BRPI0718529A2 - METACRYLATE COPOLYMER FLUIDITY POINT DEPRESSORS - Google Patents

Abstract

Polymethacrylate copolymers are disclosed which comprise from about 60 - about 96 wt.% of a C12-C16 alkyl methacrylate and from about 40 to about 4 wt.% of a C18-C30 alkyl methacrylate and provide excellent low temperature properties to lubricating oils.

Description

Report of the Invention Patent for "Methacrylate Copolymer Fluid Point Depressors".

This invention relates to polyalkyl methacrylate copolymers having excellent low temperature properties. The present invention also relates to the use of these copolymers as pour point depressants or low temperature viscosity enhancers for lubricating oils.

Polyalkyl methacrylate pour point depressants are known in the lubricating industry. Many attempts have been made to produce polyalkyl methacrylate pour point depressants that improve the low temperature viscometrics of various lubricant compositions.

Pour point depressant (PPD) additives improve the low temperature performance of oils by modifying the wax crystallization process. A wide variety of chemical types are available, and include polyalkyl methacrylates, styrene polyesters, alkylated polystyrenes, ethylene vinyl acetate, vinyl fumarate acetate, esterified olefin polymers, styrene maleic anhydride, and alkylated naphthalenes.

The present invention is directed to alkyl methacrylate polymers which exhibit desirable low temperature properties. More specifically, the invention is directed to PPDs which exhibit excellent low temperature properties in lubricating oils for applications such as automatic transmission fluids, manual transmission fluids, hydraulic fluids, greases, engine fluids, metal machining fluids. machine oil, shock absorbing fluids and crankcase engine applications. There is a growing need for PPD oil that achieves optimal low temperature performance at low concentrations. The present invention addresses the need for an improved PPD.

In particular, the invention addresses the need for a pour point depressant that can be used on a variety of oils at lower treatment rates, which exhibits less interaction with other oil components such as dispersants and inhibitors. showing stability in shear fields and lower geification rates in some cases depending on the base oil than for previous pour point polyalkyl methacrylates. It is also important that PPD be soluble and compatible with the base oil and maintain an appropriate Brookfield viscosity at low temperatures. Incorporation of inventive polyalkyl methacrylates is demonstrated. The addition of inventive polyalkyl methacrylates results in improved viscosity at low temperatures while maintaining acceptable pour point depressive activity.

United States Patent No. 2,655,479 describes a com-

depressive pour point position consisting of a mixture of two copolymers, the first copolymer having an average side chain length of about 12.7 while the second copolymer has an average side chain length of about 11 ,2.

United Kingdom Patent No. 1,559,952 describes a mixture of

of two classes of oil-soluble polyalkyl methacrylates as pour point depressors.

United States Patent No. 4,146,492 describes lubricating oil compositions comprising from about 0.5 to 30.0% by weight of a specifically defined ethylene propylene copolymer and from about 0.005 to 10%. 0% by weight of a liquid interpolymeric polyalkyl acrylate of (A) C1-C15 alkyl acrylate and (B) C16-C22 alkyl acrylate having an A: B weight ratio of about 90:10 and 50:50, a molecular weight of 1,000 to 25,000 and a side chain length of 25 alkyl average of from about 11 to 16 carbon atoms.

United States Patent No. 4,867,894 describes pour point enhancing additives for mineral oils comprising from 10 to 30 mole% methyl methacrylate, 10 to 70 mole% of a linear C 1-6 alkyl methacrylate of 10 to 80 mole% of a linear C4 -C15 alkyl methacrylate and / or a branched C4 -C40 alkyl methacrylate, and 0 to 30 mole% of a free radical polymerizable nitrogen-containing monomer having dispersing action. United States Patent Nos. 5,312,884 and 5,368,761 describe copolymers useful as pour point depressants for lubricating oils which comprise 15 to 67 mol% of Cg-C-15 alkyl (meth) acrylates, 3 to 6 40 mole% C 1 -C 24 alkyl (meth) acrylates, and 30 to 65 mole% 5 C 1 -C 4 alkyl methacrylates. These patent documents do not teach copolymers containing the specific monomers in the specific proportions required by the present invention.

United States Patent No. 5,281,329 describes copolymers useful as pour point depressants for oils containing at least two species of polyalkyl (meth) acrylate, one species having a crystallization temperature start above 15 ° C. and a species having a crystallization temperature start below 15 ° C.

United States Patent No. 5,534,175 describes copolymers of unsaturated fatty esters derived from 12-20 wt.% Of a CrClaalkyl (meth) acrylate, 45 to 72 wt. C 15 alkyl and 14 to 30% by weight of a C 16 -C 25 alkyl (meth) acrylate.

EP-A-236 844 describes pour point improving agents derived from methyl methacrylate.

United States Patent No. 6,255,261 describes copolymers formed from 5 to 60% by weight of C11-C15 alkyl (meth) acrylates and 95 to 40% by weight of C16-C30 alkyl (meth) acrylates for use. as pour point depressors.

The present invention is directed to polyalkyl methacrylates and their use as pour point depressants for lubricating oils.

The polyalkyl methacrylate copolymers of the present invention

comprise monomer units which are formed of:

(A) about 60.0 to about 96.0% by weight of a C 12 -C 16 alkyl methacrylate; and

(B) about 40.0 to about 4.0% by weight of a C18-C30 alkyl methacrylate.

Polyalkyl methacrylate copolymers may be of any structure, such as straight, cross-linked, structured, lightly structured or branched chains.

Polyalkyl methacrylate copolymers are added to a lubricating viscosity oil to form a lubricating oil composition.

A further embodiment of the invention relates to a composition

lubricating oil composition comprising:

(i) a lubricating viscosity oil;

(ii) a polyalkyl methacrylate copolymer according to claim 1; and optionally

(iii) other additives.

In addition, the above composition is used to improve the low temperature properties of a lubricating oil.

The phrase "monomer units formed of" refers to polymer monomer units formed after a monomer has been reacted.

gido. For example, a C 12 -C 16 alkyl methacrylate monomer polymerizes to determine a polymer with a unit derived from C 12 -C 16 alkyl methacrylate.

