EP2118245A2

EP2118245A2 - Multiple metal corrosion inhibitor

Info

Publication number: EP2118245A2
Application number: EP08708255A
Authority: EP
Inventors: David Eliezer Chasan; Marc Ribeaud
Original assignee: Ciba Holding AG
Current assignee: BASF Schweiz AG
Priority date: 2007-02-07
Filing date: 2008-01-28
Publication date: 2009-11-18
Also published as: CN101600784A; WO2008095805A3; US20100173808A1; US20080200357A1; KR20090109086A; CA2673613A1; WO2008095805A2; JP2010518205A

Abstract

Subject matter of the present invention is a lubricant composition comprising a) A lubricant; b) A triazole metal deactivator; c) A borate ester; and, optionally, d) An amine phosphate. The invention allows for the formulation of engine lubricants that can protect copper, lead, iron and zinc from corrosion for the life of the lubricant.

Description

Multiple metal corrosion inhibitor

The present invention is aimed at controlling the corrosion of lead, copper, iron and zinc in lubricants. Lubricants are for example low ash, low phosphorus engine oils (engine fluids) or industrial oils. The protection of metal parts of ignition engines has been provided by a combination of neutral to over-based detergents together with zinc dithiophosphate (ZnDTP).

Exhaust gas after treatment systems for vehicles are now required in order to comply with Clean Air Legislation, in particular new Japanese or European legislation. The efficiency of these systems can be impaired by lubricant ash which originates from metal, sulphur and phosphorus containing additives. Therefore, the amount of ash containing detergents and phosphorus and ash containing ZnDTP has been reduced in recently formulated oils in order to comply with current and impending specifications. This can result in diminished corrosion protection of metal parts in the engine.

U.S.Pat.Spec. No. 4, 734,209 discloses copper passivators for functional fluids. U.S.Pat. Spec. Nos. 5, 171, 463 and 5,032,300 teach benzotriazole based copper passivators. U.S. Pat.Spec. No. 6,410,490 teaches benzotriazole additives for lubricants.

U.S. Pat.Spec. Nos. 6,008, 165 and 6,010,986 teach borates as a means to control lead corrosion.

Surprisingly, it has been found that a combination of a certain metal deactivator, a borate ester and optionally an amine phosphate, when added to a lubricant, will maintain a high level of protection of bearings and other parts of an engine.

The invention allows for the formulation of engine lubricants that can protect copper, lead, iron and zinc from corrosion for the life of the lubricant. Overbased detergents are known to those skilled in the art and are for example phenates, sulphonates or salicylates. ZnDTP and detergent content are controlled by SAPS restrictions (sulphated ash, phosphorus and sulphur). ZnDTP content is controlled mainly by the maximum limits set on the %-P content in various engine oil specifications. ILSAC and API have stepped down the P content for passenger car oils as follows: Max %-P allowed

ILSAC GF-1/API SH (1992) 0.12

ILSAC GF-2 and 3/API SJ and SL (1996- 2001 ) 0.10

ILSAC GF-4/API SM (2004) 0.08 The next category, GF-5 (scheduled for 2009) requires the P-level by using a catalytic converter poisoning test. If no test is available, the P limit will go down further to either 0.06 or 0.05% P max.

In Europe, ACEA 2004 specifications for gasoline and diesel engines with after-treatment devices also required reductions in phosphorus content. %-P allowed

C1 < 0.05

C2 0.070-0.090

C3 0.070-0.090

The new ACEA E6 heavy duty diesel engine specification has a 0.08% max. limit for phos- phorus. Total ash limits are also to be lowered. This will impact detergent and ZnDTP content.

Sulphur limits are also part of the equation as they limit the contribution that can come from ZnDTP and sulphonate detergents (also sulphurized phenate detergents).

