AU695511B2

AU695511B2 - Lubricant composition

Info

Publication number: AU695511B2
Application number: AU23135/95A
Authority: AU
Inventors: Mark Anthony Edwards; Andrew Jonathan Markson; John William Anthony Pragnell
Original assignee: Castrol Ltd
Current assignee: Castrol Ltd
Priority date: 1994-04-26
Filing date: 1995-04-25
Publication date: 1998-08-13
Anticipated expiration: 2015-04-25
Also published as: WO1995029214A1; DE69515861D1; JPH10503535A; ES2148513T3; EP0757712A1; AU2313595A; GB9408235D0; CN1151174A; EP0757712B1; CN1043053C; GR3033741T3; PT757712E; CA2188936A1; DE69515861T2; JP3780323B2; DK0757712T3; KR100339777B1; NZ284520A; ATE190997T1

Abstract

A lubricant composition suitable as a helicopter transmission lubricant comprises a synthetic base stock of viscosity in the range 5.0 to 10.0 cSt at 100 DEG C, an antioxidant component, a neutral organic phosphate component, a dicarboxylic acid component, a monocarboxylic acid component, a triazole component and a phosphorus containing extreme pressure additive.

Description

Y C 1008 1 LUBRICANT COMPOSITION This invention relates to a lubricant composition and is particularly concerned with a transmission lubricant suitable, for example, for helicopter transmission systems.

The development of new transmission systems, for example, for helicopters, has led to the requirement for dedicated lubricants for such purposes which can meet demanding load carrying and corrosion protection criteria. Specifications put forward by, for example, the U.K. Ministry of Defence and the United States Navy, pose requirements to be met by new dedicated helicopter transmission lubricants that cannot be fidfilled by existing aviation turbine engine lubricants. There is thus a need for the development of new and improved lubricant compositions for such purposes. The present invention seeks to fulfil this need.

DE-A-2039785 discloses a load carrying additive composition for a gas turbine engine. The load carrying additive composition comprises a synthetic ester base stock fluid having a viscosity of 5.6 to 6.0 cs. at 99 °C (210 (see the examples).

US-A-3694382 discloses a lubricant for a gas turbine engine. The lubricant comprises a synthetic ester base stock having a viscosity ranging from 4.0 to 9.1 cs. at 99 C (210 0

F).

FR-A-2215462 discloses a lubricant having a mineral oil as its base stock.

WO-A-9410270 discloses a corrosion inhibiting lubricating composition S AMEND=' S- "IPEA/E= P 1A comprising a synthetic base stock having a viscosity of at least 4.9 cSt at 100 oC.

Accordingly, the present invention provides a lubricant composition comprising: a) a base component comprising one or more synthetic base stocks, which base component has a viscosity in the range of from 8.5 to 9.5 cSt at 100°C; b) at least one antioxidant selected from aromatic amines and hindered phenolics; c) at least one neutral organic phosphate of the formula

(R'O)

3 PO where R' is a tolyl, phenyl, xylyl, alkyl or cycloalkyl group, the alkyl or cycloalkyl group having up to 10 carbon atoms; CfV 9 if i hEA/E? ara a~ WO 95/29214 PCT/GB95/00941 d) at least one saturated and/or unsaturated dicarboxylic acid of the general formula R2 H R.

COOH

x I

H

3 wherein x+y+z is an integer in the range from 2 to 22 inclusive and where at least one of the groups R, to R 5 is a carboxylic acid group and the remaining groups R, to R 5 are selected from alkyl, hydroxy, nitro, amino, carboxyl, hydrogen or alkyl derivatives thereof, where alkyl is a short chain of up to 5 carbon atoms; and/or a dicarboxylic acid of one of the three formulae

R

2 )n wherein R, is -COOH, alkyl, hydroxy, nitro, amino, hydrogen or alkyl derivatives thereof; R( is -COOH; and n is an integer from 1 to 4 inclusive when R" is -COOH or an integer from 2 to 4 inclusive when R is not -COOH.