The term monomer alone refers to unpolymerized alkyl methacrylate.

Percentages are usually based on the total weight to be

unless otherwise specified.

The term copolymer refers to polyalkyl methacrylate formed from monomer units derived from (A) and (B).

The copolymers of the present invention have a molecular weight

relative weighted average ranging from about 5,000 to about 250,000. Typically, the weight average may range from about 10,000 to about

200,000, from about 150,000 to about 150,000 and typically about

20,000 to about 130,000. The molecular weight distribution is usually less than 2.5 and generally ranges from about 1.5 to about 2.5.

Molecular weight is determined by permeation chromatography.

gelation (GPC) using a standard polymethyl methacrylate. The determined average molecular weight is then relative to the non-absolute standard. Methacrylate long chain alkyl esters may be straight or branched.

Crosslinking agents are, for example, polyethylenically unsaturated crosslinking agents.

Examples are methylene bis (meth) acrylamide,

polyethylene glycol; polyethylene glycol dimethacrylate; N-vinyl acrylamide; vinylbenzene; tetra (ethylene glycol) diacrylate; diallyloctylamide; trimethylpropane ethoxy triacrylate; N-allylacrylamide N-methylallyl acrylamide, pentaerythritol triacrylate and combinations thereof. Other crosslinking systems 10 may be used instead of or in addition to these. For example, cross-group pendant crosslinking may be achieved, for example, by the use of ethylenically unsaturated epoxy monomers, or by the use of polyfunctional cross-linking agents from other known cross-linking systems.

Component (A) may, for example, range from about 65.0 to about 95.0% by weight or about 70.0 to about 95.0, about 80.0 to about 95.0 from about 88.0 to about 95.0% by weight of the formed polyalkyl methacrylate copolymers.

Component (B) may, for example, range from about 35.0 to about 5.0% by weight, or about 30.0 to about 5.0, about 20.0 to about 5, O, about 15.0 to about 5.0, about 12.0 to about 5.0% by weight of the formed polyalkyl methacrylate copolymers.

The weight percentages of the components (A) and (B) of the formed alkyl methacrylate are calculated by taking the total weight of the component (A) or (B) on the total weight of the polyalkyl methacrylate copolymer formed. multiplied by 100. The basis weight of the copolymer formed is the copolymer per se and does not include the diluent.

The term C12 -C16 alkyl methacrylate means a methacrylic acid alkyl ester having a straight or branched ester alkyl group of 12 to 16 carbon atoms, such as lauryl methacrylate, myristyl methacrylate, methacrylate methacrylate. cetyl, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate and mixtures thereof. 10

15

20

25

The preferred source for C 12 -C 16 alkyl methacrylate esters is lauryl methacrylate which contains a mixture of methacrylate esters formed from a mixture of C 12 -C 16 alkyl alcohols. For example, about 60.0 to about 96.0% by weight of lauryl methacrylate esters, about 65.0 to about 95.0% by weight of lauryl methacrylate esters make up the copolymers of polymethacrylate formed.

Alternatively, weight percentages for component (A) may vary as described above for lauryl methacrylate.

In the example where lauryl methacrylate esters are used to compose component (A) of polyalkyl methacrylate copolymers, the lauryl ester is derived from a linear or branched distribution of C12-C16 long chain alcohols. The weight percentages of the compositions comprising lauryl methacrylate esters may vary as follows:

Laurila Methacrylate Distribution

C 12 C 14 C 16 chain length wt% 68-74 20-26 2-6 The definition of weight percentages of the various counterparts in lauryl methacrylate means weight percent based on the total weight of lauryl methacrylate. If the total lauryl methacrylate fraction is 100 g and the contribution of C 12 is 68 g, the weight percentage of component C12 is 68% by weight of total lauryl methacrylate.

It is preferable that the alkyl chains of component (A) be substantially linear.

It is preferred that C1 -C16 alkyl esters contain only even (C 12, C 14 and C 16) ester chain lengths, but even and odd (C 12, C 13, C) ester chain lengths. 14, C 15, and C 16) are also possible. In the case where only even chain lengths are used, component (A) contains mainly C12, C14 and C1-6 alkyl esters.

(A) may consist essentially of from about 60.0 to about 96% by weight of C12, Cu and C1-6 alkyl methacrylates.

The C12 and C14 homologues will typically dominate fraction (A). For example, at least about 80.0% by weight of fraction (A) is C 12 and C 14. Typically at least 85.0 to 88% by weight of fraction (A) is C 12 and C 14.

The term "consists essentially of" means that lower levels

Other monomers polymerizable with alkyl methacrylates may be present as long as they do not adversely affect the low temperature properties of fully formulated fluids.

The average chain length for the C 12 -C 16 alkyl methacrylates of component (A) ranges from about 12 to about 13 carbon atoms.

The term C18-C30 alkyl methacrylate means a methacrylic acid alkyl ester having a straight or branched chain alkyl group of 18 to 30 carbon atoms per group, such as stearyl methacrylate, methacrylate methacrylate. octadecyl, heptadecyl methacrylate, nonadecyl methacrylate, eicosyl methacrylate, henicosyl methacrylate, docosyl methacrylate, tetracosyl methacrylate, pentacosyl methacrylate, hexacosyl methacrylate, nonacrylate methacrylate, methacrylate beenyl methacrylate and mixtures thereof.

A possible source for C8 -Csoalkyl methacrylate esters is beenyl methacrylate esters. Behenyl methacrylate used in the present examples contains a range of long chain methacrylate esters wherein the length of ester chains ranges from C-is to C22. For example, about 40.0 to about 4.0% by weight of the wasyl methacrylate esters make up the formed polyalkyl methacrylate copolymer. For example, 35.0 to about 5.0% by weight, about 30 to about

5.0 or about 20 to about 5.0 of the formed polyalkyl methacrylate copolymer are formed from beenyl methacrylate esters.

