NL2027155B1 - Antiwear agent - Google Patents

Abstract

The invention relates to an oil additive package comprising partially neutralized primary amine salts of phosphate esters that provide solvability, satisfactory wear reducing-properties with 5 a positive effect on weld load and no detrimental impact on copper corrosion and allowing a variety of amines to be used. The invention also relates to lubricating oil formulations comprising such an additive package, the use of the specific partially neutralized amine salts of phosphate esters in the preparation of lubricating oil formulations and the partially neutralized amine salts of phosphate esters as such, which are suitable for use in making the 10 lubricating oil formulations. The partially neutralized primary amine salts of phosphate esters are obtainable by reacting one or more primary amines and one or more phosphate esters, whereby the molar ratio of P:N is from 1.2 to 3.6.

Description

ANTIWEAR AGENT Field of the invention The invention relates to antiwear agents for use in lubricating fluids. Typical antiwear agents are amine salts, sometimes referred to as soaps, of phosphate esters.

Background of the invention Present day lubricants typically comprise a base fluid (base oil} and various additives, including those that improve the wear reducing-, corrosion- and/or extreme pressure- properties of the lubricant. The concentration of active ingredients may vary, depending on the base oil used and the intended application of the lubricating oil. Very often they contain antiwear agents selected from amine salts, sometimes referred to as soaps, of phosphate esters. These phosphate esters are usually mixtures of various types of esters, including mono-esters and di-esters, of phosphoric acid which may contain some (alkoxylated) alcohol residue or residual acid, depending on the process conditions and work-up procedures used when making the esters. The amine used to make the phosphate ester salts can be selected from a wide range of amines. Both the phosphate ester and the amine is usually selected depending on the base oil used and the intended application of the lubricating oil.

It is noted that neutral fatty amine salts, meaning that the molar ratio to phosphate to amine in the salt is 1, are long known for use in lubricants as rust preventive, See for instance US 2,387,537.

Similarly, US 5,552,068 teaches the importance of using fully neutralized salts, but uses the salts of specific tertiary amines. Such salts were to found to be oil-soluble and hydrolytically stable. Furthermore tertiary amines are used to improve the copper corrosion properties of the lubricant, especially for lubricants with shorter chain (C12) alkyl phosphates. The amine salts can be formed in-situ in the lubricant by adding the phosphate ester and amine separately to the base-oil formulation. However, mostly the amine and phosphate ester are reacted before they are added to the base oil. The neutral amine salt so obtained can be added to the base oil or be used in an additive package.

US 5,750,478 discloses the use of not only tertiary, but also primary and secondary amine salts of phosphate C1-12 esters in combination with sulphurized fatty acid for use in turbo oils which are based on synthetic diesters and polyol ester base oils. The P:N ratio in these salts is smaller than 1, since the phosphate diesters in the mixture are neutralized with two moles of nitrogen per mole of phosphorus.

WO 2006/107441 discloses an additive package for use in lubricants wherein a partially neutralized salt of amine, again preferably a tertiary amine, and a mono- or di-alkyl phosphate (ester) is used in combination with a sulphur-containing extreme pressure (EP) component. The partially neutralized salts herein have a P:N weight ratio, which is said not to be critical, up to 2.5 with only a weight ratio of up to 1.5 actually being disclosed. It is noted that a weight ratio of P:N of 2.5 means a molar ratio of 1.12. The additive package may comprise further additives, such as in additive packages as disclosed in US 5,204,012 and US 6,034,040. The salts of the prior art were found still to lack sufficient antiwear properties, even when used in combination with the conventional extreme pressure additives. Also the use of the preferred tertiary amines of the prior art are undesired for economic and environmental reasons. For example, they are slower to react and the tertiary substitution may interfere in the formation of protective films of the lubricant.

Summary of the invention The present invention relates to an oil additive package comprising specific antiwear additives. More specifically, it was surprisingly found that specific partially neutralized primary amine salts of phosphate esters can be comprised in the additive package which provides not only excellent antiwear properties to the oil, also under extreme pressure conditions, while providing the desired corrosion protection and allowing a variety of simple amines to be used. The invention also relates to lubricating oil formulations comprising such an additive package, the use of the specific partially neutralized primary amine salts of phosphate esters in the preparation of lubricating oil formulations and the partially neutralized primary amine salts of phosphate esters as such, which are suitable for use in making the lubricating oil formulations.