e) at least one straight and/or branched chain saturated or unsaturated monocarboxylic acid which is optionally sulphurised in an amount which may be up to 35% by weight; and/or an ester of such an acid; and

A

SUBSTITUTE SHEET (RULE 26) WO 95/29214 3 PCT/GB95/00941 f) at least one triazole of the formula: Cl )n

/NII

R

2 where R is -COOH or alkyl derivatives thereof, or short chain alkyl of up to 5 carbon atoms; n is zero or an integer between 1 and 3 inclusive; and R2is hydrogen, morphilino, alkyl, amido, amino, hydroxy or alkyl or aryl substituted derivatives thereof; or a triazole selected from 1,2,4 triazole, 1,2,3 triazole, 5-anilo-1,2,3, 4-thiatriazole, 3-amino-1,2,4 triazole, 1-H-benzotriazole-1 -yl-methylisocyanide, methylene-bis-benzotriazole and naphthotriazole; and g) at least one phosphorus containing extreme pressure additive.

In component above the bicyclic structural formula is intended to indicate that the group(s) R 2 may be attached to either or both aromatic rings.

At least one base stock of the base component, is preferably a synthetic ester base stock, especially a polyol ester base stock. The synthetic polyolester which preferably forms a base stock of the lubricating composition of the present invention may be made from C 5 to C12 monocarboxylic acids esterified with polyols or polyol ethers such as neopentylglycol, dimethylolpropane, trimethylolpropane, pentaerythritol or dipentaerythritol. These are conventional synthetic ester base stocks.

Preferred esters are those which are described in U.S. Patent 4826633.

SUBSTITUTE SHEET (RULE 26) C. 1008 4 The viscosity may be adjusted to lie within the required range by inclusion of one or more viscosity index improvers.

For adequate performance as a transmission lubricant, the base component must have a viscosity in the range of 8.5 to 9.5 cSt, preferably 8.75 to 9.25 cSt, at 100 0 C. The base component may comprise a single polyol ester but is more usually a mixture of polyol esters, for example, a mixture of a polyol ester having a viscosity of about 4.0 cSt at 100°C with a polyol ester having a viscosity of about 12.0 cSt at 100 0 C. Preferred synthetic polyol esters are reaction products of pentaerythritol and/or trimethylolpropane and an acid mixture comprising to Co straight and I branched chain acids.

The antioxidant component b) may be a hindered phenolic antioxidant such as butylated hydroxytoluene, suitably present in an amount of 0.01 to preferably 0.4 to by weight of the lubricant composition. Alternatively, or in addition, component b) may comprise an aromatic amine antioxidant such as mono-octylphenylalphanapthylamine or p,p-dioctyldiphenylamine, used singly or in admixture. The amine anti-oxidant component is suitably present in a range of from 0.01 to 5% by weight of the lubricant composition, more preferably 0.5 to The neutral organic phosphate which forms component c) of the formulation may be present in an amount of 0.01 to preferably 1.5 to by weight of the composition. The neutral organic phosphate is also a conventional ingredient of lubricating compositions and any such neutral organic phosphate falling within the formula as previously defined may be employed. Tri-cresyl phosphate is a preferred phosphate for use in the present invention.

A IVE, S H°iAIE i WO 95/29214 PCT/GB95/00941 Components e) and f) are intended to provide a corrosion inhibiting three component system. The combination has been found to enable the provision of lubricant compositions capable of passing United States Navy corrosion inhibition requirements (Ball Corrosion Test ARP 4249) in which a result of 50% non corroded specimen is deemed a satisfactory corrosion protection requirement.

The dicarboxylic acid forming the first component of the anti-corrosion combination may be any dicarboxylic acid falling within the definition given hereinbefore. The dicarboxylic acid may be present in a proportion of up to 0.15% by weight of the composition. It should be noted however, that it is desirable that sebacic acid or an equivalent thereof should always be present in the composition even if another dicarboxylic acid falling within the above definition is present because sebacic acid or an equivalent of it may be necessary to meet parts of the specification other than the ball corrosion test, for example, for satisfactory lead corrosion resistance.

