Patent Description:
Global government vehicle regulations demand ever better fuel economy to reduce greenhouse gas emissions and conserve fossil fuels. There is an increasing demand for more fuel-efficient vehicles in order to meet the targets regarding CO<NUM> emissions. Therefore, any incremental improvement in fuel economy (FE) is of great importance in the automotive sector.

Lubricants are playing an important role in reducing a vehicle's fuel consumption and there is a continuing need for improvements in fuel economy performance.

Lubricant properties are typically improved by the addition of additives to lubricating oils. Viscosity index (VI) improvers are generally added to a lubricant to improve its thickening efficiency and to protect the engine as they are applied between the surfaces of moving parts, notably metal surfaces.

The thickening efficiency of a VI improver is specified by its KV100 (kinematic viscosity at <NUM>) at a given treat rate. The thickening effect of a polymer increases as its hydrodynamic volume in the oil increases. Increasing temperature increases the solvency of the oil, which, in turn, promotes the uncoiling of the polymer and results in a larger hydrodynamic volume.

The hydrodynamic volume of a polymer in solution depends on many parameters, such as for example the polymer chain length and composition. The longer a polymer chain, the higher is usually the weight-average molecular weight Mw.

The drawback of using VI improvers with a high molecular weight is that they undergo significant and irreversible degradation under mechanical stress. Such degraded polymers then experience a decline in its thickening properties that goes along with an irreversible drop in the viscosity of the lubricant.

One way to overcome this disadvantage is to prepare polymers of lower molecular weight that can associate under higher temperatures by exchanging chemical bonds in a thermo-reversible way.

Patent applications <CIT>, <CIT> and <CIT> disclose a composition resulting from the mixing of at least one copolymer A1 resulting from the copolymerization of at least one monomer functionalized by diol functional groups and of at least one compound A2 comprising at least two boronic ester functional groups. These compounds can associate and exchange chemical bonds in a thermo-reversible way. The polymers according to the present invention are not described.

<CIT> is directed to a composition resulting from the mixing of at least one comb polymer polydiol A1 and at least one compound A2 comprising at least two boronic ester functions. The polymers according to the present invention are not described.

<CIT> is directed to a composition resulting from the mixing of at least one polydiol compound A1 and at least one comb polymer A2 comprising at least two boronic ester functions. The polymers according to the present invention are not described.

<CIT>, <CIT>, <CIT> and <CIT> are directed to a composition resulting from the mixing of at least one oligomer A1, functionalized with diols and optionally comprising repeat units from at least on styrene monomer, and at least one compound A2 comprising at least two boronic ester functions. The polymers according to the present invention are not described.

It was now an object of the present invention to provide thermo-associative polymers that can be used as viscosity index improvers in lubricating oil compositions and that are stable over a broad temperature range. Such polymers should be usable at low treat rates.

Additionally, the synthesis of such polymers should be simple and easy to upscale, and the starting materials should be commercially available.

A first embodiment of the present invention is directed to boronic ester-modified polyalkyl (meth)acrylates A, comprising <NUM> mol% to <NUM> mol% of maleic acid anhydride, and <NUM> mol% to <NUM> mol%, based on the total amount of the boronic ester-modified polyalkyl (meth)acrylates A, of an aminophenylboronic acid ester of general formula (I)
<CHM>
wherein.

A further first embodiment of the present invention is directed to boronic ester-modified polyalkyl (meth)acrylates A, comprising:.

The content of each component (a1), (a2), (a3), (a4) and (a5) is based on the total composition of the boronic ester-modified polyalkyl (meth)acrylates A.

In a particular embodiment, the proportions of components (a1), (a2), (a3), (a4) and (a5) add up to <NUM>% by weight.

In the boronic ester-modified polyalkyl (meth)acrylates A of general formula (I) as defined further above, the amino function can be in the ortho, meta or para position with regards to the bore substituent, preferably in the ortho or para position with regards to the bore substituent, more preferably in the para position with regards to the bore substituent.

A further first embodiment of the present invention is directed to boronic ester-modified polyalkyl (meth)acrylates A, wherein the C10-<NUM> alkyl (meth)acrylates are a mixture of C12-<NUM> alkyl (meth)acrylates and C16-<NUM> alkyl (meth)acrylates in a weight ratio of <NUM>:<NUM> to <NUM>:<NUM>.