The lubricating oil formulations of the present invention are based on conventional mineral base oils, although an amount of up to 50% by weight of a traditional ester oils as mentioned in US 5,750,478 may be present in the base oils. Detailed description of the invention The present invention relates to an oil additive package comprising specific antiwear additives. More specifically, the antiwear additive used in the additive package are partially neutralized primary amine salts of phosphate esters comprising a mixture of products of the formula |, Il, and III es WW jn ee 19 Ri CNH; R-0-P-0 NL R3 NL O-R (1) oo ff} ee ee 1 0) Ri CNH R--0-P-0 (ID) 0 4 OH R+ OP os (11) wherein each of Rt, R? and R? are, independent of each other, hydrogen, or a, optionally substituted, hydrocarbyl group, wherein the sum of the carbon atoms in Rt, R2, and R3 is from 9 to 150, wherein R* is a, optionally substituted, hydrocarbyl group with from 1 to 16 carbon atoms, wherein R5is hydrogen or a, optionally substituted, hydrocarbyl group with from 1 to 16 carbon atoms, and wherein the overall molar ratio of phosphorus of all phosphate ester to nitrogen of all amine is greater than 1.2 and smaller than 3.6. The hydrocarbyl groups of R* and R5 are suitably aliphatic, such as linear or branched alkyl or alkenyl, which may be substituted with hydroxy, amino and the like. Preferred hydrocarbyl groups are linear or branched alkyl, preferably branched alkyl. The molar ratio of phosphorus to nitrogen in the mixture is suitably greater than 1.3, 1.4, 1.5,

1.6, 1.8, 2.0, or 2.2 and smaller than 3.5, 3.4, 3.3, 3.2, or 3.1. In an embodiment it is not 2.5. Due to the fact that the phosphate esters are only partially neutralized with the amine, an exact composition cannot be given. The ratio between components of formulae II] is dependent of the amines and phosphate esters that are used, the ratio of these materials, as well as external factors that influence the equilibrium, such as pH. Typically, however, most (>50%w/w) of the phosphate ester will be present in the form of formulae | and II. In an embodiment the P will be present in products of formulae | and Il in an amount of 60, 70, 80, 85, or 90 % of all P of the phosphate esters. In an embodiment wherein pure phosphate di- esters are neutralized the amount of products of formula Il will be O and the composition will only contain products of formulae | and III.

It was found that this mixture, herein called partially neutralized primary amine salts of phosphate esters, not only provides excellent antiwear properties to the oil, also under extreme pressure conditions, but also provides the desired corrosion protection for materials in contact with the oil, while allowing a variety of amines, particularly the more economic primary amines, to be used.

The invention also relates to lubricating oil formulations comprising the partially neutralized primary amine salts of phosphate esters, for example by using such an additive package, the use of the partially neutralized primary amine salts of phosphate esters in the preparation of lubricating oil formulations, and the partially neutralized primary amine salts of phosphate esters as such, which are suitable for use in making the claimed lubricating oil formulations. The lubricating oil formulations of the present invention are based on conventional mineral base oils, although an amount of up to 50% by weight of a traditional ester oils as mentioned in US 5,750,478 may be present in the base oils.

The partially neutralized primary amine salts of phosphate esters of the invention are the reaction product of a mixture of phosphate mono- and di-esters of formula III with one or more amines of formula R'R2R3C-NH: , wherein Rt, R? and R® have the meaning as presented above. These phosphate esters are formed in a conventional way, except that the molar ratio of phosphate ester and amine is chosen such that the molar ratio of P to N is greater than 1.2 and smaller than 3.6.

The esters of phosphoric acid as used to prepare the partially neutralized salts of the invention suitably consist of a mixture of the monoester of phosphoric acid and diester of phosphoric acid. The molar ratio of monoacid to diacid phosphate in the commercial amine phosphates used in this invention ranges from 3:1 to 1:3. Mixed mono-/di-acid phosphate and just mono- or di-acid phosphate can be used. The diester of phosphoric acid may be represented by the above formula (Ill) wherein both R* and R5 are independently from each other a, optionally substituted, hydrocarbyl group containing from 1 to 16 carbon atoms. In an embodiment, R* and R° are not substituted. In an embodiment R* and R® are independently chosen from C+.8 hydrocarbyl.