In the case where beenila methacrylate esters are used

To make up component (B) of the polyalkyl methacrylate copolymers, the phenyl esters may be derived from a C 12 -C 22 distribution of long chain alcohols. The weight percent of beenyl methacrylate ester compositions may vary as follows:

Beenila Methacrylate Distribution

Length of C 18 C 20 C 22 chain% by weight 40-50 5-15 40-50 When referring to the percentage distribution by weight of the particular ester in beenyl methacrylate, the percentage by weight is based on the total weight of beenila methacrylate.

Behenyl methacrylate may consist essentially of from about 40.0 to about 50.0, preferably 42.0 to about 48.0% by weight of C18 alkyl methacrylate, from about 5.0 to about 15.0 preferably 6.5 10 to about 12.0% by weight of C20 alkyl methacrylate and about 40.0 to about 50.0, preferably 42.0 to about 48.0% by weight methacrylate. C22 alkyl based on the total weight of beenyl methacrylate.

Behenyl methacrylate is substantially linear and mainly contains C18-C22 alkyl methacrylates. Behenyl methacrylate may contain a small amount of C1-6 alkyl. For example, beenyl methacrylate will usually contain less than 0.8 wt% C 16 alkyl or less than 0.5 wt% C 16 alkyl.

The cumulative weight percentages of C 16 -C 18 alkyl methacrylates in the formed copolymer will generally not exceed about 22.0 to 23.0% by weight. For example, the combined weight percentages of the C1-6 alkyl and C1-8 alkyl fractions may be about 15.0, 16.0, 17.0,

18.0, 19.0 or 21.0% by weight of the alkyl methacrylate formed of components (A) and (B) with a minimum of at least 7.0, 8.0 or 9.0% by weight. for the cumulative weight percentage of C1-6 alkyl and C1-8 alkyl methacrylates. For example, components (A) and (B) are also defined as comprising a combined weight percentage of C1-6 alkyl and C1-6 alkyl methacrylates, whose combined weight ranges from a minimum of 7.0% by weight. about 23.0% by weight based on the total weight of the poly methacrylate copolymers. In addition, the alkyl methacrylate esters in the component

(B) that are equal to or greater than C 20 make up at least about

2.0 to about 40.0% by weight of the formed polyalkyl methacrylate copolymer. For example, a minimum of about 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.0, 7.0 or 8.0 wt.% Of the copolymers of Formed polyalkyl methacrylate is derived from C20-C30 alkyl methacrylate esters. The polyalkyl methacrylate copolymers formed will be formed of a maximum of about 10.0, 20.0, 30.0 or 40.0% by weight of C20-C30 alkyl methacrylate esters.

Components (B) are also defined as comprising:

a combined weight percentage of C20 -C30 alkyl methacrylate esters, the weight of which ranges from above a minimum of 2.0% by weight - above a maximum of about 40.0% by weight, based on on the total weight of the polyalkyl methacrylate copolymers.

C20-C24 alkyl homologues are preferred and homologues

C20 -C22 alkyl compounds are the most preferred homologues of component (B). For example, C20 -C22 alkyl homologs may comprise about 2.0 - about 40.0, about 4.0 - about 40.0 or about 4.0 to about 30.0% by weight of the polyalkyl methacrylate copolymers formed. The typical weight ranges for C20-C24 alkyl counterparts are about 4.0 to about 40.0, about 4.0 to about 30.0, or about 5.0 to about 20.0. % by weight of the formed polyalkyl methacrylate copolymers.

The average chain length for the alkyl methacrylates of component (B) ranges from about 20 to about 22 carbon atoms or about 20 to about 21 carbon atoms.

In a preferred embodiment, the sum of (A) and (B) is 100.0% by weight of the formed polyalkyl methacrylate copolymers.

The polymethacrylate PPD copolymers of the invention may optionally contain C1 -C10 alkyl methacrylate esters, or other polymerizable non-alkyl methacrylate monomers.

Polyalkyl methacrylates may consist essentially of monomers (A) and (B). For example, the sum of (A) and (B) is equal to 100%. Alkyl methacrylate comonomers containing 12 or more carbon atoms in the alkyl ester group are generally prepared by standard esterification procedures using technical grades of long chain aliphatic alcohols. These commercially available alcohols 5 are mixtures of alcohols of varying chain lengths containing from 12 to 30 carbon atoms in the alkyl groups. Accordingly, for purposes of this invention, alkyl methacrylate comonomers are intended to include not only the individual alkyl methacrylate esters named, but also mixtures with other alkyl methacrylate esters.

Conventional free radical polymerization methods may be used to prepare the copolymers of the present invention. Polymerization of alkyl methacrylate monomers may occur under a variety of conditions, including volume polymerization, solution polymerization, usually in an organic solvent, preferably mineral oil.

In solution polymerization, the reaction mixture comprises a diluent, alkyl methacrylate monomers, a polymerization initiator and usually chain transfer agent and optionally a crosslinker.

The diluent may be any inert hydrocarbon liquid. The weight ratio of diluent to total monomer charge may range from about 90:10 to about 60:40. The term total monomer charge means the combined amount of all monomers in the initial, ie unreacted, reaction mixture.

In preparing the copolymers of the present invention by free radical polymerization, the alkyl methacrylate monomers may be simultaneously or consecutively polymerized or the monomers may be fed over time into the reaction vessel. For example, the mixture of C1 -C30 alkyl methacrylate monomers may be fed over time through a reaction vessel together with a starter supply. Suitable polymerization initiators include initiators which dissociate upon heating to produce a free radical, for example peroxide compound such as benzoyl peroxide, t-butyl perbenzoate, t-butyl peroctoate and cumene hydroperoxide; or azo compound such as azoisobutyronitrile and 2,2'-azobis (2-methylbutanenitrile). The mixture includes from about 0.01 wt% - about 5.0 wt% of initiator, relative to the total monomer mixture. For example, 0.02 wt% - about 4.0 wt%, 0.02 wt% - about 3.5 wt% is desired. Typically about 0.02 wt% - about 2.0 wt% is used.