A further first embodiment of the present invention is directed to boronic ester-modified polyalkyl (meth)acrylates A as defined further above, wherein in general formula (I) n denotes an integer <NUM> or <NUM> and R<NUM> together with R<NUM> form a ring of general formula (lla)
<CHM>
wherein R<NUM> and R<NUM> are independently selected from the group consisting of H and C1-<NUM> alkyl, R<NUM> and R<NUM> are independently selected from the group consisting of H and C1-<NUM> alkyl, and the stars "*" represent the bonds to the oxygen atoms.

The weight-average molecular weight of the boronic ester-modified polyalkyl (meth)acrylates A according to the present invention is preferably in the range of <NUM>,<NUM> to <NUM>,<NUM>/mol, more preferably in the range of <NUM>,<NUM> to <NUM>,<NUM>/mol. The number-average molecular weight of the polyalkyl(meth)acrylate polymers according to the present invention is preferably in the range of <NUM>,<NUM> to <NUM>,<NUM>/mol, more preferably in the range of <NUM>,<NUM> to <NUM>,<NUM>/mol.

Preferably, the polyalkyl(meth)acrylate copolymers according to the present invention have a polydipersity index (PDI) Mw/Mn in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>.

Mw and Mn are determined by size exclusion chromatography (SEC) using commercially available polymethylmethacrylate standards. The determination was done by gel permeation chromatography with THF as eluent.

The term "(meth)acrylates" refers to both, esters of acrylic acid and esters of methacrylic acid. Esters of methacrylic acid are preferred.

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

Suitable C1-<NUM> 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 C<NUM>-<NUM> alkyl (meth)acrylates are methyl (meth)acrylate and n-butyl (meth)acrylate; methyl methacrylate and n-butyl methacrylate are especially preferred.

Suitable C1-<NUM> alkyl (meth)acrylates include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate) and iso-propyl (meth)acrylate. Particularly preferred C1-<NUM> alkyl (meth)acrylate is methyl (meth)acrylate.

The C10-<NUM> alkyl (meth)acrylates for use in accordance with the invention are esters of (meth)acrylic acid and straight chain or branched alcohols having <NUM> to <NUM> carbon atoms. The term "C10-<NUM> alkyl (meth)acrylates" encompasses individual (meth)acrylic esters with an alcohol of a particular length, and likewise mixtures of (meth)acrylic esters with alcohols of different lengths. Suitable C10-<NUM> alkyl (meth)acrylates include, for example, <NUM>-butyloctyl (meth)acrylate, <NUM>-hexyloctyl (meth)acrylate, decyl (meth)acrylate, <NUM>-butyldecyl (meth)acrylate, <NUM>-hexyldecyl (meth)acrylate, <NUM>-octyldecyl (meth)acrylate, undecyl (meth)acrylate, <NUM>-methylundecyl (meth)acrylate, dodecyl (meth)acrylate, <NUM>-methyldodecyl (meth)acrylate, <NUM>-hexyldodecyl (meth)acrylate, <NUM>-octyldodecyl (meth)acrylate, tridecyl (meth)acrylate, <NUM>-methyltridecyl (meth)acrylate, tetradecyl (meth)acrylate, <NUM>-decyltetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, <NUM>-methylhexadecyl (meth)acrylate, <NUM>-dodecylhexadecyl (meth)acrylate, heptadecyl (meth)acrylate, <NUM>-isopropylheptadecyl (meth)acrylate, <NUM>-tert-butyloctadecyl (meth)acrylate, <NUM>-ethyloctadecyl (meth)acrylate, <NUM>-isopropyloctadecyl (meth)acrylate, octadecyl (meth)acrylate, <NUM>-decyloctadecyl (meth)acrylate, <NUM>-tetradecyloctadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, cetyleicosyl (meth)acrylate, stearyleicosyl (meth)acrylate, docosyl (meth)acrylate and/or eicosyltetratriacontyl (meth)acrylate. <NUM>-decyl-tetradecyl (meth)acrylate, <NUM>-decyloctadecyl (meth)acrylate, <NUM>-dodecyl-<NUM>-hexadecyl (meth)acrylate, <NUM>,<NUM>-octyl-<NUM>-dodecyl (meth)acrylate, <NUM>-tetradecylocadecyl (meth)acrylate, <NUM>,<NUM>-tetradecyl-octadecyl (meth)acrylate and <NUM>-hexadecyl-eicosyl (meth)acrylate.

