulting base oil blend, with acceptable volatility, will mean that regardless of the choice of a polymer additive that increases the viscosity index, more polymer will be required. Thus, the viscosity index will be higher, and HTHS 100 lower than that of the corresponding composition without the addition of a monoester or a mixture of monoesters. Thus, the addition of a monoester or a mixture of monoesters helps to improve fuel economy regardless of the choice of polymer additives that increase the viscosity index.

Certain viscosity index increasing polymer additives used according to the present invention having an optimized architecture, such as Evonik Industries Viscoplex 3-201 comb polymer and Sanyo Chemicals Aclube V-5110 alkyl (meth) acrylate copolymer give a higher viscosity index at a given an increase in viscosity, and therefore a more significant advantage is achieved when using these polymers.

Preferably, said at least one monoester is a reaction product of a monohydric alcohol and a monocarboxylic acid, wherein said monohydric alcohol is at least one saturated branched aliphatic monohydric alcohol containing from 16 to 36 carbon atoms, and where said monocarboxylic acid is at least one saturated linear aliphatic monocarboxylic acid containing from 5 to 10, preferably from 5 to 7 carbon atoms. If desired, mixtures of these alcohols and / or these acids can be used in the esterification reaction.

Alternatively, said at least one monoester is a reaction product of a monohydric alcohol and a monocarboxylic acid, wherein said monohydric alcohol is at least one saturated linear aliphatic monohydric alcohol containing from 5 to 7 carbon atoms, and where said monocarboxylic acid is at least one saturated branched aliphatic monocarboxylic acid containing from 16 to 36 carbon atoms. If desired, mixtures of these alcohols and / or these acids can be used in the esterification reaction.

Mixtures of the monoesters described above can also be used.

In a preferred embodiment, the monoesters used according to the present invention are monoesters, which are reaction products of said branched alcohols containing from 16 to 36 carbon atoms and said linear acids containing from 5 to 10, preferably from 5 to 7 carbon atoms, as described above.

A branched monohydric alcohol can be obtained from any suitable source, and in a typical case, it can be selected from Gerbe alcohols, oxo alcohols, alcohols obtained by aldol condensation, and mixtures thereof.

More specifically, a branched monohydric alcohol is an alcohol branched at the β-position of the main carbon chain. Typically, such alcohols may be selected from 2-octadecanol-1, 2-heptylundecanol-1, 2-octadodecanol-1, 2-nonyltridecanol-1 and 2-decyltethecanol-2, and from mixtures of two or more of these alcohols. Such alcohols are Gerbeh alcohols.

Preferably, the branched monohydric alcohol is at least one alcohol containing from 16 to 28 carbon atoms, more preferably from 20 to 24 carbon atoms.

Linear monocarboxylic acid can be obtained from any suitable source, and it is selected from pentanoic acid (valerianic acid), hexanoic acid (caproic acid), heptanoic acid (enanthic acid), (octanoic acid (caprylic acid), decanoic acid (capric acid) and from mixtures of two or more of these acids.

Preferably, said at least one monoester has a kinematic viscosity at 100 ° C. (measured according to ASTM D445) of not more than 3.0 mm ² / s. Preferably, said at least one monoester has a viscosity index (measured according to ATSM 2270) of at least 140. Preferably, said at least one monoester has a yield point (according to ASTM D97) of not more than -30 ° C, more preferably not more than - 35 ° C, and in particular not more than -40 ° C. Preferably, said at least one monoester has an evaporation loss determined by the Noack method (according to ATSM D5800) of not more than 17 weight. %, more preferably not more than 15.0 weight. %

Preferably, said at least one monoester has a flash point (according to the Cleveland method in a closed crucible) of at least 200 ° C, more preferably at least 210 ° C, and in particular at least 220 ° C.

Preferably, said at least one monoester has an apolarity coefficient (NPI) as described in EP-B-0792334 of at least 80, preferably at least 90.

Preferably, said at least one monoester has a dynamic viscosity when simulated cold start (according to ASTM D5293) at −35 ° C. not more than 6200 cP.

Examples of suitable monoesters and monoester mixtures for use in the present invention include those described in WO 2009/130445.

Examples of commercially available monoesters for use in the present invention include Priolube 1544, commercially available from Croda International Plc.

In the lubricating compositions of the present invention, the base oil may contain one or more additional base oils, in addition to the above one or more monoesters or mixtures of monoesters. There are no particular restrictions on the additional base oils that can be used in the lubricating composition of the present invention, and various well-known mineral oils, synthetic oils, as well as natural esters such as vegetable oils can be used.

The base oil used according to the present invention may contain mixtures of one or more mineral oils and / or one or more synthetic oils; thus, in the present invention, the term "base oil" may mean a mixture containing more than one base oil. Mineral oils include liquid oils of petroleum origin and solvent-treated or acid-treated paraffinic, naphthenic or mixed paraffin / naphthenic type mineral lubricants that can be further treated by hydrotreating and / or dewaxing.

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 poly-alpha olefins (PAO), Fischer-Tropsch derived Group II-III base oils (preferably Group III), Group V ester base oils, and mixtures thereof.

