DE1644959C3 - lubricant - Google Patents

Description

Lubricant based on an ester lubricant, which is very good, for example, for the Suitable lubrication of aircraft gas turbines should have good oxidation stability at high temperatures and have good extreme pressure properties. Such lubricants therefore usually contain antioxidants, like certain substituted phenothiazines and certain secondary aromatic amines as well as 4-, certain maximum pressure2: additives, such as B. Triaryl esters of Phosphorothionic acid.

Although these triarylphosphorothionates are lubricants give very favorable high pressure properties, as they cause certain metals to corrosion in particular with magnesium, cadmium and with p. 82 steel. Be: i this type of steel is involved is a quality steel for aircraft gearboxes, which meets the requirements of the British Standard Specification EN39B is sufficient. On the other hand, triaryl phosphates are well known extreme pressure additives, however show lubricants containing these additives are insufficient at high temperatures Oxidation stability.

From GB-PS 8 23 086 are still cyclic _b0

organic phosphorus compounds have become known, which can also contain sulfur in the molecule and which should improve the corrosion behavior of mineral lubricating oils and synthetic lubricating oils, Due to the complex structure, these additives are not easily accessible,

Surprisingly, it has now been found that triarylphosphorothionates and triarylphosphates in Lubricants based on an ester lubricant with regard to anti-corrosion properties and anti-oxidation properties work together in a synergistic manner at high temperatures, especially when these two additives are in certain proportions voi lie.

The lubricants according to the invention therefore consist of a larger proportion of an ester lubricant and smaller proportions each of a triaryl phosphorothionate and a triaryl phosphate as well optionally other known additives.

Triaryl phosphorothionates suitable for this purpose contain 6 to 10 carbon atoms in each aryl group. Examples are triphenyl, tritolyl, tribenzyl, trixylyl and diphenyltolyl phosphorothionate in particular In the context of the invention, preference is given to triphenyl phosphorothionate, hereinafter abbreviated as TPPT

In the context of the invention, such compounds are suitable as triaryl phosphates, soft in each Aryl group also contain 6 to 10 carbon atoms, for example triphenyl, tritolyl, tribenzyl, Trixylyl and diphenyltolyl phosphate However, triphenyl phosphate is preferably used, which hereinafter abbreviated to TPP.

The ratio of triphenyl phosphate to triphenyl phosphorothionate is expediently within the range according to the invention Ester lubricants at about 0.25: 1, but preferably this ratio is no less than0.5: l.

Simple esters, complex esters, polyesters can be used as the base oil in the lubricants according to the invention or mixtures of such esters can be used, which also contain thickeners can, depending on the viscometric properties, which for a particular lubricant and for the temperature conditions under which the lubricant will be used are desired. Under In the context of the invention, a simple ester is understood to mean an ester which is derived from an aliphatic Dicarboxylic acid and an aliphatic monohydric alcohol is derived, which is preferably Ester of an aliphatic dicarboxylic acid with 6 to 10 carbon atoms in the molecule and a branched one monohydric alcohol with 6 to 12 carbon atoms in the molecule. In particular, for this Alcohols are used which do not contain any hydrogen on the beta carbon atom.

Examples of simple esters, which are used as base oil in the Esterschmiermitte..i according to the invention can be used are

Diisononyl sebacate Di (2-ethylhexyl) sebacate.

Diisooctyl azelate diisodecyl azelate,

Di (3,5,5-trimethylhexyl) adipate,

2 ethylhexyl 3,5,5-trimethylhexyl sebacate

and simple, sterically hindered esters such as 2,2,4-trimethyl pentyl azelate. A complex ester is understood to mean an ester made up of various combinations an aliphatic carboxylic acid, a glycol or polygiycol, an aliphatic monohydric acid Alcohol and / or an aliphatic monocarboxylic acid will echo. Such esters have, for example, the following structures, AD (GD) nA, A (DG) / jM and MG (DGJnM, in which A, D, G and M the at the Esterification obtained residual groups of an aliphatic monohydric alcohol, an aliphatic dicarboxylic acid, a glycol or polygiycol and one

aliphatic monocarboxylic acid and η is an integer from 1 to 6 - Examples of typical starting materials for the production of such complex esters are 2-ethylbutyl alcohol, 2-ethylhexyl alcohol, caproic acids, pelargonic acid, capric acid, tertiary acids which do not contain a hydrogen atom, neopentyl glycol, Ethylene glycol, propylene glycol, polyglycols such as polyethylene glycols, sebacic acid, adipic acid, azelaic acid and pimelic acid.