Reduction of these materials leads to a reduction in ability to protect the lubricant against copper and lead corrosion in engines. Further, fuel economy requirements necessitate increased use of friction modifiers such as glycerol monooleate and certain molybdenum compounds. These materials may be corrosive towards either copper or lead or both. U.S.Pat. Spec. No. 2,898,299 teaches the aggressiveness of glycerol monooleate towards copper- lead bearing alloys. U.S. Pat. Spec. No. 5,631,213, EP-A-1 ,382,659 and DJ. Jayne, J. R. Shanklin, and CF. Stachew, "Controlling the Corrosion of Copper Alloys in Engine Oil

Formulations: Antiwear, Friction Modifier, Dispersant Synergy", SAE Paper 2002-01-2767, teach the corrosiveness of certain molybdenum compounds towards copper and copper alloys. Additionally, certain industrial oils are aggressive to zinc.

Subject matter of the present invention is a lubricant composition comprising a) A lubricant; b) A triazole metal deactivator; c) A borate ester; and, optionally, d) An amine phosphate.

The components b), c) and d) present in the lubricant composition of the invention are as specified below. An additional subject matter of the present invention is a method for controlling the corrosion of lead, copper, iron and zinc in a lubricant, which method comprises incorporating into a lubricant b) A triazole metal deactivator; c) A borate ester; and, optionally, d) An amine phosphate.

The engine oils of this invention utilize either natural, e.g. vegetable oil, mineral or synthetic base fluids. Most commonly, API Group I, Il and III, mineral and synthetic oils, Group IV, poly-α-olefins, Group V, e.g. esters, are utilized. Synthetic oils may also be derived from Fischer-Tropsch gas-to-liquid synthetic procedures. These products may often be hydroiso- merized. Mixtures of two or more of the above base fluids may be used. The finished fluids are used, for example, in internal combustion engines, for example motor vehicles fitted for example with engines of the Otto, Diesel, two-stroke Wankel or orbital type.

The present engine oils contain for example less than about 1.1 % by weight ash. For example, the present engine oils contain less than about 0.9% by weight ash or less than about 0.8% by weight ash. The present engine oils contain less than about 0.1 % by weight phosphorus. For example, the present engine oils contain less than about 0.08, less than about 0.07 or less than about 0.06% by weight phosphorus. The present engine oils have, for example, less than about 0.5% by weight sulphur, for instance less than about 0.4% by weight sulphur. Ash is determined by the sulphated ashing technique, ASTM D 874.

Industrial lubricants are for example polyalkylene glycols and are employed for example in windmills.

The present triazole metal deactivators are of the 1 ,2,4-triazole class or the benzotriazole class. Metal deactivators of the 1 ,2,4-triazole class are disclosed for example in U.S. Pat. Spec. No. 4,734,209.

The 1 ,2,4-triazole metal deactivators are for example of the formula wherein

Ri and R₂ are the same or different and are Ci-C₂oalkyl, C₃-C₂oalkenyl, C₅-Ci₂cycloalkyl, C₇- Ci₃aralkyl or C₆-Cioaryl, or R₁ and R₂, together with the nitrogen atom to which they are each attached may form a 5-, 6- or 7-membered heterocylic ring, or R₁ and R₂ are a group of the partial formula

R₃XK-R₄-PU-R₄)- wherein X is O, S or N, R₃ is hydrogen or CrC₂₀alkyl, R₄ is CrC₁₂alkylene, n is 0 or an integer from 1 to 6, or one of R₁ and R₂ is a group of the partial formula

or R₂ is a group of the partial formula (II) and R₁ is a group of the partial formula

-[R₄]_n-N(R₅)-A-[N(R₅)₂]_m wherein m is 0 or 1 and, when m is zero, A is a group of formula (ll)and, when m is 1 , A is alkylene or C₆-C₁₀ arylene and R₅ is a group of formula (II). R₄ is, for example, a CrC₆alkylene group, for instance a C₂-C₃alkylene. The index n is, for instance, 0, 1 , 2, 3, 4, 5 or 6.

