BR102018067829B1 - COMB-TYPE POLYMERS AND THEIR USE, ADDITIVE COMPOSITION AND ITS USE, LUBRICATING OIL COMPOSITION AND PROCESS FOR PREPARING COMB-TYPE POLYMERS - Google Patents

Abstract

The present invention is directed to polyalkyl(meth) acrylate-based comb-like polymers having weight average molecular weights of 700,000 g/mol or greater and number average molecular weights of 130,000 g/mol or greater, their preparation, lubricating compositions comprising such comb-like polymers and their use to improve the high shear and high temperature performance of lubricating compositions, especially of engine oil (EO) compositions.

Description

[001] The present invention is directed to comb-type polymers based on polyalkyl (meth) acrylate with weight average molecular weights of 700,000 g/mol or greater and number average molecular weights of 130,000 g/mol or greater, their preparation, compositions lubricants comprising such comb-like polymers and their use to improve the high shear and high temperature performance of lubricating compositions, especially of engine oil (EO) compositions.

[002] Global government vehicle regulations demand increasingly better fuel economy to reduce greenhouse gas emissions and conserve fossil fuels. There is a growing demand for more energy efficient vehicles to meet CO2 emissions targets. Therefore, any further improvement in fuel economy (FE) is of great importance in the automotive sector.

[003] Lubricants play an important role in reducing a vehicle's fuel consumption and there is a continuous need for improvements in fuel economy performance.

[004] Engine oil formulations are generally defined by the SAE J300 standard (SAE = Society of Mobility Engineers). This standard classifies engine oils into SAE xW-y viscosity grades where x = 0, 5, 10, 15, 20, 35 and y = 8, 12, 16, 20, 30, 40, 50, 60. That is carried out, for example, through the kinematic viscosity KV (ASTM D445) and the high shear high temperature viscosity HTHS (ASTM D4683, D4741 and D5471), where these parameters are important for engine protection.

[005] Lubricant properties are typically improved by adding additives to lubricating oils. Viscosity Index (VI) improvers are generally added to a lubricant to improve its thickening efficiency and to protect the engine.

[006] The thickening efficiency of a VI improver is specified by its KV1 00 (kinematic viscosity at 100 ° C) at a given treatment rate. A higher KV100 at the same treatment rate is considered beneficial for the net treatment cost and performance criteria. It is known that with an increase in thickening efficiency the stability of high shear and high temperature HTHS100 also increases, which means that a careful balance is necessary in the development of new VI improvers.

[007] The thickening effect of a polymer increases as its hydrodynamic volume in the oil increases. Increasing the temperature increases the solvency of the oil, which in turn promotes polymer unwinding and results in a larger hydrodynamic volume.

[008] The hydrodynamic volume of a polymer in solution depends on several parameters, such as, for example, the length and composition of the polymer chain (Stohr et al.: Lubricant and Fuel Additives Based on Polyalkylmethacrylates; Polymer Sciences: A Comprehensive Reference , Volume 10, set 10, 453 to 478). The longer a polymer chain, typically, the higher the weight average molecular weight Mw.

[009] Comb-type polymers are well known in the art for being efficient VI improvers.

[010] Document No. 5,565,130 discloses comb-type polymers and their use as viscosity index improvers. Practical examples comprise 10 to 80% macromonomer and 20 to 90% C1-10 alkyl (meth)acrylates that show Mw molecular weights in the range of 119,000 to 325,000 g/mol. Average molecular weights in Mn number are not mentioned and an effect of the presented comb-like polymers on thickening efficiency and HTHS performance is not revealed therein.

[011] Document in WO 2007/003238 A1 describes oil-soluble comb-type polymers based on polyolefin-based macromonomers, especially polybutadiene-based methacrylic esters and C1-C10 alkyl methacrylates. Practical examples comprise 37.2 to 53.3% macromonomer, 12.3 to 61% C1-4 alkyl (meth)acrylates and 12 to 42.6% styrene. The weight-average molecular weight Mw of practical examples is in the range of 79,000 to 402,000 g/mol and D ranges from 3.7 to 16.6.

[012] Comb-type polymers can be used as an additive to lubricating oils to improve the viscosity index and shear stability. However, an effect of the presented comb polymers on thickening efficiency and HTHS performance is not revealed therein.

[013] Document in U.S. 2010/0190671 discloses the use of comb-type polymers based on polyolefin-based macromonomers, especially polybutadiene-based methacrylic esters and C1-C10 alkyl methacrylates to improve the fuel consumption of motor vehicles. The weight-average molecular weight Mw of the practical examples is in the range of 191,000 to 374,000 g/mol and D varies between 35 and 4.5.

[014] Document in U.S. 2011/306533 discloses comb-like polymers comprising 40 to 80% by weight of repeating units derived from polyolefin-based macromonomers and 3 to 20% by weight of repeating units derived from dispersion monomers ( see practical examples) and their use as anti-fatigue additives. The weight-average molecular weight Mw of these comb-type polymers is generally defined as being in the range of 20,000 to 1,000,000 g/mol, more preferably 50,000 to 500,000 g/mol and most preferably 150,000 to 450,000 g/mol. The Mn number average molecular weight of these comb polymers is generally defined as being 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. Specific values for the practical examples are not revealed. Results are given only for fatigue performance studies.

[015] There is still additional need to improve the performance of KV100, HTHS 100 and HTHS 150 of a VI improver even further to meet the stronger formulation criteria for lubricating oil compositions and especially engine oil formulations.

[016] For example, according to SAE J300, the KV100 for a 0W20 engine oil formulation must be at least 6.9 mm2/s at a given HTHS150 of 2.6 mPa^s for sufficient engine protection. This means that HTHS100 and KV40 must be minimized for optimized fuel economy while KV100 must be maintained at > 6.9 mm2/s (6.9 cSt).

[017] Furthermore, the thickening efficiency in a given HTHS150 must be increased to reduce the treatment rate of a VI improver. If the thickening efficiency of a VI improver is high, then the treatment rate is low; that is, less polymer is needed to achieve the targeted HTHS150 value.

[018] This results in the following assumptions for an optimized VI improver: It must provide high thickening efficiency under given HTHS150 conditions, in order to maintain low treatment rate, minimum KV40 and HTHS100 in order to achieve the best results fuel economy where the KV100 must be well above the value as required by the J300 specifications.

[019] Typically, when VI improvers for excellent fuel economy performance are developed, the HTHS100 value is minimized, for example, in a 0W20 formulation at a given HTHS150 of 2.6 mPa^s. A typical effect that can be seen in this case is a parallel decrease in KV100 values due to the thickening at 100 °C being reduced in a manner parallel to the decrease in high shear high temperature thickening (HTHS) at 100 °C.

[020] This trend becomes visible in the prior art, for example, in Table 2 of document no US 2010/0190671 (see paragraph [0158]). In it, formulation examples are presented, which clearly show that HTHS100 values increase with increasing KV100 values at a given HTHS150 of 2.6 mPa^s. TABLE 2

[021] This trend is further illustrated by Figure 1, in which values of HTHS100 and KV100 from practical examples 1 to 5 of document in U.S. 2010/0190671 are plotted.

[022] Until now, this tendency could not be circumvented, for example, by using different monomers or varying the composition or structure of the VI enhancer polymer, and has therefore become a major obstacle in the development of new enhancers. of VI for improved fuel economy performance. A second negative side effect of reduced thickening at higher temperatures (100 to 150 °C) was that an increased treatment rate had to be used to achieve sufficient thickening at 150 °C (HTHS150) although satisfactory fuel economy was achieved. . Increasing the polymer treatment rate has a negative impact on commercial aspects such as treatment costs or technical aspects, e.g. increased deposit formation tendency, and is therefore a second important performance criterion in economy engine oils. of modern fuel.

[023] Now, it has surprisingly been found that an increase in the average molecular weight in number Mn has a greater influence on the performance (KV100, HTHS100) of a comb-type polymer based on polyalkyl (meth) acrylate than a high Mw has; that is, preparing polymers with only a high Mw does not result in the desired effect. This means that the performance of a polymer with a given composition can be improved by increasing Mn.

[024] If only Mw had been raised a completely different GPC spectrum would be obtained, instead of a switching of the maximum peak towards the higher molecular weight, in this case, mainly a broadening of the molecular weight distribution is obtained. Maximum peak switching for the inventive examples is illustrated by Figure 2.

[025] The correlation between Mw and Mn is generally defined by the polydispersity D which is calculated by the ratio of Mw to Mn. Typically, with higher Mw, the D distribution also becomes wider.

[026] Now, it has been found that for PAMA-based comb polymers with an average molecular weight in Mn number of at least 130,000 g/mol the thickening efficiency increases with increasing Mw, while at the same time, HTHS100 decreases ( for example, for a given HTHS150 of 2.6 mPa^s).

[027] In order to predict the performance of a PAMA-based comb polymer, the number average molecular weight has to be weighted more heavily than the weight average molecular weight.

[028] For example, a polymer that has a very high Mw and moderate Mn provides a similar HTHS result as a polymer with a moderate Mw, but with a very high Mn. Therefore, Mn must be rated at a higher power than Mw to achieve improved correlation with the HTHS performance of the combs.

[029] To predict the performance of a comb polymer in a lubricating oil formulation, a new "weighted" D is introduced as "P" variable and to account for the correlation between D and Mw a new formula was developed.

[030] The present invention used an empirical approach to better illustrate the relationship and it was found that by applying a factor for Mw that is below 1 (0.8), those number average molecular weights can be predicted, which results in the advantage of better performance for a modified PAMA-based comb-like polymer:

DETAILED DESCRIPTION OF THE INVENTION

[031] A first objective of the present invention is directed to comb-type polymers based on polyalkyl (meth) acrylate, which are characterized by a weight-average molecular weight Mw of 700,000 g/mol or greater and a number-average molecular weight Mn of 130,000 g/mol or greater.

[032] The weight-average molecular weight of the comb-type polymers based on polyalkyl (meth) acrylate, according to the present invention, is preferably in the range of 700,000 to 2,000,000 g/mol, more preferably in the range of 700,000 to 1,700 ,000 g/mol and especially preferably in the range of 700,000 to 1,300,000 g/mol and the number average molecular weight of the comb-like polymers based on polyalkyl(meth)acrylate, according to the present invention, is preferably in the range range of 130,000 to 300,000 g/mol, more preferably in the range of 130,000 to 220,000 g/mol and especially preferably in the range of 150,000 to 200,000 g/mol.

[033] The comb-type polymers based on polyalkyl (meth) acrylate, according to the present invention, are additionally characterized by a P value of 2 or less, preferably 1.5 or less, and even more preferably between 0.5 and 1.5.

[034] The P value is defined as additionally mentioned above: , preferably < 1.5 and even more preferably = 0.5 to 1.5

[035] Preferably, the comb-type polymers based on polyalkyl (meth) acrylate, according to the present invention, have a polydispersity index (D) Mw/Mn in the range of 3 to 10, more preferably in the range of 4 to 9.