Under the basic oils of "Group I", "Group II", "Group III" and "Group IV" and "Group V" in the present invention understand the base lubricating oil according to the definitions of the American Petroleum Institute (API) for categories I, II, III, IV and V. Definitions for the listed API categories are given 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 monoesters, is a Fischer-Tropsch derived base oil. The Fischer-Tropsch derived base oils are known in the prior art. By the term “Fischer-Tropsch derived” is meant that the base oil is a synthesis product by the Fischer-Tropsch process, or is a derivative thereof. The Fischer-Tropsch derived base oil can also be called GTL (Gas-To-Liquids, synthetic liquid fuel) base oil. Suitable Fischer-Tropsch derived base oils which are conveniently used as a base oil in the lubricating composition of the present invention are, for example, those described in 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.

In a typical case, the aromatic content in the Fischer-Tropsch derived base oil, determined according to ASTM D 4629, is less than 1 weight. %, preferably less than 0.5 weight. %, and more preferably less than 0.1 weight. % In a typical case, the base oil has a total paraffin content of at least 80 weight. %, preferably at least 85 weight. %, more preferably at least 90 weight. %, even more preferably at least 95 weight. %, and most preferably at least 99 weight. % The content of saturated components (measured according to IP-368) is above 98 weight. % Preferably, the content of saturated components in the base oil is higher than 99 weight. %, more preferably above 99.5 weight. % More preferably, the maximum content of n-paraffins is 0.5 weight. % The base oil preferably has a naphthenic compound content of from 0 to less than 20 weight. %, more preferably from 0.5 to 10 weight. %

Typically, a Fischer-Tropsch derived base oil or base oil blend has a kinematic viscosity at 100 ° C (measured according to ASTM D 7042) in the range of 1 to 30 mm ² / s (cSt), preferably 1 to 25 mm ² / s (cSt), and more preferably from 2 mm ² / s to 12 mm ² / s. Preferably, the Fischer-Tropsch derived base oil has a kinematic viscosity at 100 ° C. (measured according to ASTM D 7042) of at least 2.5 mm ² / s, more preferably at least 3.0 mm ² / s. In one embodiment of the present invention, the Fischer-Tropsch derived base oil has a kinematic viscosity at 100 ° C. of not more than 5.0 mm ² / s, preferably not more than 4.5 mm ² / s, more preferably not more than 4.2 mm ² / s (for example, "GTL 4"). In another embodiment of the present invention, the Fischer-Tropsch derived base oil has a kinematic viscosity at 100 ° C. of not more than 8.5 mm ² / s, preferably not more than 8 mm ² / s (for example, “GTL 8”).

In addition, the Fischer-Tropsch derived base oil typically has a kinematic viscosity at 40 ° C (measured according to ASTM D 7042) of 10 to 100 mm ² / s (cSt), preferably 15 to 50 mm ² / s.

Also, the Fischer-Tropsch derived base oil preferably has a yield point (measured according to ASTM D 5950) below -30 ° C, more preferably below -40 ° C, and most preferably below -45 ° C.

The flash point (measured according to ASTM D92) of the Fischer-Tropsch derived base oil is preferably above 120 ° C, more preferably even above 140 ° C.

The Fischer-Tropsch derived base oil preferably has a viscosity index (according to ASTM D 2270) in the range of 100 to 200. Preferably, the Fischer-Tropsch derived base oil has a viscosity index of at least 125, preferably 130. It is also preferred that the viscosity index was less than 180, preferably less than 150.

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

The lubricating oil composition preferably contains 80 weight. % Fischer-Tropsch derived base oil or more.

Synthetic oils include hydrocarbon oils such as olefin oligomers (including polyalphaolefin base oils, PAOs), dibasic esters, polyol esters, polyalkylene glycols (PAGs), alkylnaphthalenes, and dewaxed waxy isomerizates.

Polyalphaolefin base oils (PAOs) and their production are well known in the prior art. Preferred polyalphaolefin base oils that can be used in the lubricating compositions of the present invention can be linear C ₂ -C ₃₂ derivatives, preferably C ₆ -C ₁₆ in alpha olefins. Particularly preferred raw materials for said polyalphaolefins are 1-octene, 1-decene, 1-dodecene, 1-tetradecene.

The use of the Fischer-Tropsch derived base oil is much preferable to the use of PAO base oil, in light of the high costs of producing PAO. So, preferably, the base oil contains more than 50 weight. %, preferably more than 60 weight. %, more preferably more than 70 weight. %, even more preferably more than 80 weight. %, most preferably more than 90 weight. % Fischer-Trogap base oil obtained. In a particularly preferred embodiment, not more than 5 weight. %, preferably not more than 2 weight. % of base oil is not Fischer-Tropsch derived base oil. Even more preferably, 100 weight. % of the base oil was one or more Fischer-Tropsch derived base oils.

The total amount of base oil included in the lubricating composition of the present invention is preferably in the range of 60 to 99 weight. %, more preferably in the range from 65 to 90 weight. %, and most preferably in the range from 70 to 85 weight. %, relative to the total weight of the lubricating composition.

Typically, the base oil (or base oil blend) used in the present invention has a kinematic viscosity at 100 ° C (according to ASTM D445) above 2.5 cSt and below 5.6 cSt. In a preferred embodiment of the present invention, the base oil has a kinematic viscosity at 100 ° C (according to ASTM D445) between 2.7 and 4.5 cSt. If the base oil contains a blend of two or more base oils, it is preferable that the blend has a kinematic viscosity at 100 ° C between 2.7 and 4.5 cSt.