Specific compounds of the formula (I) include:

1 -(or 4)-(dimethylarninomethyl)triazole, 1 -(or 4)-(diethylaminomethyl)triazole, 1 -(or 4)-(di-iso- propylaminomethyl)triazole, 1 -(or 4)-(di-n-butylaminomethyl)triazole, 1 -(or 4)-(di-n-hexylami- nomethyl)triazole, 1-(or 4)-(di-isooctylaminomethyl)triazole, 1-(or 4)-(di-(2-ethylhexyl)ami- nomethyl)triazole, 1 -(or 4)-(di-n-octylaminomethyl)triazole, 1 -(or 4)-(di-n-decylamino- methyl)triazole, 1 -(or 4)-(di-n-dodecylaminomethyl)triazole, 1 -(or 4)-(di-n-octadecylaminome- thyl)triazole, 1-(or 4)-(di-n-eicosylaminomethyl)triazole, 1-(or 4)-[di-(prop-2'-enyl)amino- methyl]triazole, 1-(or 4)-[di-(but-2'-enyl)aminomethyl] triazole, 1-(or 4)-[di-(eicos-2'-enyl)ami- nomethyl] triazole, 1-(or 4)-(di-cyclohexylaminomethyl)triazole, 1-(or 4)-(di-benzylaminome- thyl)triazole, 1 -(or 4)-(di-phenylaminomethyl)triazole, 1 -(or 4)-(4'-morpholinomethyl)triazole, 1 -(or 4)-(1 '-pyrrolidinomethyl)triazole, 1 -(or 4)-(1 '-piperidinomethyl)triazole, 1 -(or 4)-(1 '-perhy- droazepinomethyl)triazole, 1-(or 4)-(2',2"-dihydroxyethyl)aminomethyl] triazole, 1-(or 4)- (dibutoxypropyl-aminomethyl)triazole, 1 -(or 4)-(dibutylthiopropyl-aminomethyl)triazole, 1 -(or 4)-(di-butylaminopropyl-aminomethyl)triazole, N,N-bis-(1- or 4-triazolylmethyl)laurylamine, N,N-bis-(1- or 4-triazolylmethyl)oleylamine, N,N-bis-(1- or 4-triazolylmethyl)ethanolamine and N,N,N',N'-tetra(1- or 4-triazolylmethyl)ethylene diamine.

A preferred embodiment relates to lubricant composition, wherein the 1 ,2,4-triazole (I) is selected from the group consisting of 1-(di-isooctylaminomethyl)-1 ,2,4-triazole and 1-(di-(2- ethylhexyl)aminomethyl)-1 ,2,4-triazole. The benzotriazole metal deactivators are for example those disclosed in U.S. Pat. Spec. Nos. 5,032,300 and 5, 171,463.

The benzotriazole metal deactivators are for example of the formula

wherein R₆ is Ci-Ci₂alkyl,

R₇ is Ci-Ci₂alkyl, d-C^alkyl interrupted by one or more O atoms or is C₅-Ci₂cycloalkyl and R₈ and R₉ are hydrogen or methyl.

Specific examples of compounds of formula (III) include:

1 -(2-methoxyprop-2-yl)tolyltriazole,1 -(1 -methoxyethyl)tolyltriazole, 1 -(1 -methoxpropyl)tolyltri- azole, 1-(1-isobutoxybutyl)tolyltriazole, 1-(1-tert-butoxybutyl)tolyltriazole, 1-(1-hexyloxybu- tyl)tolyltriazole, 1 -(1 -octyloxybutyl)tolyltriazole, 1 -(1 -butoxy-2-methylpropyl)tolyltriazole, 1 -(1 - dodecyloxybutyl)tolyltriazole, 1 -(1 -isopropyloxyethyl)tolyltriazole, 1 -(1 -isopropyloxypropyl)- tolyltriazole, 1 -(1 -isopropyloxybutyl)tolyltriazole, 1 -(1 -cyclohexyloxypropyOtolyltriazole, 1 -(1 - cyclohexyloxyhepty^tolyltriazole, 1 -(1 -cyclohexyloxybutyl)tolyltriazole, 1 -[1 -(2-methoxyeth- oxy)butyl]tolyltriazole and 1 -[1 -(2-ethoxyethoxy)butyl]tolyltriazole.