The C12-<NUM> alkyl (meth)acrylates for use in accordance with the invention are esters of (meth)acrylic acid and alcohols having <NUM> to <NUM> carbon atoms. The term "C12-<NUM> alkyl (meth)acrylates" encompasses individual (meth)acrylic esters with an alcohol of a particular length, and likewise mixtures of (meth)acrylic esters with alcohols of different lengths.

Suitable C12-<NUM> alkyl (meth)acrylates include, for example, decyl (meth)acrylate, undecyl (meth)acrylate, <NUM>-methylundecyl (meth)acrylate, dodecyl (meth)acrylate, <NUM>-methyldodecyl (meth)acrylate, tridecyl (meth)acrylate, <NUM>-methyltridecyl (meth)acrylate, tetradecyl (meth)acrylate and/or pentadecyl (meth)acrylate.

Particularly preferred C12-<NUM> alkyl (meth)acrylates are methacrylic esters of a linear C12-<NUM> alcohol mixture (C12-<NUM> alkyl methacrylate).

The C16-<NUM> alkyl (meth)acrylates for use in accordance with the invention are esters of (meth)acrylic acid and alcohols having <NUM> to <NUM> carbon atoms. The term "C16-<NUM> alkyl (meth)acrylates" encompasses individual (meth)acrylic esters with an alcohol of a particular length, and likewise mixtures of (meth)acrylic esters with alcohols of different lengths.

Suitable C16-<NUM> alkyl (meth)acrylates include, for example, <NUM>-hexyldecyl (meth)acrylate, <NUM>-octyldecyl (meth)acrylate, undecyl (meth)acrylate, <NUM>-methylundecyl (meth)acrylate and dodecyl (meth)acrylate.

Particularly preferred C16-<NUM> alkyl methacrylates are methacrylic esters of a linear C16-<NUM> alcohol mixture (C16-<NUM> alkyl methacrylate).

The comonomers for use in accordance with the present invention can be selected from the group consisting of styrene monomers having from <NUM> to <NUM> carbon atoms, vinyl esters having from <NUM> to <NUM> carbon atoms in the acyl group, vinyl ethers having from <NUM> to <NUM> carbon atoms in the alcohol group, (di)alkyl fumarates having from <NUM> to <NUM> carbon atoms in the alcohol group, (di)alkyl maleates having from <NUM> to <NUM> carbon atoms in the alcohol group, dispersing nitrogen-functionalized monomers, and mixtures of these monomers.

Examples of styrene monomers having from <NUM> to <NUM> carbon atoms are styrene, substituted styrenes having an alkyl substituent in the side chain, for example alpha-methylstyrene and alpha-ethylstyrene, substituted styrenes having an alkyl substituent on the ring, such as vinyltoluene and para-methylstyrene, halogenated styrenes, for example monochlorostyrenes, dichlorostyrenes, tribromostyrenes and tetrabromostyrenes; preferred is styrene.

Examples of vinyl esters having from <NUM> to <NUM> carbon atoms in the acyl group include vinyl formiate, vinyl acetate, vinyl propionate, vinyl butyrate. Preferred vinyl esters include from <NUM> to <NUM>, more preferably from <NUM> to <NUM> carbon atoms in the acyl group. The acyl group here may be linear or branched.

Examples of vinyl ethers having from <NUM> to <NUM> carbon atoms in the alcohol group include vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl butyl ether. Preferred vinyl ethers include from <NUM> to <NUM>, more preferably from <NUM> to <NUM> carbon atoms in the alcohol group. The alcohol group here may be linear or branched.

The notation "(di)ester" means that monoesters, diesters and mixtures of esters, especially of fumaric acid and/or of maleic acid, may be used. The (di)alkyl fumarates having from <NUM> to <NUM> carbon atoms in the alcohol group include monomethyl fumarate, dimethyl fumarate, monoethyl fumarate, diethyl fumarate, methyl ethyl fumarate, monobutyl fumarate, dibutyl fumarate, dipentyl fumarate and dihexyl fumarate. Preferred (di)alkyl fumarates comprise from <NUM> to <NUM>, more preferably from <NUM> to <NUM> carbon atoms in the alcohol group. The alcohol group here may be linear or branched.

The (di)alkyl maleates having from <NUM> to <NUM> carbon atoms in the alcohol group include monomethyl maleate, dimethyl maleate, monoethyl maleate, diethyl maleate, methyl ethyl maleate, monobutyl maleate, dibutyl maleate. Preferred (di)alkyl maleates comprise from <NUM> to <NUM>, more preferably from <NUM> to <NUM> carbon atoms in the alcohol group. The alcohol group here may be linear or branched.

