CA2117439C

CA2117439C - Lubricating oil composition

Info

Publication number: CA2117439C
Application number: CA002117439A
Authority: CA
Inventors: Pieter J. D. Muntz
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-01-23
Filing date: 1993-01-25
Publication date: 2004-04-20
Anticipated expiration: 2013-01-25
Also published as: AU3443993A; CA2117439A1; WO1993015168A1

Abstract

The specification describes lubricating oil compositions containing an additive comprising normal paraffin and/or iso-paraffins and/or naphthenes each of which have from 10 to 20 carbon atoms. Compositions containing from .1 percent to 2 percent by volume are disclosed. The compositions are effective in reducing varnishing, sludging chemical by-products and glazing in an engine. The compositions are also useful in automatic transmissions fluid, gear oils and greases.

Description

WO 93/15168 PCf/AU93/ODD34 CA2 i X7439 LBHItICATTNO OiL COMPOSITION
The present invention relates to lubricating oil compositions, especially engine oils.
S When two metal surfaces move over each other, considerable heat is evolved due to friction. The function of a lubricant is to separate the two rubbing surfaces by a film thereby gr~atly reducing the coefficient of friction. '., if this film fails, the frictional heat produced may melt the surfaces causing them to weld together or seize. When coaditiona are such that a continuous thick (>0.001 in.) film o~ lubricant separates the solid surfaces at all points, than frictional resistance is controlled by the viscosity of the lubricant. This 18 referred to as "hydrodynamic lubrication". Under conditions of high speed or high load, thick lubricant films may be absent or incomplete and lubrication of the parts is effected by layers of adsorbed polar molecules. This situation is referred to as "boundary lubrication~. Metal surfaces, which are covered by films of metal oxides, axe highly polar and hence are not readily "wetted" by non polar hydrocarbon oils. Used alone, hydrocarbon oils are therefore poor lubricants in these circumstances.
Lubricants therefore contain additives which either react with metal surfaces or are adsorbed on the surfaces thereby allowing oil to wet the surface or provide boundary lubrication, thus presenting direct metal to metal contact.
Apart from certain speciality products and synthetic oils, the vast bulk of lubricants are based upon hydrocarbons derived from.petroleum.
Crude oils contain a number of broad classes of hydrocarbons. the proportions of which vary greatly from oil to oil.

WO 93/15168 C A 2 i i 7 4 3 9 f~~AU93/00034

2 (a) Branched alkaaea. Those include 1ao- and anteiso alkanea. and linear derivatea of isoprene such as Dhytane and pristane and degradation products from molecules such as carotene. These compounds have low melting points and so confer low pour points on lubricating oils. They are also stable to degradation by heat and oxygen and have high viscosity ineexes, so this iso-paraffin group is the preferred feedatock for lobe oil manufacture.
(b) n-Alkanea. The paraffins have similar properties to the iso-paraffina, except that, due to their higher melting points, they raise the pour point of a Tube oil.
- (c) Cycloalkanea. The naphthenica contain five-mamberad and six-membered rings with alkyl side chains. They lower the pour point of so oil but they have a low viscosity index_ (d) Aromatics. These are derivatives of ben2eae, naphthalene and other fused ring systems with alkyl side chains. This group has a low viscosity index and poor thermal stability.
(e) Sulphur compounds. This group forms a substantialproportion of many crudes, especially those from parts of the Middle East. It has similar properties to aromatics, but are usually even less stable.
In order to prepare a suitable lobe oil base stock, a manufacturer will select feeds which have appropriate molecular weight ranges and are rich in the desired classes of hydrocarbons (iao-paraffina), and low in aromatics, ONS compounds, and paraffine so that production coats can be kept low. Crudea such as those from Pennyslvanla which are ideal for lobe oil manufacture are Wa 93/'S'68 C A 2 i i 7 4 3 9 ft-f/AUH3/U0034

