WO2000069921A1

WO2000069921A1 - Amine-functionalised copolymers and methods for their preparation

Info

Publication number: WO2000069921A1
Application number: PCT/GB2000/001615
Authority: WO
Inventors: Warren Reed; Richard Henry Weatherhead
Original assignee: Bp Chemicals Limited
Priority date: 1999-05-15
Filing date: 2000-04-26
Publication date: 2000-11-23
Also published as: AU4421300A; GB9911242D0

Abstract

Non-crystalline amine-functionalised copolymers are prepared by (a) contacting (i) at least one C3-C5 alpha-olefin (ii) optionally ethylene and (iii) a masked aminoalkene with a metallocene catalyst and at least one co-catalyst to form a copolymer and then (b) optionally demasking the formed copolymer. The copolymers are soluble in iso-octane at temperatures above -20°C and are suitable for use in lubricating oils and hydrocarbon fuels.

Description

AMINE-FUNCTIONALISED COPOLYMERS AND METHODS FOR THEIR PREPARATION

The present invention relates to a copolymer having units derived from an alpha- olefin and an aminoalkene. The present invention also relates to processes for making said copolymer. The copolymer is suitable for use as an additive for a hydrocarbon fuel or a lubricating oil. Various polymeric additives are known which have both viscosity improving and dispersancy properties. One type of compound is disclosed in EP-A-0 429 565 and is comprised of a polymer backbone onto which backbone has been attached one or more monomers having polar groups. Such compounds are said to be frequently prepared by a grafting operation wherein the backbone is reacted directly with a suitable monomer usually in the presence of a free radical generating material.

An alternative method involves thermal reaction between a functionalised olefin monomer and a pre-formed polymer backbone containing unsaturated carbon-carbon bonds by a process known as the "ene" reaction. For example, maleic anhydride can react with the pendant olefin groups present in an ethylene propylene diene modified (EPDM) terpolymer. Usually the succinic derivative so obtained is further reacted with polar group containing reagents such as amines, alcohols, etc. to provide dispersant- viscosity improvers. See for example US 4,320,019 and US 4,357,250.

US 5,639,839 relates to oligomers and polymers obtained from A) from 0.001 to 100 mol % of at least one aminoalkene of the formula I: H₂C=CH-(CH₂)_xN-(SiR¹R²R³ )(SiR⁴R⁵R⁶) where x is an integer from 0 to 25 and R¹ to R⁶ are hydrogen, Ci- to Cio-alkyl, 5- to 7- membered cycloalkyl which, in turn can carry Ci- to Cβ-alkyl groups as substituents or

B) from 0 to 99.999 mol % of at least one alkene, for x=l in formula I, propene being excluded as component B). It is said that the oligomers and polymers of US 5,639,839 are distinguished by uniform incorporation of the functional groups along the polymer chain. The protected functional groups can be removed hydrolytically during working up and the molecular weight distribution of the oligomers and polymers is narrow. Preferably, the oligomers and polymers of US 5,639,839 are prepared in the presence of a metallocene catalyst system. An example is provided of a copolymer derived from 1- bis(trimethylsilyl)aminoundec- 10-ene and propene (and polyureas derivatives thereof). Such a copolymer is a partially crystalline material with a high melting point and would therefore not be suitable for use as an additive for hydrocarbon fuels or lubricating oils. US 3,761,458 is concerned with the polymerisation of monomers which have a terminal ethylenic double bond, separated by at least one carbon atom from a polar group using Ziegler-type catalysts. The resulting products are stereoregular homopolymers and random or block copolymers with terminally unsaturated olefinic hydrocarbons. It is stated that the copolymers vary widely in physical and chemical properties, depending on the polar groups employed, the ratio of polar compound to hydrocarbon compound in the product, and the relative arrangement of polar compound and hydrocarbon units in the polymer chains. A particularly suitable monoolefin for use in the copolymers of the invention is said to be propene while the polar olefin may be an aminoalkene. It is stated that some of the polymers are particularly useful in lubricating oil compositions, where they provide dispersancy and inhibitor properties, and aid in lubricating at extreme pressures. However, details of these polymers are not provided.

US 5,030,370 relates to a composition comprising (A) lubricating oil, and (B) at least one amino-substituted interpolymer (e.g. an ethylene alpha-olefin interpolymer) substituted by primary amino or secondary amino groups useful as a viscosity index improver dispersant. Such amino-substituted interpolymers can be prepared by co- polymerising ethylene (and, optionally, an alpha-olefin) with a masked nitrogen- containing monomer wherein the primary or secondary nitrogen group of the nitrogen- containing monomer is masked with an organometallic compound followed by demasking the resulting interpolymer to remove the organometallic compound and thereby form the amino-substituted interpolymer.

The catalysts used in the synthesis of the interpolymers of US 5,030,370 are Ziegler-type catalysts. Such catalysts tend to produce polymers of undesirably broad molecular v/eight distribution and alpha-olefin polymers which are tactic and partially- crystalline.

It has now been found that certain copolymers and in particular certain non- crystalline copolymers of at least one alpha-olefin and an aminoalkene are particularly suitable for use as additives for lubricating oils or fuels and in particular for use as viscosity improvers for lubricating oils and/or dispersants for fuels/lubricating oils. According to the present invention, there is provided a non-crystalline amine functionalised copolymer having units derived from (i) at least one C₃ to C₅ alpha olefin (ii) optionally ethylene and (iii) an aminoalkene, wherein said copolymer is soluble in iso-octane above a temperature of- 20^°C. By non-crystalline is meant that the copolymer does not exhibit a crystalline melting point above 0^°C as measured by differential scanning calorimetry (DSC).