Examples of dibasic acids, other than sebacic acids, which may be used in the present invention, are adipic acid, azelaic acid, dodecanedioic acid, 3-methyladipic acid, 3-nitrophthalic acid, 1,10-decanedicarboxylic acid, and fumaric acid.

The second component of the anti-corrosion combination is a straight or branch-chained, saturated or unsaturated monocarboxylic acid or ester thereof which may optionally be sulphurised in an amount up to by weight. Preferably the acid is a C 4 to C 22 straight chain unsaturated monocarboxylic acid. The preferred concentration of this additive is from 0.001% to 0.35% by weight of the total lubricant composition. The preferred monocarboxylic acid is sulphurised oleic acid.

SUBSTITUTE SHEET (RULE 26) P:\OPER\AXD\23135-95,169 19/6/98 -6- However, other suitable materials are oleic acid itself; valeric acid and erucic acid.

The third component of the anti-corrosion combination is a triazole as previously defined. The triazole should be used at a concentration from 0.005% to 0.25% by weight of the total composition. The preferred triazole is benzotriazole.

Component g) of the composition comprises at least one phosphorus containing extreme pressure additive. Examples of such additives are amine phosphate extreme pressure additives such as that known under the trade name IRGALUBE 349 and/or triphenyl 0 0 10 phosphorothionate extreme pressure/anti-wear additives such as that known under the trade name IRGALUBE TPPT. Such amine phosphates are suitably present in an amount of from 0.01 to preferably 0.2 to 0.6% by weight of the lubricant composition while such phosphorothionates are suitably present in an amount of from 0.01 to 3 preferably 0.5 to by weight of the lubricant composition. Preferably, a mixture of an amine phosphate S 15 and phosphorothionate is employed.

For the provision of a helicopter transmission lubricant the amounts of the additive are :selected so as to comply with the United States Navy requirement for the Ryder gear test, conducted at 100 0 C, (average of 6 runs) of 200 (relative rating, Herco A, a synthetic pentaerythritol ester produced by Hercules Inc., as reference fluid).

The following example is intended to illustrate a preferred lubricant composition in accordance with the invention.

yB P:\OPERAXD\23135-95.169 -19/6/98 mono-octylphenylalphanaphthylamine butylated hydroxy toluene benzotriazole sulphurised oleic acid sebacic acid tri-cresyl phosphate by weight 0.1% 0.05% 0.01% 0.4% 2ppm 95.44%

I

1 4 4 4 *r 4 44 4 t 44 4I* 4. C 4 i* 44r 10 amine phosphate triphenyl phosphorothionate silicone antifoam agent base synthetic ester fluid mixture to give a viscosity for the composition of 8.75 to 9.25 cSt The resulting composition was found to give a value of 204.7 in the Ryder gear test, 100 0 C (as relative rating, Herco A) and pass rating in the Ball Corrosion Test (in accordance with ARP method 4249).

