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EP-4308668-B1 - BASE OIL COMPOSITION, FORMULATION AND USE

EP4308668B1EP 4308668 B1EP4308668 B1EP 4308668B1EP-4308668-B1

Inventors

  • MOODY, Gareth
  • WARREN, Bethan Lora May
  • CALE, BEN

Dates

Publication Date
20260506
Application Date
20220314

Claims (14)

  1. A base oil comprising two or more compounds of formula (I) wherein, each R is independently an alkyl carbonyl, and where said alkyl groups contain between 1 and 24 carbons, m is an integer between 1 and 10, X is a linear alkyl moiety having between 1 and 20 carbon atoms, and where X may be the same or different for repeating units of m, and at least one compound contains branching in its R group(s).
  2. A base oil according to claim 1, wherein X is a linear alkyl moiety containing between 2 and 6 carbons, optionally wherein X is a linear alkyl moiety containing between 2 and 4 carbons.
  3. A base oil according to claim 1 or 2, wherein m is an integer of between 1 and 4 and represents the number of repeat alkoxy units.
  4. A base oil according to any preceding claim, wherein the compound of formula (I) comprises a poly alkoxy ether consisting of repeat alkoxy units, optionally wherein the compound of formula (I) comprises polyethylene glycol (PEG) (polyethylene oxide), polytrimethylene ether glycol (PTriMEG) (polytrimethylene oxide) and/or polytetramethylene ether glycol (PTMEG) (polytetramethylene oxide).
  5. A base oil according to any preceding claim, wherein the alkyl of the alkyl carbonyl contains between 5 and 18 carbons, optionally between 6 and 12 carbons.
  6. A base oil according to any preceding claim, wherein R is derived from an acid, optionally wherein R is derived from an aliphatic carboxylic acid which is saturated or unsaturated, linear, or branched.
  7. A base oil according to claim 6, wherein the aliphatic carboxylic acid is saturated, and/or wherein the aliphatic carboxylic acid is linear.
  8. A gear oil formulation comprising a base oil in accordance with any one of claims 1 to 7.
  9. A gear oil formulation according to claim 8, wherein the gear oil formulation comprises at least 1 wt.%, preferably at least 2 wt.%, more preferably at least 4 wt.%, even more preferably at least 5 wt.% of base oil based on the total weight of the formulation, and/or wherein the gear oil formulation comprises up to 50 wt.%, preferably up to 35 wt.%, more preferably up to 20 wt.% base oil based on the total weight of the formulation, and/or wherein the gear oil formulation comprises less than 5% water by weight based on the total weight of the formulation.
  10. A gear oil formulation according to claim 8 or 9, wherein the gear oil formulation comprises one or more of the following additive types: dispersants, antioxidants, anti-wear agents, emulsifiers, demulsifiers, extreme pressure agents, multifunctional additives, viscosity index improvers, pour point depressants, foam inhibitors and friction modifiers.
  11. A gear oil formulation according to claim 10, wherein the gear oil formulation comprises at least 0.5 wt.% of said one or more additive types, preferably at least 1 wt.%, more preferably at least 5 wt.% based on the total weight of the formulation, optionally wherein the gear oil formulation comprises up to 30 wt.% of one or more additive types, preferably up to 20 wt.%, more preferably up to 10 wt.% based on the total weight of the formulation.
  12. A gear oil formulation according to any one of claims 8 to 11, wherein the gear oil has a kinematic viscosity the range from ISO 10 to ISO 1500, more preferably ISO 68 to ISO 680, wherein an ISO grade specifies the mid-point kinematic viscosity of the gear oil formulation sample at 40°C in cSt (mm 2 /s).
  13. Use of a base oil in accordance with any one of claims 1 to 7, or use of a gear oil formulation in accordance with any one of claims 8 to 12, in an electric vehicle power train.
  14. Use in accordance with claim 13, wherein the vehicle powertrain is an electric vehicle powertrain, and/or wherein said use is in a system within the power train, said system selected from one or more of the following: axels, differentials, transmissions, battery pack(s) and power electronics.