Another important component of the lubricating composition of the present invention is one or more polymer additives that increase the viscosity index. The lubricating composition of the present invention contains one or more polymer additives that increase the viscosity index, preferably in an amount, calculated on the solid polymer, from 0.1 weight. % to 7 weight. %, more preferably from 0.25 weight. % to 5 weight. %, and even more preferably from 0.5 weight. % to 4 weight. %, relative to the total weight of the lubricating composition.

Preferably, the viscosity index increasing polymer additive has a weight average molecular weight of at least 10,000 and a weight average molecular weight to PSSI ratio of at least 0.8 × 10 ⁴ .

Suitable polymeric viscosity index improvers for use in the present invention are selected from:

(a) one or more comb-like polymers;

(b) a poly (meth) acrylate polymer containing from 1 to 70 mol. % of one or more (meth) acrylate structural fragments having the following formula (1)

where R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched hydrocarbon group containing at least 16 carbon atoms;

(c) styrene-diene hydrogenated copolymers; and

(d) mixtures thereof.

In a preferred embodiment of the present invention, the viscosity index increasing polymer additive is a comb-like polymer. A preferred comb-like polymer for use in the present invention comprises at least one repeating moiety derived from at least one polyolefin macromonomer and at least one repeating moiety derived from at least one low molecular weight monomer selected from the group consisting of from styrene monomers containing from 8 to 17 carbon atoms, alkyl (meth) acrylates containing from 1 to 10 carbon atoms in the alcohol group, vinyl esters containing about t 1 to 11 carbon atoms in the acyl group, vinyl ethers containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl fumarates containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl maleates containing from 1 to 10 carbon atoms in the alcohol group, and mixtures thereof, where the molar degree of branching is in the range from 0.1 to 10 mol. %, and the comb-like polymer contains a total of at least 80 weight. %, based on the total weight of the repeating fragments of the comb-shaped polymer (or, in another aspect, based on the total weight of the comb-shaped polymer), at least one repeating fragment obtained from at least one polyolefin macromonomer, and at least one repeating fragment obtained from at least one low molecular weight monomer.

Preferably, the comb-like polymer used in the present invention contains from 8 to 30 weight. % of repeating fragments obtained from their polyolefin macromonomers, and the molar degree of branching of the comb-shaped polymer is in the range from 0.3% to 1.1%.

The term “comb-like polymer” as used herein means that relatively long side chains are attached to the polymer backbone, which is also often referred to as a framework. Comb polymers for use in the present invention comprise at least one repeating moiety derived from polyolefin macromonomers. The exact ratio can be understood by the molar degree of branching. The term "main chain" as used herein does not necessarily mean that the length of the main chain is greater than the length of the side chains. This term refers to the composition of a given chain. While the side chain has a very high percentage of olefin repeating fragments, especially fragments derived from alkenes or alkadiene, for example ethylene, propylene, n-butene, isobutene, butadiene, isoprene, the main chain contains a relatively high percentage of polar unsaturated monomers, which have been described in detail above.

The term "repeating fragment" is known to those skilled in the art. Comb polymers can be prepared by a process that involves free radical polymerization of macromonomers and low molecular weight monomers, during which double bonds are opened to form covalent bonds. Accordingly, a repeating fragment is formed from the monomers used. However, comb-like polymers can also be obtained by polymer-like reactions and graft copolymerization. In this case, the repeating main chain repeating fragment is considered to be a repeating fragment derived from a polyolefin macromonomer. The same applies to the preparation of comb-like polymers by graft polymerization.

Other details of the methods for producing comb polymers can be found in US 2010/0190671 and US 2008/0194443, both of which are incorporated herein by reference.

Comb-like polymers preferred for use in the present invention contain repeating fragments derived from polyolefin macromonomers. These repeating fragments contain at least one group derived from polyolefins. Examples of suitable polyolefins include C ₂ -C ₁₀ alkenes, such as ethylene, propylene, n-butene, isobutene, norbornene, and / or C ₄ -C ₁₀ alkadienes, such as butadiene, isoprene, norbornadiene, and the like.

Repeating fragments derived from polyolefin macromonomers preferably contain at least 70 weight. %, more preferably at least 80 weight. %, and most preferably at least 90 weight. % of groups derived from alkene and / or alkadiene, based on the weight of the repeating fragments obtained from polyolefin macromonomers.

Polyolefin groups may also be present in hydrogenated form. In addition to groups derived from alkenes and / or alkadienes, repeating fragments derived from polyolefin macromonomers may contain other groups. These include a small proportion of copolymerizable monomers, including, but not limited to, alkyl (meth) acrylates, styrene monomers, fumarates, maleates, vinyl esters and / or vinyl ethers. The proportion of these groups formed from copolymerizable monomers is preferably not more than 30 weight. %, more preferably not more than 15 weight. %, based on the weight of the repeating fragments obtained from polyolefin macromonomers. Repeating fragments derived from polyolefin macromonomers may contain starting groups and / or end groups that are formed upon functionalization or upon receipt of repeating fragments obtained from polyolefin macromonomers. The proportion of these initial groups and / or end groups is preferably not more than 30 weight. %, more preferably not more than 15 weight. %, based on the weight of the repeating fragments obtained from polyolefin macromonomers.

