Polymers and lubricating compositions containing polymers

Abstract

A polymer comprising units having the structure (I): ##STR00001##
wherein x is 2 or 3, wherein L is (CH.sub.2).sub.y, where y is an integer from 1 to 10, or wherein L is CH(CH.sub.3)CH.sub.2S(CH.sub.2).sub.z, where z is an integer from 1 to 5; wherein [Q] is absent or is a polymerised moiety consisting of units having the structure (II): ##STR00002##
wherein R is a hydrocarbyl group, or a hydrocarbyl group containing one or more heteroatoms, wherein R may be linear, branched or cyclic, saturated or unsaturated, and wherein R has from 1 to 30 carbon atoms; wherein [Q] either consists of identical units of structure (II), or wherein [Q] consists of more than one different units of structure (II), differing in group R; and wherein X is a halogen or another chain terminating group. The polymers may find use as additives in lubricating compositions where they provide friction improvement and wear reduction.

Claims

1. A polymer comprising 2 to 200 units having the structure (I): ##STR00023## wherein x is 2 or 3, wherein L is (CH.sub.2).sub.y, where y is an integer from 1 to 10, or wherein L is CH(CH.sub.3)CH.sub.2S(CH.sub.2).sub.z, where z is an integer from 1 to 5; wherein [Q] is absent or is a polymerised moiety consisting of units having the structure (II): ##STR00024## wherein R is a hydrocarbyl group, or a hydrocarbyl group containing one or more heteroatoms, wherein R may be linear, branched or cyclic, saturated or unsaturated, and wherein R has from 1 to 30 carbon atoms; wherein [Q] either consists of identical units of structure (II), or wherein [Q] consists of more than one different unit of structure (II), differing in group R; and wherein X is a halogen or another chain terminating group.

2. The polymer according to claim 1, wherein the number of units (II) in [Q] is from 2 to 200.

3. The polymer according to claim 1, further comprising units having the structure (III): ##STR00025## wherein R.sup.1 is a linear or branched, saturated or unsaturated hydrocarbyl group having from 2 to 24 carbon atoms; and wherein w is 2 or 3.

4. The polymer according to claim 3 wherein the ratio of the number of units of structure (I) to the number of units of structure (III) in the polymer is from 1:100 to 100:1.

5. The polymer according to claim 1, consisting of units of structure (I).

6. The polymer according to claim 3, consisting of units of structure (I) and units of structure (III).

7. The polymer according to claim 1, wherein X is a bromine atom.

8. The polymer according to claim 1, having a number average molecular weight of 500 to 500,000 g/mol, as measured by Gel Permeation Chromatography with reference to linear narrow poly(methylmethacrylate) standards in the range of 550 to 600,000 g/mol.

9. A lubricating composition comprising a major amount of more than 50 percent by mass, based on the mass of the composition, of a base lubricant and a minor amount of less than 50 percent by mass, based on the mass of the composition, of the polymer according to claim 1.

10. The lubricating composition according to claim 9 which is a lubricating oil composition wherein the base lubricant is an oil of lubricating viscosity.

11. A method of reducing the friction and/or wear between contacting surfaces of a mechanical device, the method comprising lubricating the surfaces with the lubricating composition according to claim 9.

12. A compound of structure (IV): ##STR00026## where p is 1 or 2, and where q is an integer from 1 to 10.

13. A compound of structure (V): ##STR00027## where p is 1 or 2, and where r is an integer from 4 to 10.

14. A method for synthesising a compound of structure (IV); ##STR00028## where p is 1 or 2, and where q is an integer from 1 to 10; the method comprising: (a) reacting 2-isopropenyl-2-oxazoline, 2-isopropenyl-5,6-dihydro-4H-1,3-oxazine or a mixture thereof, with a mercapto alcohol; (b) performing a Steglich esterification reaction by reacting the product of step (a) with α-bromoisobutyric acid, in the presence of 4-N,N-dimethylaminopyridine and a dihydrocarbyldiimide.

