NZ245717A - Lubricating oil comprising an ester of isotridecyl alcohol,aliphatic hydrocarbons, and a minor amount of aromatics - Google Patents

Abstract

This invention relates to a lubricating oil composition which has a major proportion of a biodegradable base fluid which is a blend of (a) at least one ester of isotridecyl alcohol and a mono-, di or polycarboxylic acid, and (b) at least one hydrocarbon oil which has no more than 10%w/w of aromatic hydrocarbons, the rest being aliphatic. The proportion of (a) in the blend is from 25-55%w/w. The biodegradability of the base fluid renders the composition more environmentally friendly.

Description

New Zealand Paient Spedficaiion for Paient Number £45717 Ik 57 1 7 Priority Date(s): . £?■*■.! ;?V£, Complete Specification Filed: .

Class: Aosv. .9* //&',9n11 ./.Q[:92^/<?7Y><kv?5 '•}&) £*l!9r?%U>V?5j. IPS Publication Date: . . P.O. Journal. No: .. ttJte NO DRAWINGS Patents Form No. 5 NEW ZEALAND ..j PATENTS ACT 1953 COMPLETE SPECIFICATION LUBRICATING OIL COMPOSITIONS JAN\993o} '■ ^ *■ * WE, THE BRITISH PETROLEUM COMPANY P.L.C./ a British company of Britannic House, 1 Finsbury Circus, London EC2M 7BA, ENGLAND hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statements (followed by page la) 24 57 17 Case 7936(2) lc*- LUBRICATING OIL COMPOSITIONS The present invention relates to environmentally friendly lubricating oil compositions for automotive engines. Lubricating oil compositions for use in automotive engines are well known.

These compositions usually contain a base fluid which may comprise 5 mineral oils, hydrocarbon oils and/or synthetic fluids and conventional additives such as viscosity index (hereafter "VI") improvers, anti-oxidants, corrosion inhibitors, dispersants, anti-wear additives and sludge control agents. In recent years, automotive engine oil development has seen a steady trend towards 10 lower viscosity multigrades, principally to improve.fuel efficiency. The predominant viscosity grade has moved from a typically 20W/50 oil to a 10W/40 or a 5W/40 oil. The manufacturers of automotive engine equipment have also tightened the specifications for such oils in terms of oil consumption, bearing 15 protection and shear stability. This has meant that the engine lubricant has had to become lower in volatility and more shear stable so that these thinner oils stay in the specified grade band longer. As a result, lubricating oils compositions based solely on conventional solvent refined mineral oils are no longer adequate to 20 meet these stringent performance requirements. To meet these performance requirements, a growing demand has arisen for "special" base oils possessing superior qualities of volatility, VI and pour point. These special base oils have a VI above 120 and the requirement is primarily met by the use of paraffinic base oils 25 which include inter alia oils based on hydrocracked wax - 1 a- (followed by page 2) 2*5717 distillates. It has also been suggested to use blends o£ such hydrocracked wax distillates with aliphatic esters in order to improve the performance of such base oils. These prior art compositions usually contain 80% w/w or more of a hydrocarbon or mineral oil and upto 20% w/w of an aliphatic carboxylic acid ester in the base fluid. Such compositions, whilst being very efficient and being to some extent biodegradable, still leave room for improvement.

It has now been found that base oil blends can be formulated which not only improve the biodegradability thereof but achieve the same without loss of performance at the same time exhibiting relatively lower emissions, lower fuel consumption and lower oil consumption.

Accordingly, the present invention is a lubricating oil composition which has a major portion of a base fluid, the base fluid comprising a blend of: a) ' ' isotridecyl dodecane dioate; and b) at least one hydrocarbon oil comprising upto 99.5% w/w of aliphatic hydrocarbons and no more than 10% w/w aromatic hydrocarbons such that the total of aliphatics and aromatics is 100%, wherein the amount of component (a) in the blend is in the range from 25-55% w/w.

As described above, the base fluid comprises a blend of an ester and a hydrocarbon oil. The ester component (a) is derivable by the reaction of an aliphatic mono-, di- and/or poly-carboxylic acid with, isotridecyl alcohol under esterification conditions.