3 being depleted, so now moat manufacturers use a feed stock mix which is carefully selected to most the product mix required by the market. Some manufacturers upgrade their feedatock by using a severe hydrogenation/hydrogenolysis process called hydrocrackinQ to remove sulphur, aromatics, and to open rings sad crack larger molecules.
The residue from the Drimary distillation of selected crude oils which are rich is iso-paraffina is distilled at reduced pressure (a few mm of Hg) in the presence of steam. Most usually, three fractions are obtained: two distillate cute and the residue or bottoms.
Typical cuts are shown is the table below.
Lubricating Oil Fractions Fraction No. of C atoms Molecular Roiling Range °C
Weight (Plant conditions) Light 22-36 300-S00 370-500 (Low viscosity) Medium 29-4S 400-600 450-550 (medium viscosity) Heavy 43 600 >S00(residue) (high viscosity) The desired oily alkaae material is extracted from the viscous bottoms product Erom the vacuum tower using liquid propane (high pressure, 65~C) in a propane de-asphalting Dl~t. The more polar, high molecular weight polycyclic aromatics era less soluble in liquid propane than are the alkane (paraffin) components and are removed as a hard sludge. Evaporation of the propane leaves the heaviest grade of lubricating oil which is usually referred to as "bright stock".

WO 93/15168 C A 2 ~ J 7 ~ ~ ~ P~/AU93/00034 d Each of the Tube oil fractions fa next treated with a solvent system which selectively removes much of the '.
aromatic and O, N. 8 material. Phenol and more recently furfural have been widely used i.n elaborate multistage counter currant equipment for this purpose. The immiscible, slightly Dolar solvent selectively extracts the more polar aromatic material from the hydrocarbon mixture.
n-Alkaaea (normal pazaffina), which have higher melting Dointa than branched alkanes of similar molecular weight, must be removed to decrease the low temperature viscosity of the lubricating oil. This is accomplished by taking the oil up in a suitable solveat such as a methylethylketone-toluene mixture and chilling 5-1D°C below the required pour point. The n-alkanea are precipitated as "slack wax" which is separated by continuous filtration.
The final stage in manufacture of the base stocks is hydrogenation to convert small amounts of dark-coloured unsaturated material into saturated material and to remove sulphur from sulphur compounds Hreaent in the oil.
Lubricating oils are finally prepared by blending base stocks to give oil of the desired viscosity range, then introducing many additives to improve the life and performance of the oil.
The chemical composition of lubricating oils derived from crude oil a,s particularly complex. Normally lubricating oils contain a high proportion of naghthenic or paraffinic compounds. The hydrocarbons comprising a typical lubricating oil may have from 22 to 70 carbon atoms. Osually the hydrocarbons contained in lubricating oil have very few olefinic bonds. However there may be a significant proportion of hydrocarbons exhibiting aromatic uneaturation. A further description of base lubricating oils can be found in an article by D.V. Brock published in "Lubricant Engineering" Volume 43 pages 184-185 March 1987.