A preferred embodiment relates to a lubricant composition, wherein the benzotriazole (III) is selected from the group consisting of 1-(2-methoxyprop-2-yl)tolyltriazole, 1-(1-cyclohexy- loxypropyl)tolyltriazole, 1-(1-cyclohexyloxyheptyl)tolyltriazole and 1-(1-cyclohexyloxybu- tyl)tolyltriazole.

(1 -(2-Methoxyprop-2-yl)tolyltriazole is 1-(1-

The benzotriazole metal deactivators are for example those as disclosed in U.S. Pat. Spec. No. 6,410,490.

The benzotriazole metal deactivators are for example of the formula

wherein

Rio is hydrogen or CrC₁₂alkyl, and

Rn and Ri₂ are the same or different and are Ci-C₂oalkyl, C₃-C₂oalkenyl, C₅-Ci₂cycloalkyl, C₇ Ci₃aralkyl or C₆-Cioaryl, or R₁₁ and R₁₂, together with the nitrogen atom to which they are each attached may form a 5-, 6- or 7-membered heterocylic ring, or R₁₁ and R₁₂ are a group of the partial formula R₃X[(-R₄-)O]_n(-R₄)- wherein X is O, S or N,

R₃ is hydrogen or Ci-C₂oalkyl, R₄ is Ci-Ci₂alkylene, n is 0 or an integer from 1 to 6, or one of Rn and Ri₂ is a group of the partial formula

or R₁₂ is a group of formula (ll)and Rn is a group of the partial formula -[R₄]_n-N(R₅)-A-[N(R₅)₂]_m wherein m is 0 or 1 and, when m is zero, A is a group of formula (II) and, when m is 1 , A is alkylene or C₆-Ci₀arylene and R₅ is a group of formula (II).

R₄ is, for example, a Ci-C₆alkylene group, for instance a C₂-C₃alkylene. The index n is, for instance, 0, 1 , 2, 3, 4, 5 or 6.

The benzotriazole metal deactivators of formula (IV) are prepared by known methods, such as reacting a benzotriazole with formaldehyde and an amine, as described for example in U.S. Pat. Spec. No. 4,701,273. Preferably, R_i0 is hydrogen or methyl.

A preferred embodiment relates to a lubricant composition, wherein the benzotriazole (IV) is 1 -[bis-(2-ethylhexyl)aminomethyl-4-methylbenzotriazole.

The triazole metal deactivator is present from about 0.01 to about 0.30 percent, based on the weight of the lubricant. For instance, the triazole is present from about 0.02 to about 0.2 or from about 0.03 to about 0.1 weight percent, based on the weight of the lubricant.

The borate ester compounds are for example those disclosed in U.S. Pat. Spec. Nos. 6,008, 165 and 6,010,986. The borate esters are, for example, of the formula (R₁₅O)₃B or wherein

R₁₅ is independently hydrogen, CrC₂oalkyl, C₃-C₂oalkenyl, C₅-C₁₂cycloalkyl, C₇-C₁₃aralkyl or C₆-C₁₀aryl, with the proviso that at least one R₁₅ group is not hydrogen. R₁₅ is, for example, a C₄-C₁₆ alkyl group. For instance, all three R₁₅ groups are alkyl groups.

A preferred embodiment relates to a lubricant composition, wherein the borate ester is selected from the group consisting of triethyl borate, tripropyl borate, triisopropyl borate, tributyl borate, tripentyl borate, trihexyl borate, tricyclohexyl borate, trioctyl borate, triisooctyl borate, tridecyl borate, tri(C₈-C₁₀alkyl)borate, tri(C₁₂-C₁₅alkyl)borate and oleyl borate. The borate ester is present from about 0.02 to about 1.0 percent by weight, based on the weight of the lubricant. For instance, the borate ester is present from about 0.03 to about 0.9, from about 0.04 to about 0.7, or from about 0.05 to about 0.5 percent by weight, based on the weight of the lubricant.

Alkyl is straight or branched chain and is, for example, methyl, ethyl, n-propyl, iso-propyl, n- butyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl or n-eicosyl.

