FIELD OF INVENTION The present invention relates to a lubricating composition containing 0.25 wt % or less of a metal dialkyldithiophosphate. The invention further relates to the use of the lubricating composition in a transmission.
Gearbox manufacturers are developing gears and other transmission equipment capable of providing increasing amounts of power. The increased power results in a lubricating oil being operated at higher loads and operating temperatures. As a consequence known gear and transmission lubricants are not capable of providing adequate protection against wear, scuffing and micropitting, whilst providing acceptable oxidation stability and cleanliness. Therefore there is need for a lubricating composition capable of operating at a higher power throughput and operating temperatures.
U.S. Pat. No. 5,942,470 discloses a gear oil composition containing (i) an oil-soluble sulphur-containing extreme pressure agent or antiwear agent, (ii) at least one oil soluble amine salt of a partial ester of an acid of phosphorus, (iii) a succinimide dispersant with a N—H bond; and (iv) at least one of a nitrogen-containing ashless dispersant, an amine salt of a carboxylic acid and a trihydrocarbyl ester of a pentavalent acid of phosphorus. In one embodiment the gear oil composition is essentially devoid of any metal-containing additive component.
U.S. Pat. No. 6,617,287 discloses a manual transmission lubricating composition containing at least 0.5 wt % of a metal salt of an organic acid, 0.01 % to 2 wt % of an amine salt of a phosphorus containing acid; and optionally a metal deactivator and a boron containing dispersant.
It would be advantageous to have a lubricating composition and a method of lubricating a transmission capable of providing at least one of acceptable protection against wear, scuffing and micropitting, whilst providing acceptable hose and/or seal compatability, oxidation stability and cleanliness. The present invention provides such a lubricating composition and a method of lubricating a transmission.
In one embodiment the invention provides a lubricating composition comprising:
(a) an oil soluble phosphorus amine salt;
(b) about 0.0001 wt % to about 5 wt % of a metal containing detergent package comprising a phenate and a sulphonate;
(c) a dispersant;
(d) a dispersant viscosity modifier;
(e) a metal deactivator; and
(f) an oil of lubricating viscosity,
wherein the lubricating composition contains less than about 0.25 wt % of a metal dialkyldithiophosphate.
In another embodiment the invention provides a method of lubricating a synchronised transmission comprising:
(i) employing a lubricating composition comprising:
(a) an oil soluble phosphorus amine salt;
(b) about 0.0001 wt % to about 5 wt % of a metal containing detergent package comprising a phenate and a sulphonate;
(c) a dispersant;
(d) a dispersant viscosity modifier;
(e) a metal deactivator; and
(f) an oil of lubricating viscosity,
wherein the lubricating composition contains less than about 0.25 wt % of a metal dialkyldithiophosphate; and
(ii) lubricating a synchronised transmission with said lubricating composition.
In another embodiment the invention provides a method of lubricating a non-synchronised transmission comprising:
(i) employing a lubricating composition comprising:
(a) an oil soluble phosphorus amine salt;
(b) about 0.0001 wt % to about 5 wt % of a metal containing detergent package comprising a phenate and a sulphonate;
(c) a dispersant and/or a dispersant viscosity modifier;
(d) a metal deactivator; and
(e) an oil of lubricating viscosity,
wherein the lubricating composition contains less than about 0.25 wt % of a metal dialkyldithiophosphate; and
(ii) lubricating a non-synchronised transmission with said lubricating composition.
The invention provides a lubricating composition as defined above.
As used herein the term “free of”, as used in the specification and claims, defines the absence of a material except for the amount which is present as impurities, e.g., a trace amount. Typically in this embodiment, the amount present will be less than about 0.05% or less than about 0.005 wt % by weight of the lubricating composition.
Oil Soluble Phosphorus Amine Salt
In one embodiment the oil soluble phosphorus amine salt antiwear agent/extreme pressure agent comprises an amine salt of a phosphorus acid ester or mixtures thereof. The amine salt of a phosphorus acid ester includes phosphoric acid esters and amine salts thereof; dialkyldithiophosphoric acid esters and amine salts thereof; amine salts of phosphites; and amine salts of phosphorus-containing carboxylic esters, ethers, and amides; and mixtures thereof. The amine salt of a phosphorus acid ester may be used alone or in combination.
In one embodiment the oil soluble phosphorus amine salt comprises partial amine salt-partial metal salt compounds or mixtures thereof. In one embodiment the phosphorus compound further comprises a sulfur atom in the molecule. In one embodiment the amine salt of the phosphorus compound is ashless, i.e., metal-free (prior to being mixed with other components).
The amines which may be suitable for use as the amine salt include primary amines, secondary amines, tertiary amines, and mixtures thereof. The amines include those with at least one hydrocarbyl group, or, in certain embodiments, two or three hydrocarbyl groups. The hydrocarbyl groups may contain about 2 to about 30 carbon atoms, or in another embodiment about 8 to about 26 or about 10 to about 20 or about 13 to about 19 carbon atoms.
Primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine, and dodecylamine, as well as such fatty amines as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine and oleyamine. Other useful fatty amines include commercially available fatty amines such as “Armeen®” amines (products available from Akzo Chemicals, Chicago, Ill.), such as Armeen C, Armeen O, Armeen OL, Armeen T, Armeen HT, Armeen S and Armeen SD, wherein the letter designation relates to the fatty group, such as coco, oleyl, tallow, or stearyl groups.
Examples of suitable secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine and ethylamylamine. The secondary amines may be cyclic amines such as piperidine, piperazine and morpholine.
The amine may also be a tertiary-aliphatic primary amine. The aliphatic group in this case may be an alkyl group containing about 2 to about 30, or about 6 to about 26, or about 8 to about 24 carbon atoms. Tertiary alkyl amines include monoamines such as tert-butylamine, tert-hexylamine, 1-methyl-1-amino-cyclohexane, tert-octylamine, tert-decylamine, tertdodecylamine, tert-tetradecylamine, tert-hexadecylamine, tert-octadecylamine, tert-tetracosanylamine, and tert-octacosanylamine.
In one embodiment the phosphorus acid amine salt comprises an amine with C11to C14tertiary alkyl primary groups or mixtures thereof. In one embodiment the phosphorus acid amine salt comprises an amine with C14to C18tertiary alkyl primary amines or mixtures thereof. In one embodiment the phosphorus acid amine salt comprises an amine with C18to C22tertiary alkyl primary amines or mixtures thereof.
Mixtures of amines may also be used in the invention. In one embodiment a useful mixture of amines is “Primene® 81R” and “Primene® JMT.” Primene® 81R and Primene® JMT (both produced and sold by Rohm & Haas) are mixtures of C11to C14tertiary alkyl primary amines and C18to C22tertiary alkyl primary amines respectively.
In one embodiment the hydrocarbyl amine salt of an alkylphosphoric acid ester is the reaction product of a C14to C18alkylated phosphoric acid with Primene 81R™ (produced and sold by Rohm & Haas) which is a mixture of C11to C14tertiary alkyl primary amines.
Examples of hydrocarbyl amine salts of dialkyldithiophosphoric acid esters include the reaction product(s) of isopropyl, methyl-amyl (4-methyl-2-pentyl or mixtures thereof), 2-ethylhexyl, heptyl, octyl or nonyl dithiophosphoric acids with ethylene diamine, morpholine, or Primene 81R™, and mixtures thereof.
In one embodiment the dithiophosphoric acid may be reacted with an epoxide or a glycol. This reaction product is further reacted with a phosphorus acid, anhydride, or lower ester. The epoxide includes an aliphatic epoxide or a styrene oxide. Examples of useful epoxides include ethylene oxide, propylene oxide, butene oxide, octene oxide, dodecene oxide, styrene oxide and the like. In one embodiment the epoxide is Propylene oxide. The glycols may be aliphatic glycols having from 1 to about 12, or from about 2 to about 6, or about 2 to about 3 carbon atoms. The dithiophosphoric acids, glycols, epoxides, inorganic phosphorus reagents and methods of reacting the same are described in U.S. Pat. Nos. 3,197,405 and 3,544,465. The resulting acids may then be salted with amines. An example of suitable dithiophosphoric acid is prepared by adding phosphorus pentoxide (about 64 grams) at about 58° C. over a period of about 45 minutes to about 514 grams of hydroxypropyl O,O-di(4-methyl-2-pentyl)phosphorodithioate (prepared by reacting di(4-methyl-2-pentyl)-phosphorodithioic acid with about 1.3 moles of propylene oxide at about 25° C.). The mixture is heated at about 75° C. for about 2.5 hours, mixed with a diatomaceous earth and filtered at about 70° C. The filtrate contains about 11.8% by weight phosphorus, about 15.2% by weight sulfur, and an acid number of 87 (bromophenol blue).
In several other embodiments the amount of oil soluble phosphorus amine salt present ranges from about 0.001 wt % to about 10 wt %, or about 0.01 wt % to about 5 wt %, or about 0.05 wt % to about 2.5 wt %.
Detergent
The invention comprises a metal containing detergent package comprising: a phenate; and a sulphonate present at about 0.0001 wt % to about 0.5 wt % of the lubricating composition. As used herein the term “detergent package” represents only metal containing detergents.
In several other embodiments the amount of metal containing detergent present ranges from about 0.0001 wt % to about 5 wt %, or about 0.01 wt % to about 4 wt %, or about 0.05 wt % to about 3 wt %.
In one embodiment the metal containing detergent package comprises at least 50 wt % of a phenate. In another embodiment the metal containing detergent package contains at least 55 wt % of a phenate.