Examples of dispersing nitrogen-functionalized monomers are aminoalkyl (meth)acrylates, such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-diethylaminopentyl (meth)acrylate, N,N-dibutylaminohexadecyl (meth)acrylate; aminoalkyl(meth)acrylamides, such as N,N-dimethylaminopropyl(meth)acrylamide; heterocyclic (meth)acrylates, such as <NUM>-(<NUM>-imidazolyl)ethyl (meth)acrylate, <NUM>-(<NUM>-morpholinyl)ethyl (meth)acrylate, <NUM>-(<NUM>-methacryloyloxyethyl)-<NUM>-pyrrolidone, N-methacryloylmorpholine, N-methacryloyl-<NUM>-pyrrolidinone, N-(<NUM>-methacryloyloxyethyl)-<NUM>-pyrrolidinone, N-(<NUM>-methacryloyloxypropyl)-<NUM>-pyrrolidinone; heterocyclic vinyl compounds, such as <NUM>-vinylpyridine, <NUM>-vinylpyridine, <NUM>-methyl-<NUM>-vinylpyridine, <NUM>-ethyl-<NUM>-vinylpyridine, <NUM>,<NUM>-dimethyl-<NUM>-vinylpyridine, vinylpyrimidine, vinylpiperidine, <NUM>-vinylcarbazole, <NUM>-vinylcarbazole, <NUM>-vinylcarbazole, <NUM>-vinylimidazole, <NUM>-methyl-<NUM>-vinylimidazole, N-vinylpyrrolidone, N-vinylpyrrolidine, <NUM>-vinylpyrrolidine, N-vinylcaprolactam, N-vinylbutyrolactam, vinyloxolane, vinylfuran, vinyloxazoles and hydrogenated vinyloxazoles.

The N-dispersant monomer may specifically be at least one monomer selected from the group consisting of N-vinyl pyrrolidinone, N,N-dimethylaminoethyl methacrylate, and N,N-dimethylaminopropyl methacrylamide.

A further embodiment of the present invention is directed to the boronic ester-modified polyalkyl (meth)acrylates A as outlined further above, wherein the aminophenylboronic acid ester of general formula (I) is selected from the group consisting of <NUM>-aminophenylboronic acid pinacol ester, <NUM>-aminophenylboronic acid pinacol ester, <NUM>-aminophenylboronic acid <NUM>,<NUM>-dihydroxybenzene ester, <NUM>-aminophenylboronic acid <NUM>,<NUM>-dihydroxybenzene ester, <NUM>-aminophenylboronic acid <NUM>,<NUM>-dihydroxycyclohehyl ester and <NUM>-aminophenylboronic acid <NUM>,<NUM>-dihydroxycyclohexyl ester, preferably <NUM>-aminophenylboronic acid pinacol ester and <NUM>-aminophenylboronic acid pinacol ester, more preferably <NUM>-aminophenylboronic acid pinacol ester:
<CHM>.

A further embodiment of the present invention is directed to the boronic ester-modified polyalkyl (meth)acrylates A as outlined further above, wherein the maleic acid anhydride is grafted.

A further embodiment of the present invention is directed to grafted boronic ester-modified polyalkyl (meth)acrylates A consisting of a base polymer A1 and units A2 that are grafted thereon, wherein the base polymer A1 comprises:.

the grafted units A2 comprise repeating units prepared from:.

The content of each component (a1), (a2), (a3), (a4) and (a5) is based on the total composition of the boronic ester-modified polyalkyl (meth)acrylate A. In a particular embodiment, the proportions of components (a1), (a2), (a3), (a4) and (a5) add up to <NUM>% by weight.

The polymers according to the present invention are characterized by their ability to form association-related thickeners.

A further embodiment of the present invention is therefore directed to the use of boronic ester-modified polyalkyl (meth)acrylates A according to the present invention to prepare association-related thickeners.

A second embodiment of the present invention is directed to an additive composition, comprising:.

The content of each component (A) and (B) is based on the total weight of the additive composition. In a particular embodiment, the proportions of components (A) and (B) add up to <NUM>% by weight.

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 hydro-finishing, unrefined, refined, re-refined oils or mixtures thereof.

The base oil may also be defined as specified by the <NPL>").

The API currently defines five groups of lubricant base stocks (<NPL>). Groups I, II and III are mineral oils which are classified by the amount of saturates and sulphur they contain and by their viscosity indices; Group IV are polyalphaolefins; and Group V are all others, including e.g. ester oils. The table below illustrates these API classifications.