Alkenyl is straight or branched chain and is, for example, prop-2-enyl, but-2-enyl, 2-methyl- prop-2-enyl, pent-2-enyl, hexa-2,4-dienyl, dec-10-enyl or eicos-2-enyl.

Cylcoalkyl is, for example, cyclopentyl, cyclohexyl, cyclooctyl, cyclodecyl, adamantyl or cyclododecyl.

Aralkyl is, for example, benzyl, 2-phenylethyl, benzhydryl or naphthylmethyl. Aryl is, for example, phenyl or naphthyl.

When R₁ and R₂ together with the nitrogen atom to which they are attached form a heterocyclic group, the heterocyclic group is, for example, a morpholine, pyrrolidine, piperidine or a perhydroazepine ring.

Alkylene moieties include for example methylene, ethylene, 1 :2- or 1 :3-propylene, 1 :4-buty- lene, 1 :6-hexylene, 1 :8-octylene, 1 :10-decylene and 1 :12-dodecylene.

Arylene moieties include, for example, phenylene and naphthylene. Amine phosphates of component d) are, for instance salts comprising amines and mixed mono- and di-acid phosphates. The mono- and di-acid phosphate amines have the structural formulae:

O H O H

I ₊ I l + R ^X2₀8₀O^V -P-O ^X29 ^X31 O-P-O ^R29 ^ ^R31

OR and

27 R 30 OR 27 ^R30

wherein R₂₇ is hydrogen, Ci-C₂₅-linear or branched chain alkyl which is unsubstituted or substituted by one or more Ci-C₆alkoxy groups, a saturated acyclic or alicyclic group, or aryl; R₂₈ is Ci-C₂₅-linear or branched chain alkyl which is unsubstituted or substituted by one or more Ci-C₆alkoxy groups, a saturated acyclic or alicyclic group, or aryl;

R₂₉ is hydrogen, Ci-C₂5-linear or branched chain alkyl, a saturated or unsaturated acyclic or alicyclic group, or aryl; and

R₃O and R₃i are, each independently of the other, CrC₂₅ linear or branched chain alkyl, a saturated or unsaturated acyclic or alicyclic group, or aryl.

A preferred embodiment relates to a lubricant composition, wherein R₂₇ and R₂₃ are linear or branched CrCi₂ alkyl; and R₂₉, R₃₀ and R₃i are linear or branched Ci-Ci₈ alkyl. A further preferred embodiment relates to a lubricant composition, wherein the amine phosphates are of the formula o (R₃₃O)_x P''

(OH)_y - (HN(R₃₄)₂)_y

wherein R₃₃ is n-hexyl, R₃₄ is Cn-Ci₄ branched alkyl, and when x=1 then y=2; when x=2 then y=1. The amine phosphates are present from about 0.02 to about 0.50 percent by weight, based on the weight of the lubricant. For example, the amine phosphates are present from about 0.03 to about 0.4 percent by weight, based on the weight of the lubricant.

The lubricant may further contain viscosity index improvers. Examples of suitable viscosity index improvers are: Polyacrylates, polymethacrylates, vinylpyrrolidone/methacrylate copolymers, polyvinylpyrrolidones, polybutenes, olefin copolymers, styrene/acrylate copolymers and polyethers. The lubricant may further contain ashless dispersants, detergents and/or an antiwear systems, either ZnDTP or ashless phosphorus compounds or phosphorus free antiwear additives.