The metal of the metal containing detergent includes alkaline earth, alkali metal or mixtures thereof. Examples of a suitable alkaline earth metal include calcium, magnesium or barium; and sodium is a suitable alkali metal. In one embodiment the metal containing detergent comprises a calcium sulphonate and a calcium phenate.
The sulphonate detergent of the lubricating composition is known and includes neutral and overbased detergents. Overbasing techniques are well known.
The overbased sulphonate detergent includes those with a TBN (total base number) of at least about 300, or at least about 350, or at least about 400, or at least about 425. In several embodiments the overbased sulphonate detergent has a TBN of at least about 300, or about 400 or about 500.
The sulphonate detergent may be derived from sulphonic acids including polypropene benzene sulphonic acid, dodecyl benzene sulphonic acid, tridecyl benzene sulphonic acid, tetradecyl benzene sulphonic acid, pentadecyl benzene sulphonic acid, hexadecyl benzene sulphonic acid and mixtures thereof. In one embodiment the sulphonic acid includes undecyl benzene sulphonic acid, dodecyl benzene sulphonic acid, tridecyl benzene sulphonic acid, tetradecyl benzene sulphonic acid, octadecyl benzene sulphonic acid, tetraeicosyl benzene sulphonic acid or mixtures thereof. In one embodiment of the invention the sulphonic acid is a polypropene benzene sulphonic acid, where the polypropene often contains about 18 to about 30 carbon atoms.
In one embodiment of the invention the sulphonate components include calcium polypropene benzenesulphonate and calcium monoalkyl and dialkyl benzenesulphonates wherein the alkyl groups may be linear or branched; and contain at least about 10 carbons, for example 11, 12, 13, 14, or 15 carbon atoms. In one embodiment the alkyl groups contain at least about 20 carbon atoms, for example 22 to 32 or 22 to 28 carbon atoms.
In one embodiment the monoalkyl and dialkyl benzenesulphonates may be derived from benzene alkylated with olefins containing 20 to 30 carbon atoms, where the olefins contain a double bond randomly distributed throughout the chains.
The phenate detergent is known and includes neutral and overbased metal salts of a sulphur-containing phenate, a non-sulphurised phenate or mixtures thereof.
The phenate detergent in one embodiment has a TBN from about 30 to about 290, in another embodiment about 40 to about 265, in another embodiment about 50 to about 190 and in another embodiment about 70 to about 175. In one embodiment the sulphur containing phenate detergent has a TBN of about 150 and in another embodiment a TBN of about 225. The phenate detergent in several embodiments has a metal ratio of not more than about 4, or not more than about 3, or not more than about 2.5, or not more than about 2.1.
Dispersant
In one embodiment of the invention the lubricating composition further comprises a dispersant. The dispersant may be used alone or in combination with other dispersant additives. The dispersant includes those derived from a N-substituted long chain alkyl and/or alkenyl succinimide.
The N-substituted long chain alkenyl succinimide has a variety of chemical structures and includes a mono-succinimide and/or a di-succinimide. The long chain alkenyl group includes those with a number average molecular weight of about 350 to about 10,000, in another embodiment about 400 to about 7000, in another embodiment about 500 to about 5000 and in yet another embodiment about 500 to about 2500. In one embodiment the long chain alkenyl group is a polyisobutylene group, which has a number average molecular weight from 800 to 1600 and in another embodiment from about 1600 to about 3000. The succinimide includes those prepared by the condensation of a hydrocarbyl-substituted acylating agent (e.g., hydrocarbyl-substituted succinic anhydride) with a polyamine or an amino alcohol, a polyalkylene polyamine or poly(ethyleneamine) such as triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, still bottoms (often described as HPAX™) or mixtures thereof. In one embodiment the polyamine is still bottoms.
Another class of dispersant includes Mannich bases, which are the reaction products of alkyl phenols in which the alkyl group includes at least about 30 carbon atoms with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines) and are described in more detail in U.S. Pat. No. 3,634,515.
Another class of ashless dispersant is high molecular weight esters. These materials are similar to the above-described succinimides except that they may be seen as having been prepared by reaction of a hydrocarbyl acylating agent and a polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or sorbitol. Such materials are described in more detail in U.S. Pat. No. 3,381,022.
The dispersant may also be post-treated by reaction with any of a variety of agents. Among these are urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides, boron compounds, and phosphorus compounds. References detailing such treatment are listed in U.S. Pat. No. 4,654,403. In one embodiment the dispersant is borated dispersant especially a borated N-substituted long chain alkenyl succinimide or mixtures thereof. In one embodiment of the invention comprises a borated dispersant and a non-borated dispersant. In one embodiment the dispersant is a borated dispersant.
In several embodiments the dispersant is present in ranges including about 0 wt % to about 6 wt %, or about 0.005 wt % to about 6 wt %, or about 0.01 wt % to about 4 wt %, or about 0.1 wt % to about 2 wt % of the lubricating composition.