The copolymer of the present invention comprises a hydrocarbon backbone, having pendant amino functional groups. Preferably, the copolymer contains 0.01 to 25 mol % of units derived from the aminoalkene (i.e. units having amine functional groups). The olefinic monomers of the present copolymer are not subject to stereochemical control. Thus, the copolymer may be atactic making it especially suitable for use as a viscosity improver for lubricating oils and/or a dispersant for lubricating oils and/or fuels. The copolymer may be a block or random copolymer, preferably a random copolymer. Where the copolymer is a random copolymer, it is preferred that the amine functional groups are uniformly distributed along the backbone.

In a preferred embodiment of the present invention, the non-crystalline copolymer is an atactic, random copolymer.

The olefinic monomers which may be used to form the copolymers of the present invention are at least one C₃-C₅ alpha-olefin and optionally ethylene. Suitably, the alpha- olefin may be propylene, 1 -butene, 3-methyl-l -butene and 1 -pentene, preferably propylene or 1 -butene, most preferably propylene. The alpha-olefin may be straight- chained or branched. A mixture of two or more alpha-olefins may be used, for example, a mixture of propylene and butene(s) or a mixture of butenes. For copolymers having units derived from a mixture of ethylene and at least one C₃to C₅ alpha-olefin, the mole ratio of units derived from ethylene to units derived from the C₃to C₅ alpha-olefin is preferably in the range 1:99 to 2: 1, more preferably 1:50 to 3:2, especially 1:5 to 1:1, The aminoalkene which may be used to form the copolymer of the present invention is suitably a primary, secondary or tertiary aminoalkene, preferably a primary or a tertiary aminoalkene. Suitably, the primary, secondary or tertiary aminoalkene is masked. Prior to any masking the aminoalkene may be aliphatic such as N,N- dimethylundec-1-ene, cycloaliphatic, such as vinyl imidazole and 4-vinyl cyclohexamine, aromatic, such as paraminostyrene, or heterocyclic, such as the vinyl pyridines and vinyl pyrrole. Particularly preferred are aminoalkenes having, prior to any masking, the formula (I) below:

R^!R² N-R³-CH=CH₂ (I) wherein R¹ and R² are independently selected from hydrogen, and a hydrocarbyl group, and R³ is an aromatic group, a cycloaliphatic group or an aliphatic group, for example a branched alkyl group or a straight chain alkyl group. When R¹ and/or R²is a hydrocarbyl group, the hydrocarbyl group is preferably saturated. Suitably, R¹ and R² are independently selected from an alkyl, a substituted alkyl or an aryl group. Preferably, R^!and R² independently have 1-6 carbon atoms, such as methyl, ethyl, propyl and butyl, preferably, methyl or ethyl. Alternatively, R'and R² may be joined to form a 5 or 6 membered ring which may itself be substituted by nitrogen and/or oxygen. R³ may be an aromatic group such as naphthalene, or benzene, optionally substituted by, for example, 1-4 substituents, preferably 1-4 alkyl substituents having 1 to 6 carbon atoms. R³ may be a cycloaliphatic group, such as cyclohexane. Preferably, R³ is an aliphatic group, such as a polymethylene group -(CH₂)m- wherein m is in the range from 1 to 25, more preferably m is in the range from 2 to 15, most preferably m is in the range from 3 to 10. Examples of suitable aminoalkenes of formula (I) include undec-10-en-l -amine, dec-9-en-l -amine, N,N-dimethylundec-10-en-l -amine and N,N- dimethyldec-9-en-l -amine.

Other suitable aminoalkenes, prior to any masking, include optionally substituted vinyl pyridines, preferably optionally substituted 2- and 4- vinyl pyridines. The vinyl pyridines may be substituted on the ring and/or the nitrogen atom. The nitrogen substituent(s) may be, for example, alkyl (preferably saturated alkyl), for example Cι-C₂₅, alkyl, preferably Ci-Cβ alkyl. The alkyl group(s) may be straight-chained or branched. The pyridine ring may be substituted by, for example, 1-4 alkyl groups, preferably Ci-Cβ alkyl groups. Preferred vinyl pyridines are 2-vinyl pyridine and 4-vinyl pyridine. For the avoidance of doubt, the copolymer of the present invention may have masked amine functionalities or demasked amine functionalities, preferably demasked amine functionalities. Methods of masking and demasking amine groups are described below.

Thus, suitably, the copolymer of the present invention is a non-crystalline masked amine-functionalised copolymer having units derived from (i) at least one C₃ to C₅ alpha- olefin (ii) optionally ethylene and (iii) a masked aminoalkene and wherein said copolymer is soluble in iso-octane above a temperature of -20^°C.

Where the copolymer of the present invention is to be used as an additive for lubricating oils or fuels, the copolymer is usually used in the demasked form.

When the copolymer is used as a dispersant additive for a fuel, the copolymer preferably contains 2.5 to 25 mol %, most preferably 2.5 to 15 mol % of units derived from the aminoalkene. In contrast, when the copolymer is employed as an additive for lubricating oils, the copolymer preferably contains 0.25 to 25 mol %, most preferably 0.25 to 15 mol % of units derived from the aminoalkene.