The antiwear additives are selected from the group consisting of:

1 ) Dihydrocarbyl dithiophosphate metal salts wherein the metal is aluminum, lead, tin manganese, cobalt, nickel, zinc or copper, but most often zinc. The zinc salt (zinc dial- kyl dithiophosphate) is represented as

wherein R and R' are independently Ci-C₂o alkyl, C₃-C₂O alkenyl, C₅-Ci₂ cycloalkyl, C₇- Ci3 aralkyl or C₆-Ci₀ aryl, for example R and R' are independently CrCi₂ alkyl; and

2) Sulphur- and/or phosphorus- and/or halogen-containing compounds, such as sulphurized olefins and vegetable oils, tritolyl phosphate, tricresyl phosphate, chlorinated paraffins, alkyl and aryl di- and trisulphides, amine salts of mono- and dialkyl phosphates, amine salts of methylphosphonic acid, diethanolaminomethyltolyltriazole, di(2-ethyl- hexyl)-aminomethyltolyltriazole, derivatives of 2,5-dimercapto-1 ,3,4-thiadiazole, ethyl

[(bisisopropyloxyphosphinothioyl)thio]propionate, triphenylthiophosphate (triphenyl phosphorothioate), tris(alkylphenyl)phosphorothioates and mixtures thereof, for example tris(isononylphenyl)phosphorothioate, diphenylmonononylphenylphosphorothioate, isobutylphenyl diphenylphosphorothioate, the dodecylamine salt of 3-hydroxy-1 ,3-thia- phosphetan 3-oxide, trithiophosphoric acid 5,5,5-tris(isooctyl 2-acetate), derivatives of

2-mercaptobenzothiazole, such as 1-(N,N-bis(2-ethylhexyl)aminomethyl)-2-mercapto- 1 H-1 ,3-benzothiazole or ethoxycarbonyl 5-octyldithiocarbamate.

Suitable dispersants are selected from the group consisting of:

1 ) Mannich bases that are condensation reaction products of a high molecular weight phenol, an alkylene polyamine and an aldehyde such as formaldehyde;

2) Succinic-based dispersants that are reaction products of a olefin polymer and succinic acylating agent (acid, anhydride, ester or halide)further reacted with an organic hydroxy compound and/ or an amine; and 3) High molecular weight amides and esters such as reaction products of a hydrocarbyl acylating agent and a a polyhydric aliphatic alcohol, such as glycerol, pentaerythritol or sorbitol.

Ashless (metal-free) polymeric materials that usually contain an oil soluble high molecular weight backbone linked to a polar functional group that associates with particles to be dispersed are typically used as dispersants. Commonly used hydrocarbon backbone materials are olefin polymers and copolymers, in particular ethylene, propylene, butylene, isobutylene, styrene; there may or may not be further functional groups incorporated into the backbone of the polymer. Polar materials such as amines, alcohols, amides or esters are attached to the backbone via a bridge.

The detergents are selected from the group consisting of calcium, magnesium, barium, sodium or lithium salts of organic acids, for example sulphonates, alkylphenates, sulphurised alkyl phenates, carboxylates, salicylates, phosphonates, thiophosphonates and phosphi- nates. The salts may be neutral or may be overbased by for example metal hydroxides or carbonates.

Also subject of the present invention is a lubricant additive composition, which composition comprises b) A triazole metal deactivator; c) A borate ester; and A dispersant.

Suitable dispersants are those known for use in lubricants, for example polyisobutenylsuc- cinimides, polybutenylphosphonic acid derivatives or copolymers of vinyl acetate and fumaric acid esters.

For example, suitable dispersants are amine or alcohol products of hydrocarbyl-substituted succinic acylating agents. The dispersants are in particular polyisobutenylsuccinimides. For example, dispersants as disclosed in U.S. Pat. Spec. Nos. 5, 112,507, 6,440,905 and 5,587,432 and the references cited therein.

The weight:weight ratio of triazole metal deactivator to borate ester is from about 1 : 10 to about 10:1 , for example from about 1 :7 to about 7:1 , from about 1 :5 to about 5:1 , from about 1 :3 to about 3:1. For example the weight: weight ratio of triazole metal deactivator to borate ester is from about 1 :2 to about 1 :5 or from about 1 :2 to about 1 :4.

The weight amount of dispersant employed in the additive composition is from about 1% to about 50%, based on the total weight of triazole metal deactivator and borate ester. For in- stance, the weight amount of dispersant in the additive composition is from about 2% to about 30%, from about 3% to about 25% or from about 4% to about 20%, based on the total weight of triazole metal deactivator and borate ester.