Description

The present invention relates to a base oil. The base oil as described herein provides utility inter alia in gear oil formulations, and in particular transmission fluids, and provides improved coefficient of friction properties when in use. More especially some embodiments provide gear oil formulations which are particularly suitable for use in electrical vehicles with or without integrated gear boxes. Electric vehicles are vehicles which are propelled using one or more electric motors. Electric vehicles may be fully electric (also known as pure-electric or all-electric vehicles) or hybrid in nature (in a hybrid electric vehicle propulsion may be achieved from an alternative means, such as hydrocarbon derived fuel some of the time). Electric vehicles also include range-extended electric vehicles where the vehicle is powered by an electric motor and a plug-in battery, but the vehicle also comprises an auxiliary combustion engine which is used only to supplement battery charging and not as a primary source of propulsion. The present invention is suitable for use in all of these types of electric vehicle. Gear oil formulations are a sub-class of lubricant oil, and typically comprise a lubricant base stock (or base oil) as their majority component. The choice of lubricant base stock utilised in a lubricant oil can have a major impact on properties such as oxidation and thermal stability, volatility, low temperature fluidity, solvency of additives, contaminants and degradation products, and traction. The American Petroleum Institute (API) currently defines five groups of lubricant base stocks (API Publication 1509). Groups I, II and III are mineral oils which are classified by the amount of saturates and sulphur they contain and by their viscosity indices. Table 1 below illustrates these API classifications for Groups I, II and III. Table 1GroupSaturatesSulphurViscosity Index (VI)I<90%>0.03%80-120IIAt least 90%Not more than 0.03%80-120IIIAt least 90%Not more than 0.03%At least 120 Group I base stocks are solvent refined mineral oils, which are the least expensive base stock to produce, and currently account for most base stock sales. They provide satisfactory oxidation stability, volatility, low temperature performance and traction properties and have particularly good solvency for additives and contaminants. Group II base stocks are mostly hydroprocessed mineral oils, which typically provide improved volatility and oxidation stability as compared to Group I base stocks. The use of Group II stocks has grown to about 30% of the US market. Group III base stocks are severely hydroprocessed mineral oils or they can be produced via wax or paraffin isomerisation. They are known to have better oxidation stability and volatility than Group I and II base stocks but have a limited range of commercially available viscosities. Group IV base stocks differ from Groups I to III in that they are synthetic base stocks e.g., polyalphaolefins (PAOs). PAOs have good oxidative stability, volatility, and low pour points. Disadvantages include moderate solubility of polar additives, for example anti-wear additives. Group V base stocks are all base stocks that are not included in Groups I to IV. Examples include alkyl naphthalenes, alkyl aromatics, vegetable oils, esters (including polyol esters, diesters and monoesters), polycarbonates, silicone oils and polyalkylene glycols. Gear oil formulations suitable for use in the automotive field desirably provide a long-life oil with a relatively high viscosity (versus other lubricant application areas) for the lubrication of rear axles and some transmission systems in a vehicles power train. Additionally, final drives and driven accessories in agricultural and construction equipment may also require gear oils. More generally, gear oil formulations also desirably provide good oxidation stability and rust or anticorrosion properties. Typically, additives are provided to a lubricating base oil to provide a desirable gear oil formulation for its intended use; base oils which provide desirable properties in and of themselves are still sought to limit the formulators need to incorporate costly additives, and to provide simpler formulations which are more easily and quickly manufactured. The rapid move towards electrification of passenger vehicles has surpassed the understanding and specifications of current gear oil specifications of OEM's and regulators. Current generation hybrid and electric vehicles still use standard automatic transmission fluid (ATF) formulations which were not specifically designed for this application. Current gear oils are not fulfilling the dynamic requirements of OEM's, due to rapid advancements in electric vehicle technology, ATF base fluids, and ad-packs. Furthermore, thermal management of parts in electric vehicles is gaining importance. In the battery of the vehicle thermal management is crucial to ensure safe running and use. There is currently a great amount of res