The number average molecular weight of the repeating fragments derived from the polyolefin macromonomers is preferably in the range of 500 to 50,000 g / mol, more preferably 700 to 10,000 g / mol, even more preferably 1,500 to 4,900 g / mol, and most preferably 2,000 to 3000 g / mol.

The melting point is preferably less than or equal to -10 ° C, more preferably less than or equal to -20 ° C, even more preferably less than or equal to -40 ° C, as measured by DSC. Most preferably, for repeating fragments derived from polyolefin macromonomers, it is not possible to measure the melting point by DSC.

In addition to repeating fragments derived from polyolefin macromonomers, comb-like polymers of the present invention contain repeating fragments derived from low molecular weight monomers selected from the group consisting of styrene monomers containing from 8 to 17 carbon atoms, alkyl (meth) acrylates containing from 1 to 10 carbon atoms in the alcohol group, vinyl esters containing from 1 to 11 carbon atoms in the acyl group, vinyl ethers containing from 1 to 10 carbon atoms in the alcohol group, di ( alkyl) fumarates containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl maleates containing from 1 to 10 carbon atoms in the alcohol group, and from a mixture of the listed monomers.

The molecular weight of the low molecular weight repeating fragments or low molecular weight monomers, preferably not more than 400 g / mol, more preferably not more than 200 g / mol, and most preferably not more than 150 g / mol.

Examples of styrene monomers containing from 8 to 17 carbon atoms are styrenes, substituted styrenes having an alkyl substituent in the side chain, for example alpha-methyl styrene and alpha-ethyl styrene, substituted styrenes having an alkyl substituent in the ring, such as vinyl toluene , p-methylstyrene, halogenated styrenes, for example monochlorostyrenes, dichlorostyrenes, tribromostyrenes and tetrabromostyrenes.

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

Preferred alkyl (meth) acrylates include from 1 to 8, more preferably from 1 to 4 carbon atoms in the alcohol group. The alcohol group in this case may be linear or branched.

Examples of vinyl esters containing from 1 to 11 carbon atoms in the acyl group include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate. Preferred vinyl esters contain from 2 to 9, more preferably from 2 to 5 carbon atoms in the acyl group. The acyl group in this case may be linear or branched.

Examples of vinyl ethers containing from 1 to 10 carbon atoms in the alcohol group include vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl butyl ether. Preferred vinyl ethers contain from 1 to 8, more preferably from 1 to 4 carbon atoms in the alcohol group. In this case, the alcohol group may be linear or branched.

The term “(di) ether” as used herein means that monoesters, diesters and mixtures of ethers, especially fumaric acid and / or maleic acid, can be used. (Di) alkyl fumarates containing from 1 to 10 carbon atoms in the alcohol group include monomethyl fumarate, dimethyl fumarate, monoethyl fumarate, diethyl fumarate, methyl ethyl fumarate, monobutyl fumarate, dibutyl fumarate, dipentyl fumarate and dihexyl fumarate. Preferred (di) fumarates contain from 1 to 8, more preferably from 1 to 4 carbon atoms in the alcohol group. In this case, the alcohol group may be linear or branched.

Di (alkyl) maleates containing from 1 to 10 carbon atoms in the alcohol group include monomethyl maleate, dimethyl maleate, monoethyl maleate, diethyl maleate, methyl ethyl maleate, monobutyl maleate, dibutyl maleate. Preferred (di) alkyl maleates contain from 1 to 8, more preferably from 1 to 4 carbon atoms in the alcohol group. In this case, the alcohol group may be linear or branched.

In addition to the repeating fragments described above, the comb-like polymers of the present invention may contain additional repeating fragments obtained from other comonomers, and their content is not more than 20 weight. %, preferably not more than 10 weight. %, and more preferably not more than 5 weight. %, based on the weight of the repeating fragments.

They also include repeating fragments derived from alkyl (meth) acrylates containing from 11 to 30 carbon atoms in the alcohol group, in particular from undecyl (meth) acrylate, 5-methylundecyl (meth) acrylate, dodecyl (meth) acrylate, 2- methyldodecyl (meth) acrylate, tridecyl (meth) acrylate, 5-methyltridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, 2-methylhexadecyl (meth) acrylate, heptadecyl (meth) acrylate, 5-isopropylheptadecyl (meth) acrylate, 4-tert-butyl octadecyl (meth) acrylate, 5-ethyl-octadecyl (meth) acrylate, 3-isopr opiloctadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, cetileicosyl (meth) acrylate, stearylacosyl (meth) acrylate, docosyl (meth) acrylate and / or eicosylate.

They also include repeating fragments derived from dispersing oxygen and nitrogen containing monomers, such as those listed in paragraphs [0036] - [0059] of US 2010/0190671, which is incorporated herein by reference.