Similarly, the hydrocarbon oil component (b) in the blend suitably is a hydrocracked wax distillate. More specifically, such hydrocarbon oils can contain upto 99.5% w/w, preferably upto 97% w/w, of aliphatic hydrocarbons and no more than 10% w/w of - 2 $45717 aromatic hydrocarbons. The expression "aliphatic hydrocarbons" as used herein and throughout the specification is meant to include open chain aliphatic hydrocarbons as well as cycloaliphatic hydrocarbons such as e.g. naphthenic hydrocarbons. The total 5 polycyclic aromatic hydrocarbons in the hydrocarbon oil is suitably less than 10 ppm w/w, preferably less than 5 ppm w/w and more preferably less than 1 ppm w/w. Typically such hydrocarbon oil contains from 92-97% w/w of aliphatics and 3-8% w/w of aromatics.

The hydrocarbon oil component (b) in the blend is suitably 10 prepared by feeding a waxy distillate through a hydrocracker at 70-95% conversion under elevated temperature and hydrogen pressure. In the first stage of this hydrocracker, sulphur and nitrogen compounds are removed and in the second stage the aromatics are hydrogenated to naphthenes; the hydrogenated products including the 15 naphthenes are cleaved and rearranged to produce a controlled range of paraffins and isoparaffins. Fuels and lubricant products are separated by atmospheric distillation from the resultant hydrocracked products and the 5-35% heavy component is the hydrocarbon fraction used as the hydrocarbon oil component (b) in 20 the blend. A product produced by this method is substantially free of any unsaturates. This feedstock can be further refined, if necessary, by conventional techniques such as additional fractionation, extraction or dewaxing to obtain the finished product. The resultant hydrocarbon oil has the following physical 25 characteristics: Colour (ASTM D 1500) 1.5 Max Density (ASTM 1298) 0.83 KV(40")/cSt (ASTM D 445) 17.28 KV(100#C)/cSt (ASTM D 445) 3.99-4.22 VI (ASTM D 2270) 123 - 128 Pour point/'C (ASTM D 97) -24 - -27 % S (XRF NFM 07053) 0.08 - 0.15 Total N/ppm ca 12 Aromatics by HPLC/% ca 7.7 Aliphatics By HPLC/% ca 92.3 Polycyclic aromatics/ppm - 0.1 Of the aliphatic hydrocarbons in this hydrocarbon oil component (b), about 20% w/w comprises isoparaffins having an average carbon number of about 27. hydrocarbon oil component (b) in the base fluid within the specified ranges above will depend upon the nature of the two components and their relative viscosities. For instance, if the hydrocarbon component (b) is within the physical characteristic specification 10 defined above the amount of ester (a) in the blend may suitably vary from 30-50% w/w, preferably from 40-50% w/w.

In addition to the above blended base fluid, the lubricating composition of the present invention comprises minor proportions of 15 conventional additives which include inter alia the following: one or more sludge dispersants, one or more VI improvers, one or more anti-wear additives, and one or more anti-oxidants. Typically, the additive package used is known to comprise components which meet the stringent requirements of an API Performance Classification "SG". 20 These requirements include successful testing in the following categories: rust test, dispersancy test, piston varnish test, low temperature sludge test and wear test. Such additives are commercially available as an additives package sold e.g. as an "SG Additive Package" under the names GBX 2900 and GBX 2905 (both ex 25 Adibis Ltd, UK). Such an additive package suitably forms from -20% w/w, preferably from 11-16% w/w of the formulated lubricating composition. Examples of compounds that may be present in such a package include anti-rust agents such as the overbased calcium or magnesium sulphonates or phenates; anti-wear agents such as the zinc 30 dithiophosphates, preferably the zinc dialkyl dithiophosphates containing 5-15% w/w phosphorus (normally prepared using a mixture of secondary alcohols and representing 0.05% -0.5% w/w of phosphorus, typically 0.1-0.14% phosphorus in the finished oil); ashless dispersancy agents such as derivatives of long chain 35 hydrocarbon substituted succinimides, especially the polyisobutenyl The relative amounts of the ester component (a) and the - 4 succinimides; and sludge dispersants which are oil soluble salts such as amides, imides, oxazolines and esters of mono- or di-carboxylic acids or anhydrides.

The anti'-oxidants typically contain phenolic compounds and a 5 typical antioxidant is commercially available as ADX 545A (ex Adibis Ltd). The anti-oxidants are suitably present in an amount from 0.01-5% w/w, preferably from 0.1-2.0% w/w of the formulated lubricating composition.