The kinematic viscosity at <NUM> (KV100) of appropriate apolar base oils used to prepare an additive composition in accordance with the present invention is preferably in the range of <NUM><NUM>/s to <NUM><NUM>/s, more preferably in the range of <NUM><NUM>/s to <NUM><NUM>/s, according to ASTM D445.

Further base oils which can be used in accordance with the present invention are Group II-III Fischer-Tropsch derived base oils.

Fischer-Tropsch derived base oils are known in the art. By the term "Fischer-Tropsch derived" is meant 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 referred to as a GTL (Gas-To-Liquids) base oil. Suitable Fischer-Tropsch derived base oils that may be conveniently used as the base oil in the additive composition of the present invention are those as for example disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

Especially for engine oil formulations are used base oils of API Group III.

The additive composition of the present invention comprises preferably <NUM>% to <NUM>% by weight, of the base oil (A) and <NUM>% to <NUM>% by weight, of the boronic ester-modified polyalkyl (meth)acrylate (B), based on the total weight of the additive composition.

A third embodiment of the present invention is directed to a mixture comprising equal amounts of:.

The content of each component (A) and (B) is based on the total weight of the mixture. In a particular embodiment, the proportions of components (A) and (B) add up to <NUM>% by weight.

The content of each component (b1), (b2), (b3) and (b4) is based on the total composition of the diol-functionalized polyalkyl (meth)acrylate B. In a particular embodiment, the proportions of components (b1), (b2), (b3) and (b4) add up to <NUM>% by weight.

A further third embodiment of the present invention is directed to a mixture as defined further above, wherein component (a5) of the boronic ester-modified polyalkyl (meth)acrylate A and component (b4) of the diol-functionalized polyalkyl (meth)acrylate B are present in equal amounts of <NUM> mol% to <NUM> mol%.

The weight-average molecular weight of the diol-functionalized polyalkyl (meth)acrylates B according to the present invention is preferably in the range of <NUM>,<NUM> to <NUM>,<NUM>/mol, more preferably in the range of <NUM>,<NUM> to <NUM>,<NUM>/mol. The number-average molecular weight of the polyalkyl(meth)acrylate polymers according to the present invention is preferably in the range of <NUM>,<NUM> to <NUM>,<NUM>/mol, more preferably in the range of <NUM>,<NUM> to <NUM>,<NUM>/mol.

Preferably, the polyalkyl(meth)acrylate polymers according to the present invention have a polydipersity index (PDI) Mw/Mn in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>.

The mixtures according to the present invention are characterized by their ability to form association-related thickeners.

A further embodiment of the present invention is therefore directed to the use of the mixture comprising equal amounts of boronic ester-modified polyalkyl (meth)acrylates A and diol-functionalized polyalkyl (meth)acrylates B according to the present invention to prepare association-related thickeners.

A further embodiment of the present invention is directed to a method for preparing association-related thickeners, comprising the steps of:.

The boronic ester-modified polyalkyl (meth)acrylates A and the diol-functionalized polyalkyl (meth)acrylates B according to the present invention can 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).

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.

The usable initiators include azo initiators widely known in the technical field, such as AIBN and <NUM>,<NUM>-azobiscyclohexanecarbonitrile, and also peroxy compounds such as methyl ethyl ketone peroxide, acetylacetone peroxide, dilauryl peroxide, tert-butyl per-<NUM>-ethylhexanoate, ketone peroxide, tert-butyl peroctoate, methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl perbenzoate, <NUM>,<NUM>-bis(tert-butylperoxy)butane, tert-butyl peroxyisopropylcarbonate, <NUM>,<NUM>-bis(<NUM>-ethylhexanoylperoxy)-<NUM>,<NUM>-dimethylhexane, tert-butyl peroxy-<NUM>-ethylhexanoate, tert-butyl peroxy-<NUM>,<NUM>,<NUM>-trimethylhexanoate, dicumyl peroxide, <NUM>,<NUM>-bis(tert-butylperoxy)cyclohexane, <NUM>,<NUM>-bis(tert-butylperoxy)-<NUM>,<NUM>,<NUM>-trimethylcyclohexane, cumyl hydroperoxide, tert-butyl hydroperoxide, bis(<NUM>-tert-butylcyclohexyl) peroxydicarbonate, mixtures of two or more of the aforementioned compounds with one another, and mixtures of the aforementioned compounds with unspecified compounds which can likewise form free radicals. Preferably used in accordance with the present invention are tert-butyl perbenzoate and <NUM>,<NUM>-bis(tert-butylperoxy)butane. Suitable chain transfer agents are especially oil-soluble mercaptans, for example n-dodecyl mercaptan or <NUM>-mercaptoethanol, or else chain transfer agents from the class of the terpenes, for example terpinolene.