The copolymers of the present invention are soluble in an hydrocarbon liquid, specifically iso-octane at temperatures above -20^°C. This means that at temperatures above -20^°C, the copolymers are miscible at all proportions with a hydrocarbon liquid, specifically iso-octane. Generally, the copolymers of the present invention are soluble in a hydrocarbon liquid, specifically iso-octane at temperatures above -40^°C, such as above -30 C. Generally, the copolymers of the present invention are miscible at temperatures above -40^°C, with, for example, a) lubricating oils such as SN150, SN500, b) hydrocracked oils, c) synthetic lubricating oils such as polyalphaolefins and d) gasoline. Furthermore, the copolymers of the present invention are non-crystalli sable from a hydrocarbon oil at temperatures above -10^°C. Generally, the copolymers of the present invention are non-crystallisable from a hydrocarbon oil at temperatures above - 40 C, such as temperatures above -30 C.

The copolymer of the present invention has a number average molecular weight of between 300 and 500,000, preferably, between 1000 and 500,000, suitably between 400 and 200,000. When the copolymer of the present invention is used as a dispersant for hydrocarbon fuels, molecular weights of less than 1000 are preferred, typically between 300 and 1000. In contrast, when the copolymer of the present invention is used as a dispersant for a lubricating oil, molecular weights of less than 10,000 may be utilised, preferably, between 450 and 10,000. When it is desirable to use the copolymer of the present invention as a viscosity index improver, molecular weights of up to 500,000 may be utilised, preferably, up to 300,000.

The molecular weight distribution of the present copolymer is less than 3, preferably less than 2.5, and most preferably less than 2. Such narrow molecular weight distributions are desirable because viscosity is not a simple function of average molecular weight. Generally, in a sample of copolymers having a range of different molecular weights, those copolymers of higher molecular weight will have a larger influence on the viscosity than those copolymers of lower molecular weight. Thus, by minimising the molecular weight distribution, better and more reproducible control of viscosity properties can be achieved. For lubricating oils, it is desirable to use copolymers having an optimum molecular weight and a narrow molecular weight distribution. Above the optimum molecular weight excessive mechanical degradation will occur while below the optimum molecular weight the copolymer has reduced influence on viscosity. For fuel applications, it may be desirable to use lower molecular weight copolymers to reduce deposit formation. Molecular weight distribution may be measured by gel permeation chromatography.

Preferably, the copolymer of the present invention has a number average molecular weight of between 1000 and 500,000 and a molecular weight distribution of less than 3. In a further preferred embodiment, the copolymer of the present invention is a random, atactic copolymer having a number average molecular weight of between 1000 and 500,000 and a molecular weight distribution of less than 3.

According to a second aspect of the present invention, there is provided a process for the preparation of the non-crystalline amine-functionalised copolymer defined above, said process comprising the following steps: (A) contacting (i) at least one C₃ to C, alpha olefin (ii) optionally ethylene and (iii) a masked aminoalkene, with a metallocene catalyst and at least one co-catalyst, (B) optionally demasking the resulting copolymer of step (a) characterised in that the metallocene catalyst of step (a) is selected from

(a) an unbridged metallocene of formula (II)

wherein R is selected from hydrogen and alkyl, M is selected from titanium, hafnium and zirconium, X is selected from alkyl, halide, and a trifluoromethyl sulphonate group and n is 0 to 5;and

(b) the meso form of a metallocene of formula (III):

(C₅H(5.„)R„) (C₅H₍5._m)R_m)M(Z)Y (HI) wherein each R independently represents a hydrogen, an alkyl or an aryl substituent on the cyclopentadienyl ligand with the proviso that one R substituent on each cyclopentadienyl group are taken together and represent an Si or C bridging group linking two cyclopentadienyl groups wherein said Si or C group may itself be substituted by at least one hydrogen atom and/or at least one C₂-C₃ alkyl group; M is a metal selected from hafnium, zirconium and titanium; Z is selected from a hydrogen atom, a halide, a trifluoromethyl sulphonate group, an alkyl and an aryl group; Y is selected from a halide, an alkyl or a 1,3-diketone, a β-ketoester and a trifluoromethyl sulphonate group; and each of m and n is the same or different and has a value from 1 to 3.

The present invention further provides a non-crystalline amine-functionalised copolymer obtainable by the process as defined above, wherein said copolymer is soluble in iso-octane above a temperature of -20^°C.

Where the metallocene is of formula (II), R may be alkyl, preferably C1-C4 alkyl, especially methyl. Where X is alkyl, it is suitably a C1-C4 alkyl. Preferably, the metallocene of formula (II) is where R is alkyl, especially methyl, M is titanium, zirconium, hafnium, especially zirconium, X is halide or a trifluoromethyl sulphonate group and n is 0-3. Suitably, metallocenes of formula (II) may be bis (1,3- dimethylcyclopentadienyl)zirconium dichloride, bis (1,3- - dimethylcyclopentadienyl)zirconium methyl trifluorosulphonate, bis (cyclopentadienyl)zirconium dichloride, bis (cyclopentadienyl)zirconium methyl trifluorosulphonate, bis (1 -methyl cyclopentadienyl)zirconium dichloride, bis (1- methylcyclopentadienyl)zirconium methyl trifluorosulphonate.