Suitable chain transfer agents include

those conventional in the art such as mercaptans and alcohols. For example, tridecyl mercaptan, dodecyl mercaptan and ethyl mercaptan may be used as chain transfer agents. Selection of the amount of chain transfer agent to be used is based on the desired molecular weight of the polymer being synthesized, as well as the desired level of shear stability for the polymer, that is, if a more shear stable is desired. More chain transfer agent may be added to the reaction mixture. The chain transfer agent is added to the reaction mixture or monomer supply 20 in an amount of 0.01 - 3.0% by weight relative to the monomer mixture.

By way of example and without limitation, all components are loaded into a reaction vessel which is equipped with a stirrer, thermometer and reflux condenser and heated with stirring under a blanket of nitrogen at a temperature of about 50 °. C - about 125 ° C over a period of from about 0.5 hours to about 15 hours to perform the polymerization reaction.

A viscous solution of the copolymers of the present invention in the diluent is obtained as the process product described above.

To form the lubricating oils of the present invention, an oil

The base compound is treated with the copolymer of the invention in a conventional manner, that is, by adding the copolymers to the base oil to provide a lubricating oil composition having the desired low temperature properties. The lubricating oil contains from about 0.01 - about 5.0 parts by weight, for example about 0.01 - about 2.0, more typically about 0.02 - about 0.5, of the copolymer. pure (ie excluding oil 5 diluent) per 100 parts by weight of the base oil. The preferred dosage will certainly depend on the base oil.

In a particularly preferred embodiment, the copolymer is added to the base oil as a relatively concentrated solution of the copolymer in a diluent. The diluent oil may be any of the oils listed below which are suitable for use as base oils.

Preferred base oils include mineral oils, synthetic polyolefin oils and mixtures thereof. Suitable base oils also include base materials obtained by isomerization of synthetic wax and slag wax, as well as base materials produced by hydrocracking (rather than solvent extraction) of the aromatic components and poles of the raw product. In general, both mineral and synthetic base oils will each have a kinematic viscosity ranging from about 1 - about 40 cSt at 100 ° C, although typical applications will require each oil to have a viscosity ranging from about 2 - about 20 ° C at 100 ° C.

Mineral oils useful in this invention include all common mineral oil base feedstocks. This would include oils that are naphthenic, paraffinic or aromatic in the chemical structure.

Naphthenic oils are composed of methylene groups disposed in the ring formation with paraffinic side chains attached to the rings. The pour point is generally lower than the pour point for paraffin oils. Paraffin oils comprise straight chain or branched saturated hydrocarbons. High molecular weight straight chain paraffins increase the pour point of oils and are often removed by de-waxing. Aromatic oils are closed carbon ring hydrocarbon of a semi-unsaturated character and may have attached side chains. This oil is more easily degraded than paraffinic and naphthalene oils leading to corrosive byproducts.

A base raw material usually contains a chemical composition that contains some proportion of all three (paraffinic, naphthenic and aromatic). For a description of types of base raw materials, see Motor Oils and Engine Lubrication by A. Schilling, Scientific Publications, 1968, section 2.2 - 2.5.

Polyalkyl methacrylate copolymer can be used in paraffinic, naphthenic and aromatic oils. For example, the polymethacrylate copolymer may be used in Group 1-V base oils. These groups are known to those skilled in the art. Additionally, the polymethacrylate copolymer may be used in gas to liquid oils.

Gas-to-liquid (GTL) oils are known in the art. Gas sources include a wide variety of materials such as natural gas, methane, C1-C3 alkanes, landfill gases, and the like. Such gases may be converted to liquid hydrocarbon products suitable for use as lubricating base oils by a gas-to-liquid (GTL) process, such as the process described in United States Patent No. 6,497,812.

Base oils derived from a gaseous source, hereinafter referred to

"GTL base oils" typically have a viscosity index of greater than about 130, a sulfur content of less than about 0.3 weight percent, contain more than about 90%. by weight of saturated hydrocarbons (isoparaffins), typically from about 95.0 - about 100.0% by weight of branched aliphatic hydrocarbons, have a pour point below -15 ° -20 ° C.

GTL base oils may be mixed with more conventional base oils such as Groups I - V as specified by the American Petrol Institute. For example, the base oil component of the lubricating compositions may include 1-100 weight percent for a GTL base oil.

A lubricating oil composition may be at least partially derived from a gaseous source and contains the polymethacrylate ester present as a pour point depressant.

The oils may be refined by conventional methodology using acid, alkali, and clay or other agents such as aluminum chloride, 5 or they may be extracted oils produced, for example, by solvent extraction with solvents such as phenol, carbon dioxide. sulfur, furfural, dichlordiethyl ether, etc. They may be hydrotreated or hydrorefined, deselected by cooling or catalytic deaeration processes, or hydrocracked. Mineral oil may be produced from natural crude sources or may be composed of isomerized wax materials or residues from other refinement processes. Preferred synthetic oils are α-olefin oligomers, particularly 1-decene oligomers, also known as poly-α-olefins (PAO).

Base oils may be derived from refined, refined oils, or mixtures thereof. Unrefined oils are obtained directly from a natural source or synthetic source (eg coal bitumen, shale, or tarred sand) without further purification or treatment. Examples of unrefined oils include a shale oil obtained directly from a replication operation, a petroleum oil obtained directly from a distillation, or an ester oil obtained directly from a esterification process, each of which is then used without further treatment. Refined oils are similar to unrefined oils except that refined oils have been treated in one or more purification steps to improve one or more properties. Suitable purification techniques include distillation, hydrotreating, de-daring, solvent extraction, acid or base extraction, filtration, and percolation, all of which are known to those skilled in the art. Refined oils are obtained by treating oils used in processes similar to those used to obtain refined oils. These refined oils are also known as refurbished or reprocessed oils and are often further processed by techniques for removing oil decomposition products and spent additives. Addition of at least one additional usual oil additive to the composition is possible. The mentioned lubricating compositions, for example, greases, engine fluids, metalworking fluids and hydraulic fluids, may additionally comprise additional additives which are added to improve their basic properties as well. Such additives include: additional antioxidants, metal passivators, rust inhibitors, viscosity index enhancers, additional flow point depressants, dispersants, detergents, additional extreme pressure additives and anti-additive additives. Such additives are added in the usual amounts for each, which varies in each case from approximately