[036] Mw and Mn are determined by size exclusion chromatography (SEC) using commercially available polymethyl methacrylate standards. The determination is carried out using gel permeation chromatography with THF as eluent.

[037] A first preferred objective of the present invention is directed to comb-like polymers based on polyalkyl (meth) acrylate, as mentioned additionally above, which comprise: (a) 10 to 30% by weight of an acid ester (meth) acrylic and a hydroxylated hydrogenated butadiene; (b) 50% to 80% by weight of C1-4 alkyl (meth)acrylates; (c) 5% to 20% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (d) 0% to 15% by weight of additional comonomers.

[038] The content of each component (a), (b), (c) and (d) is based on the total composition of the comb-type polymer based on polyalkyl (meth) acrylate.

[039] In a particular embodiment, the proportions of components (a), (b), (c) and (d) add up to 100% by weight.

[040] A comb-type polymer in the context of this invention comprises a first polymer, which is also called the main chain, and several additional polymers that are called side chains and are linked by covalent bond to the main chain. In the present example, the main chain of the comb-like polymer is formed by the interconnected unsaturated groups of the mentioned (meth)acrylates. The ester groups of the (meth)acrylic esters, the phenyl radicals of the styrene monomers, and the substituents of the additional free radical polymerizable comonomers form the side chains of the comb-like polymer.

[041] The term "acrylate" refers to acrylic acid esters; the term "methacrylate" refers to methacrylic acid esters; and the term "(meth)acrylate" refers to both acrylic acid esters and methacrylic acid esters.

[042] The hydrogenated and hydroxylated polybutadiene for use in accordance with the invention has an average molar mass in number Mn of 4,000 to 6,000 g/mol, preferably 4,500 to 5,000 g/mol. Due to their high molar mass, hydrogenated and hydroxylated polybutadienes can also be called macroalcohols in the context of this invention.

[043] The average molar mass in number Mn is determined by size exclusion chromatography using commercially available polybutadiene standards. The determination is carried out in DIN 55672-1 by gel permeation chromatography with THF as eluent.

[044] Preferably, the hydrogenated and hydroxylated polybutadiene has a hydrogenation level of at least 99%. An alternative measure of the level of hydrogenation that can be determined in the copolymer of the invention is the iodine number. The iodine number refers to the number of grams of iodine that can be added in 100 g of copolymer. Preferably, the copolymer of the invention has an iodine number of no more than 5 g of iodine per 100 g of copolymer. The iodine number is determined by the Wijs method in accordance with DIN 53241-1:199505.

[045] Preferred hydrogenated and hydroxylated polybutadienes can be obtained according to document GB 2270317.

[046] Some hydrogenated and hydroxylated polybutadienes are also commercially available. Commercial hydrogenated and hydroxylated polybutadienes include, for example, an OH-functional hydrogenated polybutadiene to a degree of about 98% by weight (also called OCP olefin copolymer) that is each about 50% 1.2 units. of repeat and 1.4 repeat units, of Mn = 4,200 g/mol, from Cray Valley (Paris), a company belonging to Total (Paris).

[047] Preference is given to monohydroxylated hydrogenated polybutadienes. More preferably, the hydrogenated and hydroxylated polybutadiene is a hydroxyethyl or hydroxypropyl terminated hydrogenated polybutadiene. Particular preference is given to hydroxypropyl-terminated polybutadienes.

[048] These monohydroxylated hydrogenated polybutadienes can be prepared by first converting monomers through anionic polymerization into polybutadiene. Subsequently, by reacting polybutadiene monomers with ethylene oxide or propylene oxide, a hydroxy-functional polybutadiene can be prepared. Such hydroxylated polybutadiene can be hydrogenated in the presence of a suitable transition metal catalyst.

[049] The (meth)acrylic acid esters for use in accordance with the invention, and a hydrogenated and hydroxylated polybutadiene described, are also called macromonomers in the context of this invention, due to their high molar mass.

[050] Macromonomers for use in accordance with the invention can be prepared through transesterification of alkyl (meth) acrylates. The reaction of alkyl (meth)acrylate with hydrogenated and hydroxylated polybutadiene forms the ester of the invention. Preference is given to the use of methyl (meth)acrylate or ethyl (meth)acrylate as a reagent.

[051] This transesterification is widely known. For example, it is possible for this purpose to use a heterogeneous catalyst system, such as a mixture of lithium hydroxide/calcium oxide (LiOH/CaO), pure lithium hydroxide (LiOH), lithium methoxide (LiOMe) or lithium methoxide. sodium (NaOMe), or a homogeneous catalyst system, such as isopropyl titanate (Ti(OiPr)4) or dioctyltin oxide (Sn(OCt)2O). The reaction is an equilibrium reaction. Therefore, the low molecular weight alcohol released is typically removed, for example, through distillation.

[052] Additionally, macromonomers can be obtained through a direct esterification procedure, for example, from (meth)acrylic acid or (meth)acrylic anhydride, preferably under acid catalysis through p-toluenesulfonic acid or methanesulfonic acid, or from free methacrylic acid using the DCC (dicyclohexylcarbodiimide) method.

[053] Furthermore, the present hydrogenated and hydroxylated polybutadiene can be converted into an ester through reaction with an acid chloride, such as (meth) acryloyl chloride.

[054] Preferably, in the preparations detailed above of the esters of the invention, polymerization inhibitors are used, for example, the 4-hydroxy-2,2,6,6-tetramethylpiperidine-oxyl radical and/or hydroquinone-monomethyl ether.

[055] C1-4 alkyl (meth)acrylates for use in accordance with the invention are esters of (meth)acrylic acid and straight-chain or branched alcohols having from 1 to 4 carbon atoms. The term "C1-4 alkyl methacrylates" encompasses individual (meth)acrylic esters with an alcohol of a particular length and, likewise, mixtures of (meth)acrylic esters with alcohols of different lengths.

[056] Suitable C1-4 alkyl (Meth)acrylates include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate and tert-butyl (meth)acrylate. Particularly preferred C1-4 alkyl (meth)acrylates are methyl (meth)acrylate and n-butyl (meth)acrylate; methyl methacrylate, n-butyl methacrylate and n-butyl acrylate are especially preferred.

[057] C10-30 alkyl (meth)acrylates for use in accordance with the invention are esters of (meth)acrylic acid and straight-chain or branched alcohols having from 10 to 30 carbon atoms. The term "C10-30 alkyl methacrylates" encompasses individual (meth)acrylic esters with an alcohol of a particular length and, likewise, mixtures of (meth)acrylic esters with alcohols of different lengths.

[058] Suitable C10-30 alkyl (Meth)acrylates include, for example, 2-butyloctyl (meth)acrylate, 2-hexyloctyl (meth)acrylate, decyl (meth)acrylate, 2- butyldecyl, 2-hexyldecyl (meth)acrylate, 2-octyldecyl (meth)acrylate, undecyl (meth)acrylate, 5-methylundecyl (meth)acrylate, dodecyl (meth)acrylate, 2-methyldodecyl (meth)acrylate , 2-hexyldodecyl (meth)acrylate, 2-octyldodecyl (meth)acrylate, tridecyl (meth)acrylate, 5-methyltridecyl (meth)acrylate, tetradecyl (meth)acrylate, 2-decyltetradecyl (meth)acrylate , pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, 2-methylhexadecyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, heptadecyl (meth)acrylate, 5 -isopropylheptadecyl, 4-tert-butyloctadecyl (meth)acrylate, 5-ethyloctadecyl (meth)acrylate, 3-isopropyloctadecyl (meth)acrylate, octadecyl (meth)acrylate, 2-decyloctadecyl (meth)acrylate, 2- tetradecyloctadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, cetyleicosyl (meth)acrylate, stearyleicosyl (meth)acrylate, docosyl (meth)acrylate and/or (meth)acrylate of eicosyltetratriacontlia. 2-decyl-tetradecyl (meth)acrylate, 2-decyloctadecyl (meth)acrylate, 2-dodecyl-1-hexadecyl (meth)acrylate, 1,2-octyl-1-dodecyl (meth)acrylate, (meth) )2-tetradecylocadecyl acrylate, 1,2-tetradecyl-octadecyl (meth)acrylate and 2-hexadecyl-eicosyl (meth)acrylate.

[059] C10-15 alkyl methacrylates for use in accordance with the invention are esters of methacrylic acid and alcohols having 10 to 15 carbon atoms. The term "C10-15 alkyl methacrylates" encompasses individual methacrylic esters with an alcohol of a particular length and, likewise, mixtures of methacrylic esters with alcohols of different lengths.

[060] Suitable C10-15 alkyl methacrylates include, for example, decyl methacrylate, undecyl methacrylate, 5-methylundecyl methacrylate, dodecyl methacrylate, 2-methyldodecyl methacrylate, tridecyl methacrylate, 5-methyltridecyl methacrylate, tetradecyl methacrylate and/or pentadecyl methacrylate.

[061] Particularly preferred C10-15 alkyl methacrylates are methacrylic esters of a mixture of C12-14 linear alcohol (C12-14 alkyl methacrylate).

[062] Comonomers that can be used in accordance with the present invention are selected from the group consisting of styrene monomers having from 8 to 17 carbon atoms, vinyl esters having from 1 to 11 carbon atoms in the acyl group , vinyl ethers that have 1 to 10 carbon atoms in the alcohol group, nitrogen and oxygen dispersing monomers, heterocyclic (meth)acrylates, heterocyclic vinyl compounds and monomers that contain a phosphorus atom linked by a covalent bond.

[063] Suitable styrene monomers having 8 to 17 carbon atoms are selected from the group consisting of styrene, 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 on the ring, such as vinyl toluene and para-methyl styrene, halogenated styrenes, for example, monochlorostyrenes, dichlorostyrenes, tribromostyrenes and tetrabromostyrenes; where styrene is preferred.

[064] Suitable vinyl esters that have from 1 to 11 carbon atoms in the acyl group are selected from the group consisting of vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate; preferably, vinyl esters that include from 2 to 9, more preferably from 2 to 5 carbon atoms in the acyl group, wherein the acyl group may be linear or branched.

[065] Suitable vinyl ethers having from 1 to 10 carbon atoms in the alcohol group are selected from the group consisting of vinylmethyl ether, vinylethyl ether, vinylpropyl ether, vinylbutyl ether; preferably, vinyl ethers that include from 1 to 8, more preferably from 1 to 4 carbon atoms in the alcohol group, wherein the alcohol group may be linear or branched.