Dispersant Viscosity Modifier
In one embodiment the lubricating composition further comprises a dispersant viscosity modifier. The dispersant viscosity modifier (often referred to as DVM) includes a (co)polymer with a nitrogen containing monomer, a nitrogen containing compound capable of reacting with a functionalised polymer backbone or mixtures thereof.
In several embodiments the dispersant viscosity modifier is present in ranges including about 0 wt % to about 34 wt %, or about 0.005 wt % to about 34 wt %, or about 0.01 wt % to about 24 wt %, or about 0.1 wt % to about 21 wt % of the lubricating composition.
As used hereinafter the term “(meth)acrylate” is used to refer to a methacrylate and a acrylate; and “(meth)acrylamide” is used to refer to a acrylamide and a methacrylamide.
As described hereinafter the molecular weight of the dispersant viscosity modifier has been determined using known methods, such as GPC analysis using a polystyrene standard.
The dispersant viscosity modifier includes functionalised polyolefins (for example, ethylene-propylene copolymers that have been functionalized with the reaction product of maleic anhydride and an a nitrogen containing compound), a poly(meth)acrylate functionalised with an a nitrogen containing compound, or an esterified polymer derived from monomers comprising: (i) a vinyl aromatic monomer; and (ii) an unsaturated carboxylic acid or derivatives thereof (for example, styrene-maleic anhydride copolymers reacted with an a nitrogen containing compound). In several embodiments the dispersant viscosity modifer includes amine functionalised polyolefins, a poly(meth)acrylate functionalised with an a nitrogen containing compound, an esterified polymer derived from monomers comprising: (i) a vinyl aromatic monomer; and (ii) an unsaturated carboxylic acid or derivatives thereof, or mixtures thereof.
The nitrogen containing monomer includes a vinyl substituted nitrogen heterocyclic monomer, a dialkylaminoalkyl (meth)acrylate monomer, a dialkylaminoalkyl (meth)acrylamide monomer, a tertiary-(meth)acrylamide monomer or mixtures thereof. The alkyl in several embodiments contains 1 to about 8, or from 1 to about 3 carbon atoms.
Useful nitrogen containing monomers include vinyl pyridine, N-vinyl imidazole, N-vinyl pyrrolidinone, and N-vinyl caprolactam, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminobutylacrylamide dimethylamine propyl methacrylate, dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, dimethylaminoethylacrylamide, tertiary butyl acrylamide or mixtures thereof.
The nitrogen containing compound includes an amine such as a monoamine, a polyamine or mixtures thereof. The amine includes primary functionality, secondary functionality or mixtures thereof. The amine includes cyclic, linear or branched and examples include an alkylenemonoamine, a heterocyclic monoamine, an alkylenepolyamine, a heterocyclic polyamine or mixtures thereof. In one embodiment the amine contains not more than one primary or secondary amino group, for example N,N-dimethyl-aminopropylamine.
In one embodiment the amine may be a hydroxy-substituted hydrocarbyl amine such as a hydroxyalkyl amine. Examples of a suitable hydroxy-substituted hydrocarbyl amine include aminoethyl ethanolamine, aminopropyl ethanolamine, aminobutyl ethanolamine or mixtures thereof.
Suitable cyclic amines include 4-aminodiphenylamine, 4-(3-aminopropyl)morpholine, 4-(2-aminoethyl)morpholine or mixtures thereof. In one embodiment the cyclic amine is 4-(3-aminopropyl) morpholine or mixtures thereof.
The poly(meth)acrylate dispersant viscosity modifier includes a copolymer derived from a (meth)acrylate monomer in several embodiments containing an alkyl group with 1 to about 30, or 1 to about 26, or 1 to about 20 carbon atoms. The alkyl group includes mixtures derived from an alcohol containing 1 to about 4, about 8 to about 10, about 12 to about 14, about 12 to about 15, about 16 to about 18 or about 16 to about 20 carbon atoms. Examples of commercially available alcohol mixtures include the following products sold under the brand names of Dobanol™ 25, Neodol™ 25, Lial™ 125, and Alchem™ 125. In one embodiment the alcohol is a single alcohol i.e. not a mixture.
The poly(meth)acrylate has a molecular weight (Mw) including from about 5000 to about 350,000, in another embodiment about 10,000 to about 150,000, in another embodiment about 15,000 to about 120,000, in another embodiment about 10,000 to about 50,000 and in yet another embodiment about 15,000 to about 35,000.
In one embodiment the dispersant viscosity modifier is a functionalised polyolefin and/or an esterified polymer containing an unsaturated carboxylic acid or derivatives thereof. The carboxylic acid or derivatives thereof includes a mono- acid, a di-acid or mixtures thereof. Optionally the unsaturated carboxylic acid or derivatives thereof is further substituted with a hydrocarbyl group. The hydrocarbyl group includes substituted, unsubstituted, branched, unbranched or mixtures thereof, although, unsubstituted is especially useful.