0.01 - 10.0%, preferably 0.1 - 1.0% by weight. Examples of additional additives are given below:

1. Examples of Phenolic Antioxidants:

1.1. Alkylated monophenols: 2,6-di-tert-butyl-4-methylphenol, 2-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl -4-n-butylphenol,

2,6-di-tert-butyl-4-iso-butylphenol, 2,6-dicyclopentyl-4-methylphenol, 2- (alpha-methylcyclohexyl) -4,6-dimethylphenol, 2,6-dioctadecyl-4-one methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxyphenol, linear nonylphenols or branched side chain nonylphenols such as 2,6-dinonyl-4-methylphenol 2,4-dimethyl-6- (1'-

methyl-undec-1'-yl) -phenol, 2,4-dimethyl-6- (1'-methyl-heptadec-1'-yl) -phenol, 2,4-dimethyl-6- (1'- methyltridec-1'-yl) -phenol and mixtures thereof;

1.2. Alkylthiomethylphenols: 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-didodecylthiomethyl-4-nonylphenol;

1.3. Hydroquinones and alkylated hydroquinones: 2,6-di-tert-butyl

4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone,

2,6-diphenyl-4-octadecyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl, bis (3,5-di-tert-butyl-4-hydroxyphenyl) adipate;

1.4. Tocopherols: alpha-, beta-, gamma- or delta-tocopherol and mixtures

of these (vitamin E);

1.5. Hydroxylated thiodiphenyl ethers: 2,2'-thio-bis (6-tert-butyl-4-methylphenol), 2,2-thio-bis (4-octylphenol), 4,4'-thio-bis (6-tertyl) butyl-3-methylphenol), 4,4'-thio-bis (6-tert-butyl-2-methylphenol), 4,4'-thio-bis (3,6-di-sec-amylphenol) disulphide 4,4'-bis (2,6-dimethyl-4-hydroxyphenyl);

1.6. Alkylidene Bisphenols: 2,2'-methylene-bis (6-tert-butyl-4-methylphenol), 2,2'-methylene-bis (6-tert-butyl-4-ethylphenol), 2,2'-methylene -bis [4-

methyl-6- (alpha-methylcyclohexyl) phenol], 2,2'-methylene-bis (4-methyl-6-cyclohexylphenol), 2,2'-methylene-bis (6-nonyl-4) -methylphenol), 2,2'-methylene-bis (4,6-di-tert-butylphenol), 2,2'-ethylidene-bis (4,6-di-tert-butylphenol), 2,2'-ethylidene -bis (6-tert-butyl-4-isobutylphenol), 2,2'-methylene-bis [6- (alpha-methylbenzyl) -4-nonylphenol], 2,2'-methylene-bis [6- (alpha, alpha-dimethyl-benzyl) -4-nonylphenol], 4,4'-methylene-bis (2,6-tert-butylphenol), 4,4'-methylene-bis (6-tert-butyl-2-methylphenol ), 1,1-bis (5-tert-butyl-4-hydroxy-2-methylphenyl) butane, 2,6-bis (3-tert-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenol, 1 1,3-tris (5-tert-butyl-4-hydroxy-2-methylphenyl) butane, 1,1-bis (5-tert-butyl-4-hydroxy-2-methylphenyl) -3-n-dodecylmercaptobutane, bis [3,3-bis (3'-tert-butyl-4'-hydroxyphenyl) butyrate] ethylene glycol, bis (3-tert-butyl-4-hydroxy-5-methylphenyl) dicyclopentadiene, bis [ 2- (3'-tert-Butyl-2'-hydroxy-5'-methylbenzyl) -6-tert-butyl-4-methylphenyl], 1,1-bis (3,5-dimethyl-2-hydroxyphenyl ) butane, 2,2- bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis (5-tert-butyl-4-hydroxy-2-methylphenyl) -4-n-dodecylmercaptobutane, 1,1, 5,5-tetra (5-tert-butyl-4-hydroxy-2-methylphenyl) pentane;

1.7. O-, N- and S-benzyl compounds: 3,5,3 ', 5'-tetra-tert-butyl-4,4'-dihydroxybenzyl ether, octadecyl-4-hydroxy-3,5-dimethylbenzyl mercaptoacetate, tridecyl-4-hydroxy-3,5-di-tert-butylbenzyl mercaptoacetate, tris (3,5-di-tert-butyl-4-hydroxybenzyl) amine, bis (4-tert-butyl dithiotherephthalate -3-hydroxy

2,6-dimethylbenzyl), bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, isooctyl

3,5-di-tert-butyl-4-hydroxybenzyl mercaptoacetate;

1.8. Hydroxybenzylated malonates: dioctadecyl-2,2-bis (3,5-di-tert-butyl-2-hydroxybenzyl) -malonate, dioctadecyl-2- (3-tert-butyl-4-hydroxy-5-methyl-benzyl) - malonate, didodecyl mercaptoethyl-2,2-bis (3,5-di-tert-butyl-4-hydroxybenzene)

zyl) malonate, di [4- (1,1,3,3-tetramethylbutyl) phenyl] -2,2-bis (3,5-di tert-butyl-4-hydroxybenzyl) malonate;

1.9. Hydroxybenzyl aromatic compounds: 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, 1,4-bis (3,5-di-tert-butyl) butyl-4-hydroxybenzyl) -2,3,5,6-tetramethylbenzene, 2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) phenol;

1.10. Triazine Compounds: 2,4-bis-octylmercapto-6- (3,5-di-tert-butyl-4-hydroxyanilino) -1,3,5-triazine, 2-octylmercapto-4,6-bis (3, 5-di-tert-butyl