Where the metallocene is of formula (III), preferably, m and n have the same value. Preferably, the R substituents on each cyclopentadienyl group when taken together represent a Si or carbon group which is substituted by two methyl groups i.e. the R substituents form a dimethyl silyl bridging group or a dimethyl carbon bridging group, especially, a dimethyl silyl bridging group, M is titanium, hafnium or zirconium, Z is halide or a triflurosulphonate group, Y is methyl or halide, m=l, n=l. Suitably, metallocenes of formula (III) may be dimethylsilyl(biscyclopentadienyl)zirconium dichloride, dimethylsilylbis(l- indenyl)zirconium dichloride and ethylenebis(4,5,6,7-tetrahydro-l-indenyl) zirconium dichloride.

Particularly preferred are the metallocenes of formula (II). The metallocene is converted into an active polymerisation catalyst by reacting or combining it with at least one co-catalyst.

By using the metallocene catalysts of formula (II) or formula (III), the copolymer is produced under conditions which result in low stereochemical control. This generally results in copolymers having atactic properties. Moreover, the metallocene catalysts above may be employed to prepare copolymers having a narrow molecular weight distribution of less than 3, preferably, less than 2.5, and most preferably, less than 2. The metallocene catalysts also give a more uniform distribution of amino groups along the hydrocarbon chain.

The aminoalkenes may be prepared by conventional methods. The aminoalkene is masked prior to copolymerisation. An unmasked aminoalkene would tend to react almost immediately with the metallocene catalyst and thereby prevent polymerisation. The aminoalkene may be masked by (a) agents which are capable of forming an ionic or covalent bond with the aminoalkene (hereinafter referred to as 'chemical masking') or (b) agents which can accept an electron lone pair and are thus capable of forming a physical or dative bond with the aminoalkene (hereinafter referred to as 'complexation masking').

The masked aminoalkene so formed either by chemical masking or complexation masking is used as the actual comonomer in the polymerisation process.

Examples of suitable chemical masking agents include metal alkyls and metal alkyl hydrides, such as those described in US 5,030,370, the disclosure of which is incorporated herein by reference. Other suitable chemical masking agents are trialkylsilyl compounds such as those described in US 5,639,839, the disclosure of which is incorporated herein by reference.

Suitable complexation masking agents include metal alkyls such as aluminium trialkyls and aluminium alkyl halides, preferably an aluminium trialkyl. Suitably, the aluminium trialkyl is of formula A1R₃ wherein each R is a Ci-Cβ alkyl. Suitable trialkyl aluminiums are triethylaluminium or triisobutylaluminium, preferably, tri- isobutylaluminium. A suitable aluminium alkyl halide is diethyl aluminium chloride.

Where the aminoalkene is a primary and/or a secondary amine, the masking agent is preferably a chemical masking agent and preferably a trialkylsilyl compound. Where the aminoalkene is a tertiary amine, the masking agent is preferably a complexation masking agent and is preferably an aluminium trialkyl as defined above. The masking reaction, which can be performed in a batchwise, continuous or semi- continuous manner, is preferably carried out by adding the aminoalkene to the selected masking agent, preferably in the presence of an inert solvent or diluent. Suitable reaction conditions for the masking reaction are disclosed in US 5,030,370. The desired amino functional group incorporated into the amine-flinctionalised copolymer as the masked functional group can be regenerated by removal of the masking group through the use of conventional demasking techniques. Where a chemical masking agent has been used, the masking group can be removed by, for example, hydrolysis, as described in US5, 030,370 and US 5,639,839. Where a complexation masking route has been employed the masking agent can be removed from the polymer product, for example, by distillation. This route has the advantage that the masking agent can be recovered for re-use.

As an alternative to masking the aminoalkene prior to polymerisation, an alkene having a hydroxyl functionality (i.e. a hydroxyalkene) may be employed to generate an intermediate non-crystalline copolymer of (i) at least one C₃ to C₅ alpha-olefin (ii) optionally ethylene and (iii) a hydroxyalkene. The hydroxyalkene is masked in a similar manner to an aminoalkene. Removal of the masking agent may be carried out using conventional techniques as described above. The hydroxyl functionalities of this intermediate non-crystalline copolymer are subsequently converted into amine functionalities using methods apparent to a person skilled in the art. For the avoidance of doubt, the term "units having amine functional groups" encompasses such groups derived from hydroxyalkenes.

Thus, according to a further embodiment of the present invention, there is provided an alternative process for the preparation of the non-crystalline amine-flinctionalised copolymer defined above which process comprises the following steps: a) forming an intermediate non-crystalline copolymer by contacting (i) at least one C₃ to C₅ alpha olefin (ii) optionally ethylene and (iii) a masked hydroxyalkene with a metallocene catalyst of the type defined above and at least one co-catalyst; b) demasking the intermediate copolymer of step (a); and c) converting the hydroxyl functionalities of said intermediate non-crystalline copolymer into amine functionalities.

The hydroxyalkene, prior to any masking, is preferably of the formula (IN) below HO-R⁴-CH=CH₂ (IV) wherein R⁴is as R³ as described in relation to formula (I) above. Examples of suitable hydroxyalkenes include 10-undecen-l-ol, 9-decen-l-ol and 5-hexen-l-ol.