In an embodiment R* and R?® are the same hydrocarbyl group.

The monoesters are in accordance with the same formula, except that R® is hydrogen.

Suitable phosphate esters for preparing the antiwear additive of the invention include butylphosphoric acid, isobutylphosphoric acid, amylphosphoric acid, hexylphosphoric acid, 5 heptylphosphoric acid, 2-ethylhexylphosphoric acid, octylphosphoric acid, nonylphosphoric acid, decylphosphoric acid, dodecylphosphoric acid, tridecylphosphoric acid, tetradecylphosphoric «acid, hexadecylphosphoric acid, octadecylphosphoric acid, oleylphosphoric acid, benzylphosphoric acid, cyclohexylphosphoric acid, p-tolylphosphoric acid, xylylphosphoric acid, and mixtures thereof.

As said, the phosphate esters are typically mixtures of mono- and di-esters of phosphoric acid.

They are of the conventional type and are commercially available from, for example, Nouryon, LEAPChem.

Kowa American, and AK Scientific.

As mentioned above, the antiwear additive is product of the controlled neutralization of the phosphoric acid ester with an amine.

The amine salts of the present invention can be prepared by reaction of the above-described phosphoric acid esters with at least one primary amine compound of which the hydrocarbyl residue can be of primary, secondary, or tertiary nature.

Suitably the amines are primary hydrocarbyl amines represented by the general formula IV: NH, RS (IV) wherein R® equates to the R'R?R3C- moiety presented above, and is a, optionally substituted, hydrocarbyl moiety containing up to 150 carbon atoms.

In an embodiment R® is an aliphatic group containing from 4 to 30 carbon atoms, preferably from 8 to 20 carbon atoms.

In an embodiment R® is an aliphatic moiety selected from alkyl, alkenyl and alkoxyalkyl groups.

The hydrocarbyl group may be saturated or unsaturated.

Suitably the amine is derived from a natural source, meaning that a mixture of amines of the formula IV is used.

It is noted that some amines, particularly commercial mines of technical quality, may comprise some secondary and tertiary amine components, typically as undesired products.

Also amine mixtures comprising up to 15, 10, or 5 percent by weight of each of these secondary and/or tertiary amines can be used.

Representative examples of primary saturated amines are those known as aliphatic primary fatty amines.

Primary amines in which the hydrocarbon chain comprises olefinic unsaturation are also suitable.

Therefore, R® may contain one or more olefinic unsaturation depending on the length of the chain.

Representative amines are dodecenylamine, myristoleylamine, palmitoleylamine, oleylamine and linoleylamine.

Commercial representatives of such amines are known as “Armeen ©” primary amines. Typical fatty amines include alkyl amines such as n-hexylamine, n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n- octadecylamine (stearyl amine), etc., which are commercially available. In an embodiment mixtures of the fatty amines are used, which are preferably from natural origin, such as Armeen-C, Armeen-O, Armeen OL, Armeen-T, Armeen-HT, Armeen-S and Armeen SD ex Nouryon. Also amines with a tertiary hydrocarbyl moiety can be used, for example those represented by the formula V: CH, R7 — C — NH, CH, (V) wherein R’ is a hydrocarbyl group containing from one to 30 carbon atoms. Examples of such amines useful for this invention are tertiary-butyl amine, tertiary-hexyl primary amine, 1- methyl-1-amino-cyclohexane, tertiary-octyl primary amine, tertiary-decyl primary amine, tertiary-dodecyl primary amine, tertiary-tetradecyl primary amine, tertiary-hexadecyl primary amine, tertiary-octadecyl primary amine, tertiary-tetracosanyl primary amine, tertiary- octacosanyl primary amine. Mixtures of these amines are also useful for the purposes of this invention, and can be exemplified by the commercially available “Primene®© JM-T” ex Dow, which is a mixture of Cs-Cz2 tertiary alkyl primary amines.