The ATRP method is known per se. It is assumed that this is a "living" free-radical polymerization, but no restriction is intended by the description of the mechanism. In these processes, a transition metal compound is reacted with a compound having a transferable atom group. This 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 onto ethylenic groups. However, the transfer of the atom group to the transition metal compound is reversible, and so the atom group is transferred back to the growing polymer chain, which results in formation of a controlled polymerization system. It is accordingly possible to control the formation of the polymer, the molecular weight and the molecular weight distribution.

This reaction regime is described, for example, by <NPL>), by <NPL>). In addition, patent applications <CIT>, <CIT>, <CIT>, <CIT> and <CIT> disclose variants of the above-elucidated ATRP. In addition, the polymers of the invention can also be obtained via RAFT methods, for example. This method is described in detail, for example, in <CIT> and <CIT>.

The polymerization can be conducted under standard pressure, reduced pressure or elevated pressure. The polymerization temperature is also uncritical. In general, however, it is in the range from -<NUM> to <NUM>, preferably <NUM> to <NUM> and more preferably <NUM> to <NUM>.

The polymerization can be conducted with or without solvent. The term "solvent" should be understood here in a broad sense. The solvent is selected according to the polarity of the monomers used, it being possible with preference to use 100N oil, comparatively light gas oil and/or aromatic hydrocarbons, for example toluene or xylene.

As outlined further above, the boronic ester-modified polyalkyl (meth)acrylates A comprise either copolymerized or grafted units of maleic acid anhydride.

In cases where the boronic ester-modified polyalkyl (meth)acrylates A are subsequently grafted with maleic acid anhydride, this is preferably done by a polymer-analogous reaction after the above-described preparation of boronic ester-modified polyalkyl (meth)acrylates A. Accordingly, it is possible with preference first to prepare a polymer by the use of reactive polar unsaturated monomers like maleic acid anhydride. The reactive units are subsequently further reacted with an aminophenylboronic acid ester of general formula (I) as described further above.

The reaction of the reactive polar unsaturated monomer present in the polymer, preferably of the maleic acid anhydride, with the mentioned aminophenylboronic acid esters can be effected typically between <NUM> and <NUM>, preferably between <NUM> and <NUM> and more preferably between <NUM> and <NUM>. The aminophenylboronic acid ester can preferably be added in an equimolar amount to the reactive polar groups, preferably to the anhydride. If excessive amounts of aminophenylboronic acid ester are added, it can subsequently be removed from the mixture. In the case of excessively small proportions, reactive groups remain, which can optionally be converted to less reactive groups by addition of small amounts of water.

The aminophenylboronic acid ester can be added in pure form to the reaction mixture or in a suitable solvent. Preference is given to polar solvents, especially esters, e.g. butyl acetate, diisononyl adipate or dioctylsebacate.

According to the nature of the reactive reactant group converted, water may be formed. For example, in the case of use of anhydride groups, water is released, which, in a particular aspect of the present invention, can be removed substantially completely from the reaction mixture, it being possible to drive out water, for example, by means of dry nitrogen. In addition, it is possible to use desiccants. Volatile solvents such as butyl acetate, if used, can be distilled off after the reaction, preferably under reduced pressure.

The following figures illustrate the results retrieved for the viscosity indices when using the polymer compositions of the present invention:.

The boronic ester-modified polyalkyl (meth)acrylates A and the diol-functionalized polyalkyl (meth)acrylates B according to the present invention were characterized with respect to their molecular weight and PDI.

The weight-average molecular weights (Mw) of the boronic ester-modified polyalkyl (meth)acrylates A and the polyalkyl (meth)acrylates B according to the present invention were determined by gel permeation chromatography (GPC) using polymethyl methacrylate calibration standards according to DIN <NUM>-<NUM> using the following measurement conditions:.

The additive compositions including the boronic ester-modified polyalkyl (meth)acrylates A according to the present invention were characterized with respect to their viscosity index (VI) to ASTM D <NUM>, kinematic viscosity at <NUM> (KV40) and <NUM> (KV100) to ASTM D445.

If not stated otherwise, the term "%" means % by weight (wt.