The processes of the present invention may be carried out continuously in a liquid phase polymerisation medium or by using a fixed bed. When the polymerisation is carried out in the liquid phase, typically the reactants and catalysts are dissolved in the polymerisation medium. The polymerisation medium may include an inert diluent. Typically, the inert diluent may be a saturated, unsaturated, aromatic or halogenated hydrocarbon which does not adversely interfere with the polymerisation reaction. Suitable inert diluents include toluene, xylene, isobutane, propane and hexane. Preferably the catalyst is present in the polymerisation medium at a concentration in the range 1 to 100 micromoles/litre, more preferably in the range 5 to 20 micromoles/litre. Where the processes of the present invention are carried out in a continuous fixed bed, the catalyst is supported on a support material.

The co-catalyst used in the present invention may be comprised of an alkyl aluminoxane, preferably methyl aluminoxane, with or without the addition of an alkyl aluminium. A preferred alkyl aluminium is tri-isobutyl aluminium.

The aluminoxane is preferably used in an amount such that the molar ratio of metallocene catalyst to aluminoxane lies in the range 1 : 1 to 1 :2000, more preferably the ratio lies in the range 1 : 10 to 1 :400 (based on the molar amount of aluminium). When tri-isobutyl aluminium is used the molar ratio of metallocene catalyst to aluminoxane to tri-isobutyl aluminium suitably lies in the range from 1:50:400 to 1:500:500.

The co-catalyst may also be a Lewis acid such as tris (pentafluorophenyl) boron or trityl tetra(pentafluorophenyl) borate when used in combination with a dialkyl derivative of the metallocene. Alternatively, the co-catalyst may be a combination of tris(pentafluorophenyl)boron and a trialkylboron. Typically the boron or borate co- catalyst is present in an equimolar amount to the metallocene catalyst. The co-catalyst may be supported. When a supported catalyst system is used preferably the catalyst and co-catalyst are supported on the same material. The polymerisation can take place in an inert atmosphere at atmospheric or super atmospheric pressure, preferably at a pressure in the range 10 to 200 bar, more preferably at a pressure in the range 10 to 50 bar. The polymerisation may take place at a temperature in the range -50 to 300^°C, more preferably at a temperature in the range 20 to 120°C. Variation of the reaction temperature, monomer or catalyst/cocatalyst concentrations or pressure can be used to control both the molecular weight of the copolymers, the quantity of aminoalkene polymerised and the rate of copolymer production. For example, a copolymer of relatively low molecular weight may be achieved by running the reaction at a higher temperature.

The polymerisation reaction can be quenched by methods known in the art, for example by adding water or a lower alcohol such as ethanol or isopropanol. Alternatively, where a trialkylaluminium is used as a masking agent, any excess trialkylaluminium may be removed by distillation (preferably at sub-ambient pressure together with a solvent) or by countercurrent liquid extraction with fresh monomer, after which any remaining catalyst and aluminium residues may be removed by passage of a polymer solution through a fixed bed of hydrophilic material, such as silica gel.

The catalyst residues can be removed by filtration, if necessary, or left in the 30 product or on the catalyst support. The diluent can be removed from the reaction medium (which comprises the polymer product, diluent, unreacted masked aminoalkene or unreacted masked hydroxyalkene, alpha-olefin and optional ethylene, inactive residues of catalyst and cocatalyst) by evaporation under reduced pressure.

The copolymers of the present invention may be used as additives for fuel and lubricating oil compositions in addition to conventional additives, such as detergents and corrosion inhibitors. Where the copolymer is to be used in a lubricating oil composition, the copolymer may be employed in amounts of 0.1 to 20wt%, such as 0.1 to 10 wt%, preferably 0. l-5wt%. Where the copolymer is to be used in a fuel composition, the copolymer may be employed in amounts of 200-800 ppm, preferably 250-500 ppm. The invention will now be illustrated by the following Examples.

Differential Scanning Calorimetrv (DSC) Measurement

The instrument used to was DSC30 manufactured by Mettler-toledo. It was calibrated against the true melting points of Mercury (Aldrich, 99.99+%, -38.9°C), Indium (Goodfellow, 99.999%, 156.6°C) and Zinc (Goodfellow, 99.999%, 419.6°C). Prior to this work the calibration was checked by running a fresh sample of Mercury at both 1 and 5°C/min. Both results were within the accepted tolerance band of +/-0.5°C of the true melting point and differed from each other at the two heating rates by only 0.1°C. The heat of melting for Indium was found to be 5% high. Thus, the reported values for the polymer samples were corrected by this amount.

A copolymer sample (25+/-5mg sample size) was placed in a Mettler tall aluminium pan (volume = 150 micro-litres) with a crimped lid with a circa 1mm diameter pinhole. A similar but empty pan was used as the reference. The DSC cell was constantly purged with lOOml/min dry nitrogen. The sample was first slow cooled from 25 to -60°C at 0.1°C/min followed by a heating step back to 25°C at 10°C/min. The resultant melting endotherm was integrated using Mettler TA4000 software.