A lubricating oil containing amine phosphate salts of the formula (I) and {II} can be used in essentially any application where wear protection, extreme pressure activity and/or friction reduction is required. Thus, as used herein, "lubricating oil" (or "lubricating oil composition") is meant to include aviation lubricants, automotive lubricating oils, industrial oils, gear oils, transmission oils, and the like. The amine phosphate salts of this invention are particularly useful in automotive oils, industrial oils, and hydraulic oils. The amine phosphates are used in an amount by weight in the range of from 50, 100, 150, or 200 parts per million by weight (ppm), up to 4 %w/w, 2 %wiw, 1%w/w, or 5000 ppm, based on the weight of the final formulated oil.

The base lubricant oil in which the partially neutralized amines of the invention are used are suitably selected from natural and synthetic oils.

The lubricating oil may be derived from unrefined, refined, re-refined oils, or mixtures thereof.

Unrefined oils are obtained directly from a natural source or synthetic source (e.g., coal, shale, or tar sands bitumen) without further purification or treatment.

Examples of unrefined oils include a shale oil obtained directly from a retorting operation, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process, each of which is then used without further treatment.

Refined oils are similar to the unrefined oils except that refined oils have been treated in one or more purification steps to improve one or more properties.

Suitable purification techniques include distillation, hydrotreating, dewaxing, solvent extraction, acid or base extraction, filtration, and percolation, all of which are known to those skilled in the art.

Re-refined oils are obtained by treating used oils in processes similar to those used to obtain the refined oils.

These re-refined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques for removal of spent additives and oil breakdown products.

Suitable base lubricant oils may fall into any of the well-known American Petroleum Institute (API) categories of Group | through Group V.

The API defines Group | stocks as solvent- refined mineral oils.

Group | stocks contain the least saturates and sulphur and have the lowest viscosity indices.

Group | defines the bottom tier of lubricant performance.

Group II and lll stocks are high viscosity index and very high viscosity index base stocks, respectively.

The Group III oils contain fewer unsaturated species and sulphur than the Group Il oils.

With regard to certain characteristics, both Group II and Group lll oils perform better than Group | oils, particularly in the area of thermal and oxidative stability.

Group IV stocks consist of polyalphaolefins (PAOs), which are produced via the catalytic oligomerization of linear alphaolefins (LAOS), particularly LAOs selected from Cs-C+4 alpha-olefins, preferably from 1- hexene to 1-tetradecene, more preferably from 1-octene to 1-dodecene, and mixtures thereof, with 1-decene being the preferred material, although oligomers of lower olefins such as ethylene and propylene, oligomers of ethylene/butene-1 and isobutylene/butene-1, and oligomers of ethylene with other higher olefins, as described in U.S.

Patent 4,956,122 and the patents referred to therein, and the like may also be used.

PAOs offer superior volatility, thermal stability, and pour point characteristics to those base oils in Group I, Il, and Ill.

Group V includes all the other base stocks not included in Groups | through IV.

Group V base stocks includes the important group of lubricants based on or derived from esters.

It also includes alkylated aromatics, polyinternal olefins (POs), polyalkylene glycols (PAGS), etc.

One of the great benefits of the present invention is that it is applicable to base oils fitting into any of the above five categories, API Groups | to V, as well as other materials, such as described below.

As used herein, whenever the terminology "Group ..." (followed by one or more of Roman Numerals | through V) is used, it refers to the API classification scheme set forth above.

It will be recognized that commercially-available hydrocarbon fluids also typically contain small amounts of heteroatom-containing species (e.g., oxygen, sulphur, nitrogen, and the like), typically on the order of less than 1 %w/w, preferably less than 100 ppm.

Suitable natural lubricating oils include animal oils, vegetable oils (e.g., castor oil and lard oil}, petroleum oils, mineral oils, and oils derived from coal or shale.

Suitable synthetic oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins which may be hydrogenated or non-hydrogenated (e.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes), etc., and mixtures thereof); alkylbenzenes (e.g., dodecylbenzenes, etc.); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls, etc); alkylated diphenyl ethers, alkylated diphenyl sulphides, as well as their derivatives, analogues, and homologs thereof; and the like.

The synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers and derivatives thereof wherein the terminal hydroxyl groups have been modified by esterification, etherification, etc.