4-hydroxyanilino) -1,3,5-triazine, 2-octylmercapto-4,6-bis (3,5-di-tert-butyl-4-hydroxyphenoxy) -1,3,5-triazine, 2,4, 6-tris (3,5-di-tert-butyl-4-hydroxyphenoxy) -1,2,3-triazine, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl isocyanurate) ), 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, 2,4,6-tris (3,5-dimethyl)

tert-butyl-4-hydroxyphenylethyl) -1,3,5-triazine, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hexahydro-1,3,5 -triazine, 1,3,5-tris (3,5-dicyclohexyl-4-hydroxybenzyl) isocyanurate;

1.11. Acylaminophenols: 4-hydroxyluric acid anilide, 4-hydroxystearic acid anilide, N- (3,5-di-tert-butyl-4-acid octyl ester)

hydroxyphenyl) carbamic;

1.12. Beta- (5-tert-Butyl-4-hydroxy-3-methylphenyl) propionic acid esters: with polyhydric alcohols, for example with 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2 -propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate,

N, N'-bis (hydroxyethyl) oxalic acid diamide, 3-thiaundecanol, 3-thiapentadanol, trimethylexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospho-2,6,7-trioxabicyclo [2.2.2] octane;

1.13. Beta- (3,5-Di-tert-Butyl-4-hydroxyphenyl) propionic acid esters, Gamma (3,5-dicyclohexy-4-hydroxyphenyl) propionic acid, 3,5-dihydroxy acid

tert-butyl-4-hydroxyphenylacetic: with mono- or polyhydric alcohols, for example with methanol, ethanol, n-octanol, isooctanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N'-bishydroxyethyl oxalic acid diamide, 3-

thiaundecanol, 3-thiapentadecanol, trimethylexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospho-2,6,7-trioxabicyclo [2.2.2] octane;

1.14. Beta- (3,5-di-tert-Butyl-4-hydroxyphenyl) propionic amides: N, N'-bis (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hexamethylenediamine, N, N 'bis (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) trimethylenediamine, N, N'-bis (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine;

1.15 Ascorbic acid (vitamin C);

5 1.16. Amino Antioxidants: N, N'-Diisopropyl-p-phenylenediamine

nas, Ν, Ν'-di-sec-butyl-p-phenylenediamine, N, N'-bis (1,4-dimethylpentyl) -p-phenylenediamine, N, N'-bis (1-ethyl-3- methylpentyl) -p-phenylenediamine, N, N'-bis (1-methylheptyl) -p-phenylenediamine, N, N'-dicyclohexyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N, N'-di (naphth-2-yl) -p-phenylenediamine, N-isopropyl-NT-phenyl-p-10 phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N- (1-methylheptyl) -N'-phenyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine (4- (p-toluenesulfonamido) diphenylamine, N, N'-dimethyl -N, N'-di-sec-butyl-p-phenylnodiamine, diphenylamine, N-allylphenylamine, 4-isopropoxydiphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoyl-15-aminophenol, 4 -octadecanoylaminophenol, di (4-methoxyphenyl) amine, 2,6-tert-butyl-4-dimethylaminomethyl phenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N, N, N ,, N '-tetramethyl-4,4, -diaminodiphenylmethane, 1,2-di [(2-methylphenyl) amino] -ethane, 1,2-di (phenylamino) propane, (o-tolyl) biguanide, di [4- (1 ', 3'-dimethylbutyl) phenyl] amine, N-phenyl Tert-butyl-1-naphthylamine, mixture of mono- and dialkylated tert-butyl / tert-octyl diphenylamines, mixture of mono- and dialkylated non-diphenylamines, mixture of mono- and dialkylated dodecylphenylamines, isopropyl / iso-mixture mono- and dialkylated -hexyl diphenylamines, mixtures of mono- and dialkylated tert-butyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, tert-butyl mixture mono- and dialkylated tert-octylphenothiazines, mixtures of mono- and dialkylated tert-octylphenothiazines, N-allylphenothiazine, Ν, Ν, Ν ', Ν'-tetrafenyl-1,4-diaminobut-2-ene, N, N-bis (2,2,6,6-tetramethylpiperidin-4-yl) hexamethylenediamine, bis (2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 2,2,6,6-tetramethylpiperidin -4-one, 2,2,6,6-tetramethylpiperidin-4-ol.

2. Examples of additional antioxidants: aliphatic phosphites or

aromatics, thiodipropionic acid or thiodiacetic acid esters or dithiocarbamic acid salts, 2,2,12,12-tetramethyl-5,9-dihydroxy-3,7,11-tritiatridecane and 2,2,15 , 15-tetramethyl-5,12-dihydroxy-3,7,10,14-tetratiahexadekan.

3. Examples of Metal Deactivators, for example for Copper:

3.1. Benzotriazoles and derivatives thereof: 2-mercaptobenzotriazole,

2,5-dimercaptobenzotriazole, 4- or 5-alkylbenzotriazoles (e.g., tolutriazole) and derivatives thereof, 4,5,6,7-tetrahydrobenzotriazole, 5,5'-methylene-bis-benzotriazole; Mannich benzotriazole or tolutriazole bases such as 1- [di (2-ethylhexyl) aminomethyl] tolutriazole and 1- [di (2-ethylhexyl) aminomethyl] benzotriazole;

alkoxyalkylbenzotriazoles, such as 1- (nonyloxymethyl) benzotriazole, 1- (1-butoxyethyl) benzotriazole and 1- (1-cyclohexyloxybutyl) tolutriazole;

3.2. 1,2,4-Triazoles and derivatives thereof: 3-alkyl (or -aryl) 1,2,4-triazoles, Mannich bases of 1,2,4-triazoles, such as 1- [di (2-ethyl -hexyl) amino methyl] -1,2,4-triazole; alkoxyalkyl-1,2,4-triazoles, such as 1- (1-butoxyethyl) -1,2,4-

triazole; Acylated 3-amino-1,2,4-triazoles;

3.3. Imidazole derivatives: 4,4'-methylene-bis (2-undecyl-5-methyl) imidazole and bis [(N-methyl) imidazol-2-yl] carbinol-octyl ether;