Comb polymers suitable for use in the present invention preferably have a molar degree of branching in the range of 0.1 to 10 mol. %, more preferably from 0.3 to 6 mol. %, even more preferably from 0.3 to 1.1 mol. %, in particular from 0.4 to 1.0 mol. %, and most preferably from 0.4 to 0.6 mol. %

The molar degree of branching of comb-like polymers branch is calculated by the formula:

Where:

A represents the number of types of repeating fragments derived from polyolefin macromonomers,

B represents the number of types of repeating fragments derived from low molecular weight monomers selected from the group consisting of styrene monomers containing from 8 to 17 carbon atoms, alkyl (meth) acrylates containing from 1 to 10 carbon atoms in the alcohol group, vinyl esters containing from 1 to 11 carbon atoms in the acyl group, vinyl ethers containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl fumarates containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl maleates, containing from 1 up to 10 carbon atoms in the alcohol group, and from mixtures of the listed monomers,

n _a represents the number of repeating fragments derived from type a polyolefin macromonomers in a comb-like polymer molecule,

n _b represents the number of repeating fragments derived from low molecular weight monomers selected from the group consisting of styrene monomers containing from 8 to 17 carbon atoms, alkyl (meth) acrylates containing from 1 to 10 carbon atoms in the alcohol group, vinyl esters containing from 1 to 11 carbon atoms in the acyl group, vinyl ethers containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl fumarates containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl maleates, containing from 1 to 10 carbon volumes alcohol group, and mixtures of these monomers, the type b in the comb polymer molecule.

The molar degree of branching is generally determined by the ratio of monomers used if the comb-like polymer was obtained by copolymerization of low molecular weight and macromolecular monomers. For calculations in this case, the number average molecular weight of the macromonomer can be used.

If the comb-like polymer was obtained by a polymer-like reaction or graft copolymerization, the molar degree of branching is calculated by known methods from the conversion value.

A proportion of at least 80 weight. %, preferably at least 90 weight. % low molecular weight repeating fragments derived from monomers selected from the group consisting of styrene monomers containing from 8 to 17 carbon atoms, alkyl (meth) acrylates containing from 1 to 10 carbon atoms in the alcohol group, vinyl esters containing from 1 up to 11 carbon atoms in the acyl group, vinyl ethers containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl fumarates containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl maleates containing from 1 to 10 carbon atoms in alcohol group, and from a mixture of the listed monomers and repeating fragments obtained from polyolefin macromonomers, is calculated based on the weight of the repeating fragments. In addition to repeating fragments, polymers usually also contain initial groups and end groups, which are formed during the initiation and chain termination reactions. In one aspect of the present invention, the proportion of at least 80 weight. %, preferably at least 90 weight. %, low molecular weight repeating fragments obtained from monomers selected from the group consisting of styrene monomers containing from 8 to 17 carbon atoms, alkyl (meth) acrylates containing from 1 to 10 carbon atoms in the alcohol group, vinyl esters containing from 1 up to 11 carbon atoms in the acyl group, vinyl ethers containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl fumarates containing from 1 to 10 carbon atoms in the alcohol group, (di) alkyl maleates containing from 1 to 10 carbon atoms in alcohol group, and from a mixture of the listed monomers and repeating fragments obtained from polyolefin macromonomers, is calculated based on the weight of the repeating fragments.

A preferred comb-like polymer for use in the present invention contains 8-30 weight. %, more preferably 10-26 weight. % repeating fragments obtained from polyolefin macromonomers, based on the total weight of the repeating fragments.

Preferred comb polymers for use in the present invention include polymers having a weight average molecular weight Mw in the range of 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.

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

Preferred comb-like polymers used in the present invention have a polydispersity coefficient Mw / Mn in the range of 1 to 5, more preferably in the range of 2.5 to 4.5. The number average and weight average molecular weights can be determined by known methods, such as gel permeation chromatography (GPC).

In a particular aspect of the present invention, a preferred comb-like polymer has a low olefin double bond fraction. The iodine number is preferably less than or equal to 0.2 grams per gram of comb-like polymer, more preferably less than or equal to 0.1 grams per gram of comb-like polymer. This fraction 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 present invention, the lubricating composition comprises a comb-like polymer containing repeating fragments derived from n-butyl methacrylate and / or from n-butyl acrylate. Preferably, the proportion of repeating fragments derived from n-butyl methacrylate and / or from n-butyl acrylate is at least 50 weight. %, more preferably at least 60 weight. %, based on the total weight of the repeating fragments.

In a preferred embodiment of the present invention, the comb-shaped polymer comprises repeating moieties derived from styrene. The proportion of repeating fragments derived from styrene is preferably in the range from 0.1 to 30 weight. %, more preferably from 5 to 25 weight. %

In a preferred embodiment of the present invention, comb-like polymers contain repeating fragments derived from an alkyl (meth) acrylate containing 11-30 carbon atoms in an alkyl radical, preferably in an amount in the range from 0.1% to 15 weight. %, more preferably in the range from 1 to 10 weight. %

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

In another preferred embodiment, the comb-shaped polymer comprises repeating fragments derived from methyl methacrylate and repeating fragments derived from n-butyl methacrylate, preferably in a weight ratio of from 1: 1 to 0: 100, more preferably from 3: 7 to 0: one hundred.

A commercially available comb-like 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 selected from additives containing from 1 to 70 mol. % of one or more (meth) acrylate structural fragments having the formula (1) shown below.

In the formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched hydrocarbon group containing at least 16 carbon atoms, preferably at least 18 carbon atoms, more preferably at least 20 carbon atoms, and even more preferably a branched hydrocarbon group containing at least 20 carbon atoms.

These poly (meth) acrylate viscosity index improvers may be prepared without the use of a dispersant or with the use of a dispersant, but the latter are more preferred.