Minor improvements in the performance of a lubricating oil can yield significant economic benefits far in excess of the cost of the additive that provides the improved 5 performance. The present invention is based on the discovery that the performance of lubricating oil compositions can be significantly improved by the addition of small amounts of medium molecular weight paraffins and naphthenes to lubricating oil.
Accordingly, the present invention provides a lubricating oil composition comprising a base lubricating oil having hydrocarbon molecules with between 22 and 70 carbon atoms, and 0.1% to 2% by volume of an additive to improve lubricating properties and reduce varnishing, blazing and sludge build up, said additive comprising an n-paraffin, an iso-paraffin, or a mixture thereof, wherein the iso-paraffin has from 10 to 20 carbon atoms and the n-paraffin has from 10 to 20 carbon atoms when mixed with the iso-paraffin and from 14 to 20 carbon atoms when used alone.
In another broad aspect, the present invention provides a lubricating oil composition improved in lubricating properties comprising a base hydrocarbon lubricating oil having hydrocarbon molecules with between 22 and 70 carbon atoms, and 0.1% to 2% by volume of an additive of saturated hydrocarbons selected from at least one member from the group consisting of an n-paraffin, an iso-paraffin, wherein the iso-paraffin has from l0 to 20 carbon atoms and the n-paraffin has from 10 to 20 carbon atoms when mixed with the iso-paraffin, and from 14 to 20 carbon atoms when used alone.
In one preferred embodiment, the additive is a technical white oil that has a flash point in a range from 50°C
to 140°C, a boiling point in a range from 180°C to 320°C, a (a) density at 15°C in a range from 0.765 to 0.81 kilograms per 5 liter and an aniline point in a range from 78°C to 97°C.
In a further preferred embodiment, the additive comprises about 42% naphthenes and 58% paraffins and the paraffins contain 35 mole per cent of n-paraffins.
The additive may comprise any compound or any mixture of compounds having a carbon number in the range specified. Compounds having in excess of 14 carbon atoms are generally preferred because of their high boiling point and flash point.
The naphthene may comprise from 10 to 90 percent by weight of the additive. The naphthenes may be alkyl, cyclohexane or alkyl cyclopentane or any other naphthene normally found in crude oil. The additive may comprise at least 35% naphthenes. Preferably n-paraffins comprise at least 35% of the paraffins.
The lubricating oil composition may contain as little as .1 percent by volume of the additive for an improvement in performance to be observed. Preferably, however, the lubricating oil composition of the present invention contains from .5 to 1 percent by volume of the -~~-.-____ r__~ ______,~_ L____ .____ _w~____a ...;~~. ..~.......

percent by volume o~ the a8ditive.
The addiCive may comprise a number ef paraffins and a cumber of naphthenes. A numbez of examples are set out in Table 1_ , TABLB 1 r Carbon R.an.Qe ApprOxxmau.a CogpoBitfoin (%) a-Paratfins Iaopaxatfilas Naphthenes 10' 12-17 ' 50 20 30 10-11 7, 1 98 . ~ 11-15 99 0 , 1 10-20 1.00 Preerxecq a8ditives are those that carp be described as technioa7. va-hite oils these are . Typical o Drod~sets such as ShelZ sol T'* ~ ShelleoZ.'72L;
Shell *and Shell P874 * These pro ducts have the followingtyp~.cal analy'8xs --Proverty SST 72L F8~8 P874 DBlz.sity @ 15C 0.8074 0.8034 Flash point C 50 80 106 136 Pour point C
-. is o Carbon atom an81YS3.s ' Naphtheues % 35 21 paraffins -s 100 7.00 65 79 -n-parat~in.e mole % 35 56 * Denotes Trade Mark i The cou~poaits.ons of the present invention may be prepared as coaaq~ositions ready for use or as concentrates for premixing or mixing in situ ~_g_ in the sump of an engine . Concentrates may contain as mv.eh as z5~k of the additive. The eff8ctive amount of additive required depends on the ult3.u~.ta purpose for its inclusion and may also depend upon the additive selected.
The lubric,a.tznQ oil ~aoa4positiona of the present ' 3avent~.on are ba~aed on commercially available base stocks.
The coiapositiona of the inv~sration may 3.nclude various additives such as diapersants, detergents, oxidation inhibitors, foam iszhibitors, pour point depressant~a and viscosity inqprovers. A discussion of the function and formulation of lubricating oil. compositions can be found in the "Handbook of Twbricatian" Theory and practice of Tribology volume 1 edited by E. ~tichard Hooaer and ~publiahed by CRC Fress. in 1983;
The co~osition of the present invention many also be incoz~orated into a grease com~posi.tion with corresponding improvements i.n performance. c3rease co~apositiona normally comprise a metallic soap and a lubricating oil.
S~.mila.rly, the co~oBiti.oa of the present invention may be used in other automotive applications such as gear boxes. diffGreatial~. e~,c..
The flnotor oils o~ the present invention provide a number of si~tnif3cx~nt advantages over the existing formulations . These ~ anelude the following .
~.. A noticeable reduction in varnishing;
2. A reduction in aludqinQ;
3. Reduced production of harmful chemical by-products such as acids;