Polyesters are understood as meaning esters which are derived from aliphatic alcohols with at least 3 hydroxyl groups derive in the molecule, for example esters of trimethylolpropane, such as the trimethylolpropane tripelargonic acid ester.

Tetraesters are also suitable for this purpose, for example tetraesters of pentaerythritol or one Dimers or trimers of this alcohol and also esters of dipentaerythritol. Such esters are im Commercially available. These are fatty acid esters. Preferably each fatty acid residue contains des Esters 4 to 18 carbon atoms and especially 6 to 14 carbon atoms.

As a thickening agent in the invention Ester lubricants Polymers of esters of acrylic acid or an alkyl substituted acrylic acid can be used, for example of lauryl methacrylate Ethers of a polyoxyalkylene glycol of the general formula are also suitable for this purpose

R ₅ O (R ₇ O) _n R ₆ ,

in which Rs is an alkyl group, R _{b is} a hydrogen atom or an alkyl group jnd R? represents an alkylene group having 2 to 7 carbon atoms, v; While η is an integer greater than 1. Suitable compounds of this type are commercially available.

Copolymers of propylene oxide and ethylene oxide are also suitable as thickeners, which are also commercially available. Depending on the desired viscometric properties you can these thickeners in concentrations of up to 50% by weight, calculated on the finished lubricant, in the ester lubricants according to the invention are present.

The ester lubricants according to the invention can furthermore contain additional additives, for example Extreme pressure additives, antioxidants, metal deactivators. Anticorrosive agents, antifoam agents, dyes and others for ester lubricants known additives.

Suitable extreme pressure additives are chlorinated di- or polyphenyls and salts of tert-alkyl. primary Amines with monochloromethylphosphonic acid.

Suitable antioxidants are substituted phenothiazines, secondary aromatic amines, alkylated Phenols and bisphenols.

A particularly favorable antioxidant in the context of the invention is a substituted one Phenothiazine of the general formula below

Substituents Ri, Rj, Rj and R-i are an alky! - or Is alkoxy, while the other substituents are hydrogen atoms.

Furthermore, a secondary aromatic amine is very suitable as an antioxidant, in which two aromatic groups are attached directly to the nitrogen atom. Examples of such additives are N-benzyl-3,7-dioctylphenothiazine and phenyl-cc-naphthylamine.

Suitable metal deactivators are triazoles, such as 1,23- and 1,2,4-triazoles, especially when these have amino and hydrocarbon substituents as well Contain acyl or aroyl substituents.

Suitable anti-corrosion agents are carboxylic acids such as sebacic acid, azelaic acid and adipic acid and also metal salts of petroleum sulfonic acids.

Polydimethylsiloxanes with viscosities of 100-100 cSt at 25 ° C can be used as antifoam agents will.

The invention is explained in more detail by the following examples:

Different amounts of triphenyl phosphate and triphenyl phosphorothionate are used in a basic lubricant A (TPP or TPPT) added. All quantities are given in% by weight.

Lubricant A

64.5% »HercolubeA« *)
31.9% »Hercolube F« **)

1.7% N-benzyl-SJ-dioctylphenothiazine

1.5% PhenyI-A.-tiaphthylamine

0.02% azelaic acid

0.0005% silicone liquid MS 200/12 500 * »*)

0.17% JMT / MCMPA - Ci ₈ Q ₂ primary amine salt
of monochloromethylphosphonic acid

0.2% triazole

Lubricant B

A + 0.5% TPPT (for comparison)

Lubricant C

A + 0.5% TPP (for comparison)

Lubricant D

A + 1% TPP (for comparison)

Lubricant E.