The unsaturated carboxylic acid anhydride or derivatives thereof may be wholly esterified, partially esterified or mixtures thereof. When partially esterified other derivatives include acids, salts or mixtures thereof. Suitable salts include alkali metals, alkaline earth metals or mixtures thereof. The salts include lithium, sodium, potassium, magnesium, calcium or mixtures thereof. The unsaturated carboxylic acid or derivatives thereof includes an acrylic acid, a methyl acrylate, a methacrylic acid, a maleic acid or anhydride, a fumaric acid, an itaconic acid or anhydride or mixtures thereof.
Suitable examples of the unsaturated dicarboxylic acid anhydride or derivatives include itaconic anhydride, maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, dimethyl maleic anhydride or mixtures thereof. The unsaturated carboxylic acid anhydride or derivatives thereof functionality may be used alone or in combination.
In one embodiment the dispersant viscosity modifier is a functionalised polyolefin. In one embodiment the functionalised polyolefin further contains a nitrogen derived from a nitrogen containing compound capable of reacting with a functionalised polymer backbone. Commercially available dispersant viscosity modifier functionalised polyolefin are known. Examples of a commercially available dispersant viscosity modifier include those derived from an alpha-olefin available as mixtures especially as C16-C18or ethylene-propylene copolymers, ethylene-l-butene copolymers or mixtures thereof.
In one embodiment the dispersant viscosity modifier is derved from functionalised polyolefin, functionalised with an unsaturated carboxylic acid anhydride or derivatives thereof (described above). The functionalised polyolefin has a molecular weight (Mw) in the range including from about 600 to about 300,000, in another embodiment about 600 to about 100,000, in another embodiment about 1000 to about 50,000 and in another embodiment about 2000 to about 20,000.
In one embodiment the dispersant viscosity modifier is an esterified polymer derived from monomers comprising: (i) a vinyl aromatic monomer; and (ii) an unsaturated carboxylic acid or derivatives thereof. The polymer prior to esterification is generally referred to as an interpolymer. In one embodiment the esterified polymer is substantially free of to free of a (meth)acrylate ester. In one embodiment the interpolymer is a styrene-maleic anhydride copolymer. In one embodiment the esterified polymer contains a nitrogen derived from a nitrogen containing compound capable of reacting with a functionalised polymer backbone to form an amidated polymer.
The molecular weight of the interpolymer may also be expressed in terms of the “reduced specific viscosity” of the polymer which is recognized means of expressing the molecular size of a polymeric substance. As used herein, the reduced specific viscosity (abbreviated as RSV) is the value obtained in accordance with the formula RSV=(Relative Viscosity−1)/Concentration, wherein the relative viscosity is determined by measuring, by means of a dilution viscometer, the viscosity of a solution of about 1 g of the polymer in about 10 cm3of acetone and the viscosity of acetone at about 30° C. For purpose of computation by the above formula, the concentration is adjusted to about 0.4 g of the interpolymer per 10 cm3of acetone. A more detailed discussion of the reduced specific viscosity, also known as the specific viscosity, as well as its relationship to the average molecular weight of an interpolymer, appears in Paul J. Flory, Principles of Polymer Chemistry, (1953 Edition) pages 308 et seq. The interpolymer polymer of the invention has a RSV from about 0.05 to about 2 in one embodiment about 0.06 to about 1 and in another embodiment about 0.06 to about 0.8. In one embodiment the RSV is about 0.69. In another embodiment the RSV is about 0.12. In one embodiment the Mw of the interpolymer is about 10,000 to about 300,000.
Examples of a vinyl aromatic monomer include styrene (often referred to as ethenylbenzene), substituted styrene or mixtures thereof. Examples of a suitable substituted styrene include alpha-methylstyrene, para-methylstyrene (often referred to as vinyl toluene), para-tert-butylstyrene, alpha-ethylstyrene or mixtures thereof.
The dispersant viscosity modifier of the invention is known in the art and commercially available from a number of corporations, including The Lubrizol Corporation, Degussa AG and Rohmax GmbH.
Metal Deactivator
The invention comprises a metal deactivator. Examples of metal deactivators include benzotriazoles or derivatives thereof, 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, 2-alkyldithiobenzothiazoles, 2-(N,N-dialkyldithiocarbamoyl)benzothiazoles, 2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles, 2,5-bis(N,N-dialkyldithiocarbamoyl)-1,3,4-thiadiazoles, 2-alkyldithio-5-mercapto thiadiazoles and mixtures thereof. In one embodiment the metal deactivator is a derivative of benzotriazole. In one embodiment the metal deactivator is a 2,5-bis(alkyl-dithio)-1,3,4-thiadiazole. The metal deactivator may be used alone or in combination with other metal deactivators. In one embodiment the metal deactivator is present as a mixture of two or more compounds.