[066] Suitable monomers that are derived from dispersant nitrogen and oxygen function monomers are selected from the group consisting of aminoalkyl (Meth)acrylates, such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl, N,N-diethylaminopentyl (meth)acrylate, N,N-dibutylaminohexadecyl (meth)acrylate; aminoalkyl(meth)acrylamides, such as N,N-dimethylaminopropyl(meth)acrylamide; Hydroxyalkyl (meth)acrylates, such as 3-hydroxypropyl (meth)acrylate, 3,4-dihydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, ( 2,5-dimethyl-1,6-hexanediol meth)acrylate, 1,10-decanediol (meth)acrylate; C1-8-alkyloxy-C2-4-alkyl (meth)acrylates, such as methoxypropyl (meth)acrylate, methoxy-butyl (meth)acrylate, methoxyheptyl (meth)acrylate, methoxy (meth)acrylate -hexyl, methoxy-pentyl (meth)acrylate, methoxy-octyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, ethoxy-butyl (meth)acrylate, ethoxy (meth)acrylate -heptyl, ethoxyhexyl (meth)acrylate, ethoxypentyl (meth)acrylate, ethoxyoctyl (meth)acrylate, proximethyl (meth)acrylate, proxiethyl (meth)acrylate, proxipropyl (meth)acrylate, proximethyl (meth)acrylate proxibutyl, proxiheptyl (meth)acrylate, proxihexyl (meth)acrylate, proxipentyl (meth)acrylate, proxioctyl (meth)acrylate, butoxymethyl (meth)acrylate, butoxyethyl (meth)acrylate, (met )butoxypropyl acrylate, butoxybutyl (meth)acrylate, butoxyheptyl (meth)acrylate, butoxyhexyl (meth)acrylate, butoxypentyl (meth)acrylate and butoxyoctyl (meth)acrylate, where (meth)acrylate ethoxyethyl and butoxyethyl (meth)acrylate are preferred.

[067] Suitable heterocyclic (Meth)acrylates are selected from the group consisting of 2-(1-imidazolyl)ethyl (meth)acrylate, 2-(4-morpholinyl)ethyl (meth)acrylate, 1-(2 -methacryloyloxyethyl)-2-pyrrolidone, N-methacryloylmorpholine, N-methacryloyl-2-pyrrolidinone, N-(2-methacryloyloxyethyl)-2-pyrrolidinone, N-(3-methacryloyloxypropyl)-2-pyrrolidinone.

[068] Suitable heterocyclic vinyl compounds are selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine, 2,3-dimethyl-5-vinylpyridine , vinylpyrimidine, vinylpiperidine, 9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole, 1-vinylimidazole, 2-methyl-1-vinylimidazole, N-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinylpyrrolidine, N-vinyl-caprolactam, N-vinylbutyrolactam , vinyloxolane, vinylfuran, vinyloxazoles and hydrogenated vinyloxazoles.

[069] Monomers containing a covalently bonded phosphorus atom are selected from the group consisting of 2-(dimethylphosphate)propyl (meth)acrylate, 2-(ethylenephosphite)propyl (meth)acrylate, (meth) dimethylphosphinomethyl acrylate, dimethylphosphonoethyl (meth)acrylate, diethyl(meth)acryloyl phosphonate, dipropyl(meth)acryloyl phosphate, 2-(dibutylphosphono)ethyl (meth)acrylate, diethylphosphateethyl (meth)acrylate, (meth)acrylate 2-(dimethylphosphate)-3-hydroxypropyl, 2-(ethylenephosphite)-3-hydroxypropyl (meth)acrylate, 3-(meth)acryloyloxy-2-hydroxypropyl diethylphosphonate, 3-(meth)acryloyloxy-2- dipropylphosphonate hydroxypropyl, 3-(dimethylphosphate)-2-hydroxypropyl (meth)acrylate, 3-(ethylenephosphite)-2-hydroxypropyl (meth)acrylate, 2-(meth)acryloyloxy-3-hydroxypropyl diethylphosphonate, 2-(dipropylphosphonate) meth)acryloyloxy-3-hydroxypropyl and 2-(dibutylphosphono)-3-hydroxypropyl (meth)acrylate.

[070] A second object of the present invention is directed to comb-like polymers based on polyalkyl (meth) acrylate, which are characterized by a weight-average molecular weight Mw of 700,000 g/mol or greater and a number-average molecular weight Mn of 130,000 g/mol or greater, comprising: (a) 10 to 25% by weight of a (meth)acrylic acid ester and a hydroxylated hydrogenated butadiene; (b) 0% to 5% by weight C4-18 alkyl acrylates; (c) 0% to 0.3% by weight methyl methacrylate; (d) 60% to 75% by weight n-butyl methacrylate; (e) 5% to 20% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (f) 0% to 2% by weight of styrene monomers.

[071] A second preferred objective of the present invention is directed to comb-like polymers based on polyalkyl (meth) acrylate, which are characterized by a weight average molecular weight Mw of 700,000 g/mol or greater and a number average molecular weight Mn of 130,000 g/mol or greater, which comprises: (a) 10 to 25% by weight of a (meth)acrylic acid ester and a hydroxylated hydrogenated butadiene; (b) 0% to 5% by weight C4-18 alkyl acrylates; (c) 0% to 0.3% by weight methyl methacrylate; (d) 65% to 75% by weight n-butyl methacrylate; (e) 10% to 15% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (f) 0% to 2% by weight of styrene monomers.

[072] The content of each component (a), (b), (c), (d), (e) and (f) is based on the total composition of the comb-type polymer based on polyalkyl (meth) acrylate.

[073] In a particular embodiment, the proportions of components (a), (b), (c), (d), (e) and (f) add up to 100% by weight.

[074] C4-18 alkyl acrylates for use in accordance with the invention are esters of acrylic acid and alcohols that have 4 to 18 carbon atoms. The term "C4-18 alkyl acrylates" encompasses individual acrylic esters with an alcohol of a particular length and, likewise, mixtures of acrylic esters with alcohols of different lengths.

[075] Suitable C4-18 alkyl acrylates include, for example, butyl acrylate, pentyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, heptyl acrylate, 2-tert-butylheptyl acrylate, octyl acrylate, 3-isopropylheptyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, 5-methylundecyl acrylate, dodecyl acrylate, 2-methyldodecyl acrylate, tridecyl acrylate, 5-methyltridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, 2-methylhexadecyl acrylate, heptadecyl acrylate and/or octadecyl acrylate.

[076] Particularly preferred C4-18 alkyl acrylates are butyl acrylate, especially n-butyl acrylate, and acrylic esters of a mixture of C16-18 linear alcohol (C16-18 alkyl acrylate).

[077] Polyalkyl (meth) acrylate-based comb polymers for use in accordance with the invention can be characterized on the basis of their level of molar branching ("f-branching"). The molar branching level refers to the mol% percentage of macromonomers (component (a)) used, based on the total molar quantity of all monomers in the monomer composition. The molar quantity of the macromonomers used is calculated on the basis of the average molar mass in number Mn of the macromonomers. The branch level calculation is described in detail in the document in WO 2007/003238 A1, especially on pages 13 and 14, to which reference is made explicitly here.

[078] The comb-type polymers based on polyalkyl (meth) acrylate according to the invention preferably have a molar degree of branching of 0.1 to 2 mol%, more preferably 0.3 to 1.5% in mol and most preferably 0.5 to 1.0% in mol.

[079] The molar degree of branching is calculated as described in the document in U.S. 2010/0190671 A1 in paragraphs [0060] to [0065].

[080] The polymers according to the present invention are characterized by their contribution to low values of KV40, HTHS80 and HTHS100 (for example, at a given HTHS150 of 2.6 mPa^s) of lubricating oil compositions comprising the same.

[081] The polyalkyl (meth) acrylate-based comb polymers according to the present invention can therefore be used in all common grades of engine oils that have the viscosity characteristics defined in the SAE J300 document.

[082] A further objective of the present invention is therefore directed to the use of polyalkyl(meth)acrylate-based comb-like polymers, in accordance with the present invention, to improve the kinematic viscosity and HTHS performance of lubricating oil compositions. , especially from engine oil formulations.

[083] A further objective of the present invention is directed to a method for improving the kinematic viscosity and HTHS performance of lubricating oil compositions, especially engine oil formulations, by adding polyalkyl (meth)-based comb polymers acrylate, according to the present invention.

[084] An additional objective of the present invention is directed to the use of comb-type polymers based on polyalkyl (meth) acrylate, according to the present invention, to increase KV100 and, in parallel, decrease HTHS100 and HTHS80 of lubricating oil compositions , especially from engine oil formulations (when formulated at a HTHS150 set, for example, to HTHS150 of 2.6 mPa^s for a 0W20 formulation).

[085] A further object of the present invention is directed to a method of increasing KV100 and, in parallel, decreasing HTHS100 and HTHS80 of lubricating oil compositions, especially of engine oil formulations (when formulated at a defined HTHS150, e.g. for HTHS150 of 2.6 mPa^s for a 0W20 formulation), adding comb-type polymers based on polyalkyl (meth) acrylate, according to the present invention.

[086] A third objective of the present invention is directed to an additive composition comprising: (A) a base oil and (B) a comb-type polymer based on polyalkyl (meth) acrylate, which is characterized by a weight molecular weight average Mw of 700,000 g/mol or greater and a number average molecular weight Mn of 130,000 g/mol or greater.

[087] A third preferred objective of the present invention is directed to an additive composition, as mentioned above, in which the weight-average molecular weight Mw of the polyalkyl (meth) acrylate-based comb-type polymer is preferably in the range of 700,000 to 2,000. 000 g/mol, more preferably in the range of 700,000 to 1,700,000 g/mol, especially preferably in the range of 700,000 to 1,300,000 g/mol and the average molecular weight in Mn number is in the range of 130,000 to 300,000 g/mol mol, even more preferably in the range of 130,000 to 220,000 g/mol and especially preferably in the range of 150,000 to 200,000 g/mol.

[088] A third additional preferred objective of the present invention is directed to an additive composition, characterized by the fact that the comb-like polymer based on polyalkyl (meth) acrylate (B) is additionally characterized by a P value of 2 or less, preferably 1.5 or less, and even more preferably between 0.5 and 1.5.

[089] The P value is defined as additionally mentioned above: , preferably < 1.5 and even more preferably = 0.5 to 1.5

[090] A third additional preferred objective of the present invention is directed to an additive composition, characterized by the fact that the comb-like polymer based on polyalkyl (meth) acrylate (B) comprises the following monomers: (a) 10 to 30% by weight of an ester of (meth)acrylic acid and a hydroxylated hydrogenated butadiene; (b) 50% to 80% by weight of C1-4 alkyl (meth)acrylates; (c) 5% to 20% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (d) 0% to 15% by weight of additional comonomers.

[091] The content of each component (A) and (B) is based on the total weight of the additive composition.

[092] In a particular embodiment, the proportions of components (A) and (B) add up to 100% by weight.

[093] The content of each component (a), (b), (c) and (d) is based on the total composition of the comb-type polymer based on polyalkyl (meth) acrylate.

[094] In a particular embodiment, the proportions of components (a), (b), (c) and (d) add up to 100% by weight.