A solution of <NUM>% of initiator <NUM>,<NUM>-bis(tert-butylperoxy)butane in the monomer mixture is prepared at room temperature (compositional details of the monomer mixtures are shown in Tables <NUM> and <NUM>). An apparatus with <NUM>-neck flask and precision glass saber stirrer was initially charged with <NUM> NB3043. After heating to <NUM> under nitrogen, <NUM> of a monomer-initiator-mixture was added within <NUM> hours. Then the reaction mixture was cooled down to <NUM> and <NUM>% (based to the total amount of monomers) of <NUM>,<NUM>-bis(tert-butylperoxy)butane was added and the resulting mixture stirred at <NUM> overnight. <NUM> of a <NUM>% solution of polymer in NB3043 was obtained.

The conversion of the used monomers was around <NUM>%; i.e. the net compositions of the resulting polymers correspond to the mixtures used in the copolymerizations.

Maleic acid anhydride was heated up at <NUM>. An apparatus with a <NUM>-neck flask and precision glass saber stirrer was charged with <NUM> of the base polymer mixture as prepared under (<NUM>) and heated up to <NUM> under nitrogen. Subsequently, <NUM> of molten maleic anhydride was added followed by an addition of <NUM> of tert-butyl perbenzoate. Subsequently, the reaction temperature was increased to <NUM>. After <NUM> hour and <NUM> hours, another <NUM> of tert-butyl perbenzoate was each added to the reaction mixture. The mixture was then cooled down to <NUM> to add after <NUM> hours <NUM> of <NUM>,<NUM>-bis(tert-butylperoxy)butane and after <NUM> hours <NUM> of <NUM>,<NUM>-bis(tert-butylperoxy)butane and the mixture is stirred overnight. <NUM> of a <NUM>% solution of polymer in NB3043 was obtained.

Maleic acid anhydride was heated up at <NUM>. An apparatus with a <NUM>-neck flask and precision glass saber stirrer was charged with <NUM> of the base polymer mixture as prepared under (<NUM>) and heated up to <NUM> under nitrogen. Then <NUM> of molten maleic anhydride was added followed by an addition of <NUM> of tert-butyl perbenzoate. Subsequently, the reaction temperature was increased to <NUM>. After <NUM> hour and <NUM> hours, another <NUM> of tert-butyl perbenzoate was each added to the reaction mixture. The mixture was then cooled down to <NUM> to add after <NUM> hours <NUM> of <NUM>,<NUM>-bis(tert-butylperoxy)butane and after <NUM> hours <NUM> of <NUM>,<NUM>-bis(tert-butylperoxy)butane and the mixture is stirred overnight. <NUM> of a <NUM>% solution of polymer in NB3043 was obtained.

Maleic anhydride was heated up at <NUM>. An apparatus with a <NUM>-neck flask and precision glass saber stirrer was charged with <NUM> of the base polymer mixture as prepared under (<NUM>) and heated up to <NUM> under nitrogen. Then <NUM> of molten maleic anhydride was added followed by an addition of <NUM> of tert-butyl perbenzoate. Subsequently, the reaction temperature was increased to <NUM>. After <NUM> hour and <NUM> hours, another <NUM> of tert-butyl perbenzoate was each added to the reaction mixture. The mixture was then cooled down to <NUM> to add after <NUM> hours <NUM> of <NUM>,<NUM>-bis(tert-butylperoxy)butane and after <NUM> hours <NUM> of <NUM>,<NUM>-bis(tert-butylperoxy)butane and the mixture is stirred overnight. <NUM> of a <NUM>% solution of polymer in NB3043 was obtained.

The net compositions of the grafted polymers are shown in the following Table <NUM>.

A solution of <NUM> wt. % of <NUM>-aminophenylboronic acid pinacol ester in dioctylsebacate was prepared. Then an apparatus with a <NUM>-neck flask, precision glass saber stirrer and condenser was charged with <NUM> of the polymer mixture prepared as described under steps (<NUM>) or (<NUM>). After heating to <NUM> under nitrogen, <NUM> of the <NUM>-aminophenylboronic acid pinacol ester solution was added within <NUM> hour. The post-grafting reaction was finished <NUM> hours after the addition of the <NUM>-aminophenylboronic acid pinacol ester and the mixture was diluted to a solids content of <NUM>% with NB3043.