In poly (meth) acrylate viscosity index improvers, the proportion of (meth) acrylate structural moiety represented by formula (1) is preferably from 1 to 70 mol. %, more preferably not more than 60 mol. %, even more preferably not more than 50 mol. %, particularly preferably not more than 40 mol. %, and in particular not more than 30 mol. %; and preferably not less than 3 mol. %, more preferably not less than 5 mol. %, and even more preferably not less than 10 mol. %

Said viscosity index increasing poly (meth) acrylate additives may preferably be a copolymer of one or more monomers represented by formula (2) and a monomer other than that represented by formula (2).

In the formula (2), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched hydrocarbon group containing at least 16 carbon atoms.

Any monomer can be combined with a monomer of formula (2), and for example, a monomer having the following formula (3) is preferred.

The copolymer of formula (2) and formula (3) is a poly (meth) acrylate additive that increases the viscosity index, a non-dispersant type.

In the formula (3), R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents a linear or branched hydrocarbon group containing from 1 to 15 carbon atoms.

As another monomer for combination with a monomer of formula (2), one or more monomers having formula 4 or formula 5 are preferred.

In formula 4, R ⁵ represents a hydrogen atom or a methyl group, R ⁶ represents an alkylene group containing from 1 to 18 carbon atoms, E ¹ represents an amine or heterocyclic residue containing from 1 to 2 nitrogen atoms and from 0 to 2 oxygen atoms, and a is 0 or 1.

In formula 5, R ⁷ represents a hydrogen atom or a methyl group, E ² represents an amine or heterocyclic residue containing from 1 to 2 nitrogen atoms and from 0 to 2 oxygen atoms.

The copolymer of monomers having the formula (2), formula (4) and formula (5) is a poly (meth) acrylate additive that increases the viscosity index, dispersant type. This poly (meth) acrylate dispersant viscosity index improver may further comprise a monomer of formula (3) as a component.

Particular examples of the alkylene group R ⁶ in the formula (4) may include ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylen, dodecylene, tridecylene, hendecylene, hexadecylene, pentadecylene, g groups can be linear or branched).

Group E ¹ in formula (4) and group E ² in formula (5) may independently be dimethylamine, diethylamine, dipropylamine, dibutylamine, aniline, toluidine, xylidine, acetylamine, benzoylamine, morpholine, pyrrolyl, pyrrolidino, pyrrolidino, pyrrolidino, pyrrolidino, pyrrolidino, pyrrolidino, pyrrolidino, pyrrolidino, pyrrolidino, pyrrolidino , piperidinyl, quinolyl, pyrrolidonyl, pyrrolidine, imidazoline or pyrazine groups.

Preferred examples of monomers having the formulas (4) and (5) may include dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, diethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, morpholinomethylmethylene-methylene vinyl methylenediamine.

The molar ratio during copolymerization for a copolymer of monomers having the formula 2 and the formula 3-5 is not specifically limited, and the ratio of the monomer of the formula 2: the monomer of the formulas 3-5 is preferably from 10:90 to 40:60.

A viscosity index improver can be obtained, for example, by radical polymerization in solution of a mixture of monomers of formula (1) and formulas (3) - (5) in the presence of a polymerization initiator, such as benzoyl percoside.

As used herein, “PSSI” means the permanent shear stability index for a polymer, calculated from data measured in accordance with ASTM D 6278-02 taking ASTM D 6022-01 into account.

The PSSI of said poly (meth) acrylate viscosity index improver is preferably not more than 35, more preferably not more than 30, even more preferably not more than 25; and preferably not less than 5, more preferably not less than 10, and even more preferably less than 20, and in particular not less than 20.

The weight average molecular weight (M _w ) of the poly (meth) acrylate viscosity index improver is preferably not less than 10,000, more preferably not less than 50,000, even more preferably not less than 100,000, even more preferably not less than 150,000, and most preferably not less than 200,000 ; and preferably not more than 1,000,000, more preferably not more than 700,000, even more preferably not more than 600,000, and particularly preferably not more than 500,000.

The ratio of the weight average molecular weight to number average molecular weight for the poly (meth) acrylate viscosity index improver is preferably from 0.5 to 5.0, more preferably from 1.0 to 3.5, even more preferably from 1.5 to 3, and in particular from 1.7 to 2.5.

The ratio of weight average molecular weight to PSSI for a poly (meth) acrylate viscosity index improver is preferably not less than 0.8 × 10 ⁴ , more preferably not less than 1 × 10 ⁴ , even more preferably not less than 2 × 10 ⁴ , and still more preferably not less than 2.5 × 10 ⁴ .

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

A commercially available poly (meth) acrylate polymer suitable for use in the present invention is available from Sanyo Chemicals under the trade name Aclube 5110.

Another suitable viscosity index polymeric additive for use in the present invention is a styrene-diene hydrogenated copolymer.

An example of a commercially available styrene-diene hydrogenated copolymer suitable for use in the present invention is available from Infineum under the trade name Infineum SV600.

In preferred embodiments of the present invention, the weight ratio of one or more viscosity index increasing polymer additives to one or more monoesters or a mixture of monoesters is in the range of 1: 8 to 1:40, more preferably in the range of 1:10 to 1: thirty.

Typically, the lubricating compositions of the present invention are used (but are not necessarily limited to) in the viscosity ranges of SAE J300: OW-16, OW-20, 0W-30, OW-40, 5W-20, 5W-30 and 5W- 40, because these are brands that focus on fuel efficiency. As new SAE J300 viscosity grades are published with lower viscosity than the current 0W-16, the present invention will also be highly applicable to these new viscosity grades. The present invention can also be applied to higher viscosity grades.