This class of synthetic oils is exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide; the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g. methyl-polyisopropylene glycol ether having an average molecular weight of 1000, diphenyl ether of polyethylene glycol having a molecular weight of 500-1000, diethyl ether of polypropylene glycol having a molecular weight of 1000- 1500); and mono- and polycarboxylic esters thereof (e.g., the acetic acid esters, mixed C: - Cs fatty acid esters, and C13 oxo acid diester of tetraethylene glycol). Other synthetic lubricating oils include liquid esters of phosphorus-containing acids (e.g. tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid), polymeric tetrahydrofurans, polyalphaolefins, and the like as well as esters of dicarboxylic acids (e.g. phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc.). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid, and the like. Esters useful as synthetic oils also include those made from linear or branched Cs to C42 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, pentaerythritol monoethylether, and the like. This class of synthetic oils is particularly useful as aviation turbine oils. The ester base oils are less preferred for use in accordance with the invention. It is considered that the ester moiety is susceptible to the acidic nature of the partially neutralized phosphate ester salt, with the risk of undesired hydrolysis. If such oils are present in the base lubricating oil then it is considered that they should be present in an amount less than 50, 35, 25, 15, or 12.5 percent by weight (%w/w) of the final lubricating oil composition. The additive package for the base lubricating oils in accordance with the invention comprises the partially neutralized amine salt of phosphate esters and at least one other regular additive for the base oil. Such additives include conventional additives selected from the group consisting of dispersants, fluidizing agents, friction modifiers, corrosion inhibitors, rust inhibitors, antioxidants, detergents, seal swell agents, extreme pressure additives, other antiwear additives, pour point depressants, lubricity agents, viscosity index improvers, deodorizers, defoamers, also known as foam inhibitors, demulsifiers, dyes and, optionally fluorescent, colouring agents. The additive package is suitably used in an amount of from 0.1,

0.2, 0.3, 0.5, 1, or 2, up to 25, 20, 15, or 12.5 weight percent, based on the total weight of the lubricating oil composition. For example, suitable dispersants useful in the present invention comprise oil-soluble ashless dispersants having a basic nitrogen and/or at least one hydroxyl group in the molecule. Suitable dispersants include alkenyl succinimides, alkenyl succinic acid esters, alkenyl succinic ester-amides, Mannich bases, hydrocarbyl polyamines, or polymeric polyamines. Suitable corrosion inhibitors include, but are not limited to, various triazols, e.g., tolyl triazol, 1,2,4-benzene triazol, 1,2,3-benzene triazol, carboxy benzotriazole, alkylated benzotriazol and organic diacids, e.g., sebacic acid. The corrosion inhibitors are typically used in an amount in the range 0.02 to 0.5 %w/w, preferably 0.05 to 0.25 %w/w, based on the weight of the base lubricating oil. Suitable fluidizing agents may be used in the present invention. Suitable fluidizing agents include oil-soluble diesters. The preferred diesters include the adipates, azelates, and sebacates of Cs -C13 alkanols (or mixtures thereof), and the phthalates of C4 -C+3 alkanols (or mixtures thereof). Mixtures of two or more different types of diesters (e.g., dialkyl adipates and dialkyl azelates, etc.) can also be used. Examples of such materials include the n-octyl, 2-ethylhexyl, isodecyl, and tridecyl diesters of adipic acid, azelaic acid, and sebacic acid, and the n-butyl, isobutyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and tridecyl diesters of phthalic acid. However, if hydrolytic stability of these esters is too low in the final oil formulation, then other fluidizing agents are preferred. Suitable friction modifiers include such compounds as aliphatic amines or ethoxylated aliphatic amines, aliphatic fatty acid amides, aliphatic carboxylic acids, aliphatic carboxylic esters, aliphatic carboxylic ester-amides, aliphatic phosphonates, aliphatic phosphates, aliphatic thiophosphonates, aliphatic thiophosphates, or mixtures thereof. Preferably they are chosen such that they do not react with the partially neutralized amine salt of phosphate esters. The aliphatic group of the friction modifier typically contains at least eight carbon atoms so as to render the compound suitably oil soluble. Also suitable are aliphatic substituted succinimides formed by reacting one or more aliphatic succinic acids or anhydrides with ammonia. One preferred group of friction modifiers is comprised of the N- aliphatic hydrocarbyl-substituted diethanol amines in which the N-aliphatic hydrocarbyl- substituent is at least one straight chain aliphatic hydrocarbyl group free of acetylenic unsaturation and having in the range of 14 to 20 carbon atoms. Antioxidants may also be present in the lubricant formulations of the present invention. Suitable antioxidants include phenolic antioxidants, aromatic amine antioxidants, sulphurized phenolic antioxidants, and organic phosphites, among others. Examples of phenolic antioxidants include 2,6-di-tert- butylphenol, liquid mixtures of tertiary butylated phenols, 2,6-di-tert-butyl-4-methylphenol,