[095] The base oil to be used in the additive composition comprises an oil of lubricating viscosity. Such oils include natural and synthetic oils, oil derived from hydrocracking, hydrogenation and hydrofinalization, unrefined, refined, re-refined oils or mixtures thereof.

[096] Base oil may also be defined as specified by the American Petroleum Institute (API) (see the April 2008 version of "Appendix E-API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils", section 1.3 Sub-heading 1.3. "Base Stock Categories").

[097] The API currently defines five groups of basic lubricant stocks (API 1509, Annex E - API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils, September 2011). Groups I, II and III are mineral oils that are classified by the amount of saturates and sulfur they contain and by their viscosity indexes; Group IV are poly-alpha-olefins; and Group V are all others, including, for example, ester oils. The Table below illustrates these API classifications.

[098] The kinematic viscosity at 100 ° C (KV100) of suitable non-polar base oils used to prepare an additive composition or lubricating composition, in accordance with the present invention, is preferably in the range of 3 mm2 / s to 10 mm2 / s, more preferably in the range of 4 mm2/s to 8 mm2/s, in accordance with ASTM D445.

[099] Additional base oils that can be used in accordance with the present invention are Group II-III Fischer-Tropsch derived base oils.

[0100] Fischer-Tropsch derived base oils are known in the art. The term "Fischer-Tropsch derivative" means that a base oil is, or is derived from, a synthesis product of a Fischer-Tropsch process. A Fischer-Tropsch derived base oil may also be called a GTL (Gas to Liquids) base oil. Suitable Fischer-Tropsch derived base oils which may conveniently be used as the base oil in the lubricating composition of the present invention are those as, for example, disclosed in documents in EP 0,776,959, EP 0,668,342, 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 1,029,029, WO 01/18156, WO 01/57166 and WO 2013/189951.

[0101] Especially for engine oil formulations, API Group III base oils are used.

[0102] The additive composition of the present invention preferably comprises 60% to 80% by weight, more preferably 70% to 75% by weight, of the base oil (A) and 20% to 40% by weight, more preferably 25% to 30% by weight of the comb-like polymer based on polyalkyl (meth) acrylate (B), based on the total weight of the additive composition.

[0103] A fourth objective of the present invention is directed to an additive composition comprising: (A) 60 to 80% by weight, preferably 70 to 75% by weight, of a base oil and (B) 20 to 40% by weight weight, preferably 25 to 30% by weight, of a comb-like polymer based on polyalkyl(meth)acrylate, which is characterized by a weight-average molecular weight Mw of 700,000 g/mol or greater and a number-average molecular weight Mn of 130,000 g/mol or greater, comprising the following monomers: (a) 10 to 25% by weight of a (meth)acrylic acid ester and a hydroxylated hydrogenated butadiene; (b) 0% to 5% by weight C4-18 alkyl acrylates; (c) 0% to 0.3% by weight methyl methacrylate; (d) 60% to 75% by weight n-butyl methacrylate; (e) 5% to 20% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (f) 0% to 2% by weight of styrene monomers.

[0104] A fourth preferred objective of the present invention is directed to an additive composition, as described in the fourth objective, characterized by the fact that the comb-like polymer based on polyalkyl (meth) acrylate (B) comprises the following monomers: (a ) 10 to 25% by weight of an ester of (meth)acrylic acid and a hydroxylated hydrogenated butadiene; (b) 0% to 5% by weight C4-18 alkyl acrylates; (c) 0% to 0.3% by weight methyl methacrylate; (d) 65% to 75% by weight n-butyl methacrylate; (e) 10% to 15% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (f) 0% to 2% by weight of styrene monomers.

[0105] A fourth additional preferred objective of the present invention is directed to an additive composition, as mentioned above, in which the weight average molecular weight Mw of the polyalkyl (meth) acrylate-based comb-like polymer is preferably in the range of 700,000 to 2,000 ,000 g/mol, more preferably in the range of 700,000 to 1,700,000 g/mol, especially preferably in the range of 700,000 to 1,300,000 g/mol and the average molecular weight in Mn number is in the range of 130,000 to 300,000 g /mol, even more preferably in the range of 130,000 to 220,000 g/mol and especially preferably in the range of 150,000 to 200,000 g/mol.

[0106] A fourth additional preferred objective of the present invention is directed to an additive composition, characterized by the fact that the comb-like polymer based on polyalkyl (meth) acrylate (B) is further characterized by a P value of 2 or less, preferably 1.5 or less, and even more preferably between 0.5 and 1.5.

[0107] The P value is defined as further mentioned above: , preferably < 1.5 and even more preferably = 0.5 to 1.5

[0108] Additive compositions are characterized by their contribution to kinematic viscosity and HTHS performance of lubricating oil compositions.

[0109] A further object of the present invention is therefore directed to the use of an additive composition, according to the present invention, to improve the kinematic viscosity and HTHS performance of lubricating oil compositions, especially of engine oil formulations. .

[0110] A further object of the present invention is directed to a method for improving the kinematic viscosity and HTHS performance of lubricating oil compositions, especially engine oil formulations, by adding an additive composition, in accordance with the present invention. .

[0111] A further object of the present invention is directed to the use of an additive composition, according to the present invention, to increase KV100 and, in parallel, decrease HTHS100 of lubricating oil compositions, especially of engine oil formulations (when formulated at a defined HTHS150, for example, for HTHS150 of 2.6 mPa^s for a 0W20 formulation).

[0112] A further object of the present invention is directed to a method of increasing KV100 and, in parallel, decreasing HTHS100 of lubricating oil compositions, especially of engine oil formulations (when formulated in an HTHSi50 defined, for example, for HTHS150 of 2.6 mPa^s for a 0W20 formulation), adding an additive composition according to the present invention.

[0113] A fifth object of the present invention is directed to a lubricating oil composition comprising: (A) 80 to 99.5% by weight of a base oil; (B) 0.5 to 5% by weight of a comb-like polymer based on polyalkyl(meth)acrylate, which is characterized by a weight-average molecular weight Mw of 700,000 g/mol or greater and a number-average molecular weight Mn of 130,000 g/mol or greater; and (C) 0 to 15% by weight of one or more additional additives.

[0114] A fifth preferred objective of the present invention is directed to a lubricating oil composition, in which the comb-like polymer based on polyalkyl (meth) acrylate (B) comprises: (a) 10 to 30% by weight of an ester of (meth)acrylic acid and a hydroxylated hydrogenated butadiene; (b) 50% to 80% by weight of C1-4 alkyl (meth)acrylates; (c) 5% to 20% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (d) 0% to 15% by weight of additional comonomers.

[0115] The content of each component (A), (B) and (C) is based on the total composition of the lubricating oil composition.

[0116] In a particular embodiment, the proportions of components (A), (B) and (C) add up to 100% by weight.

[0117] The content of each component (a), (b), (c) and (d) is based on the total composition of the comb-type polymer based on polyalkyl (meth) acrylate.

[0118] In a particular embodiment, the proportions of components (a), (b), (c) and (d) add up to 100% by weight.

[0119] A fifth additional preferred objective of the present invention is directed to an additive composition, as mentioned above, in which the weight average molecular weight Mw of the polyalkyl (meth) acrylate-based comb-like polymer is preferably in the range of 700,000 to 2,000 ,000 g/mol, more preferably in the range of 700,000 to 1,700,000 g/mol, especially preferably in the range of 700,000 to 1,300,000 g/mol and the average molecular weight in Mn number is in the range of 130,000 to 300,000 g /mol, even more preferably in the range of 130,000 to 220,000 g/mol and especially preferably in the range of 150,000 to 200,000 g/mol.

[0120] A fifth additional preferred objective of the present invention is directed to an additive composition, characterized by the fact that the polyalkyl (meth) acrylate-based comb-like polymer (B) is further characterized by a P value of 2 or less, preferably 1.5 or less, and even more preferably between 0.5 and 1.5.

[0121] The P value is defined as additionally mentioned above: preferably < 1.5 and even more preferably = 0.5 to 1.5.

[0122] A sixth object of the present invention is directed to a lubricating oil composition comprising: (A) 80 to 99.5% by weight of a base oil; (B) 0.5 to 5% by weight of a comb-like polymer based on polyalkyl(meth)acrylate, which is characterized by a weight-average molecular weight Mw of 700,000 g/mol or greater and a number-average molecular weight Mn of 130,000 g/mol or greater, which comprises the following monomers: (a) 10 to 25% by weight of an ester of (meth)acrylic acid and a hydroxylated hydrogenated butadiene; (b) 0% to 5% by weight C4-18 alkyl acrylates; (c) 0% to 0.3% by weight methyl methacrylate; (d) 60% to 75% by weight n-butyl methacrylate; (e) 5% to 20% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (f) 0% to 2% by weight of styrene monomers; and (C) 0 to 15% by weight of one or more additional additives.

[0123] A sixth preferred objective of the present invention is directed to a lubricating oil composition, in which the comb-like polymer based on polyalkyl (meth) acrylate (B) comprises: (a) 10 to 25% by weight of an ester of (meth)acrylic acid and a hydroxylated hydrogenated butadiene; (b) 0% to 5% by weight C4-18 alkyl acrylates; (c) 0% to 0.3% by weight methyl methacrylate; (d) 65% to 75% by weight n-butyl methacrylate; (e) 10% to 15% by weight of C10-30 alkyl (meth)acrylates, preferably C10-15 alkyl methacrylates, more preferably C12-14 alkyl methacrylates; and (f) 0% to 2% by weight of styrene monomers.

[0124] A sixth additional preferred object of the present invention is directed to a lubricating oil composition, as mentioned above, in which the weight average molecular weight Mw of the polyalkyl (meth) acrylate-based comb-like polymer is preferably in the range of 700,000 to 2,000,000 g/mol, more preferably in the range of 700,000 to 1,700,000 g/mol, especially preferably in the range of 700,000 to 1,300,000 g/mol and the average molecular weight in Mn number is in the range of 130,000 to 300,000 g/mol, even more preferably in the range of 130,000 to 220,000 g/mol and especially preferably in the range of 150,000 to 200,000 g/mol.

[0125] A sixth additional preferred objective of the present invention is directed to a lubricating oil composition, as mentioned above, characterized by the fact that the comb-like polymer based on polyalkyl (meth) acrylate (B) is further characterized by a value P of 2 or less, preferably 1.5 or less, and even more preferably between 0.5 and 1.5.

[0126] The P value is defined as additionally mentioned above: , preferably < 1.5 and even more preferably = 0.5 to 1.5

[0127] The lubricating oil compositions according to the present invention are characterized by their low KV40 and high KV100 values, determined for ASTM D445, their low HTHS80 and HTHS100 values, determined for CEC L-036 and their low treatment rate.

[0128] When formulated to a given HTHS150 target of 2.6 mPa^s for a 0W20 formulation, in accordance with SAE J300, the lubricating oil formulations of the present invention show KV40 values in the range of 22 to 24 mm2/s (when formulated without DI package) and in the range of 7.5 to 8.5 mm2/s (when formulated with DI package).