In one embodiment the metal deactivator comprises 2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles, benzotriazoles or derivatives thereof or mixtures thereof.
Derivatives of benzotriazoles containing hydrocarbyl substitutions include at least one of the following ring positions 1- or 2- or 4- or 5- or 6- or 7-. The hydrocarbyl groups may contain a number of carbon atoms in ranges from about 1 to about 30, or from 1 to about 15, or from 1 to about 7 carbon atoms. In one embodiment the metal deactivator is tolyltriazole. In one embodiment hydrocarbyl benzotriazoles substituted at positions 4- or 5- or 6- or 7- can be further reacted with an aldehyde and a secondary amine.
Examples of suitable aldehydes include formaldehyde, acet aldehyde, propionaldehyde and mixtures thereof. In one embodiment the aldehyde is formaldehyde, which can be monomeric, polymeric (paraformaldehyde) or in aqueous solution.
Suitable examples of amines include dimethylamine, diethylamine, dipropylamine, dipropenylamine, diisobutylamine, diisobutenylamine, dipentylamine, dipentenylamine, dibenzylamine, dinaphthylamine, di-2-ethylhexylamine and mixtures thereof. In one embodiment the amine is di-2-ethylhexylamine. The amine can be used alone or in combination with other amines.
Examples of metal deactivators include N,N-bis(heptyl)-ar-methyl-1H-Benzotriazole-1-methanamine, N,N-bis(nonyl)-ar-methyl-1H-Benzotriazole-1-methanamine, N,N-bis(decyl)-ar-methyl-1H-Benzotriazole-1-methanamine, N,N-bis(undecyl)-ar-methyl-1H-Benzotriazole-1-methanamine, N,N-bis (dodecyl)-ar-methyl-1H-Benzotriazole-1-methanamine N,N-bis(2-ethylhexyl)-ar-methyl-1H-Benzotriazole-1-methanamine and mixtures thereof. In one embodiment the metal deactivator is N,N-bis(2-ethylhexyl)-ar-methyl-1H-Benzotriazole-1-methanamine.
In one embodiment, the metal deactivator is 2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles. The alkyl groups of 2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles may contain 1 to about 30 or about 4 to about 20 carbon atoms. Examples of suitable 2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles include 2,5-bis(tert-octyldithio)-1,3,4-thiadiazole 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-decyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-undecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tridecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tetradecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-pentadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-hexadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-heptadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-octadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-nonadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-eicosyldithio)-1,3,4-thiadiazole and mixtures thereof.
The metal deactivator may be present in several ranges including about 0.0001 wt % to about 2 wt %, or about 0.001 wt % to about 1 wt %, or about 0.005 wt % to about 0.5 wt % of the lubricating composition.
Oil of Lubricating Viscosity
The lubricating oil composition includes natural or synthetic oils of lubricating viscosity, oil derived from hydrocracking, hydrogenation, hydrofinishing, and unrefined, refined and re-refined oils and mixtures thereof.
Natural oils include animal oils, vegetable oils, mineral oils and mixtures thereof. Synthetic oils include hydrocarbon oils, silicon-based oils, and liquid esters of phosphorus-containing acids. Synthetic oils may be produced by Fischer-Tropsch gas-to-liquid synthetic procedure as well as other gas-to-liquid oils. In one embodiment the polymer composition of the present invention is useful when employed in a gas-to-liquid oil. Often Fischer-Tropsch hydrocarbons or waxes may be hydroisomerised.
In one embodiment the base oil comprises a polyalphaolefin including a PAO-2, PAO-4, PAO-5, PAO-6, PAO-7 or PAO-8. The polyalphaolefin in one embodiment is prepared from dodecene and in another embodiment from decene.
In one embodiment the oil of lubricating viscosity may be an ester such as an adipate.
In one embodiment the oil of lubricating viscosity may be a polymer (may also be referred to as a viscosity modifier) including hydrogenated copolymers of styrene-butadiene, ethylene-propylene polymers, polyisobutenes, hydrogenated styrene-isoprene polymers, hydrogenated isoprene polymers, polymethacrylate acid esters, polyacrylate acid esters, polyalkyl styrenes, alkenyl aryl conjugated diene copolymers, polyolefins, polyalkylmethacrylates and esters of maleic anhydride-styrene copolymers. In several embodiments the viscosity modifier includes polymethacrylate acid esters, polyacrylate acid esters, polyalkylmethacrylates and esters of maleic anhydride-styrene copolymers, polyisobutenes or mixtures thereof.
In several embodiments the oil of lubricating viscosity may contain a polymer (or viscosity modifier) present in ranges from 0 wt % to 70 wt %, or about 5 wt % to 65 wt %, or about 10 to about 60 wt %, or about 15 to about 50 wt % of the lubricating composition. In one embodiment the lubricating composition comprises an oil of lubricating viscosity containing mixtures of a viscosity modifier and an API Group III or IV base oil. In one embodiment the lubricating composition contains a synthetic oil of lubricating viscosity.