A solution of <NUM> wt. % of <NUM>-aminophenylboronic acid pinacol ester in dioctylsebacate was prepared. Then an apparatus with a <NUM>-neck flask, precision glass saber stirrer and condenser was charged with <NUM> of the polymer mixture prepared as described under step (<NUM>) or (<NUM>). After heating to <NUM> under nitrogen, <NUM> of the <NUM>-aminophenylboronic acid pinacol ester solution was added within <NUM> hour. The post-grafting reaction was finished <NUM> hours after the addition of the <NUM>-aminophenylboronic acid pinacol ester and the mixture was diluted to a solids content of <NUM>% with NB3043.

The net compositions of the resulting boronic ester-modified polyalkyl (meth)acrylates A are shown in the following Table <NUM>.

A solution of a monomer mixture (compositional details of the examples of the used monomer mixtures are given in Table <NUM>) and <NUM>% (based to the total amount of monomers) of initiator <NUM>,<NUM>-bis(tert-butylperoxy)butane was prepared at room temperature. An apparatus with <NUM>-neck flask and precision glass saber stirrer was initially charged with <NUM> butyl acetate. After heating to <NUM> under nitrogen, <NUM> of the monomer-initiator-mixture was added within <NUM> hours. Then the reaction mixture was cooled down to <NUM> and <NUM>% (based to the total amount of monomers) of <NUM>,<NUM>-bis(tert-butylperoxy)butane was added and the mixture was stirred at <NUM> overnight. <NUM> of a <NUM>% solution of polymer in butyl acetate was obtained. The solvent was then exchanged by adding NB3043 to the solution of polymer in butyl acetate. Subsequently, the butyl acetate was removed by vacuum distillation resulting in a <NUM>% solution of polymer in NB3043.

Table <NUM> shows the net compositions of the working examples and comparative examples. The monomer components will add up to <NUM>%. As the residual monomer content in the retrieved polymers is significantly below <NUM>%, the net compositions of the polymers correspond to the used monomer compositions.

The properties of the boronic ester-modified polyalkyl (meth)acrylates A and the diol-functionalized polyalkyl (meth)acrylate B are presented in the following Table <NUM>.

The resulting polymers were characterized by their molecular weight and PDI. The results are shown in the following Table <NUM>.

The weight-average molecular weights are in the range of <NUM>,<NUM>/mol (Example 4b) and <NUM>,<NUM>/mol (Example 2c). The number-average molecular weights are in the range of <NUM>,<NUM>/mol (Example 5c) and <NUM>,<NUM>/mol (Examples 1c and 6c).

The thickening efficiency of a VI improver is specified by its KV100 (kinematic viscosity at <NUM>) at a given treat rate.

The single polymers were dissolved in a base oil and the retrieved solutions were characterized by their KV40, KV100 and VI. The results are shown in the following Table <NUM>.

It can be seen that the KV40-values are between <NUM> and <NUM><NUM>/s, the KV100-values are between <NUM> and <NUM><NUM>/s and the viscosity indices are in the range of <NUM> (Example <NUM>) and <NUM> (Example <NUM>).

To show the associative effect of the polymers, mixtures comprising equal parts of an AMBER polymer and a diol-polymer, compositions comprising <NUM>% of a <NUM>:<NUM> polymer mixture in a base oil were prepared and, subsequently, KV40, KV100 and viscosity indices were measured.

The corresponding values are outlined in the following Table <NUM>.

Claim 1:
Boronic ester-modified polyalkyl (meth)acrylates A, comprising <NUM> mol% to <NUM> mol% of maleic acid anhydride, and <NUM> mol% to <NUM> mol% of an aminophenylboronic acid ester of general formula (I)
<CHM>
wherein n denotes an integer from <NUM> to <NUM>, R<NUM> and R<NUM> are independently selected from the group consisting of hydrogen and C1-<NUM> alkyl, or R<NUM> together with R<NUM> form a ring of general formula (lla)
<CHM>
wherein R<NUM>, R<NUM>, R<NUM> and R<NUM> are independently selected from the group consisting of H and C1-<NUM> alkyl and the stars "*" represent the bonds to the oxygen atoms, or
R<NUM> together with R<NUM> form a ring of general formula (IIb)
<CHM>
wherein R<NUM> and R<NUM> are independently selected from the group consisting of H and C1-<NUM> alkyl and the stars "*" represent the bonds to the oxygen atoms, or
R<NUM> together with R<NUM> form a ring of general formula (llc)
<CHM>
wherein R<NUM> denotes a hydrogen atom or C1-<NUM> alkyl and the stars "*" represent the bonds to the oxygen atoms.