15. A method for synthesising a compound of structure (V); ##STR00029## where p is 1 or 2, and where r is an integer from 4 to 10; the method comprising: (a) ring-opening a lactone via reaction with 2-amino-1-ethanol, 3-amino-1-propanol, or a mixture thereof; (b) ring-closing the product of step (a) via an organometallic-catalysed condensation-cyclisation reaction by heating in the presence of transition metal catalyst, preferably Ti(OnBu).sub.4; (c) performing a Steglich esterification reaction by reacting the product of step (b) with a α-bromoisobutyric acid, in the presence of 4-N,N-dimethylaminopyridine and a dihydrocarbyldiimide.

16. The polymer according to claim 1, having a number average molecular weight of 5000 to 500,000 g/mol, as measured by Gel Permeation Chromatography with reference to linear narrow poly(methylmethacrylate) standards in the range of 550 to 600,000 g/mol.

17. The polymer according to claim 1, having a number average molecular weight of 10,000 to 500,000 g/mol, as measured by Gel Permeation Chromatography with reference to linear narrow poly(methylmethacrylate) standards in the range of 550 to 600,000 g/mol.

18. The polymer according to claim 1, wherein the number of units (I) is from 2 to 100.

19. The polymer according to claim 1, said polymer having 10 units of structure (I) and where [Q] consists of 20 units of structure (II) where each group R is 2-ethylhexyl.

20. The polymer according to claim 1, said polymer having 50 units of structure (I) and where [Q] consists of 5 units of structure (II) where each group R is 2-ethylhexyl.

21. The polymer according to claim 1, said polymer having 10 units of structure (I) and where [Q] consists of 10 units of structure (II) where each group R is 2-ethylhexyl.

22. The polymer according to claim 1, said polymer having 10 units of structure (I) and where [Q] consists of 10 units of structure (II) where each group R is 2-ethylhexyl and a single terminal unit of structure (II) where R is a catechol group.

23. The polymer according to claim 1, said polymer having 10 units of structure (I) and where [Q] consists of a random copolymer of 10 units of structure (II) where each group R is 2-ethylhexyl and 5 units of structure (II) where each group R is heptadecylethyleneglycol methyl ether.

24. The polymer according to claim 1, wherein the number of units (I) is from 5 to 200.

25. The polymer according to claim 1, wherein the number of units (I) is from 5 to 30.

26. The polymer according to claim 1, wherein L is (CH.sub.2).sub.y and y is an integer from 2 to 7.

27. The polymer having an Mn of 10,700 to 33,700 g/mol represented by the formula: ##STR00030## where m is 5 to 15, n is 10 to 50 and 2EH is 2-ethylhexyl, and the ratio of n:m is from 1.33 to 10.

28. The polymer having an Mn of 14, 100 to 27,900 g/mol represented by the formula: ##STR00031## where p is 0 to 9, q is 0 to 7 and r is 0 or 1.

29. The lubricating composition according to claim 9 which is a lubricating oil composition wherein the base lubricant is Group I, II or III base stock.

30. The polymer according to claim 1, wherein L is CH(CH.sub.3)CH.sub.2S(CH.sub.2).sub.z where z is 1 to 5.

Description

EXAMPLES

(1) Example Synthesis of Polymers According to the Invention

(2) As a first stage, 2-isopropenyl-2-oxazoline (5.06 g, 44.09 mmol) and 2-mercaptoethanol (3.2 ml, 44.99 mmol) were stirred in a round-bottom flask for 15 minutes under an inert atmosphere. The reaction mixture was then diluted with anhydrous dichloromethane before addition of 4-(dimethylamino) pyridine (DMAP, 5.54 g, 0.45 mmol) and ca-bromoisobutyric acid (7.50 g, 44.99 mmol). The solution was then cooled in an ice bath and N,N′-diisopropylcarbodiimide (6.97 ml, 44.99 mmol) was slowly added dropwise and the mixture left to stir over-night. Following filtering, washing and solvent removal, and purification by flash chromatography, a colourless oil was obtained (6.67 g, 43.8% yield).

(3) As a second stage, the product obtained in the first stage was combined with p-toluenesulfonic acid, sealed into a microwave vial and purged with nitrogen. Dry acetonitrile was then added to the mixture to form a 4M solution and the vial was re-sealed. The mixture was heated to 60° C. and stirred until full conversion, confirmed by GPC and .sup.1H NMR.