4.4'-methylenebis(2,6-di-tert-butylphenol}, 2,2'-methylenebis{4-methyl-6-tert-butylphenol), mixed methylene-bridged polyalkyl phenols, and 4,4'-thiobis{2-methyl-8-tert-butylphenol). N,N'-di-sec-butyl-p-phenylenediamine, 4-isopropylaminodiphenyl amine, phenyl-naphthyl amine, and ring-alkylated diphenylamines serve as examples of aromatic amine antioxidants. Most preferred are the sterically hindered tertiary butylated phenols, the ring alkylated diphenylamines and combinations thereof. All of these further additive package components are well known to the person skilled in the art and are preferably used in conventional amounts. Preparation of partially neutralized amine salts of phosphate esters The amine phosphate can be prepared by controlled neutralization of the above-described acid phosphate with amine. The neutralization reaction of the acid phosphate with the amine can be controlled as described in US 5,552,068. Excessive neutralization adversely affects the load carrying properties and oxidation stability. Therefore in an embodiment the amine is added to the phosphate ester (neat or in a suitable diluent, such as lubricating oil).

One preferred method of forming these amine salts involves a process which comprises: (i) introducing at a suitable amount of the phosphoric acid ester, (ii) introducing the amine, at a rate such that the temperature does not exceed 70 °C, while agitating the mixture so formed. The exothermic reaction between the two components is preferably controlled by keeping the temperature of the reaction mixture in the range from 30 °C to 70 °C, and preferably from 50 °C to 70 °C, followed by cooling. Reaction rates are controlled by cooling the reaction mixture and/or by controlling the addition rate of the reactants, as is conventional. If so desired additional phosphate ester can be added in step (ii).

At various places throughout this specification, reference has been made to U.S. Patents. All such cited documents are expressly incorporated in full into this disclosure as if fully set forth herein. Embodiments may be listed separately, however they are to be read and understood such that they can be combined as appropriate. Where ranges are presented such ranges disclose any subrange running from any of the mentioned lower limits to any of the mentioned upper limits. Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. As used throughout the specification and claims, "a" and/or "an" may refer to one or more than one. Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, percent, ratio, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least each numerical parameter should at construed in the light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. The term “comprising” is used to indicate that the comprised elements are included but that other element are not excluded, so a list of comprised elements may contain further elements.

Unless non-sensible, the word “containing” is to be interpreted the same way as the word “comprising”.

This invention will now be illustrated with reference to the following examples.

Examples The following examples are offered to specifically illustrate this invention.

These examples and illustration are not to be construed in any way limiting the scope of this invention.

Testing protocols The extreme pressure antiwear properties of the various oil formulations prepared were measured by means of the well-known and widely accepted Four-Ball Wear Test Machine.

A preliminary evaluation of the antiwear properties of fluid lubricants in sliding contact was performed using ASTM D4172-18 and a modified ASTM D2266-01 method.

Three 12,7 mm diameter steel balls are clamped together and covered with the lubricant to be evaluated.

A fourth 12,7 mm diameter steel ball, referred as the top ball, is pressed with a force of 40 kgf into the cavity formed by the three clamped balls for three-point contact.

In the ASTM D4172- 18 the temperature of the test lubricant is regulated at 75 °C and the top ball is rotated at 1200 rpm for 60 minutes.

Lubricants are compared by using the average size of the scar diameters worn on the three lower clamped balls.

In the modified ASTM D2266-01, the pressing force of the top ball is 20 kgf, the temperature of the test lubricant is controlled at 55 °C and the top ball is rotated at 1800 rpm for 60 minutes.

The weld-point of lubricating oils was determined by means of the four-ball extreme pressure (EP) tester following the ASTM D2783-03 method.