[0129] When formulated to a given HTHS150 target of 2.6 mPa^s for a 0W20 formulation, in accordance with SAE J300, the lubricating oil formulations of the present invention show HTHS80 values in the range of 5.9 to 6. 0 mPa^s and HTHS100 values in the range of 4.0 to 4.2 mPa^s (when formulated without DI package).

[0130] When formulated to a given HTHS150 target of 2.6 mPa^s for a 0W20 formulation, in accordance with SAE J300, the lubricating oil formulations of the present invention show HTHS80 values in the range of 7.0 to 7. 5 mPa^s and HTHS100 values in the range of 4.8 to 5.2 mPa^s (when formulated with DI package).

[0131] KV100 values are > 6.9 mPa^s, as defined by the J300 specification.

[0132] The lubricating oil compositions according to the present invention are additionally characterized by a high viscosity index (VI). The VI is at least 245, preferably in the range of 245 to 350, more preferably in the range of 250 to 310.

[0133] The concentration of the polyalkyl (meth) acrylate polymer (B) in the lubricating oil composition is preferably in the range of 1 to 4% by weight, based on the total weight of the lubricating oil composition.

[0134] Preferably, the total concentration of the one or more additives (C) is 0.05% to 15% by weight, more preferably 3% to 10% by weight, based on the total weight of the lubricating oil composition.

[0135] Additional preferred contents of components (A), (B) and (C) in the lubricating oil compositions, according to the present invention, are as detailed in the following Table:

[0136] In a particular embodiment, the proportions of components (A), (B) and (C) add up to 100% by weight.

[0137] Component (A) can be described as further mentioned above in the first objective, the first preferred objective, the second objective and the second preferred objective.

[0138] The lubricating oil composition according to the invention may also contain, as component (C), additional additives selected from the group consisting of conventional VI improvers, dispersants, defoamers, detergents, antioxidants, pour point, anti-wear additives, extreme pressure additives, friction modifiers, anti-corrosion additives, dyes and mixtures thereof.

[0139] Conventional VI improvers include hydrogenated styrene and diene copolymers (HSDs, US4116 917, US3772196 and US4788316), especially based on butadiene and isoprene, and also olefin copolymers (OCPs, K. Marsden: “Literature Review of OCP Viscosity Modifiers", Lubrication Science 1 (1988), 265), especially of the poly(ethylene-co-propylene) type, which can also often be present in N/O functional form with dispersing action, or PAMAs, which are normally present in functional form N with advantageous additive properties (enhancers) such as dispersants, wear protection additives and/or friction modifiers (document no DE 1,520,696 to Rohm and Haas, document no WO 2006/007934 to RohMax Additives).

[0140] Compilations of VI improvers and pour point improvers for lubricating oils, especially engine oils, are detailed, for example, in T. Mang, W. Dresel (editions): "Lubricants and Lubrication", Wiley-VCH , Weinheim 2001: R. M. Mortier, S. T. Orszulik (editions): "Chemistry and Technology of Lubricants", Blackie Academic & Professional, London 1992; or J. Bartz: "Additive für Schmierstoffe", Expert-Verlag, Renningen-Malmsheim 1994.

[0141] Suitable dispersants include poly(isobutylene) derivatives, for example, poly(isobutylene) succinimides (PIBSIs), including boron PIBSIs; and ethylene and propylene oligomers that have N/O functions.

[0142] Dispersants (including boron dispersants) are preferably used in an amount of 0 to 5% by weight, based on the total amount of the lubricating oil composition.

[0143] Suitable defoamers are silicone oils, fluorosilicone oils, fluoroalkyl ethers, etc.

[0144] The antifoam agent is preferably used in an amount of 0.005 to 0.1% by weight, based on the total amount of the lubricating oil composition.

[0145] Preferred detergents include metal-containing compounds, for example, phenoxides; salicylates; thiophosphonates, especially thiopirophosphonates, thiophosphonates and phosphonates; sulfonates and carbonates. As a metal, these compounds can especially contain calcium, magnesium and barium. These compounds can preferably be used in neutral form or with excess base.

[0146] Detergents are preferably used in an amount of 0.2 to 1% by weight, based on the total amount of the lubricating oil composition.

[0147] Suitable antioxidants include, for example, phenol-based antioxidants and amine-based antioxidants.

[0148] Phenol-based antioxidants include, for example, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 4,4'-methylenebis(2,6-di-tert-butylphenol); 4,4'-bis(2,6-di-t-butylphenol); 4,4'-bis(2-methyl-6-t-butylphenol); 2,2'-methylenebis(4-ethyl-6-t-butylphenol); 2,2'- methylenebis (4-methyl-6-t-butyl phenol); 4,4'-butylidenebis(3-methyl-6-t-butylphenol); 4,4'-isopropylidenebis(2,6-di-t-butylphenol); 2,2'-methylenebis(4-methyl-6-nonylphenol); 2,2'- isobutylidenebis(4,6-dimethylphenol); 2,2'-methylenebis(4-methyl-6-cyclohexylphenol); 2,6-di-t-butyl-4-methylphenol; 2,6-di-t-butyl-4-ethyl-phenol; 2,4-dimethyl-6-t-butylphenol; 2,6-di-t-amyl-p-cresol; 2,6-di-t-butyl-4-(N,N'-dimethylaminomethylphenol); 4,4'-thiobis(2-methyl-6-t-butylphenol); 4,4'-thiobis(3-methyl-6-t-butylphenol); 2,2'-thiobis(4-methyl-6-t-butylphenol); bis(3-methyl-4-hydroxy-5-t-butylbenzyl)sulfide; bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide; n-octyl-3-(4-hydroxy-3,5-di-t-butylphenyl)propionate; n-octadecyl-3-(4-hydroxy-3,5-di-t-butylphenyl)propionate; 2,2'-thio [diethyl-bis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], etc. Of these, bis-phenol-based antioxidants and ester group-containing phenol-based antioxidants are especially preferred.

[0149] Amine-based antioxidants include, for example, monoalkyldiphenylamines, such as mono-octyldiphenylamine, monononyldiphenylamine, etc.; dialkyldiphenylamines, such as 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldiphenylamine, etc.; polyalkyldiphenylamines such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine, etc.; naphthylamines, specifically alpha-naphthylamine, phenyl-alpha-naphthylamine and additionally alkyl-substituted phenyl-alpha-naphthylamines, such as butylphenyl-alpha-naphthylamine, pentylphenyl-alpha-naphthylamine, hexylphenyl-alpha-naphthylamine, heptylphenyl-alpha-naphthylamine, octylphenyl -alpha-naphthylamine, nonylphenyl-alpha-naphthylamine, etc. Of these, diphenylamines are preferred to naphthylamines, from the point of view of their antioxidation effect.

[0150] Suitable antioxidants may be further selected from the group consisting of compounds containing sulfur and phosphorus, e.g. metal dithiophosphates, e.g. zinc dithiophosphates (ZnDTPs), "OOS tri-esters" = reaction products of dithiophosphoric acid with activated double bonds from olefins, cyclopentadiene, norbornadiene, alpha-pinene, polybutene, acrylic esters, maleic esters (without burning ash); organosulfur compounds, for example, dialkyl sulfides, diaryl sulfides, polysulfides, modified thiols, thiophene derivatives, xanthates, thioglycols, thioaldehydes, sulfur-containing carboxylic acids; heterocyclic sulfur/nitrogen compounds, especially dialkyldimercaptothiadiazoles, 2-mercaptobenzimidazoles; zinc bis(dialkyldithiocarbamate) and methylene bis(dialkyldithiocarbamate); organophosphorus compounds, for example triaryl and trialkyl phosphites; organo-copper compounds and phenoxides and salicylates based on calcium and magnesium with excess base.

[0151] Antioxidants are used in an amount of 0 to 15% by weight, preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, based on the total amount of the lubricating oil composition.

[0152] Pour point reducers include ethylene-vinyl acetate copolymers, chlorinated paraffin and naphthalene condensates, chlorinated paraffin and phenol condensates, polymethacrylates, polyalkyl styrenes, etc. Polymethacrylates having a mass average molecular weight of 5,000 to 50,000 g/mol are preferred.

[0153] The amount of the pour point reducer is preferably 0.1 to 5% by weight, based on the total amount of the lubricating oil composition.

[0154] Preferred extreme pressure and antiwear additives include sulfur-containing compounds such as zinc dithiophosphate, zinc di-C3-12-alkyldithiophosphates (ZnDTPs), zinc phosphate, zinc dithiocarbamate, molybdenum dithiocarbamate, zinc dithiophosphate molybdenum, disulfides, sulfonated olefins, sulfonated oils and fats, sulfonated esters, thiocarbonates, thiocarbamates, polysulfides, etc.; phosphorus-containing compounds such as phosphites, phosphates, e.g. trialkyl phosphates, triaryl phosphates, e.g. tricresyl phosphate, neutralized amine monoalkyl and dialkyl phosphates, ethoxylated monoalkyl and dialkyl phosphates, phosphonates, phosphines, salts of amine or metal salts of these compounds, etc.; antiwear agents containing sulfur and phosphorus, such as thiophosphites, thiophosphates, thiophosphonates, amine salts or metal salts of these compounds, etc.

[0155] The antiwear agent may be present in an amount of 0 to 3% by weight, preferably 0.1 to 1.5% by weight, more preferably 0.5 to 0.9% by weight, based on the total amount of the lubricating oil composition.

[0156] Friction modifiers used may include mechanically active compounds, for example molybdenum disulfide, graphite (including fluorinated graphite), poly(trifluoroethylene), polyamide, polyimide; compounds that form adsorption layers, for example, long-chain carboxylic acids, fatty acid esters, ethers, alcohols, amines, amides, imides; compounds that form layers through tribochemical reactions, for example, saturated fatty acids, phosphoric acids and thiophosphoric esters, xanthogenates, sulfonated fatty acids; compounds that form polymer-like layers, e.g., ethoxylated dicarboxylic partial esters, dialkyl phthalates, methacrylates, unsaturated fatty acids, sulfonated olefins, or organometallic compounds, e.g., molybdenum compounds (molybdenum dithiophosphates and molybdenum dithiocarbamates MoDTCs) and combinations of them with ZnDTPs, organic compounds that contain copper.

[0157] Friction modifiers can be used in an amount of 0 to 6% by weight, preferably 0.05 to 4% by weight, more preferably 0.1 to 2% by weight, based on the total amount of the oil composition lubricant.

[0158] Some of the compounds listed above can fulfill several functions. ZnDTP, for example, is mainly an anti-wear additive and extreme pressure additive, however, it also has the character of an antioxidant and corrosion inhibitor (here: metal passivator/deactivator).