Example 1

In this Example, undecenylamine is treated using hexamethyldisilazane and ammonium sulphate. The reaction produces a di(trimethylsilyl) protected undecenylamine, which is copolymerised with propylene in a second reaction step. The reaction produces a copolymer having protected functionalities. These functionalities are deprotected by hydrolysis. Preparation of Di(trimethylsilyl) Protected Undecenylamine

Method

The amine (33.2 g, 0.196 mol) was dissolved in hexamethyldisilazane (HMDS) (189 g, 1.1.8 mol) and ammonium sulphate (3 g, 10 wt. %> on undecenylamime) was added. The whole mixture was heated under reflux for 24-3 6 hours. The resultant mixture was then evaporated to remove all the HMDS and then carefully distilled to give a clear oil (55 g). The ¹³C nmr showed 89-90% product, 7-9% unreacted undecenylamine and 2% alcohol.

The mixture was used for the polymerisation reaction without further purification.

Copolymerisation of Propene and Di(trimethylsilyl) Protected Undecenylamine

Into a 300ml dried autoclave was placed by syringe, 20ml toluene (dry), 20ml of a 1M solution of triisobutylaluminium (TEBA) in toluene. 10.2g of the bis( N,N- trimethylsilyl) 10-undecenylamine mixture was added. Table 1 below shows the composition of the bis(N,N-trimethylsilyl) 10-undecenylamine mixture.

Table 1

Mol % as measured by 13 C. nmr

The autoclave was sealed and 50ml (0.7 mol) of liquid propene added. The contents of the autoclave were then stirred at 50 °C which was maintained by external circulation through the outer jacket of the vessel from a heater / cooler bath. The pressure and temperature of the autoclave were logged continuously. After three hours, a solution containing 10 micromoles of bis( l,3-dimethylcyclopentadienyl)zirconium dichloride and 25ml of a solution of 10% methylaluminoxane (32mmoles) in toluene was added. No reaction was observed A further 20ml of 20% MAO solution was added along with 50 micromoles of catalyst. Reaction commenced as shown by a decrease in pressure and from heat of reaction. The reaction was run for four hours during which time the pressure in the reactor decreased by half. At the end of the reaction, the propene was vented and 20ml of ethanol added to the reactor to kill off excess aluminium alkyls. The product was drained from the reactor and stirred with 2g moist silica gel to remove the aluminium and zirconium alkoxides.

This was filtered, the solvents removed and the unreacted monomers removed by heating the sample under high vacuum. ¹³C nmr analysis of the viscous liquid product showed (Table 2).

Table 2

These results indicate that the sample has a small amount of residual monomer left. The copolymer contains about 15 mol% of a mixture of primary amine and bis (trimethylsilyl)amine derivatives if undecene in the ratio 3:7. This is slightly different from the feed ratio ( 2:8) and may indicate either preferential reaction of the primary amine or hydrolysis of the bis(trimethylsilyl) derivative during work up.

The molecular weight (Mn) of the copolymer was about 600. The copolymer chains were found to be mostly terminated by a vinylidene group. The copolymer was then hydrolysed to form the deprotected product.

Example 2

In this Example, propylene was copolymerised with N,N-dimethyl-aminoundec-10- ene A 3-litre autoclave was thoroughly purged by heating under nitrogen. Into the autoclave was introduced 0.5 litre of dry toluene by transfer line and 166 ml of triisobutylalumiium as a 1M solution in toluene The autoclave was held under nitrogen as 28.3g N,N-dimethylamino undec-10-ene was slowly added. The autoclave was then sealed and 0.75 litre of liquid propylene transferred into it. The contents of the autoclave were then stirred at 70°C which was maintained by external circulation through the outer jacket of the vessel. The pressure and temperature of the autoclave were logged continuously. The 50 ml of methylaluminoxane as a 10% by weight solution in toluene and 20 micromoles of bis[l,3-dimethylcyclopentadienyl] zirconium dichloride as a solution 20 mis of toluene were injected into the autoclave under a positive pressure and the reaction run for three hours. After venting off the excess propene from the reactor, about 50ml of ethanol was added to deactivate the remaining aluminium alkyl. The liquid product was then drained from the reactor and stirred with about lOg of moist silica gel to react with aluminium and zirconium alkoxides, then filtered and the solvent removed by evaporation. The viscous liquid was diluted with heptane, then placed in a continuous liquid - liquid extractor and extracted with methanol to remove all tertiary amine as shown by thin layer chromatography on heptane phase. The heptane phase was removed from extractor and the solvent removed. The product obtained was a viscous liquid. The product was analysed by ¹ C nmr as shown in Table 3 below:

Table 3

The ¹³C nmr data was used to calculate the triad mole fractions (mm 0.25; mr 0.52; m 0.24). The calculated probabilities for insertion (P_nl/_r = 0.51; P_r/m = 0.52) indicated that the copolymer was atactic.

0.1 g of the copolymer was diluted with iso-octane 10ml to form a clear solution. This solution was stored in a sealed vial and placed in a refrigerator at -20^°C for a week. The solution remained water-white. The solution was then placed in a freezing mixture of acetonitrile / cardice [-42 C] contained in a dewar. Observation of this solution for four days indicated that some cloudiness had developed in the sealed vial. This indicates that the copolymer is soluble in iso-octane at temperatures above -20°C but that on further cooling remains in dispersion ( ie some cloudiness develops).

Melting behaviour was determined by DSC in accordance with the method given above. The copolymer was found to have a melting point at -20°C.