For instance, a typical additive composition is about 5% dispersant, about 25% triazole metal deactivator and about 70% borate ester, each by weight.

Examples

For the corrosion bench test see: CM. Cusano and J. C. Wang, Corrosion of Copper and Lead Containing Materials by Diesel Lubricants, J. Soc. Tribologists and Lubrication Engineers, 51 (1 )89-95, 1994; and ASTM D 5968 and D 6594. This test is commonly used in engine oil specifications to validate a lubricants' ability to protect against copper and lead corrosion.

Example 1

The following formulations are prepared in a 5W-30 SM type passenger car motor oil containing 0.05% phosphorus and friction modifiers in an API Group Il base oil. Components are specified in weight percent, based on the total formulation.

Table 1

The borate ester is (R₁₅O)₃B wherein R₁₅ is a mixed C₅-C₁₃ alkyl. The borate is employed at 60 ppm and 120 ppm B treat level. The triazole metal deactivator A is 1-(di-(2-ethylhexyl)- aminomethyl)-1 ,2,4-triazole. The triazole metal deactivator B is methyl-1-(di-(2-ethylhexyl)- aminomethyl)-benzotriazole.

High Temperature Corrosion Bench Test is performed according to ASTM D 6594, 168 hours at 135°C. Corrosion results are as follows in ppm increase by weight. Table 2

Example 2

An additive mixture is prepared by blending together 5% by weight a succinimde dispersant, HITEC 646, 25% by weight 1-(di-(2-ethylhexyl)aminomethyl)-1 ,2,4-triazole and 70% by weight the borate ester (R₁₅O )sB wherein R₁₅ is a mixed C₅-C-i₃alkyl. The mixture is incorporated into a polyalkylene glycol industrial oil.

The following results for zinc corrosion in polyalkylene glycol (PAG) are shown below. Corrosion results are in ppm Zn obtained after 30 hours at 125°C.

Table 2

Claims

1. A lubricant composition comprising a) A lubricant; b) A triazole metal deactivator; c) A borate ester; and, optionally, d) An amine phosphate; wherein the triazole metal deactivator is a 1 ,2,4 triazole of the formula

wherein Ri and R₂ are the same or different and are CrC₂oalkyl, C₃-C₂oalkenyl, C₅-C₁₂cyclo- alkyl, C₇-Ci₃aralkyl or C₆-Ci₀aryl, or R₁ and R₂, together with the nitrogen atom to which they are each attached may form a 5-, 6- or 7-membered heterocylic ring, or R₁ and R₂ are a group of the paratial formula

R₃XK-R₄-PU-R₄)- wherein

X is O, S or N,

R₃ is hydrogen or CrC₂₀alkyl,

R₄ is CrC₁₂alkylene, n is 0 or an integer from 1 to 6, or one of R₁ and R₂ is a group of the partial formula

-[R₄]_n-N(R₅)-A-[N(R₅)₂]_m wherein m is 0 or 1 and, when m is zero, A is a group of formula (ll)and, when m is 1 , A is al- kylene or C₆-Ci₀ arylene and R₅ is a group of formula (II); or wherein the triazole metal deactivator is a benzotriazole of the formula (III)

wherein R₆ is Ci-Ci₂alkyl,

R₇ is Ci-Ci₂alkyl, d-C^alkyl interrupted by one or more O atoms or is C₅-Ci₂cyclo- alkyl and

R₈ and R₉ are hydrogen or methyl; or wherein the triazole metal deactivator is a benzotriazole of the formula (IV)

wherein

Rio is hydrogen or d-C^alkyl, and

Rn and Ri₂ are the same or different and are Ci-C_2oalkyl, C₃-C_2oalkenyl,

C₅-Ci₂cycloalkyl, C₇-Ci₃aralkyl or C₆-Ci₀aryl, or Rn and Ri₂, together with the nitrogen atom to which they are each attached may form a 5-, 6- or 7-membered heterocylic ring, or Rn and Ri₂ are a group of the partial formula

R₃XK-R₄-PU-R₄)- wherein X is O, S or N, R₃ is hydrogen or Ci-C₂oalkyl,

R₄ is Ci-Ci₂alkylene, n is 0 or an integer from 1 to 6, or one of Rn and Ri₂ is a group of the partial formula

or R₁₂ is a group of formula (ll)and Rn is a group of the partial formula -[R₄]_n-N(R₅)-A-[N(R₅)₂]_m wherein m is 0 or 1 and, when m is zero, A is a group of formula (II) and, when m is 1 , A is al- kylene or C₆-Ci₀arylene and R₅ is a group of formula (II).