4, zmproved seal life particularly seals in gear WO 93/15168 PCf/AU93/00034 boxes, differantiala an8 engines;

5. Reduced glazing especially when used in the preferred range;

6. Extended life of the engine oil; and

7. Reduced coefficient of friction of surfaces to which it is aDDlied.
The present invention also includes within its scope methods for any one or more of the following:
s. reducing varnishing in an engine;
b. reducing sludging in an engine;
o. reducing the production of harmful chemical by-products in an engine;
d. improving seal life in an engine;
and e. reducing glazing in an engine f. reducing friction in an engine by incorporating into motor oil used in the angina an effective amount of an additive selected from the group compr3.sing~a paraffin, an ieoparaffia, a naphthene or mixture thereof wherein the paraffin, isoparafEin and the naphthene are of medium molecular weight and have from 10 to 20 carbon atoms. or Dart thereof.
Benefits provided by the pr~eant invention are illustrated by the accompanying comparativeexamples.
Bxamole 1 The performance of the compositions of the present invention was compared with the performance of the compositions without the additive of the present invention using a Din on ball testing.machine. The pin on ball testing machine comprises an electric motor driving a single shaft through a net of pulleys- A rotatable disc having a diameter of approximately dcm is attached to the shaft and is rotated at a speed of 1200 - 1500 rpm. A
separate shaft is pivoted at one end of the apparatus so

8 C A 2 i i 7 4 3 9 r~~~"~3~00034

9 that a hardened steel bearing ~lament can be applied to the rotating disc. A torque wrench type configuration fitted to the pivoted shaft is used to determine the load applied to the rotating disc by the hardened steal bearing element.
Lubricant under teat was applied to the bearing surface by splashing lubricant from a bath held at a base of the rotating 8iac. At all times during the test a continuous film of lubricant was in contactwith. the bearing.
A aeries of seven oil samples was tasted with the apparatus both with and without the addition of the additive. Samples including the additive contained additive in the ratio of 1:160 additive to base lubricating oil coaqaoaition.
The teat procedure was as follows. with the disc rotating, a piece of coarse wet and dry emery paper was used to smooth any imperfections and score marks from the rotating disc prior to test. The bearing was moved to ensure a fresh unmarked surface was available for contact with the rotating disc. Prepared samples were poured into an oil bath containing approximately 20 to 40 mls and held in close contact at the base of the rotating disc which picked oil up and carried it across the bearing surface.
the bearing fixed to the pivoted shaft was lowere8 onto the rotating lubricated disc and allowed to settle in. A
continuoua load was manually applied to the handle of the pivoted shaft. The load was maintained and gradually increased until the bearin0 surfaces began to squeal. At the point when sQuealinff commenced, the torque applied was measured in ft.lb units. The results are set out in Table C A 2117 4 3 9 P~/AU93/00034 RBSOI~S FOR OIL APDITTVS 1~8SEST
Applied Torque.
Sample ft.lb v~ithout Additive lPith Additive 1. Shell RMO 75-90 150-160 2. Shell Marine 011 120 160

10 3. BP Engine oil 70-100 150 d. BP dear 011 80 150 5. BP firease 130 160+

6. Caltax CXT 70 150 7. 8sso Tiger 75 140 The additive used in this experiment Was Shallsol T. Similar results were obtained ~rith Shellsol 72L and Shall P878.
Th~ results demonstrate that. the oil additive provides enhanced performance under the harsh boundary lubrication coaditioas utilis~d.
Example 2 Engine Teat illustrating anti-varnish benefits:
When added to a d litre 6 cylinder engine. which had done over 130,000 kms, sad which mss beginning to show noticeable bypass - due to "varnishing". and after approximately d.000 kms runainQ with an oil change after 2,000 kma with additive, all bypass ceased, as observed with the naked eye. The additive used was 6hallsol T in the ratio of 1:160. Similar results were nlso obtain~d with Shellaol 72L and Bhal1 P87$. Combustion was noticeably steadier and more ev~n.
The same experiment was performed with another anQiae of similar aQa, and the eam~ results were achieved.
SUBSTITUTE SHEET
J