[0159] The additives detailed above are described in detail, inter alia, in T. Mang, W. Dresel (editions): "Lubricants and Lubrication", Wiley-VCH, Weinheim 2001; R. M. Mortier, S. T. Orszulik (editions): "Chemistry and Technology of Lubricants".

[0160] Polyalkyl(meth)acrylate-based comb polymers in accordance with the invention can generally be prepared by free radical polymerization and by related methods of controlled free radical polymerization, for example, ATRP ( = atom transfer radical polymerization) or RAFT (= reversible addition fragmentation chain transfer).

[0161] Standard free radical polymerization is detailed, inter alia, in Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition. In general, a polymerization initiator and, optionally, a chain transfer agent are used for this purpose.

[0162] The ATRP method is known per se. It is assumed that this is a "live" free radical polymerization, however, no restriction is intended by describing the mechanism. In these processes, a transition metal compound is reacted with a compound that has a transferable atom group. involves transfer of the transferable atom group to the transition metal compound, as a result of which the metal is oxidized. This reaction forms a free radical which adds into ethylene groups. However, the transfer of the atom group to the transition metal compound It is reversible and thus the atom group is transferred back to the growing polymer chain, which results in the formation of a controlled polymerization system. Consequently it is possible to control the polymer formation, molecular weight and molecular weight distribution.

[0163] This reaction regime is described, for example, by J. -S. Wang, et al., J. Am. Chem. Soc, vol. 117, pages 5,614 to 5,615 (1995), by Matyjaszewski, Macromolecules, vol. 28, pages 7,901 to 7,910 (1995). Additionally, Patent applications in WO 96/30421, WO 97/47661, WO 97/18247, WO 98/40415 and WO 99/10387 disclose variants of the ATRP elucidated above. Additionally, the polymers of the invention can also be obtained using RAFT methods, for example. This method is described in detail, for example, in documents in WO 98/01478 and WO 2004/083169.

[0164] Polymerization can be conducted under standard pressure, reduced pressure or elevated pressure. The polymerization temperature is also noncritical. In general, however, it is in the range of -20 to 200 °C, preferably 50 to 150 °C and most preferably 80 to 130 °C.

[0165] The polyalkyl (meth) acrylate-based comb polymers according to the present invention, with molecular weights as further defined above, are accessible using a more specified process.

[0166] A seventh objective of the present invention is therefore directed to a process for preparing comb-like polymers based on polyalkyl (meth) acrylate, as further specified above in the first and second embodiments, the process comprising the steps of : (a) preparing a reaction mixture comprising monomers and dilution oil 1, in which the monomers are present in an amount of 40 to 65% by weight, preferably 40 to 50% by weight; (b) heating 50% of the reaction mixture prepared in step (a) to a temperature in the range of 80 to 120 °C, preferably 90 to 100 °C; (c) add 0.05 to 0.1%, based on the total amount of monomers, of an initiator 1 to the reaction mixture, as prepared in step (b), the initiator having a half-life T1/2 in the range of 100 to 200 minutes, preferably 150 to 170 minutes, at the given temperature, according to step (b); (d) adding additional amounts of the reaction mixture prepared in (a) and a further 0.05 to 0.1% of initiator 1 over a period of 2 to 4 hours, preferably over 3 h; (e) maintain the reaction mixture prepared in step (d) for a time of 0.5 to 3 hours, preferably 2 hours, at the given temperature; (f) diluting the reaction mixture prepared in step (e) for a time of 0.5 to 3 hours by 30% with dilution oil 2 comprising additional amounts of initiator 1; (g) optionally adding additional amounts of a starter 1 or a starter 2, which may be the same as or different from the starter 1, to the reaction mixture prepared in step (e) and maintaining for at least 2 hours; and (h) diluting the reaction mixture prepared in step (g) to the targeted concentration by adding dilution oil 1 or a dilution oil 2, which may be the same as or different from dilution oil 1.

[0167] The initiator concentration and initiator addition are selected so that the Mn and Mw of the resulting polymer remain approximately constant during the main part of the polymerization reaction and good monomer conversion is achieved.

[0168] Initiator 1 and 2 may be the same or different, and are independently selected from the group consisting of azo-type initiators, such as azobis-isobutyronitrile (AIBN), 2,2'-azobis(2-methylbutyronitrile) (AMBN ) and 1,1-azobiscyclohexanecarbonitrile, and peroxy compounds such as methyl ethyl ketone peroxide, acetylacetone peroxide, dilauryl peroxide, tert-butyl per-2-ethylhexanoate, ketone peroxide, tert-butyl peroctoate, methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropylcarbonate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane, peroxy tert-butyl-2-ethylhexanoate, tert-butyl peroxy-3,5,5-trimethylhexanoate, dicumyl peroxide, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis (tert-butylperoxy)-3,3,5-trimethylcyclohexane, cumyl hydroperoxide, tert-butyl hydroperoxide and bis(4-tert-butylcyclohexyl)peroxydicarbonate.

[0169] Preferably, initiator 1 and 2 are independently selected from the group consisting of 2,2'-azobis(2-methylbutyronitrile), tert-butylperoxy 2-ethylhexanoate, 1,1-di-tert-butylperoxy -3,3,5-trimethylcyclohexane, tert-butyl peroxybenzoate and tert-butylperoxy-3,5,5-trimethylhexanoate.

[0170] Especially preferably 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane is used as initiator 1 and 2-ethylhexanoate of tert-butylperoxy or 1,1-di-tert-butylperoxy -3,3,5-trimethylcyclohexane as initiator 2.

[0171] The targeted concentration can be in the range of 20 to 30% and preferably be 25%.

[0172] Dilution oil 1 and 2 may be the same or different, and are independently selected from the group consisting of API Group I, III, III, IV, V and mixtures thereof. They are preferably selected from API Group III oils and mixtures thereof.

[0173] The monomers that can be used are selected from the embodiments, as further defined above.

[0174] The reaction temperature mentioned in step (b) has to be carefully balanced between viscosity rate and polymerization in process.

[0175] The invention is partially illustrated by the attached Figures.

[0176] Figure 1: Trends in kinematic viscosity (KV) versus high shear high temperature viscosity (HTHS) at 100 ° C in practical examples 1 to 5 of prior art document in US 2010/0190671 versus practical examples herein invention.

[0177] Figure 2: GPC results showing switching in molecular weight distributions towards the higher molecular weight of polymer A17 prepared in accordance with the present invention versus comparative example A14.

[0178] Figure 3: The relative thickening contribution (RTC) that varies with increased weight-average molecular weight Mw.

[0179] Figure 4: Molecular weight (Mw and Mn) versus HTHS100 of examples A5 to A11 and comparative examples A1 to A3 in a 0W20 formulation.

[0180] Figure 5: Molecular weight (Mw and Mn) versus HTHS80 of examples A5 to A11 and comparative examples A1 to A3 in a 0W20 formulation.

[0181] Figure 6: Molecular weight (Mw and Mn) versus HTHS80 of examples and comparative examples, in which 2 examples with almost similar Mw and slightly different Mn are highlighted.

[0182] Figure 7: HTHS100 is plotted versus the P factor, which is calculated from Mw and Mn in order to evaluate promising molecular weight distributions.

[0183] Figure 8: HTHS80 is plotted versus the P factor, which is calculated from Mw and Mn in order to evaluate promising molecular weight distributions (Examples A2, A3 and A5 to A11).

[0184] Figure 9: HTHS100 is plotted versus the P factor, which is calculated from Mw and Mn in order to evaluate promising molecular weight distributions (Examples A12 and A14 to A19).

[0185] Figure 10: HTHS80 was plotted versus the P factor. P values equal to or less than 1.5 resulted in the best (lowest) HTHS80 values (Examples A12 and A14 to A19).

[0186] The invention was further illustrated by the following examples without limitation. EXPERIMENTAL PART ABBREVIATIONS AA C4 alkyl acrylate AA C4 alkyl acrylate = C16/18 n-butyl acrylate AA C16/18 alkyl acrylate AMA C1 alkyl methacrylate AMA C1 alkyl methacrylate = methyl methacrylate (MMA) C4 AMA C1 methacrylate C4 alkyl = n-butyl methacrylate C12-15 AMA C12-15 alkyl methacrylate DDM Dodecanethiol HTHS80 High shear, high temperature viscosity at 80 °C, measured according to CEC L-036 HTHS100 High shear, high temperature viscosity at 100°C, measured in accordance with CEC L-036 HTHS150 High shear, high temperature viscosity at 150°C, measured in accordance with CEC L-036 KV Kinematic viscosity measured in accordance with ASTM D445 KV40 Kinematic viscosity at 40°C, measured according to ISO 3104 KV100 Kinematic viscosity at 100°C, measured according to ISO 3104 MM Macromonomer Mn Number average molecular weight Mw Number average molecular weight NB 3020 Nexbase® 3020, Neste Group III base oil with a KVioo 2.2 mm2/s (2.2 cSt) NB 3043 Nexbase® 3020, Neste Group III base oil with a KV100 of 4.3 mm2/s (4.3 cSt) OLOA 55501 PCMO DI Package commercially available from Oronite PCMO Passenger car engine oils D Polydispersity index VI Viscosity index, measured in accordance with ISO 2909 Yubase 4 Group III base oil from SK Lubricants with a KV100 of 4.2 mm2/s (4 .2 cSt)

TEST METHODS

[0187] The comb-type polymers, according to the present invention, and the comparative examples were characterized with respect to their molecular weight and PDI.

[0188] Molecular weights were determined by size exclusion chromatography (SEC) using commercially available polymethylmethacrylate (PMMA) standards. The determination is carried out using gel permeation chromatography with THF as eluent (flow rate: 1 ml/min; injected volume: 100 μl).

[0189] The additive compositions that include the comb-like polymers, according to the present invention, and comparative examples were characterized with respect to their viscosity index (VI) for ASTM D 2270, kinematic viscosity at 40 ° C (KV40) and 100 °C (KV100) for ASTM D445 and with respect to its shear stability.

[0190] To show the shear stability of the additive compositions, the PSSI (Permanent Shear Stability Index) was calculated in accordance with ASTM D 6022-01 (Standard Practice for Calculating Permanent Shear Stability Index) based on data measured in accordance with ASTM D 2603-B (Standard Test Method for Sonic Shear Stability of Polymer-Containing Oils).

[0191] The lubricating oil compositions that include the comb-like polymers, according to the present invention, and comparative examples were characterized with respect to kinematic viscosity at 40 ° C (KV40) and 100 ° C (KV100) for ASTM D445, to viscosity index (VI) for ASTM D 2270, high shear and high temperature viscosity at 80 °C, 100 °C and 150 °C for CEC L-036, Noack evaporation loss at 250 °C for 1 hour for CEC L-40B and apparent viscosity of CCS (Cold Start Simulator) at -35 °C for ASTM D 5293. SYNTHESIS OF A HYDROGENATED AND HYDROXYLATED POLYBUTADIENE

[0192] The macroalcohol prepared was a hydrogenated polybutadiene with a hydroxypropyl termination that has an average molar mass Mn = 4,750 g/mol.