The lubricating compositions also contain one or more VI 10 improvers. Examples of such VI improvers include polymethacrylate type dispersants commercially sold as Flexol 1420 VX (Regd Trade Mark, ex Rohm GmbH) and hydrotreated polyisoprenes commercially sold as Shellvis 200 (Regd Trade Mark, ex Shell UK Ltd). In the case of the latter, it may used as a solution in the hydrocarbon oil 15 component (b) above. The VI improvers are suitably present in an amount from 2 to 5% w/w of the formulated lubricating composition. Thus a typical formulated lubricating composition (A) can be represented by the following components in w/w %: SG Additives Package (GBX 2905, ex Adibis Ltd) - 15.4 ADX 545A (anti-oxidant, ex Adibis Ltd) - 1.0 Plexol* 1420 (VI improver, ex Rohm GmbH) - 3.1 Shellvis* 200 (VI improver, 10% soln, ex Shell UK Ltd) - 6.0 Isotridecyldodecanedioate - 22.59 and Hydrocarbon oil** - 52.71 * Registered Trade Mark ** The hydrocarbon oil is a hydrotreated wax distillate containing 92.3% w/w aliphatics and 7.7% w/w aromatics which is substantially free of any unsaturates and had a polycyclic aromatic content of about 0.1 ppm. An oil of this type is 30 described above.

Variations of the formulated lubricating composition (A) shown above can also be formulated in which the relative amounts of ester and hydrocarbon oil are (B) 32.28% and 49.32% respectively or (C) 39.5% each.

It was found that the performance of the lubricating 2 4 5 7 1 compositions formulated in this manner upon engine testing showed relatively lower emissions, lower fuel consumption, lower oil consumption and low nitrogen oxides emission. In addition, the formulated lubricating compositions according to the present invention were at least 80% biodegradable as measured by the CEC standard test procedure. The present invention is further illustrated with reference to the following Examples: Examples - General A base fluid was prepared using isotridecyldodecanedioate, a hydrocracked wax distillate having the following physical characteristics: and Property Colour Density KV 40/cSt KV 100/cSt VI PMC/*C Pour Point Demulse/mins Noack volatility/% Sulphur/% CA/% Typical Specification 1.5 max 0.83 17.28 3.99 128 220 -27 <5 .8 0.08 2 Test Method ASTM D 1500 ASTM D 1298 ASTM d 445 ASTM d 445 ASTM D 2270 ASTM D 93 ASTM D 97 NFT* 60-125 DIN 51581 XRF NFM 07053 Brandes Method Correlates with ASTM D 1401 This hydrocarbon oil was used to prepare formulated lubricating oil compositions according to the formulation in (A) in the following Examples 1-3.

Example 1 SG Additive Package (GBX 2905, ex Adibis Ltd) - 15.4% w/w ADX 545A (Anti-oxidant, ex Adibis Ltd) - 1.0% w/w Plexol* 1420 (VI improver, ex Rohm GmbH) - 3.1% w/w Shellvis* 200 (VI improver, 10% solution, ex Shell UK Ltd) - 6.0% w/w Isotridecyl dodecanedioate - 22.59% w/w Hydrocarbon oil (as above) - 52.71% w/w *Registered Trade Mark 24 5 7 The formulation was prepared using standard lubricant blending techniques described e.g. in "Lubricants and Related Products" by D Klamann, published by Verlag Chemie, 1984.

The formulated composition had the following characteristics: Property Viscosity @ 100'C Viscosity @ 40#C Viscosity @ -25*C Noack volatility Biodegradability Calcium Phosphorus Zinc Example 2 Limits 13.6-14.5 cSt 75.0-83.0 cSt <3500 cP 8.5-11.0% >80% 0.300-0.332 0.102-0.114 0.105-0.135 Methods ASTM D 445 ASTM D 445 ASTM D 2602 DIN 51581 CEC-L-3 3-T-8 2 ICP ICP ICP SH Additive Package (eg OS 99099, ex Lubrizol Ltd) - 15% w/w Viscoplex* 2540 (VI Improver, ex Rohm GmbH) - 3.0% w/w Shellvis* 201 (VI Improver, ex Shell UK Ltd) - 3.8% w/w Isotridecyl dodecanedioate - 38.1% w/w Hydrocarbon oil (as above) - 40.1% w/w *Registered Trade Mark The formulated composition had the following characteristics: Property Limits Viscosity @ 100*C 14.0 cSt Viscosity @ -25"C 3200 cP Noack volatility 10.7% Biodegradability 87% Calcium content 0.283 Phosphorus content 0.119 Zinc content 0.128 Example 3 SG Additive Package (eg GBX2905, ex Adibis Ltd) Plexol* 1420 (VI Improver, ex Rohm GmbH) GBX 2715 (VI Improver, ex Adibis Ltd) Isotridecyl dodecanedioate Hydrocarbon oil (as above) *Registered Trade Mark Method ASTM D445 ASTM D2602 DIN 51581 CEL-L-33-T-82 ICP ICP ICP - 16.4% w/w - 3.1% w/w - 5.0% w/w - 40.0% w/w - 35.5% w/w 24 5 7 The formulated composition had the following properties: Property Limits Method Viscosity @ 100°C 14.5 cSt ASTM D445 Viscosity @ -25°C 3300 cP ASTM D2602 Noack volatility .4% DIM 51581 Biodegradability 86% CEC-L-33-T-82 Calcium content 0.310% ICP Phosphorus content 0.108% ICE Zinc content 0.125% ICP Upon standard engine testing each o£ the formulations described in Examples 1-3 above using the API-GS method, the following properties were observed: Property Volatility Low Temperature Oxidation Stability Industrial Automotive 10W/40 5W/40,50 Detergency 10W/40 (a) 10W/40 (b) Dispersancy 10W/40 5W/40,50 Seal Compatibility 10W/40 (a) 10W/40 (b) Wear/Friction 10W/40 (a) 10W/40 (b) 5W/40,50 Additive Solubility Performance Good Good Very Good Very Good Good Very Good Very Good Very Good Very Good Good Good Very Good Very Good Very Good Good The biodegradability of the formulated lubricating composition according to the present invention was tested and compared with commercially available products using the test method shown in the table above. The results are tabulated below: Present Invention 91% Mobil 1 45% Castrol GTX 631 Shell Gemini 66% Castrol Syntron 41% From the above it is clear that the formulated compositions according to the present invention containing the blended base fluid according to the present invention show superior properties to those of prior art, especially in respect of their biodegradability. 24571 Case 7936(2)