Example 3

Copolymerisation of aluminium alkyl protected 10-undecen-l-ol with propene A 3-litre autoclave was thoroughly purged by heating under nitrogen. Into the autoclave was introduced 1 litre of dry toluene by transfer line and 0.25 moles of triisobutylaluminium as a IM solution in toluene. The autoclave was held under nitrogen as 0.25 moles of 10-undecen-l-ol was slowly added. The autoclave was then sealed and 1 litre of liquid propylene transferred into it. The contents of the autoclave were then stirred at 70°C which was maintained by external circulation through the outer jacket of the vessel. The pressure and temperature of the autoclave were logged continuously. The required amount of methylaluminoxane [20ml as a 10% by weight solution in toluene ex Albemarle] and a solution of 25 micromoles of bis[ 1,3- dimethylcyclopentadienyl] zirconium dichloride catalyst in toluene was injected into the autoclave under a positive pressure and the reaction run for 3 hours until the initial pressure had halved. After venting off the excess propene from the reactor, about 50ml of ethanol was added deactivate the remaining aluminium alkyl. The liquid product was then drained from the reactor. The resultant product was stirred with about lOg of moist silica gel to react with aluminium and zirconium alkoxides, then filtered and the solvent removed by evaporation. Unreacted alcohol was removed initially by vacuum distillation at >5mbar at 140°C followed by a continuous liquid liquid extraction a heptane solution of the copolymer with methanol until thin layer chromatography indicated no residual trace of free alcohol. The copolymer product was analysed by ¹³C nmr and results are as shown in Table 4 below:

Table 4

The ratio of the end group types is as expected for polymerisations of propene with this metallocene catalyst. Analysis indicates that each copolymer chain contains approximately two hydroxy groups. The hydroxy functionalities on the resulting copolymer are then converted into amino functionalities.

The ¹³C nmr data was used to calculate the triad mole fractions (mm 0.26; mr 0.52; m 0.22). The calculated probabilities for insertion (P„,_r = 0.50; P_rm = 0.54) indicated that the copolymer was atactic.

Melting behaviour was determined by DSC in accordance with the method given above. The copolymer was found to have a melting point at -10°C.

Example 4

Copolymerisation of propene with N,N-di methyl-aminoundec-10-ene.

A 3-litre autoclave was thoroughly purged by heating under nitrogen. Into the autoclave was introduced 0.5 litre of dry toluene by transfer line and 250 mis of triisobutylaluminium as a IM solution in toluene. The autoclave was held under nitrogen as 47.2g (0.24 mol) N,N-dimethylamino undec-10-ene in 20ml of toluene was slowly added. The autoclave was then sealed and 200ml of liquid propylene transferred into it. The contents of the autoclave were then stirred at 80°C which was maintained by external circulation through the outer jacket of the vessel. The pressure and temperature of the autoclave were logged continuously. 20 ml of methylaluminoxane (MAO) as a 10%) by weight solution in toluene and 12.5 micromoles of bis[ 1,3 - dimethylcyclopentadienyl] zirconium dichloride as a solution in 20 mis of toluene were injected into the autoclave under a positive pressure. Reaction commenced when pressure had dropped by 3 bar. When the pressure had dropped by a further 3 bar, an additional 75ml of propene was added together with further aliquots of catalyst and

MAO. When the reaction pressure had dropped to 5 bar, the reactor was rapidly cooled and the excess propene was vented. Ethanol [75ml] was added to deactivate the remaining aluminium alkyl. The liquid product was then drained from the reactor and stirred with about 16g of moist silica gel to react with the aluminium and zirconium alkoxides, then filtered and the solvent removed by evaporation. The viscous liquid was diluted with heptane, then placed in a continuous liquid - liquid extractor and extracted with methanol to remove all tertiary amine as shown by thin layer chromatography on heptane phase. The heptane phase was removed from extractor and the solvent and light ends removed by vacuum stripping. The copolymer product was analysed by ¹³C nmr and results are as shown in Table 5 below:

Table 5

0. lgm of the copolymer was diluted with iso-octane 10ml to form a clear solution. This solution was stored in a sealed vial and placed in a refrigerator at -20°C for a week. The solution remained water-white. The solution was then placed in a freezing mixture of acetonitrile / cardice [-42^°C] contained in a dewar. Observation of this solution for four days indicated that some cloudiness had developed but no material was deposited. This shows that the copolymer is soluble in iso-octane at temperatures above -20^°C and but that on further cooling remains in dispersion ( ie some cloudiness develops).

Claims

1. A non-crystalline amine-functionalised copolymer having units derived from (i) at least one C to C₅ alpha olefin (ii) optionally ethylene and (iii) an aminoalkene, wherein said copolymer is soluble in iso-octane above a temperature of -20^°C.

2. A copolymer according to claim 1 wherein the amine functionalities are masked.

3. A copolymer according to claim 1 or claim 2 wherein the copolymer contains 0.01 to 25 mol% of units derived from the aminoalkene.

4. A copolymer according to any one of claims 1 to 3 wherein the copolymer is an atactic, random copolymer.

5. A copolymer according to any one of claims 1 to 4 wherein the copolymer has a molecular weight distribution of less than 3 and a number average molecular weight of between 1000 and 500,000.