3.4. Sulfur-containing heterocyclic compounds: 2-mercapto-benzothiazole, 2,5-dimercapto-1,3,4-thiadiazole, 2,5-dimercaptobenzothiadiazole and

derivatives thereof; 3,5-bis [di (2-ethylhexyl) aminomethyl] -1,3,4-thiadiazolin-2-one;

3.5 Amino compounds: salicylidene propylenediamine, salicylminoguanidine and salts thereof.

4. Examples of Rust Inhibitors:

4.1. Organic acids, their esters, metal salts, anhydrides and

amine salts: alkyl and alkenyl succinic acids and their partial esters with alcohols, diols or hydroxycarboxylic acids, partial amides of alkyl and alkenyl succinic acids, 4-nonylphenoxyacetic acid, alkoxy and alkoxycarboxylic acids, such as dodecyloxyacetic acid, dodecyloxy (ethoxy) acetic acid and amine salts thereof, and also N-oleoyl sarcosine, mono-

sorbitan oleate, lead naphthenate, alkenyl succinic acid anhydrides, for example dodecenyl succinic acid anhydride, 2- (2-carboxyethyl) -1-dodecyl-3-methylglycerol and salts thereof, especially sodium salts and triethanamine of these.

4.2. Nitrogen-containing compounds:

4.2.1. Tertiary aliphatic or cycloaliphatic amines and amino salts of organic and inorganic acids, for example alkyl carboxylates

oil-soluble lammonium, and 1- [N, N-bis (2-hydroxyethyl) amino] -3- (4-nonylphenoxy) propan-2-ol;

4.2.2. Heterocyclic compounds: substituted imidazolines and oxazolines, for example 2-heptate-cenyl-1- (2-hydroxyethyl) -imidazoline;

4.2.3. Sulfur-containing compounds: barium dinonylinaphthalene sulfonates, calcium petroleum sulfonates, aliphatic carboxylic acids

substituted by alkylthio, aliphatic 2-sulfocarboxylic acid esters and salts thereof.

5. Examples of viscosity index enhancers: polyacrylates, polymethacrylates, nitrogen-containing polymethyl methacrylates, copolymers

vinylpyrrolidone / methacrylate, polyvinylpyrrolidone, polybutenes, polyisobutylenes, olefin copolymers such as ethylene propylene copolymers, styrene isoprene copolymers, styrene / acrylate copolymers and polyethers. Multifunctional viscosity enhancers, which also have dispersing and / or antioxidant properties, are known and may optionally be used in addition to the products of this invention.

6. Examples of pour point depressants: polymethacrylates, ethylene / vinyl acetate copolymers, alkyl polystyrenes, fumarate copolymers, alkylated naphthalene derivative.

7. Examples of dispersants / surfactants: amides or imides of

polybutenyl succinic acid, polybutenylphosphonic acid derivatives, basic magnesium, calcium and barium sulfonates and phenolates.

8. Examples of extreme pressure and anti-odor additives: sulfur and halogen containing compounds, eg chlorinated paraffins, sulphurised olefins or vegetable oils (soybean oil, rapeseed oil), alkyl or aryl di- or trisulfides, benzotriazoles or derivatives thereof, such as bis (2-ethylhexyl) aminomethyl tolutriazoles, dithiocarbamates, such as methylene bis-dibutyladithiocarbamate, 2-mercaptobenzothiazole derivatives, such as 1- [N, N-bis (2-ethyl] hexyl) aminomethyl] -2-mercapto-1H-1,3-benzothiazole, derived from

2,5-dimercapto-1,3,4-thiadiazole, such as 2,5-bis (tert-nonylditio) -1,3,4-thiadiazole.

9. Examples of coefficient of friction reducers: base oil

pigmeat, oleic acid, tallow, rapeseed oil, sulphurised fats, amines, amines. Other examples are given in EP-A-O 565 487.

10. Examples of special additives for use in water / oil metal working fluids and hydraulic fluids: Emulsifiers: Sul-

petroleum phonates, amines such as polyoxyethylated fatty amines, nonionic surfactants; buffers: such as alkanolamines; biocides: triazines, thiazolinones, tris-nitromethane, morpholine, sodium pyridenethiol; processing speed enhancers: calcium and barium sulphonates.

Inventive pour point depressant can be mixed

with the above directly in a lubricant. It is also possible to prepare a concentrate or so-called "additive package" which may be diluted to produce the operating concentrations for the desired lubricant.

Lubricating oils containing the copolymers of this

The invention can be used in a number of different applications including automatic transmission fluids, manual transmission fluids, hydraulic fluids, greases, engine fluids, metal machining fluids, engine oil applications and shock absorbing fluids.

A further embodiment of the invention relates to the method for

to improve the low temperature properties of a lubricating oil comprising adding to a lubricating viscosity oil a polyalkyl methacrylate copolymer as defined above.

EXAMPLES

Example 1: Synthesis of lauryl-beenyl methacrylate copolymers (weight ratio of monomer 90/10)

140 g of high temperature oil (neutral hydrotreated oil) is charged to a reactor and heated to 95 ° C under nitrogen. 0.406 g t-Butyl peroctoate in 7.7 g oil is added to the heated oil in the reactor. Two separate parallel supplies are arranged for measurement in the reactor. The first supply consists of a mixture of 252.0 g lauryl methacrylate, 28 g behenal methacrylate, 1.12 g dodecyl mercaptan (DDM) and 235.2 g high temperature oil and is measured over a period of 2 hours. The second supply consists of 1.22 g of t-butyl peroctoate in 23.14 g of oil and is fed over a period of 3 hours. Both first and second supplies are started simultaneously. At the end of 2 hours of supply, the second initiator supply rate is doubled. The reaction mixture is maintained for an additional hour at 95 ° C after which an additional initiator charge, 0.56 g in 10.64 g of oil, is added to the reaction mixture and maintained for an additional hour at room temperature. 95 ° C. The average chain length for lauryl methacrylate is about 12.6 carbon atoms. The average carbon chain length for beenyl methacrylate is about 20.3 carbon atoms. The polyalkyl methacrylate formed (90/10 lauryl / beenyl polymethacrylate) formed in Example 1 has an average chain length of about 13.4 carbon atoms.