In this procedure, the tester is operated with one steel ball under load rotating against three steel balls held stationary in the form of cradle.

Test lubricant covers the lower three balls.

The rotating speed is 1760 rpm at a temperature between 19 and 35 °C during a series of 10-s duration tests at increasing loads until fusion of metal between the metal balls is sufficient to weld the four balls together (weld- point). Similarly, the compliance with the specification requirements for copper corrosion of the present invention was evaluated according to the method ASTM D130-18, to evaluate the suitability of a lubricant for use in copper-containing equipment.

According to ASTM D130- 18, a polished copper strip is immersed in a specific volume of the sample being tested and heated under conditions of temperature and time specified to the class of material being tested.

At the end of the heating period, the copper strip is removed, washed and the colour and tarnish level assessed against the ASTM Copper Strip Corrosion Standard.

Using ASTM D130-18, copper corrosion is measured on a scale of 1 to 4, wherein a result of 1 represents slight tarnish and a result of 4 represents copper corrosion.

Example 1 1710 mmoles (mmol) of n-Hexyl acid phosphate were added to a glass lined vessel. 580 mmol of C1s-C+8 amine from the list described above, were pre-heated at 50 °C and added slowly with stirring. The molar ratio of P:N is 2.95. The reaction was exothermic and the temperature was controlled to be kept below 70 °C. Blending with stirring was continued for at least 30 minutes, and the reaction mixture allowed to cool. The resulting product was a yellow bright and clear liquid which had a pH of 3.60. The pH was measured in a mixture of demi-water and isopropanol in a weight ratio of 1:3.

Example 2 In this example n-hexyl acid phosphate from another supplier was used for the synthesis of the component described in Example 1. Following the same protocol as in Example 1, same amounts of reactants were used for the synthesis process. The obtained fluid was a yellow liquid which had a pH of 3.54 when measured as mentioned in Example 1. Example 3 In the following example, the reaction product was again synthesized following the protocol as described in Example 1, with the exception of using 660 mmol of amine and 1620 mmol of acid phosphate. The molar P:N ratio is 2.45. The reaction mixture obtained by this production method was a bright and clear liquid with a pH of 3.91 when measured as mentioned in Example 1. Example 4 Lubrication test fluids were prepared containing additive compositions prepared using the methods described in Examples 1, 2 and 3. The composition from Examples 1, 2 and 3, was added to an additive package suitable for use in formulated gear oil. The additive package obtained was an amber yellow oily homogeneous clear and bright liquid. The analytical data are: Phosphorus 0.47 0.54 0.64 |

Example 5 The additive package described in Example 4 above was blended into mineral oil-based fluids as given in the table below to give an industrial gear oil ISO VG 220. The blends were subjected to a series of standard tests as given in the Table below.

Tw TW [ee] ee 1h, 20 kg, 1800 rpm, 75 | ASTM mm 0,34 0,32 0,28 ee en 4 ball weld load ASTM kgf 250 220 220 A = a Cwercore | _ 3h, 100 °C ASTM 1b 1b 1b

RA A A It follows from the above results that the preparations of the examples give good wear reducing-properties with a positive effect on weld load and no detrimental impact on copper corrosion.

Example 6 Additive packages described in Example 4 above were blended into base fluids as given in the following table to give a multigrade automotive transmission oil 80W90. The blends were subjected to a series of standard tests as given in the Table.

ae Jem] ee 1h, 20 kg, 1200 | ASTM D4172 mm 0,43 0,42 mas © a ee TT

The salts of Example 1 and 2 gave analogous wear reducing-properties and no detrimental impact on copper corrosion. Example 2 gave a slightly better weld load, albeit the chemistry was the same.

Compared to products of the prior art with a lower P:N ratio, the present invention provided gear oil with an improved weld load and wear scar diameter performance. Also, the finished lubricants blended with the component synthesized in the present invention have been found to provide improved solvability, satisfactory wear reducing-properties with an unexpected good effect on weld load and no detrimental impact on copper corrosion. Further partially neutralized salts of phosphate esters could be prepared and used which are more economic and have a better ecological footprint then conventional antiwear additives.