Oils of lubricating viscosity may also be defined as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. In one embodiment the oil of lubricating viscosity comprises an API Group I, II, III, IV, V, VI or mixtures thereof, and in another embodiment API Group II, III, IV or mixtures thereof. In another embodiment the oil of lubricating viscosity is a Group III or IV base oil and in another embodiment a Group IV base oil.
The oil of lubricating viscosity may be present in several embodiments in ranges from about 15.5 wt % to about 99.9 wt %, or from about 44 wt % to about 99.9 wt %, or from about 64 wt % to about 99.7 wt % of the lubricating composition. The oil of lubricating viscosity may be used alone or in combination.
Metal Hydrocarbyl Dithiophosphate
The invention further contains about 0 wt % to less than about 0.25 wt % of a metal dialkyldithiophosphate.
In several other embodiments the invention contains about 0.15 wt % or less, about 800 ppm or less, about 600 ppm or less or about 300 ppm or less of the metal dialkyldithiophosphate. Examples of suitable range metal dialkyldithiophosphate may be present in include about 0 ppm to about 1000 ppm, about 0 ppm to about 900 ppm, about 0 ppm to about 750 ppm or about 0 ppm to about 400 ppm.
In one embodiment the lubricating composition is free of a metal hydrocarbyl dithiophosphate.
Examples of a metal hydrocarbyl dithiophosphate include zinc dihydrocarbyl dithiophosphates (often referred to as ZDDP, ZDP or ZDTP).
Additional Performance Additive
In one embodiment the method optionally includes at least one additional performance additive. The additional performance additive includes at least one of antiscuffing agents, detergents other than (b), friction modifiers, extreme pressure agents, antioxidants, corrosion inhibitors, foam inhibitors, demulsifiers, pour point depressants, seal swelling agents and mixtures thereof. In one embodiment the additional performance additives may be used alone or in combination.
The total combined amount of the additional performance additives present in several embodiments ranges from about 0 wt % to about 25 wt %, or from about 0.01 wt % to about 15 wt %, or from about 0.1 wt % to about 5 wt % of the lubricating composition. Although one or more of the additional performance additives may be present, it is common for the other additional performance additives to be present in different amounts relative to each other.
In one embodiment the lubricating composition is free of an antioxidant sulphurised olefin. In another embodiment the lubricating composition is free of a sulphide capable of providing antiscuffing properties.
If the present invention is in the form of a concentrate (which may be combined with additional oil to form, in whole or in part, a finished lubricant), the ratio of components (a) to (d) of the invention and the optional additional performance additives in an oil of lubricating viscosity, to diluent oil including in the range of about 80:20 to about 10:90 by weight.
Antioxidants include a molybdenum dithiocarbamate, a sulphurised olefin, a hindered phenol, a diphenylamine; detergents other than (b) of the invention include neutral or overbased, Newtonian or non-Newtonian, basic salts of alkali, alkaline earth and transition metals with one or more of a carboxylic acid, a phosphorus acid, a mono- and/or a di- thiophosphoric acid, a saligenin, an alkylsalicylate and a salixarate.
Antiscuffing agents including organic sulphides and polysulphides, such as benzyldisulphide, bis-(chlorobenzyl) disulphide, dibutyl tetrasulphide, di-tertiary butyl polysulphide, di-tert-butylsulphide, sulphurised Diels-Alder adducts or alkyl sulphenyl N′N-dialkyl dithiocarbamates; and Extreme Pressure (EP) agents including chlorinated wax, organic sulphides and polysulphides, such as benzyldisulphide, bis-(chiorobenzyi) disuiphide, dibutyl tetrasulphide, sulphurised methyl ester of oleic acid, sulphurised alkylphenol, sulphurised dipentene, sulphurised terpene, and sulphurised Diels-Alder adducts; phosphosulphurised hydrocarbons, metal thiocarbamates, such as zinc dioctyldithiocarbamate and barium heptylphenol diacid; may also be used in the lubricating composition of the invention.
The friction modifiers include fatty amines, esters such as borated glycerol esters (such as glycerol monooleate), fatty phosphites, fatty acid amides, fatty epoxides, borated fatty epoxides, alkoxylated fatty amines, borated alkoxylated fatty amines, metal salts of fatty acids, fatty imidazolines, condensation products of carboxylic acids and polyalkylene-polyamines, amine salts of alkylphosphoric acids.
Additional performance additives such as corrosion inhibitors include octylamine octanoate, condensation products of dodecenyl succinic acid or anhydride and a fatty acid such as oleic acid with a polyamine; foam inhibitors including copolymers of ethyl acrylate and 2-ethylhexylacrylate and optionally vinyl acetate; demulsifiers including polyethylene glycols, polyethylene oxides, polypropylene oxides and (ethylene oxide-propylene oxide) polymers; pour point depressants including esters of maleic anhydride-styrene, polymethacrylates, polyacrylates or polyacrylamides; and seal swell agents including Exxon Necton-37™ (FN 1380) and Exxon Mineral Seal Oil (FN 3200); may also be used in the lubricating composition of the invention.