Claims (14)

WHAT WE CLAIM IS: -

1. A lubricating oil composition which has a major portion of a base fluid, the base fluid comprising a blend of: ) isotridecyl dodecane dioate; and b) at least one hydrocarbon oil comprising up to 99.5% w/w of aliphatic hydrocarbons and no more than 10Z w/w of aromatic hydrocarbons such that the total of aliphatics and aromatics is 100%, wherein the amount of component (a) in the blend is in the range from 25-55% w/w.

2. A lubricating oil composition according to claim 1 wherein the hydrocarbon oil component (b) is a hydrocracked wax distillate.

3. A lubricating oil composition according to any one of the preceding claims wherein the hydrocarbon oil component (b) contains less than 10 ppm w/w of polycyclic arcmatic hydrocarbons, frcm 92-97% w/w of aliphatic hydrocarbons and 3-8% w/w of non-polycyclic aromatic hydrocarbons. 24571/ 11

4. A lubricating oil composition according to any one of the preceding claims wherein the aliphatic hydrocarbons in the hydrocarbon oil component (b) comprise about 20% w/w of isoparaffins having an average carbon number of about 27.

5. A lubricating oil composition according to any one of the preceding claims wherein the amount of isotridecyl dodecane dioate in the blend is in the range from 30-50% w/w.

6. A lubricating oil composition according to any one of the preceding claims wherein said composition comprises, in addition, minor proportions of one or more additives selected from: sludge dispersants, ashless dispersancy agents, VI improvers, anti-wear additives, anti-rust agents and antioxidants .

7. A lubricating oil composition according to claim 6 wherein the anti-rust agent is an overbased calcium or magnesium sulphonate or phenate; the anti-wear agent is a zinc dithiophosphate; the ashless dispersancy agent is a long chain hydrocarbon substituted succinimide; the sludge dispersant is an oil soluble salt; the anti-oxidant is a phenolic compound; and the VI improver comprises a polymethacrylate dispersant or a hydrotreated polyisoprene.

8. A lubricating oil composition according to claim 7 wherein the sludge dispersant is an oil soluble amide of mono- or di-carboxylic acids or anhydrides.

9. A lubricating oil composition according to claim 7 wherein the sludge dispersant is an oil soluble imide of mono- or di-carboxylic acids or anhydrides.

10. A lubricating oil composition according to claim 7 wherein the sludge dispersant is an oil soluble oxazoline of mono- or di- carboxylic acids or anhydrides. - 12 - 245717

11. A lubricating oil composition according to claim 7 wherein the sludge dispersant is an oil soluble ester of mono- or di- carboxylic acids or anhydrides.

12. A lubricating oil composition according to any one of the preceding claims wherein said composition is at least 80% biodegradable as measured by the CEC standard test procedure.

13. A lubricating oil composition according to any one of the preceding claims, substantially as herein described.

14. A lubricating oil composition according to claim 1, substantially as described with reference to any one of the Examples. THE BRITISH PETROLEUM COMPANY P.L.C