Claims (14)

AMENDED CONCLUSIONS (clean) A lubricating oil additive package comprising one or more partially neutralized primary amine salts of phosphate esters, obtainable by reaction of one or more primary amines and one or more phosphate esters, containing a mixture of products of the formulas |, II and III je LH 6 / R2 yf 0 \ | | | JD | Ri CNH, R 0 P 0 | | | SR J O-R® (1) on ml} ww 204 { R? yi 0 3 Ri CNH R°-0-P-0 1 a i . O i (ID O 'OH ROP < ~Q-RS (113, wherein each of Rt, R2 and R3 are, independently of each other, hydrogen or an optionally substituted hydrocarbyl group, wherein the sum of the carbon atoms in Rt, R2 and R3 from 9 to 150, wherein R* is an optionally substituted hydrocarbyl group of 1 to 16 carbon atoms, wherein R® is hydrogen or an optionally substituted, hydrocarbyl group of 1 to 16 carbon atoms, and wherein the total molar ratio of phosphorus of all phosphate esters until nitrogen of the amine is greater than 1.2 and less than 3.8, and at least one other conventional oil additive, wherein R* and R5 are branched alkyl or alkenyl. The lubricating oil additive package of claim 1, wherein the hydrocarbyl groups of R* and R® are aliphatic groups which can be substituted with hydroxy and amino groups. The lubricating oil additive package of claim 2, wherein R* and R® are branched alkyl. The lubricating oil additive package of claim 1, wherein the phosphate ester used to prepare the partially neutralized salts is selected from butylphosphoric acid, isobutylphosphoric acid, amylphosphoric acid, hexylphosphoric acid, heptylphosphoric acid, 2-ethylhexylphosphoric acid, octylphosphoric acid, nonylphosphoric acid, decylphosphoric acid, dodecylphosphoric acid, triphosphoric acid, hexadecylphosphoric acid, octadecylphosphoric acid, oleylphosphoric acid, benzylphosphoric acid, cyclohexylphosphoric acid, p-tolylphosphoric acid, xylylphosphoric acid, and mixtures thereof. The lubricating oil additive package of claim 4, wherein the phosphate ester is a mixture of mono- and diesters or a diester alone. A lubricating oil additive package according to any preceding claim, wherein the amines used to prepare the phosphate salts are primary hydrocarbylamines represented by the general formula IV, NH, -R 6 (IV) wherein R® is an optionally substituted, hydrocarbyl group containing up to 150 carbon atoms, preferably an optionally substituted aliphatic group containing 4 to 30 carbon atoms, preferably 8 to 20 carbon atoms. The lubricating oil additive package of claim 6, wherein R® is an aliphatic group selected from alkyl, alkenyl and alkoxyalkyl groups. The lubricating oil additive package of claim 6 or 7, wherein the amine is derived from a natural source. The lubricating oil additive package of claim 6, 7 or 8, wherein the amine is selected from dodecenylamine, myristoleylamine, palmitoleylamine, oleylamine, linoleylamine, n-hexylamine, n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n -pentadecylamine, n-hexadecylamine, n-octadecylamine, tertiary-butylamine, tertiary-hexylamine, 1-methyl-1-amino-cyclohexane, tertiary-octylamine, tertiary-decylamine, tertiary-dodecylamine, tertiary-tetradecylamine, tertiary-tetradecylamine, tertiary-tetradecylamine, tertiary-hexadecylamine -octadecylamine, tertiary-tetracosanylamine, tertiary-octacosanyl primary amine, and mixtures thereof. The lubricating oil additive package of any preceding claim wherein the phosphorus to nitrogen molar ratio of the amine is greater than 1.3, 1.4, 1.5, 1.8, 1.8, 2.0 or 2.2 and less than 3.5, 3.4, 3.3, 3.2, or 3.1. A lubricating oil containing an additive package according to any preceding claim. The lubricating oil of claim 11, wherein a lubricating base oil is used which is selected from natural and synthetic oils, which are unrefined, refined or re-refined oils, and mixtures thereof. A partially neutralized primary amine salts of phosphate esters comprising a mixture of products of formulas I, II and III as presented in claim 1, suitable for use in a lubricating oil formulation. Use of partially neutralized primary amine salts of phosphate esters, which are a mixture of products of formulas I, II and III as presented in claim 1, in the process of making a lubricating oil additive package or in making a lubricating oil.