(4) As a final stage, the product of the second stage was combined with 2-ethylhexyl acrylate, deactivator (Cu.sub.2Br) and ligand (Me.sub.6TREN) in a the desired ratios. This mixture was combined with isopropanol (50 wt %) and the resultant solution purged under an inert atmosphere for 30 minutes. Pre-activated copper wire, wound round a magnetic stirrer was added to the reaction vessel. The reaction vessel was placed in an oil bath at 25° C. and left to stir until full conversion.

(5) Test Data

(6) Polymers having the general structure shown below were prepared as described above, varying reactant ratios to give the desired values of n and m.

(7) ##STR00021##

(8) Details of the polymers are shown in the table below.

(9) TABLE-US-00003 n m n:m Mn (g/mol) Polymer 1 20 15 1.33 33700 Polymer 2 10 5 2 10700 Polymer 3 50 5 10 21500

(10) ‘2EH’ represents a 2-ethylhexyl group.

(11) 1 g of each polymer was added to 99 g of an API Group I mineral oil. These samples were subjected to traction and wear testing together with a sample of the same mineral oil without the addition of any polymer.

(12) Each oil was tested using a High Frequency Reciprocating Rig (HFRR) available from PCS Instruments, London, UK. This machine employs a 6 mm diameter ball as an upper specimen which is reciprocated under an applied load against a lower specimen in the form of a disc. The ball and disc are made AISI 52100 polished steel. The test conditions are given in the table below:

(13) TABLE-US-00004 Oil temperature 140° C. Reciprocating frequency 40 Hz Stroke length 1 mm Applied load 400 g Contact pressure 1 GPa Test duration 45 minutes

(14) The wear scars formed on the lower disc specimens were analysed using a Zemetrics ZeScope 3D optical profilometer using non-contact interferometric focal scanning. This permitted a measurement of the amount of wear by determining the material lost from the disc during the test. This was reported as a wear scar volume (WSV) in units of μm.sup.3. The HFRR machine is equipped with a piezoelectric transducer which gives a measurement of the average co-efficient of friction between the ball and the disc. Wear results are shown in the table below where each value is the average of three tests using each test oil.

(15) TABLE-US-00005 Test Oil WSV/μm.sup.3 Friction co-efficient Base oil (no polymer) 323000 0.158 Polymer 1 273000 0.129 Polymer 2 145000 0.128 Polymer 3 187000 0.123

(16) It is clear that the polymers of the invention led to a significant reduction in the amount of wear measured on the test samples compared to the base oil alone. These data confirm that the polymers were effective anti-wear agents.

(17) The friction data give an indication of the mechanism of wear protection which is provided by the polymers of the invention. In all cases, the presence of the polymers led to a marked decrease in recorded friction indicating a greater separation of the contacting surfaces.

(18) Further Example Synthesis of Polymers According to the Invention

(19) Synthesis of caprolactone derived hydroxyl oxazoline: ε-caprolactone (30.01 g, 262.84 mmol) was added to a flask and heated to 80° C. under inert conditions. Ethanolamine (17.45 mL, 262.84 mmol) was then added to the flask and subsequently heated at 120° C. for 2 hr. Titanium (IV) butoxide (0.5 mL) was then added to the reaction mixture and heated at 230° C. for 2 hr. The reaction mixture was then distilled in vacuo to obtain s-hydroxy-pentyl oxazoline as a clear yellow oil (7.53 g, 18.2%).

(20) Synthesis of inimer: ε-hydroxy-pentyl oxazoline (5.50 g, 35.00 mmol) was placed in a round bottom flask with DCM. To this mixture, 4-(dimethylamino) pyridine (DMAP, 0.44 g, 3.50 mmol) and α-bromoisobutyric acid (5.89 g, 35.00 mmol). The solution was then cooled to in an ice bath and N,N′-diisopropylcarbodiimide (5.5 mL, 35.00 mol) was slowly added dropwise and left to stir overnight. The urea byproduct was then filtered off and the crude was washed with saturated NaHCO.sub.3 and brine. The solvent was then removed in vacuo and the product was purified by flash chromatography (silica gel, EA, TEA 2%) to obtain the inimer as a colourless oil (6.74 g, 62.9%).