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

B

~D i i, _kl e~ t x: i

A

Claims

4-. C 1008 8 CLAIMS 1. A lubricant composition comprising: a) a base component comprising one or more synthetic base stocks, which base component has a viscosity in the range of from 8.5 to 9.5 cSt at 100 0 C; b) at least one antioxidant selected from aromatic amines and hindered phenolics; c) at least one neutral organic phosphate of the formula (R'O) 3 PO where R' is a tolyl, phenyl, xylyl, alkyl or cycloalkyl group, the alkyl or cycloalkyl group having up to 10 carbon atoms; d) at least one saturated and/or unsaturated dicarboxylic acid of the general formula R2 H R.- S H R 4 wherein x+y+z is an integer in the range from 2 to 22 inclusive and where at least one of the groups R t to R, is a carbcxylic acid group and the remaining groups R, to R, are selected from alkyl, hydroxy, nitro, amino, carboxyl, hydrogen or alkyl derivatives thereof, where alkyl is a short chain of up to carbon atoms; and/or a dicarboxylic acid of one of the three formulae AMENDED SHEET IPEA/EP WO 95/29214 9 PCT/GB95/00941 )n )n wherein R is -COOH, alkyl, hydroxy, nitro, amino, hydrogen or alkyl derivatives thereof; R1 is -COOH; and n is an integer from 1 to 4 inclusive when R"is -COOH or an integer from 2 to 4 inclusive when R, is not -COOH. e) at least one straight and/or branched chain saturated or unsaturated monocarboxylic acid which is optionally sulphurised in an amount which may be up to 35% by weight; and/or an ester of such an acid; and f) at least one triazole of the formula: where R is -COOH or alkyl derivatives thereof, or short chain alkyl of up to 5 carbon atoms; n is zero or an integer between 1 and 3 inclusive; and R2is hydrogen, morphilino, alkyl, amido, amino, hydroxy or alkyl or aryl substituted derivatives thereof; or a triazole selected from 1,2,4 triazole, 1,2,3 triazole, 5-anilo-1,2,3, 4-thiatriazole, 3-amino-1,2,4 triazole, 1-H-benzotriazole-1 -yl-methylisocyanide, methylene-bis-benzotriazole SUBSTITUTE SHEET (RULE 26) it j P;\OPER\AXD\23135-95.169 23/6198 1,2,3 triazole, 5-anilo-1,2,3, 4-thiatriazole, 3-amino-1,2,4, triazole, 1-H-benzotriazole-l-yl- methylisocyanide, methylene-bis-benzotriazole and naphthotriazole; and g) at least one phosphorus containing extreme pressure additive. 2. A lubricant composition according to claim 1 wherein at least one base stock of the base component is a polyol ester. 3. A lubricant composition according to claim 2 wherein the polyol ester base stock 10 comprises one or more C 5 to C 2 monocarboxylic acids esterified with. one or more polyols or polyol ethers. 4. A lubricant composition according to any one of claims 1 to 3 wherein the base S" component has a viscosity in the range of from 8.75 to 9.25 cSt at 100 0 C. A lubricant composition according to any one of the preceding claims wherein the antioxidant comprises a hindered phenolic antioxidant present in an amount of 0.4 to 0.8% by weight of Qa composition. &its 20 6. A lubricant composition according to any one of the preceding claims wherein the antioxidant comprises an aromatic amine antioxidant present in an amount of 0.5 to 1.5% by weight of the composition.
7. A lubricant composition according to any one of the preceding claims wherein the neutral organic phosphate is present in an amount of 1.5 to 2.5% by weight of the composition. 1 u r s t WO 95/29214 PCT/GB95/00941 11
8. A lubricant composition according to any one of the preceding claims wherein the saturated and/or unsaturated dicarboxylic acid component is present in an amount of up to 0.15% by weight of the composition.
9. A lubricant composition according to any one of the preceding claims wherein the saturated and/or unsaturated dicarboxylic acid component comprises sebacic acid. A lubricant composition according to any one of the preceding claims wherein the monocarboxylic and component is present in an amount of from 0.001 to 0.35% by weight of the composition.
11. A lubricant composition according to any one of the preceding claims wherein the monocarboxylic acid component comprises sulphurised oleic acid.
12. A lubricant composition according to any one of the preceding claims wherein the triazole component is present in an amount of from 0.005 to 0.25% by weight of the composition.
13. A lubricant composition according to any one of the preceding claims wherein the triazole component comprises benzotriazole. SUBSTITUTE SHEET (RULE 26) -1 P;\OPER\AXD23135-95.169 -23/6/98 -12-