6. A process for the preparation of a copolymer as claimed in any one of claims 1 to 5, said process comprising the following steps:

(A) contacting (i) at least one C₃ to C₅ alpha olefin (ii) optionally ethylene and (iii) a masked aminoalkene, with a metallocene catalyst and at least one co-catalyst,

(B) optionally demasking the resulting copolymer of step (a) to form the amine- flinctionalised copolymer, characterised in that the metallocene catalyst of step (a) is selected from

(a) an unbridged metallocene of formula (II) (C₅H(₅-„)R_n)₂MX₂ (II) wherein R is selected from hydrogen and alkyl, M is selected from titanium, hafnium and zirconium, X is selected from alkyl, halide, and a trifluoromethyl sulphonate group and n is 0 to 5;and

(b) the meso form of a metallocene of formula (III):

(C₅H₍₅._m)Rm)M(Z)Y (III) wherein each R independently represents a hydrogen, an alkyl or an aryl substituent on the cyclopentadienyl ligand with the proviso that one R substituent on each cyclopentadienyl group are taken together and represent an Si or C bridging group linking two cyclopentadienyl groups wherein said Si or C group may itself be substituted by at least one hydrogen atom and/or at least one C₂-C₃ alkyl group;

M is a metal selected from hafnium, zirconium and titanium; Z is selected from a hydrogen atom, a halide, a trifluoromethyl sulphonate group, an alkyl and an aryl group;

Y is selected from a halide, an alkyl or a 1,3-diketone, a β-ketoester and a trifluoromethyl sulphonate group; and each of m and n is the same or different and has a value from 1 to 3

7. A process according to claim 6 wherein the aminoalkene is, prior to any masking, an aminoalkene of formula (I)

R'R²N-R³-CH=CH₂ (I) wherein R¹ and R² are independently selected from hydrogen, and a hydrocarbyl group, and R³is an aromatic group, a cycloaliphatic group or an aliphatic group. Alternatively, R¹ and R² may be joined to form a 5 or 6 membered ring which may itself be substituted by nitrogen and/or oxygen.

8. A process according to claim 7 wherein the aminoalkene of formula (I) is selected from the group consisting of undec-10-en-l -amine, dec-9-en-l -amine, N,N- dimethylundec-10-en-l -amine and N,N-dimethyldec-9-en-l -amine.

9. A process according to claim 6 wherein the aminoalkene is an optionally substituted vinyl pyridine.

10. A process according to claim 6 wherein the aminoalkene is a tertiary amine.

11. A process according to any one of claims 6 to 10 wherein the aminoalkene is masked by an aluminium trialkyl

12. A process according to claim 11 wherein the metallocene of formula (II) and R is alkyl, M is titanium, zirconium, hafnium, X is halide or a trifluoromethyl sulphonate group and n is 0-3.

13. A process according to claim 12 wherein the metallocene of formula (II) is selected from the group consisting of bis (1, 3-dimethylcyclopentadienyl)zirconium dichioride, bis (l,3-dimethylcyclopentadienyl)zirconium methyl trifluorosulphonate, bis (cyclopentadienyl)zirconium dichioride, bis (cyclopentadienyl)zirconium methyl trifluorosulphonate, bis (l-methylcyclopentadienyl)zirconium dichioride and bis (1- methylcyclopentadienyl)zirconium methyl trifluorosulphonate.

14. A process according to any one of claims 6 to 11 wherein the metallocene of formula (III) and the R substituents on each cyclopentadienyl group form a dimethyl silyl bridging group or a dimethyl carbon bridging group, M is titanium, hafnium or zirconium, Z is halide or a triflurosulphonate group, Y is methyl or halide, m=l, n=l.

15. A process according to claim 14 wherein the metallocene of formula (III) is selected from the group consisting of dimethylsilyl(biscyclopentadienyl)zirconium dichloride, dimethylsilylbis(l-indenyl)zirconium dichloride and ethylenebis(4,5,6,7- tetrahydro-l-indenyl)zirconium dichloride.

16. A copolymer obtainable by a process as claimed in any one of claims 6 to 15, wherein said copolymer is soluble in iso-octane above a temperature of- 20 C.

17. A process for the preparation of a copolymer as claimed in any one of claims 1 to 5 which process comprises the following steps: a) forming an intermediate non-crystalline copolymer by contacting (i) at least one C₃ to C₅ alpha olefin (ii) optionally ethylene and (iii) a masked hydroxyalkene with a metallocene catalyst of the type defined above and at least one co-catalyst; b) demasking the intermediate copolymer of step (a), and c) converting the hydroxyl functionalities of said intermediate non-crystalline copolymer into amine functionalities

18. A process according to claim 17 wherein the hydroxyalkene, prior to masking, is of the formula (IV)

HO-R⁴-CH=CH₂ (IV) wherein R⁴ is an aromatic group, a cycloaliphatic group or an aliphatic group

19. Use of a copolymer as claimed in any one of claims 1 to 5 or claim 16 or as prepared by the process of any one of claims 6 to 15 or claims 17 to 18 as an additive for lubricating oils and/or fuels.

20. Use of a copolymer according to claim 19 as a dispersant

21. Use of a copolymer as claimed in any one of claims 1 to 5 or claim 16 or as prepared by the process of any one of claims 6 to 15 or claims 17 to 18 as a viscosity improver for lubricating oils

22. A lubricating oil composition comprising a lubricating oil and 0.1 to 20wt% of a copolymer as claimed in any one of claims 1 to 5 or claim 16 or as prepared by the process of any one of claims 6 to 15 or claims 17 to 18

23. A fuel composition comprising a fuel and 200-800 ppm of a copolymer as claimed in any one of claims 1 to 5 or claim 16 or as prepared by any one of claims 6 to 15 or claims 17 to 18.