(21) General procedure for Cationic Ring Opening Polymerisation (CROP): Monomer, p-toluenesulfonic acid (in appropriate molar ratios) were sealed into microwave vial and purged with N.sub.2 for several minutes. Dry acetonitrile was then added to the reaction mixture to form a 4 M solution and the vial was resealed. The reaction mixture was then left to stir at 60° C. until full or near full conversion, which was confirmed by GPC and .sup.1H NMR.

(22) General procedure for the synthesis of brush polymers via Cu(0)-RDRP with chain extension: The acrylate monomer, brush initiator, deactivator (Cu.sub.2Br), ligand (Me.sub.6TREN), in ratio of [Monomer:1:0.05:0.18] and solvent (isopropanol, 50 wt %) were charged to a Schlenk tube in the following order: deactivator, ligand, initiator, monomer, solvent. After sealing with a rubber septum and purging the mixture under inert atmosphere for at least 30 min, 5 cm of pre-activated Cu wire (0.25 mm) wrapped in a magnetic stirrer was added. The reaction mixture was then placed in an oil bath set to 25° C. and left to stir until full conversion. Conversion was measured by .sup.1H NMR spectroscopy and SEC analysis was carried out with samples diluted in THF which were filtered over basic alumina prior to analysis to remove residual copper species

(23) Test Data

(24) Polymers having the general structure shown below were prepared as described above, varying reactant ratios to give the desired values of p and r, and varying monomer choice to give the desired value of q.

(25) Details of the polymers are shown in the table below.

(26) TABLE-US-00006 P q r Mn (g/mol) Polymer 4 0 0 0 14100 Polymer 5 3 2 0 15100 Polymer 6 7 2 0 23000 Polymer 7 9 2 0 27900 Polymer 8 1 3 0 16900 Polymer 9 3 3 0 21000 Polymer 10 5 3 0 25000 Polymer 11 5 7 0 10000 Polymer 12 0 0 1 12700 Polymer 13 0 0 1 17000

(27) 1 g of each polymer was added to 99 g of an API Group I mineral oil. These samples were subjected to traction testing together with a sample of the same mineral oil without the addition of any polymer.

(28) Each oil was tested using a Mini Traction Machine (MTM) available from PCS Instruments, London, UK. This machine employs a % inch diameter ball as an upper specimen which is run under an applied load against a lower specimen in the form of a disc. Both ball and disc are driven independently, allowing a range of slide to roll ratios to be achieved. The ball and disc are made of AISI 52100 polished steel. The test conditions are given in the table below:

(29) TABLE-US-00007 Load 30N Contact pressure 0.9 GPa Test duration 45 minutes Step Type Temperature (° C.) Rolling speed (mm/s) 1 Traction 40 1000 2 Traction 60 1000 3 Stribeck 60 20-2000 4 Traction 80 1000 5 Stribeck 80 20-2000 6 Traction 100 1000 7 Stribeck 100 20-2000 8 Traction 135 1000 9 Stribeck 135 20-2000

(30) The MTM machine is equipped with a piezoelectric transducer which gives a measurement of the co-efficient of friction between the ball and the disc. Friction results are shown in the table below where each value is the average of at least two tests using each test oil. The data reported is the 20 min/s data point from the 100° C. Stribeck step (Step 7).

(31) TABLE-US-00008 Test Oil Friction co-efficient at 20 mm/s and 100° C. Base oil (no polymer) 0.0965 Polymer 4 0.0819 Polymer 5 0.0584 Polymer 6 0.0493 Polymer 7 0.0612 Polymer 8 0.0731 Polymer 9 0.0663 Polymer 10 0.0508 Polymer 11 0.0447 Polymer 12 0.0761 Polymer 13 0.0756

(32) It is clear that the polymers of the invention led to a significant reduction in the friction coefficient measured on the test samples compared to the base oil alone, indicating a greater separation of the contacting surfaces.