[0193] The macroalcohol was synthesized by an anionic polymerization of 1,3-butadiene with butyllithium at 20 to 45 °C. After obtaining the desired degree of polymerization, the reaction was stopped by adding propylene oxide and lithium was removed by methanol precipitation. Subsequently, the polymer was hydrogenated under a hydrogen atmosphere in the presence of a noble metal catalyst at up to 140 °C and 20 MPa (200 bar) pressure. After hydrogenation was complete, the noble metal catalyst was removed and organic solvent was removed under reduced pressure. Finally, NB 3020 base oil was used for dilution to a polymer content of 70 wt%.

[0194] The vinyl content of the macroalcohol was 61%, the hydrogenation level > 99% and the OH function > 98%. These values were determined by H NMR (nuclear resonance spectroscopy).

MACROMONOMER SYNTHESIS (MM)

[0195] In a 2 l stirred apparatus equipped with a stirrer know, air inlet tube, thermocouple with controller, heating mantle, column having a random packing of 3 mm metal spirals, vapor divider, top thermometer, reflux condenser and substrate cooler, 1,000 g of the macroalcohol described above are dissolved in 450 g of methyl methacrylate (MMA) while stirring at 60 °C. 20 ppm of 2,2,6,6-tetramethylpiperidin-1-oxyl radical and 200 ppm of hydroquinone-monomethyl ether are added to the solution. After heating to reflux of MMA (bottom temperature of about 110°C) while passing air through it for stabilization, about 20 g of MMA is distilled for azeotropic drying. After cooling to 95 °C, 0.30 g of LiOCH3 is added and the mixture is heated back to reflux. After the reaction time of about 1 hour, the top temperature dropped to ~64 °C due to the formation of methanol. The formed methanol/MMA azeotrope is distilled constantly until a constant top temperature of about 100 °C is again established. At this temperature, the mixture is left to react for another hour. For further constitution, the MMA volume is drained under reduced pressure. Insoluble catalyst residues are removed by pressure filtration (Seitz T1000 depth filter). The "entrained" NB 3020 content in the copolymer syntheses described below was consequently taken into account.

SYNTHESIS OF COMB-TYPE POLYMERS

[0196] An apparatus with a 4-neck flask and precision glass shaker is initially charged with a 50% mixture of monomer and oil (175 g of monomer mixture and 262.5 g of oil mixture). After heating to 96 °C under nitrogen, 0.15% by weight of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (I-3) (50% in isododecane) is added and the temperature is maintained. Another 50% of the monomer and oil mixture and 0.2% of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (I-3) (50% in isododecane) is added within 3 hours. Then, the reaction is maintained at 96 °C for another 2 h. Subsequently, the reaction mixture is diluted to 30% solids with NB 3043 and 0.2% 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (I-3) (50% in isododecane) within 3 hours. Then, the reaction is maintained at 96 °C for another 2 h and after that, another 0.2% of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (I-3) (50% in isododecane) is added and the mixture is stirred at 96°C overnight. The next day, the mixture is diluted to 25% solids with NB 3043. 700 g of a 25% solution of comb polymers in mineral oil is obtained. Monomer components added up to 100%. The amounts of initiator and dilution oil are given in relation to the total amount of monomers. Details regarding monomer mixtures are given in Table 1 below.

PROCESS DETAILS

[0197] Conventional polymerization of comb-type polymers is carried out at 90 to 95 ° C with I-1 as initiator (see Table 1; I-1 = commercially available tert-butylperoxy 2-ethylhexanoate). In this temperature range, the half-life of I-1 is between 40 and 70 minutes. Depending on the composition of the polymer, this process typically results in weight average molecular weights Mw in the range of 300,000 g/mol and 500,000 g/mol while compositions with a higher degree of branching result in higher Mw.

[0198] In the new process described in this document, the polymerization of comb-type polymers is carried out at temperatures that correspond to a much higher half-life of the initiator of 150 to 170 minutes. Different initiators and polymerization temperatures were tested, always maintaining the initiator half-life at 150 to 170 minutes (please find the examples in Table 1 below). For example, for I-1 such conditions can be obtained at 83 °C. At the same time it was found that higher polymerization temperatures result in lower in-process viscosities and easier polymerization handling and, therefore, initiators with higher degradation temperatures are preferred in this new process. For example, I-3 exhibits a half-life of 196 minutes at 96 °C and can be polymerized at very low in-process viscosities.

[0199] Comb-like polymers with significantly increased molecular weight (Mw and Mn) can be obtained using the new process, which were not accessible before. TABLE 1: INITIATORS AND THEIR POLYMERIZATION TEMPERATURES IN HALF-LIVES BETWEEN 150 AND 170 °C, AS USED IN THE NEW PROCESS, COMPARED TO THE TYPICAL HALF-LIFE AND POLYMERIZATION TEMPERATURE OF I-1.

[0200] Table 2 shows the reaction mixtures used to prepare practical examples and comparative examples, as well as the initiator used, the total initiator concentration and the process details, i.e., reaction mixture concentration and polymerization temperature.

[0201] Monomer components added up to 100%. The amount of initiator is given in relation to the total amount of monomers. At the end of the reaction, the resulting reaction mixture is diluted to a polymer content of 25%. The remaining amount (about 75%) is dilution oil, as described above in the general procedures, used to prepare the polymers. TABLE 2: REACTION MIXTURES USED TO PREPARE PRACTICAL EXAMPLES AND COMPARATIVE EXAMPLES. *)comparative example **)starting concentration of monomer mixture

[0202] The liquid compositions of the resulting comb-type polymers, as well as their weight-average molecular weights Mw, characteristic number-average molecular weights Mn, their polydispersity indices (D) and the resulting P factor are summarized in the following Table 3.

[0203] Table 3 additionally shows the MMconv macromonomer conversion rate. and the molar degree of branching of the resulting comb-like polymers.

[0204] Examples A1 to A5, A13 to A16 and A20 to A24 are comparative examples in which Mw and Mn are below the claimed ranges. Examples A6 to A12, A17 to A19 and A25 are in accordance with the present invention and comprise comb-like polymers based on polyalkyl (meth) acrylate having Mw and Mn within the defined ranges. TABLE 3: LIQUID COMPOSITIONS OF COMB-TYPE POLYMERS PREPARED ACCORDING TO THE PRESENT INVENTION. *)comparative example 41/51

[0205] As already mentioned additionally above, Examples A1 to A5, A13 to A16 and A20 to A24 are comparative examples in which Mw is below 700,000 g/mol and/or Mn is below 130,000 g/mol. Examples A6 to A12, A17 to A19 and A25 to A26 are in accordance with the present invention and comprise comb-like polymers based on polyalkyl(meth)acrylate with Mw of 700,000 g/mol or greater and Mn of 130,000 g/mol or greater .

[0206] Examples A1 to A11 are a first group of examples in which all comprise similar amounts of monomers (12 to 13% by weight of MM and about 4% by weight of alkyl acrylates), however, they were prepared with Mw and Different mn. It can be seen that with higher Mw Mn also increases as D, while the P factor decreases.

[0207] Example A12 also shows a composition similar to that of A1 to A11, however, they were prepared without C16/18 alkyl acrylates.

[0208] Examples A13 to A19 are a second group of examples that also comprise similar amounts of monomers (22 to 23% by weight of MM and no alkyl acrylate), however, they were prepared with different Mw and Mn. Again, it can be seen that with higher Mw Mn also increases as D, while the P factor decreases.

[0209] Figure 2 shows GPC results from example A17 that visualize switching in molecular weight distributions towards higher molecular weight. The reduced area at low molecular weight results in significantly increased Mn and therefore improved HTHS100 and treatment rate, e.g. A17 (see Formulation Example C6 in Table 5 below).

[0210] Examples A23 to A26 are a third group of examples that also comprise similar amounts of monomers (12 to 13% by weight of MM, without alkyl acrylate and about 15% by weight of C12-15 (meth) acrylates alkyl), however, were prepared with different Mw and Mn. Again, it can be seen that with higher Mw Mn also increases as D, while the P factor decreases.

[0211] Figure 3 shows that the relative thickening contribution (RTC) selectively increases at higher temperature (above 80 °C) for candidates with higher molecular weight distributions (Example A7 compared to Examples A2, A4 and A23). At temperatures below 80 °C the thickening of all candidates is comparably low. This exceptional thickening behavior is considered the reason for the unexpectedly low HTHS100 and HTHS80 values, while the treatment rate at the given HTHS150 of 2.6 mPa^s is decreased (see Tables 4 and 5 below).

EVALUATION OF VI IMPROVERS IN FORMULATIONS

[0212] To demonstrate the effect of polyalkyl (methacrylate)-based comb polymers, according to the present invention, on the performance of KV100 and HTHS100 of lubricating oil compositions, different examples of formulation B were prepared and the corresponding values are measured. Formulations with Yubase 4 as base oil were prepared using 0W20 formulation targets according to SAE J300; that is, they were formulated to a HTHS150 target of 2.6 mPa^s by adding additives A1 to A11, as described in Table 3 above. The resulting additive content was typically between 11 and 14% by weight. Characteristic EO formulation properties (KV100, HTHS100, HTHS80) were measured and are summarized in Table 4. TABLE 4: 0W20 B ENGINE OIL FORMULATIONS WITHOUT DI PACKAGE IN YUBASE 4 AS BASE OIL.

[0213] The results presented in Table 4 clearly show that when increasing Mw and especially Mn, KV100 increases, while HTHS80 and HTHS100 decrease (see comparative examples B1 to B5 compared to practical examples B6 to B11).

[0214] Figure 7 visualizes this effect. In this diagram, HTHS100 is plotted versus P, the factor calculated from Mw and Mn, in order to evaluate promising molecular weight distributions. P values below 1.5 resulted in the best (lowest) HTHS100 values corresponding to Mw > 570,000 g/mol and Mn > 134,000 g/mol (HTHS data were generated from 0W20 formulations shown in Table 4 using Examples A2, A3 and A5 to A11).

[0215] Figure 8 visualizes the effect on HTHS80. In this diagram, HTHS80 is plotted versus P, the factor calculated from Mw and Mn in order to evaluate promising molecular weight distributions (HTHS data was generated from 0W20 formulations shown in Table 4 using Examples A2, A3 and A5 to A11).

[0216] Figure 9 visualizes the effect on Examples A12 and A14 to A19. In this diagram, HTHS100 is plotted versus P, the factor calculated from Mw and Mn, in order to evaluate promising molecular weight distributions. P values below 1.3 resulted in the best (lowest) HTHS100 values corresponding to Mw > 780,000 g/mol and Mn > 133,000 g/mol. (HTHS data was generated from 0W20 formulations shown in Table 5 using examples A12 and A14 to A19).