The lubricating composition of the present invention preferably has a Noack volatility (according to ASTM D 5800) below 15 weight. % In a typical case, the volatility by the Noack method (according to ASTM D 5800) of the described composition is from 1 to 15 weight. %

The lubricating composition of the present invention additionally contains one or more additives, such as antioxidants, antiwear additives, dispersants, detergents, overbased detergents, extreme pressure additives, friction modifiers, viscosity index improvers, yield point additives, metal passivators, inhibitors corrosion, demulsifiers, antifoam agents, additives that enhance compatibility with the sealant and dilute base oils, etc.

Since those skilled in the art are familiar with the above and other additives, they are not discussed in more detail in this text. Particular examples of such additives are described, for example, in the book Kirk-Othmer Encyclopedia of Chemical Technology, third edition, volume 14, pages 477-526.

Antioxidants that can be used in the present invention include phenyl naphthylamines (such as "IRGANOX L-06", available from Ciba Specialty Chemicals) and diphenylamines (such as "IRGANOX L-57", available from Ciba Specialty Chemicals), described for example in WO 2007/045629 and EP 1058720 B1, phenolic antioxidants, etc. The provisions of documents WO 2007/045629 and EP 1058720 B1 are incorporated herein by reference.

Anti-wear additives that can be used according to the present invention include zinc-containing compounds, such as zinc dithiophosphate compounds selected from zinc dialkyl, diaryl and / or alkylaryl dithiophosphates, molybdenum-containing compounds, boron-containing compounds and ash-free anti-wear additives such as substituted or unsubstituted thiophosphoric acids and their salts.

Examples of such molybdenum-containing compounds may include molybdenum dithiocarbamates, molybdenum triatomic compounds, such as those described in WO 98/26030, molybdenum sulfides and molybdenum dithiophosphate.

Boron-containing compounds that can be used according to the present invention include borate esters, borate derivatives of fatty amines, borate derivatives of epoxides, borates of alkali metals (or mixtures of alkali metals or alkaline earth metals) and borate derivatives of superbasic metal salts.

The dispersant used is preferably an ashless dispersant. Suitable examples of ashless dispersants are polybutylene succinimide polyamines and Mannich base type dispersants.

The detergent used is preferably an overbased detergent additive or a mixture of detergent additives containing, for example, detergent additives of the salicylate, sulfonate and / or phenate type.

Examples of other types of viscosity index improvers that can be used in the lubricant composition of the present invention include styrene-butadiene star copolymers, styrene-isoprene star copolymers and polymethacrylate copolymers and ethylene-propylene copolymers (also known as olefin copolymers) of crystalline and non-crystalline type . In the lubricating composition of the present invention, a dispersant additive can be used to increase the viscosity index.

Preferably, the described composition contains at least 0.1 weight. % additive, reducing the yield point. As an example, as effective additives that reduce the yield point, you can use alkyl naphthalene and phenolic polymers, polymethacrylates, maleate / fumarate copolymer esters. Preferably, no more than 0.3 weight is used. % additive, reducing the yield point.

In addition, compounds such as alkenyl succinic acid or its ester derivatives, benzotriazole compounds and thiadiazole compounds can be used as corrosion inhibitors in the lubricating composition of the present invention.

Compounds such as polysiloxanes, dimethyl polycyclohexane and polyacrylates can be used as antifoam agents in the lubricating composition of the present invention.

Compounds that can be used in the lubricant composition of the present invention as additives to increase compatibility with the sealant include, for example, commercially available aromatic esters.

The lubricating compositions of the present invention can be prepared by mixing a base oil containing one or more monoesters or a mixture of monoesters and polymer additives that increase the viscosity index with, optionally, one or more additives.

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

Preferably, the described composition contains at least 9.0 weight. %, preferably at least 10.0 weight. %, more preferably at least 11.0 weight. % additive set including antiwear additive, metal cleaning additives, ashless dispersant and antioxidant.

The lubricating compositions of the present invention may be so-called “low-SAPS” (SAPS = sulfate ash, phosphorus and sulfur), “medium-SAPS” or “normal-SAPS” formulations.

For motor oils for passenger cars (RSMO), the above ranges mean:

- sulfate ash content (according to ASTM D 874) up to 0.5 weight. %, up to 0.8 weight. % and up to 1.5 weight. %, respectively;

- phosphorus content (according to ASTM D 5185) up to 0.05 weight. %, up to 0.08 weight. % and usually up to 0.1 weight. %, respectively; and

- sulfur content (according to ASTM D 5185) up to 0.2 weight. %, up to 0.3 weight. % and usually up to 0.5 weight. %, respectively.

For heavy duty diesel engine oils, the above ranges mean:

- the content of sulfate ashes (according to ASTM D 874) up to 1 weight. %, up to 1 weight. % and up to 2 weight. %, respectively;

- phosphorus content (according to ASTM D 5185) up to 0.08 weight. % (low-SAPS) and up to 0.12 weight. % (average SAPS), respectively; and

- sulfur content (according to ASTM D 5185) up to 0.3 weight. % (low-SAPS) and up to 0.4 weight. % (mid-SAPS), respectively.