Table I

The resulting composition of the polyalkyl methacrylate copolymer formed in Example 1 is:

Polymer components% by weight based on the total weight of the copolymer Dodecyl methacrylate 61 T Etradecyl methacrylate 23 Hexadecyl methacrylate 7 Octadecyl methacrylate 4 Eicosyl methacrylate 1 Docosyl methacrylate 4 Example 2: Synthesis of lauryl methacrylate / C30-weight monomer / copolymer monomer copolymers 10)

100.0 g of high temperature oil (neutral hydrotreated oil) is charged to a reactor and heated to 95 ° C under nitrogen. 0.213 g t-Butyl peroctoate in 4.05 g oil is added to the heated oil in the reactor. Two separate parallel supplies are structured for measurement in the reactor. The first supply consists of a mixture of 180.1 g of lauryl methacrylate, 31.48 g of C30 alkyl methacrylate, 1.46 g of dodecyl mercaptan (DDM) and 175.8 g of high temperature oil. and is measured over a period of 2 hours. The first supply is also stirred and gently heated because C30-alkyl methacrylate is not completely soluble in the base oil at room temperature. The second supply consists of 0.64 g of t-butyl peroctoate in 12.14 g of oil and is fed over a period of 3 hours. The first and second supplies start simultaneously. At the end of 2 hours, the second initiator supply rate is doubled. The reaction mixture is kept for an additional hour at 95 ° C after which an additional initiator charge, 0.29 g in 3.61 g of oil is added to the reaction mixture and kept for an additional hour at 95 ° C. ° C. The average chain length of Csoalkyl methacrylate is 30.4 carbon atoms. The average chain length of the formed (90/10 lauryl / C30 alkyl) polymethacrylate copolymers of Example 2 is 14.4.

Table Il

The resulting composition of the polyalkyl methacrylate copolymer formed in Example 2 is:

Alkyl Chain-Based Carbon Atoms N0% Weight Total Copolymers 12 65.1 14 21.1 16 4.3 18 0.5 20 0.6 N-Weight Carbon Atoms Based N-weight N0 in the Alkyl Chain Total Copolymer Weight 22 0.7 24 0.8 26 0.8 28 0.9 30 0.8 32 0.8 34 0.7 0.7 38 0.5 40 0.4 42 0.3 44 0.3 46 0.2 48 0.1 50 0.1 52 0.08 54 0.06 56 0.04 58 0.02 Example 3

Application data for pour point depressants: comparison of viscosities at low temperatures.

The copolymer of Example 1 and a commercial flow point depressant are each added separately to the hydrotreated Group II mineral oil. Pour point and viscosity are recorded in Table 3. Table Ill

Properties of 0.2% by weight of PPD in Group II Hydrotreated Mineral Oil

PPD1 Brookfield Viscosity Point Viscosity Fluidity Low Temperature Kinematic [(C] at -35 ° C [cP] 40 ° C [cSt] Group II Oil -18 Very viscous to measure 35.48 Hydrotreated Comparative Example 2 -42 (- 39) 244 000 35.82 Example 1 -45 80 600 35.5 The compositions of Example 1 and Comparative Example comprise 40 wt% of polyalkyl methacrylates in hydrotreated oil 0.2 wt% of this solution is added to the oil hydrotreated to determine viscosity and pour point The 0.2 wt% in Table 3 represents

0.8% by weight of assets (copolymers).

2) The composition according to Comparative Example comprises a commercially available polyalkyl methacrylate copolymer. The polymer is formed of (C 12) methacrylate long chain esters.

The pour point in parenthesis represents a second execution of the same test. The commercially available polyalkyl methacrylate copolymer is determined to be a distribution of mainly 15 C12-Ciealkyl methacrylates. No C22 alkyl methacrylate is detected by pyrolysis GC / MS. Brookfield Low Temperature Viscosity is determined by ASTM D2983. Kinematic Viscosity is determined by ASTM D445. Pour point is determined by ASTM D5950. Table 3 shows that Example 1 (invention) has a significantly lower viscosity at lower temperatures than commercially available polyalkyl methacrylate.

Claims (9)

1. Polyalkyl methacrylate copolymers comprising monomer units formed from: (A) 60.0 to 96.0% by weight of a C 12 -C 16 alkyl methacrylate; and (B) 40.0 to 4.0% by weight of a C 1-8 C 30 alkyl alkyl methacrylate. Copolymers according to claim 1, wherein the copolymer has a weighted average molecular weight of 5,000 to 250,000. Copolymers according to claim 1, wherein component (A) is 65.0 - 95.0% by weight of the formed polyalkyl methacrylate copolymer. Copolymers according to claim 1, wherein component (B) is 35.0 - 5.0% by weight of the polyalkyl methacrylate copolymer formed. Copolymers according to claim 1, wherein component (A) of claim 1 is a straight or branched chain alkyl ester of methacrylic acid selected from the group consisting of lauryl methacrylate, myristyl methacrylate, cetyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate and mixtures thereof. Copolymers according to claim 1, wherein component (B) is a straight or branched chain alkyl ester of methacrylic acid selected from the group consisting of etearyl methacrylate, octadecyl methacrylate, heptadecyl methacrylate , nonadekyl methacrylate, eicosyl methacrylate, henicosyl methacrylate, docoshia methacrylate, tricosyl methacrylate, tetracosyl methacrylate, pentacosilase methacrylate, octacosyl methacrylate, noacrylate methacrylate, triacontyl and beenila methacrylate and mixtures thereof. Copolymers according to claim 1, wherein component (A) is lauryl methacrylate and component (B) is beenyl methacrylate. A lubricating oil composition comprising: (i) a lubricating viscosity oil; (ii) a polyalkyl methacrylate copolymer as defined in claim 1; and optionally (iii) other additives. Lubricating oil composition according to claim 8, wherein component (ii) is present in an amount of 0.01 - about 5 parts by weight of active copolymer per 100 parts by weight of oil.