WO 93/15168 ~ ~ ~ i 1 7 4 3 9 p~/AU93/0003a x1 011 leaks from each of the moto=a were also reduced and in particular around the crankshaft protrusions.
With the additive included in further oil changes - the result of "no breathing" was continued indefinitely, with the benefit of cleaner oil, next to no oil burning and better running.
of course along with this other benefits were observed such as imq~roved fuel efficiency, increased engine Derformance and reduced enffine wear.
Examvle 3 Shellaol 72L waa added to Shell Spirex xn gear oil i.n the. proportion 1:160 by volume. A Four Ball wear test ands Timkin teat according to ASTM standards D-2783 and D-2782 respectively Were conducted. The results obtained were as followa:-E.P. Four Ball West Test Load Wear Index 67.2 Weld print kg 400 Timkin Test OK Value 1b 75 Score Value 1b 80 The results for both teats Were higher than average for this type of lubricant. Furthermore no last "Non-seizure Load" occurred in the E.P. Four Ball teat according to the definition in ASTM D-2783.
Bxsmple 4 Shellsol 72L was added to Exxon Superflow 10 W -motor oil in the proportion 1:160 by volume. Sequence 6 30 tests were then performed on the mixture. The SeQuence 6 test records engine performance over a 32 hour ageing period.
The formulation showed a 0.8 to 1~ improvement in fuel efficiency for 28 of the 32 hours of the Sequence 6 tast_ One Sequence 6 test was done, using Shelleol 72L at a S proportion 1:600 by volume.
The improvement in fuel efficiency was still between 1 to .5 percent till approximately 11 hours. in order words, very small amounts can still produce a very signicant effect_ Example 5 Supporting evidence that a Sequence 6 test repeated using a formulation comprising Shell P878 or such as P874 and 8xxon Superflow 10 W-30 in the same proportions ~' as for Example d shows that an improvement in fuel efficiency similar to that of Example d but for the full 32 hours ageing period of the teat and into the calculation stage, was attainable.
The improved perfozmauce of this formulation is attributable to the higher boiling point of the additive as a result of the higher carbon number of its componanta_ Sealed and laboratory tests reveal that Shell P878 or eveb 9he11 P874 result in an improvement of friction modification, increase of engine idle speed and an increase in fuel efficiency virtually identical to Shellsol 72L.
Example 6 A SeQuence 3E test was performed an a formulation comprising Shell P878 With 20~ added mixture of paraffins, ' 18 and 19 carbon atoms. and a base motor oil in the proportion 1:150 by volume. The SeQuence 3E teat involves running an engine containing the teat formulation for 64 hours, pulling the engine down and assessing engine wear, sludge yroduction, varnishing and ring land deposits.

C A 2 t i 7 4 3 9 P~/"~93/aoo~l viscosity is measured during the teat. The results obtaine8 for the test formulation are compared with results obtained with the base motor oil on the same engine. The formulation showed a marked improvement over the base oil u. in mostly all characteristics. Cylinder base wear was particularly low.
Example 7 In order to simulate an oil change the engine used in Example 6 was re-assembled and run with the similar formulation for a further 6 hours. This tact demonstrated the ability of the additive to remove any remaining varnish and sludge deposits sad maintain a very high degree of cleanliness during the working life of an engine; in other words preventing deposit build ups. It also the additive particularly works best at the earlier stages of use and where there already exists some build up of various deposits.
Example 8 ~ Shell P878 was added to the oil in a rebuilt d54 Chevrolet angina in the proportion 1.200 by volume. After 5 tan the engine idle speed increaaed by 100 to 110 rpm.
Example 9 An enS,Tine that had used Shellsol 72L, Shell P878 and an assimilation of E87d, as additives to its motor oil was pulled down after 170.000 kilometres. The engine had no visible oil ataina, acid ataina or varnish deposits throughout the bore and the head; neither were there any sludge depoaita. In summary the engine Was comparable with an engine that had done 30.000 km using normal motor oil.
t9ith reapeet to wear. the engine showed minimal wear especially for the age of the engine.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1 A lubricating oil composition comprising a base lubricating oil having hydrocarbon molecules with between 22 and 70 carbon atoms, and 0.1%
to 2% by volume of an additive to improve lubricating properties and reduce varnishing, glazing and sludge build up, said additive comprising an n-paraffin, an iso-paraffin, or a mixture thereof, wherein the iso-paraffin has from 10 to 20 carbon atoms and the n-paraffin has from 10 to 20 carbon atoms when mixed with the-iso-paraffin and from 14 to 20 carbon atoms when used alone.