In another aspect, the present invention describes the use of the lubricating composition of the present invention as a motor oil in an engine crankcase, in order to increase fuel economy. Motor oil may include engine oil for heavy-duty diesel vehicles, motor oil for cars, and other types of engine oils.

The present invention is described below with reference to the examples given, which in no way limit the scope of the present invention.

Examples

Lubricating compositions having the compositions shown in table 1 (examples 1-4) were prepared using traditional methods for the preparation of lubricants by mixing GTL base oils and monoester (Priolube 1544, commercially available from Croda International Pic.) With a set of additives and a polymer additive increasing viscosity index (either Viscoplex 3-201 comb polymer, commercially available from Evonik Industries, or Aclube V-5110 poly (meth) acrylate commercially available from Sanyo Chemicals).

1. The Fischer-Tropsch derived base oil having a kinematic viscosity at 100 ° C. of about 4 cSt, which can be obtained according to the method described in WO 02/070631.

2. A Fischer-Tropsch derived base oil having a kinematic viscosity at 100 ° C. of about 8 cSt, which can be obtained according to the method described in WO 02/070631.

3. Monoester from Croda International Pic.

4. Comb-like polymer from Evonik Industries.

5. Poly (meth) acrylate viscosity index improver from Sanyo Chemicals.

Lubricating compositions having the compositions shown in table 2 (examples 5-12) were prepared using traditional methods for the preparation of lubricants. The monoester used in examples 8, 9, 11 and 12 was sample 2 of WO 2009/130445. The viscosity index improvers used in Examples 6-12 were selected from Viscoplex 3-201 (comb-like polymer from Evonik Industries), Aclube 5110 (poly (meth) acrylate polymer from Sanyo Chemicals) and Infineum SV277 (hydrogenated styrene-diene copolymer from Infineum).

To demonstrate the improved fuel economy of the lubricant compositions of the present invention, Examples 5-9 were subjected to various tests, shown in Table 2 below.

Discussion

From table 2 it is seen that for this HTHS 150 (2.6) the addition of a polymer additive that increases the viscosity index increases the viscosity index and reduces the HTHS 100.

When selecting a comb-like polymer (such as Viscoplex 3-210) or a poly (meth) acrylate polymer with an optimized architecture (such as Aclube 5110), the viscosity index is higher and the HTHS 100 is lower. This leads to improved fuel economy (as can be seen in comparative example 7 and example 10).

When a monoester is added (Example 4 and 5, and Examples 7 and 8), the viscosity index increases further, and the HTHS 100 decreases. This leads to improved fuel economy (as can be seen in example 8 in comparison with comparative example 7).

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

Claims (18)

1. A lubricating composition for use in an engine crankcase, comprising: (i) a base oil containing at least one monoester or a mixture of monoesters, where the specified monoester or mixture of monoesters is present from the total weight of the lubricating composition in an amount of at least 10 wt.% and up to 75 wt.% and has a kinematic viscosity at 100 ° C not more than 4 mm ² / s, a viscosity index of at least 130 and evaporation losses, determined by the Noack method, not more than 20 wt.%; moreover, the base oil further comprises a Fischer-Tropsch derived base oil, and (ii) viscosity index increasing polymer additives that are present in an amount of dry polymer residue of from 0.1 wt.% to 7 wt.%, based on the weight of the lubricant composition, selected from (a) one or more comb-like polymers; (b) a poly (meth) acrylate polymer containing from 1 to 70 mol% of one or more (meth) acrylate structural fragments having the following formula (1)

, (one) where R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched hydrocarbon group containing at least 16 carbon atoms; (c) mixtures thereof, wherein said at least one monoester is a reaction product of a monohydric alcohol and a monocarboxylic acid, wherein said monohydric alcohol is at least one saturated branched aliphatic monohydric alcohol containing from 16 to 36 carbon atoms and wherein said monocarboxylic acid is at least one saturated linear aliphatic monocarboxylic acid containing from 5 to 10 carbon atoms. 2. The lubricating composition according to claim 1, wherein said monoester or mixture of monoesters has a kinematic viscosity at 100 ° C. of not more than 3.3 mm ² / s. 3. The lubricating composition according to claim 1, wherein said monoester or mixture of monoesters has an evaporation loss determined by the Noack method of not more than 15 wt.%. 4. The lubricating composition according to claim 1 or 2, where the polymer additive that increases the viscosity index is a comb-like polymer. 5. The lubricating composition according to claim 1 or 2, wherein said at least one monoester or a mixture of said monoesters has an apolarity coefficient of at least 90. 6. The lubricating composition according to claim 1 or 2, wherein said at least one monoester or a mixture of said monoesters has a pour point of no higher than -30 ° C. 7. The lubricating composition according to claim 1 or 2, wherein said at least one monoester or mixture of said monoesters has a kinematic viscosity at 100 ° C. of not more than 3.0 cSt and / or a viscosity index of at least 140 and / or a point yield no more than -35 ° C and / or evaporation loss, determined by the Noack method, not more than 15.0 wt.%. 8. The lubricating composition according to claim 1 or 2, wherein said alcohol is an alcohol that is branched at the β-position of the main carbon chain and which contains 20 carbon atoms. 9. The lubricating composition according to claim 1 or 2, wherein said acid is pentanoic acid and / or heptanoic acid. 10. The use of a lubricating composition according to any one of paragraphs. 1-9 in the crankcase, in order to increase fuel efficiency.