[0217] Figure 10 visualizes the effect on Examples A12 and A14 to A19. In this diagram, HTHS80 is plotted versus the P factor. P values below 1.3 resulted in the best (lowest) HTHS80 values (HTHS data were generated from 0W20 formulations shown in Table 5 using examples A12 and A14 to A19). TABLE 5: 0W20 C ENGINE OIL FORMULATIONS WITH DI PACKAGE IN YUBASE 4 AS BASE OIL. *)comparative example **)polymer was not soluble na = not determined

[0218] In addition to the performance advantage in HTHS80 and HTHS100, the inventive examples exhibit lower treatment rates than the comparative examples. This results in a significant advantage in engine oil formulation. For example, the treatment rate of A12 in the 0W20 formulation, which shows the best HTHS performance of all polymers with this composition, is reduced by 22% compared to A14. The lower treatment rate results in huge economic advantages as well as potentially improved deposits in diesel engines. The reason for the decreased treatment rate can be found in the special viscosity and temperature behavior of the inventive polymers in oils. As shown in Figure 3, the relative thickening contribution of the new polymers selectively increases in the temperature range between 100 °C and 150 °C, while the low-temperature thickening remains low. Especially, the thickening contribution at 150 °C has a great influence on the treatment rate in the 0W20 formulation and the greater the thickening at 150 °C, the lower the treatment rate is in the formulation. This effect is very surprising because, normally, when the thickening of a polymer is increased, for example, at 150 °C, it increases at lower temperatures as well. This is not the case for inventive polymers; they selectively contribute to thickening in the high temperature range above 100 °C. TABLE 6: 0W20 D ENGINE OIL FORMULATIONS WITH DI PACKAGE IN YUBASE 4 AS BASE OIL.

[0219] In Table 6, a 0W20 engine oil formulation is shown. It was formulated for a target value of HTHS150 = 2.6 mPa^s using 8.9% of the Di OLOA 55501 package, Yubase 4 as base oil and the respective amount of additive. Inventive example A12 with higher molecular weight (706,000 g/mol) than the comparative example (376,000 g/mol) shows improved lower HTHS80 and HTHS100 values which are indicators for improved fuel economy. At the same time the treatment rate was improved (=reduced) significantly by 12%, which demonstrates the effectiveness of the inventive additive. The reduction in treatment rate can be directly linked to a reduction in total formulation costs.

[0220] Furthermore, reducing the treatment rate is expected to reduce formulation deposits, since it is known that the treatment rate of additives has a great influence on the formation of deposits. This relationship can be verified, for example, using the Microcoking test (GFC-LU-27-A-13) of the formulation examples shown here.

Claims (20)

1. Polyalkyl(meth)acrylate-based comb polymers consisting of: (a) 10 to 25% by weight of a (meth)acrylic acid ester and a hydroxylated hydrogenated polybutadiene; (b) 0% to 5% by weight C4-18 alkyl acrylates; (c) 0% to 0.3% by weight methyl methacrylate; (d) 60% to 75% by weight n-butyl methacrylate; (e) 5% to 20% by weight of C10-15 alkyl methacrylates; and (f) 0% to 2% by weight of styrene monomers, which are characterized by a weight average molecular weight Mw of 700,000 g/mol or greater and a number average molecular weight Mn of 130,000 g/mol or greater, determined by size exclusion chromatography (SEC) using commercially available polymethyl methacrylate standards. 2. Comb-type polymers based on polyalkyl (meth) acrylate, according to claim 1, characterized in that the monomers (e) are C12-14 alkyl methacrylates. 3. Comb-type polymers based on polyalkyl (meth) acrylate, according to claim 1 or 2, characterized in that the weight-average molecular weight Mw is in the range of 700,000 to 2,000,000 g/mol, and the number-average molecular weight Mn be in the range of 130,000 to 300,000 g/mol, determined by size exclusion chromatography (SEC) using commercially available polymethylmethacrylate standards. 4. Comb-type polymers based on polyalkyl (meth) acrylate, according to claim 1 or 2, characterized in that the weight-average molecular weight Mw is in the range of 700,000 to 1,300,000 g/mol, and the number-average molecular weight Mn be in the range of 150,000 to 200,000 g/mol, determined by size exclusion chromatography (SEC) using commercially available polymethylmethacrylate standards. 5. Comb-like polymers based on polyalkyl (meth) acrylate, according to any one of claims 1 to 4, characterized by a P value of 1.5 or less: 6. Use of comb-type polymers based on polyalkyl (meth) acrylate, as defined in any one of claims 1 to 5, characterized by increasing KV100 and, in parallel, decreasing HTHS100 and HTHS80 of lubricating oil compositions, especially oil formulations of engine. 7. Additive composition comprising: (a) 60 to 80% by weight of a base oil and (b) 20 to 40% by weight of a polyalkyl (meth) acrylate-based comb polymer consisting of the following monomers: (c) 10 to 25% by weight of an ester of (meth)acrylic acid and a hydroxylated hydrogenated polybutadiene; (d) 0% to 5% by weight C4-18 alkyl acrylates; (e) 0% to 0.3% by weight methyl methacrylate; (f) 60% to 75% by weight n-butyl methacrylate; (g) 5% to 20% by weight of C10-15 alkyl (meth)acrylates; and (h) 0% to 2% by weight of styrene monomers, which is characterized by a weight average molecular weight Mw of 700,000 g/mol or greater and a number average molecular weight Mn of 130,000 g/mol or greater. 8. Additive composition according to claim 7, characterized in that the monomers (e) of component (B) are C12-14 alkyl methacrylates. 9. Additive composition according to claim 7 or 8, characterized in that the weight-average molecular weight Mw of component (B) is in the range of 700,000 to 2,000,000 g/mol, and the number-average molecular weight Mn is in the range from 130,000 to 300,000 g/mol, determined by size exclusion chromatography (SEC) using commercially available polymethylmethacrylate standards. 10. Additive composition according to claim 7 or 8, characterized in that the weight-average molecular weight Mw of component (B) is in the range of 700,000 to 1,300,000 g/mol, and the number-average molecular weight Mn is in the range from 150,000 to 200,000 g/mol, determined by size exclusion chromatography (SEC) using commercially available polymethylmethacrylate standards. 11. Use of an additive composition, as defined in any one of claims 7 to 10, characterized by increasing KV100 and, in parallel, decreasing HTHS100 of lubricating oil compositions, especially engine oil formulations. 12. Lubricating oil composition comprising: (A) 80 to 99.5% by weight of a base oil; (B) 0.5 to 5% by weight of a polyalkyl(meth)acrylate-based comb polymer consisting of the following monomers: (a) 10 to 25% by weight of a (meth)acrylic acid ester and a hydroxylated hydrogenated polybutadiene; (b) 0% to 5% by weight C4-18 alkyl acrylates; (c) 0% to 0.3% by weight methyl methacrylate; (d) 60% to 75% by weight n-butyl methacrylate; (e) 5% to 20% by weight of C10-15 alkyl methacrylates (meth)acrylates; and (f) 0% to 2% by weight of styrene monomers, which is characterized by a weight average molecular weight Mw of 700,000 g/mol or greater and a number average molecular weight Mn of 130,000 g/mol or greater; and (C) 0 to 15% by weight of one or more additional additives. 13. Lubricating oil composition, according to claim 12, characterized in that the monomers (e) of component (B) are C12-14alkyl methacrylates. 14. Lubricating oil composition according to claim 12 or 13, characterized in that the weight-average molecular weight Mw of component (B) is in the range of 700,000 to 2,000,000 g/mol, and the number-average molecular weight Mn is in the range of 130,000 to 300,000 g/mol, determined by size exclusion chromatography (SEC) using commercially available polymethyl methacrylate standards. 15. Lubricating oil composition according to claim 12 or 13, characterized in that the weight-average molecular weight Mw of component (B) is in the range of 700,000 to 1,300,000 g/mol, and the number-average molecular weight Mn is in the range of 150,000 to 200,000 g/mol, determined by size exclusion chromatography (SEC) using commercially available polymethyl methacrylate standards. 16. Lubricating oil composition according to any one of claims 12 to 15, characterized in that component (C) is selected from the group consisting of conventional VI improvers, dispersants, defoamers, detergents, antioxidants, set point reducers fluidity, anti-wear additives, extreme pressure additives, friction modifiers, anti-corrosion additives, dyes and mixtures thereof. 17. Process for preparing the polyalkyl (meth) acrylate-based comb polymers, as defined in any one of claims 1 to 6, wherein the process is characterized by comprising the steps of: (a) preparing a reaction mixture comprising monomers and oil of dilution 1, in which the monomers are present in an amount of 40 to 65% by weight; (b) heating 50% of the reaction mixture prepared in step (a) to a temperature in the range of 80 to 120 ° C; (c) add 0.05 to 0.1%, based on the total amount of monomers, of an initiator 1 to the reaction mixture, as prepared in step (b), the initiator having a half-life T1/2 in the range of 100 to 200 minutes, at the given temperature, according to step (b); (d) adding additional amounts of the reaction mixture prepared in (a) and an additional 0.05 to 0.1% of initiator 1 over a period of 2 to 4 hours; (e) maintain the reaction mixture prepared in step (d) for a time of 0.5 to 3 hours, at the given temperature; (f) diluting the reaction mixture prepared in step (e) for a time of 0.5 to 3 hours by 30% with dilution oil 2 comprising additional amounts of initiator 1; (g) optionally adding additional amounts of a starter 1 or a starter 2, which may be the same as or different from the starter 1, to the reaction mixture prepared in step (e) and maintaining for at least 2 hours; and (h) diluting the reaction mixture prepared in step (g) to the targeted concentration by adding dilution oil 1 or a dilution oil 2, which may be the same as or different from dilution oil 1. 18. Process according to claim 17, characterized in that initiators 1 and 2 are the same or different, and are independently selected from the group consisting of azo-type initiators, such as azobis-isobutyronitrile (AIBN), 2,2' -azobis(2-methylbutyronitrile) (AMBN) and 1,1-azobiscyclohexanecarbonitrile and peroxy compounds such as methyl ethyl ketone peroxide, acetylacetone peroxide, dilauryl peroxide, tert-butyl per-2-ethylhexanoate, peroxide ketone, tert-butyl peroctoate, methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropylcarbonate, 2,5-bis(2-ethylhexanoylperoxy)-2 tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxy-3,5,5-trimethylhexanoate, dicumyl peroxide, 1,1-bis(tert-butylperoxy)cyclo -hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, cumyl hydroperoxide, tert-butyl hydroperoxide and bis(4-tert-butylcyclohexyl)peroxydicarbonate. 19. Process according to claim 17 or 18, characterized in that 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane is used as initiator 1 and tert-butylperoxy 2-ethylhexanoate or 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane as initiator 2. 20. Process according to any one of claims 17 to 19, characterized in that dilution oils 1 and 2 are the same or different, and are independently selected from the group consisting of API Group I, II, III, IV, V and mixtures thereof.