2 A lubricating oil composition improved in lubricating properties comprising a base hydrocarbon lubricating oil having hydrocarbon molecules with between 22 and 70 carbon atoms, and 0.1% to 2% by volume of an additive of saturated hydrocarbons selected from at least one member from the group consisting of an n-paraffin, an iso-paraffin, wherein the iso-paraffin has from 10 to 20 carbon atoms and the n-paraffin has from to 20 carbon atoms when mixed with the iso-paraffin, and from 14 to 20 carbon atoms when used alone.

3 A lubricating oil composition according to claim 1 or 2, wherein the additive comprises a mixture of said members.

4 A lubricating oil composition according to claim 1 or 2, wherein the additive is an iso-paraffin.

5 A lubricating oil composition according to claim 3 in which the additive is a mixture of a normal paraffin and an iso-paraffin.

6 A lubricating oil composition according to claim 5, wherein the mixture contains at least 40 mole per cent of an iso-paraffin.

7 A lubricating oil composition according to claim 3, wherein the additive is a technical white oil.

8 A lubrication oil composition according to claim 7, wherein the additive has a flash point in a range from 50°C to 140°C, a boiling point in a range from 180°C to 320°C, a density at 15°C in a range from 0.765 to 0.81 kilograms per liter and an aniline point in a range from 78°C to 97°C.

9 A lubricating oil composition according to claim 8, wherein the additive comprises more than 99% paraffins.

A lubricating oil composition according to claim 1 or 2, wherein the additive includes naphthenes having from 10 to 20 carbon atoms.

11 A lubricating oil composition according to claim 8 or 10, wherein the additive comprises about 42% naphthenes and 58% paraffins and the paraffins contain 35 mole per cent of n-paraffins.

12 A lubricating oil composition according to claim 8 or 10, wherein the additive comprises about 35% naphthenes and about 65% paraffins of which 35 mote per cent are n-paraffins.

13 A lubricating oil composition according to claim 8 or 10, wherein the additive comprises about 21 % naphthenes and about 79% paraffins of which 56 mole per cent are n-paraffins.

14 A lubricating oil composition according to any one of claims 1 to 13, wherein the additive comprises saturated hydrocarbons having between

14 and 19 carbon atoms.

A lubricating oil composition according to any one of claims 1 to 13, wherein the additive comprises saturated hydrocarbons having between 13 and 20 carbon atoms.

16 A lubricating oil composition according to any one of claims 1 to 13, wherein the additive comprises mixtures of saturated hydrocarbons having between 13 and 20 carbon atoms.

17 A method of reducing varnishing in an engine which method comprises lubricating the engine with a lubricating oil composition according to any one of claims 1 to 16.

18 A method of reducing sludging in an engine which method comprises lubricating the engine with a lubricating oil composition according to any one of claims 1 to 16.

19 A method of reducing glazing in an engine which method comprises lubricating the engine with a lubricating oil composition according to any one of claims 1 to 16.

20 A method of improving the seal life in an engine which method comprises lubricating the engine with a lubricating oil composition according to any one of claims 1 to 16.

21 A grease composition comprising a soap and a lubricating oil composition as claimed in any one of claims 1 to 16.