2. A lubricant composition according to claim 1 , wherein the 1 ,2,4-triazole (I) is selected from the group consisting of 1-(di-isooctylaminomethyl)-1 ,2,4-triazole and 1-(di-(2- ethylhexyl)aminomethyl)-1 ,2,4-triazole.

3. A lubricant composition according to claim 1 , wherein the benzotriazole (III) is selected from the group consisting of 1-(2-methoxyprop-2-yl)tolyltriazole, 1-(1-cyclohexyloxypro- pyl)tolyltriazole, 1-(1-cyclohexyloxyheptyl)tolyltriazole and 1-(1-cyclohexyloxybu- tyl)tolyltriazole.

4. A lubricant composition according to claim 1 , wherein the benzotriazole (IV) is 1-[bis-(2- ethylhexyl)aminomethyl-4-methylbenzotriazole.

5. A lubricant composition according to claim 1 , wherein the borate ester is of the formula

OR₁₅

(Ri₅θ)₃B or i i wherein

R₁₅O^ O ^₀R₁₅

R₁₅ is independently hydrogen, CrC₂₀alkyl, C₃-C₂₀alkenyl, C₅-C₁₂cycloalkyl, C₇-C₁₃ar- alkyl or C₆-C₁₀aryl, with the proviso that at least one R₁₅ group is not hydrogen.

6. A lubricant composition according to claim 5, wherein the borate ester is selected from the group consisting of triethyl borate, tripropyl borate, triisopropyl borate, tributyl bo- rate, tripentyl borate, trihexyl borate, tricyclohexyl borate, trioctyl borate, triisooctyl borate, tridecyl borate, tri(C₈-Ci₀alkyl)borate, tri(Ci₂-Ci₅alkyl)borate and oleyl borate.

7. A lubricant composition according to claim 1 , which comprises a mono- or di-acid amine phosphate of the formula

O H O H

+

R₂₈O-P-O R₂₉-N⁺-R₃₁ - O-P-O ^R29 ^{N R}31 O^R27 ^■ R₃₀ °^{r OR}27 ^R30

wherein

R₂7 is hydrogen, C₁-C₂5 linear or branched chain alkyl which is unsubstituted or substituted by one or more Ci-C₆alkoxy groups, a saturated acyclic or alicyclic group, or aryl;

R₂₃ is C₁-C₂5 linear or branched chain alkyl which is unsubstituted or substituted by one or more Ci-C₆alkoxy groups, a saturated acyclic or alicyclic group, or aryl;

R₂9 is hydrogen, C₁-C₂5 linear or branched chain alkyl, a saturated or unsaturated acyclic or alicyclic group, or aryl; and

R30 and R3₁ are, each independently of the other, C₁-C₂5 linear or branched chain alkyl, a saturated or unsaturated acyclic or alicyclic group, or aryl.

8. A lubricant composition according to claim 7, wherein R₂₇ and R₂₈ are linear or branched CrCi₂ alkyl and R₂₉, R30 and R3₁ are linear or branched CrCi₈ alkyl.

9. A lubricant composition according to claim 7, wherein the amine phosphates are of the formula

wherein R₃₃ is n-hexyl and R₃₄ is Cn-Ci₄ branched alkyl, and when x=1 then y=2; when x=2 then y=1.

10. A method for controlling the corrosion of lead, copper, iron and zinc in a lubricant, which method comprises incorporating into a lubricant b) A triazole metal deactivator; c) A borate ester; and, optionally, d) An amine phosphate.