14. A lubricant composition according to any one of the preceding claims wherein the extreme pressure additive component comprises an amine phosphate extreme pressure additive present in an amount of from 0.2 to 0.6% by weight of the composition. 4 0S 9, 'a r
15. A lubricant composition according to any one of the preceding claims wherein the extreme pressure additive component comprises a phosphorothionate extreme pressure additive present in an amount of from 0.5 to 1.5% by weight of the composition.
16. A helicopter transmission lubricant comprising components to as defined in any one of the preceding claims.
17. A lubricant substantially as hereinbefore described with reference to the Examples. DATED this 23rd day of June, 1998 Castrol Limited By DAVIES COLLISON CAVE Patent Attorneys for the Applicant i r u ~7t\. re ;4 ;:1 INTERNATIONAL SEARCH REPORT Intei nal Applicaton No PCT/GB 95/00941 A. CLASSIFICATION OF SUBJECT MATTER IPC 6 C10M169/04 //(C10M169/04,105:38,129:10,129:34,129:40,129:42, 129:52,129:70,133:12,133:32,133:40,133:44,135:02,135:06,137:04, 137:08,137:10),C10N30:06,C10N40:04 According to International Patent Classificaton (IPC) or to both natonal classificaton and [PC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC 6 C1OM Documentation searched other than nunimum documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the intemational search (name of data base and, where practical, search terms used) C. DOCUMENTS CONSIDERED TO BE RELEVANT Category Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. P,X WO,A,94 10270 (CASTROL LTD) 11 May 1994 1-3, 6-13,16, 17 see page 1, line 31 page 5, line 29 X DE,A,20 39 785 (STAUFFER CHEMICAL) 25 1-3,6, February 1971 8-13,16, 17 Y see page 5 page 6; example 1 4,5,14, Y US,A,3 694 382 (J.P.KLEIMAN) 26 September 1972 see column 5 column 6; example 2 see column 9; table 4 Further documents are listed in the continuation of box C. Patent farmly members arc listed in annex. SSpecial categories of cted documents later document published after the international filing date document defining the general state of the art which is not r prioittnde dt and othe n flict r the upplicndin thut considered to be of partcular relevance invention earlier document but published on or after the international document of particular relevance; the claimed invention filing date cannot be considered novel or cannot be considered to document which may throw doubts on priorty claim(s! -r involve an inventive step when the document is taken alone which is cited to establish the publication date of a "Y document of partcular relevance; the claimed invention citation or other special reason (as specified) cannot be considered to involve an inventive step when the "0 document referrng to an oral disclosure, use, cxhit or document is combined with one or more other such docu- other means ments, such combination being obvious to a person skilled document published pror to the internatonal filing date but in the art. later than the pnority date claimed document member of the same patent family Date of the actual completion of the international search Date of mailing of the internatonal search report 3 August 1995 11.08.95 Name and mailing address of the ISA Authorized officer European Patent Office, P.B. 5818 Patentlaan 2 NL 2280 [IV Rilswilk Tel. (+31-70) 340-2040, Tx. 31 651 epo n, Rotsaert, L Fax: (+31-70) 340-3016, Form PCT!ISAIl0 (iecond shet) (July 1992) page 1 of 2 WO-A-94 10270 discloses a corrosion inhibiting lubricating composition I V t\~ I t '-1 AMENDE7 -'rHEET IPEA/E? INTERNATIONAL SEARCH REPORT Inter. ial Application No PCT/GB 95/00941 C.(Continualion) DOCUMENTS CONSIDERED TO BE RELEVANT Category *Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. FR,A,2 215 462 (ESSO RESEARCH AND ENGINEERING) 23 August 1974 see page 2, line 11 page 3, line 14, Form PCTIISA.110 (contiuation orf second shett) (July 1991) page 2 of 2A L INTERNATIONAL SEARCH REPORT informaton on patent farmly members Intern al Applicaton No PCT/GB 95/00941 Patent document Publication Patent family Publication cited in search report date member(s) date WO-A-9410270 11-05-94 GB-A- 2272000 04-05-94 AU-B- 5343194 24-05-94 CN-A- 1087669 08-06-94 DE-A-2039785 25-02-71 BE-A- 754710 11-02-71 FR-A- 2058219 28-05-71 GB-A- 1287647 06-09-72 NL-A- 7011135 16-02-71 US-A-3694382 26-09-72 DE-A- 2034383 14-01-71 FR-A- 2051665 09-04-71 GB-A- 1301003 29-12-72 NL-A- 7010293 12-01-71 FR-A-2215462 23-08-74 DE-A- 2357199 01-08-74 GB-A- 1415964 03-12-75 NL-A- 7315445 29-07-74 i-,-AI.-a-MI* Form PCTTSA310 (patent family anrex) (July 1992)