The invention is useful for lubricating a transmission, a driveshaft (transaxle), a gear, an axle or mixtures thereof. In several embodiments the lubricating composition is a transmission oil, a driveshaft oil, a gear oil, an axle oil or mixtures thereof.
In one embodiment the invention is capable of providing a lubricating composition and a method of lubricating a transmission, a gear, a transaxle, and/or an axle; and capable of providing at least one of acceptable protection against wear, scuffing and micropitting, whilst providing acceptable hose and/or seal compatability, oxidation stability and cleanliness.
In one embodiment the transmission is manual and in another embodiment the transmission is automatic. In one embodiment the manual transmission in non-synchronised. As used herein the term “non-synchronised” relates to a transmission that does not contain a synchroniser (or synchromesh).
When a transmission does not contain a synchroniser, the lubricating composition further comprises at least one of a dispersant and/or a dispersant viscosity modifier. In one embodiment both a dispersant and/or a dispersant viscosity modifier are present.
The following examples provide an illustration of the invention. These examples are non exhaustive and are not intended to limit the scope of the invention.
A lubricating composition is prepared by blending into an oil of lubricating viscosity about 1.3 wt % of a oil soluble phosphorus amine salt; about 1.5 wt % of a detergent package containing a phenate and a sulphonate detergent; about 0.004 wt % of at least one metal deactivator; about 20 wt % of a dispersant viscosity modifier; and about 0.8 wt % of a dispersant. The lubricating composition has a Kinematic Viscosity (at 100° C. as determined by ASTM method D2270) of about 18 mm2/s (or cSt); and a Viscosity at 40° C. (as determined by D2270) of 130.5 mm2/s.
Reference Example 1 is a commercially available manual transmission fluid.
Test 1: Scuffing Test
A FZG scuffing test is carried out on the lubricating composition of Example 1. The FZG scuffing test is carried out using “A” type gears, with diameter of about 10 mm, at a speed of about 16.6 in reverse and at about 120° C. (test also referred to as A10/16.6R/120 test). Acceptable results are obtained for samples with a pass at load stage 7 or higher. The result obtained is a pass at load stage 9. Therefore the lubricating composition of Example 1 passes the scuffing test.
Test 2: Pitting Test
A FZG pitting text is carried out employing C-type gears, at load 9 and at about 120° C. (also referred to as C/9/120 conditions) for over about 64 hours. The results obtained for pitting are rated from 0 to 2 for the pinion and wheel. Generally the lower the number indicates less micropitting with rating 0 equivalent to less than about 10% of surface micropitted; a rating of 1 is equivalent to about 10 to about 30% of the surface being micropitted and 3 has greater than about 30% of the surface micropitted. The results obtained indicate that Example 1 performs equal to and better than Reference Example 1. Therefore the lubricating composition of Example 1 passes the pitting test.
Test 3: Oxidative Stability
The oxidative stability test is carried out as described in ASTM method D5704, for a period of about 300 hours. Acceptable results are obtained for samples with a viscosity increase at 100° C. of less than 50%. Example 1 provided has a viscosity increase at 100° C. as determined by D5704 of 37.6%. Therefore the lubricating composition of Example 1 passes the oxidative stability test.
Test 4: Mack Cyclic Durability
The Mack Cyclic Durability test is carried out as described in ASTM D5579. Acceptable results are obtained for samples with a greater number of cycles than a reference sample. Reference Example 1 reached about 85,000 cycles before failure. Example 1 reached over 127,000 cycles before the test is stopped without failure. Therefore the lubricating composition of Example 1 passes the Mack Cyclic Durability test.
Test 5: Cooler Hose Compatability
The cooler hose compatability test is carried out using a chlorinated polypropylene hose and the procedure of SAE J 1019 (Title: “Tests and Procedures for High-Temperature Transmission Oil Hose, Engine Lubricating Oil Hose and Hose Assemblies”). Acceptable results are obtained for samples capable of reaching 750 hours without failure. The results indicate that Reference Example 1 fails before 750 hours. The lubricating composition of Example 1 passes as it reaches 750 hours.
Test 6: Cooler Hose Static Immersion
The Cooler Hose Static Immersion test is carried out as described in ASTM method D471. Acceptable results are obtained for a sample with a reported volume change from 0 to 65%. The results obtained for a triplicate test of Example 1 are 42.8, 41.7 and 41.7. Therefore, the lubricating composition of Example 1 passes the Cooler Hose Static Immersion test.
In summary the lubricating composition of the invention is capable of providing at least one of acceptable protection against wear, scuffing and micropitting, whilst providing acceptable hose and/or seal compatability, oxidation stability and cleanliness.