A + 1% TPPT (for comparison)

Lubricant F.

A + 0.5% TPP + 1% TPPT

Lubricant G

A + 1% TPP + 1% TPPT

Schmie ^r medium H

A + 0.5% TPP + 0.5% TPPT

Lubricant J

A + 0.3% TPP + 1% TPPT

*) Pentaerythritol esters of saturated fatty acids with a average ketlene length of 8 carbon atoms in a mixture with a smaller proportion of dipentaerythritol esters.

**) Dipentaerythritol esters of saturated solid acids in a mixture with smaller amounts of mono and tripentaerythritol esters.

***) A dimethyl silicone polymer with a viscosity of approx. l2 500cSt at 25 ° C.

in which R is an alkyl, aryl-Ί aikafyl ·, aralkyl or Cyanoalkyl radical means and at least one of the various tests with these lubricants carried out, the results obtained are summarized in Tables 1 to V below.

"Bristol Siddeley" Corros! On test (Table I)

In this test, samples of certain metals are used for 24 hours. long at a temperature of 285 ° C Effect of the ester lubricants to be tested

exposed. The changes in weight of the metal samples are measured.

Table 1 Weight change in mg / cmr Male Alumi bronze P.82- Cast iron silver S110B- cadmium Magne nickel [ Brass metal nium stole stole sium Corrosion Tesl zero nullo -0.14 -19 -2.7 zero -0.24 -11 > -130 zero Lubricant -2.0 zero +0.04 zero -0.19 -0.64 -0.06 +0.07 -2.7 -28 +0.04 middle -0.56 zero zero zero -0.17 -0.46 H 0.04 zero -0.69 -29.8 -0.06 -0.74 +0.10 -0.03 -0.2 -21.0 -4.03 +0.01 -1.59 -49.0 > -130 +0.03 B. -0.70 zero zero -0 ..- J7 -0.37 zero zero zero -3.9 -12 +0.08 C. -0.13 zero zero zero zero zero zero zero -2.90 -11.1 +0.07 D. +0.01 zero zero zero zero zero zero zero -3.20 -10.4 zero E. zero zero zero -0.13 -5.1 -0.81 zero -0.04 -0.51 -100 +0.10 F. -0.51 G H J

The Slahl type SIlOB is a corrosion-resistant, rust-free chair that can be used to Welding is suitable and meets the requirements of the British Standard Specification En58C

"Rolls-Royce" - Oxidation Blow Tesi (Table II)

In this test a Rolls-Royce device r. For 24 hours at a temperature of 250 ° C through each used and blowing 50 ml of the ester lubricant to be tested with steam, saturated air at a fixed rate

Tables

Lubricant viscosity increase at 37.8 C in%

κ π

663; 548

320; 298

155; 159

343; 346

From Table I it can be seen that the combined use of triphenyl phosphate and Triphenyl phosphorothionate the corrosion is significantly reduced, in comparison to triphenyl phosphorothionate alone, especially in the case of magnesium, cadmium and the S. 82 Slahl. Although the result for Magnesium is disappointing when using lubricant J, but improved results can be achieved can be achieved by increasing the ratio of TPP to TPPT.

From Table II it can be clearly seen that a favorable antioxidant effect at high temperatures by the synergetic interaction of the two additives is achieved.

»Rolls-Roycew corrosion test, method 1002, Working method A, scheme no. L (200 ° C, 192 hours)

After pretreatment according to the RoIIs ^ Royce 1004, Iss. 1, Sup, 2 for 5 hours at 325 ° C.

With this corrosion resistance, the change in weight of selected metal samples is determined, which 192 Sld. at a temperature of 200 ° C the Exposed to the effect of the ester lubricant to be tested. The pretreatment consists of

that about 100 ml of the lubricant to be tested in a stainless steel container for 5 hours 325 ° C are heated, the container has a tightly closing cap, which with a narrow steel capacitor is connected.

The results achieved are shown in Table III summarized.

Table III

Lubricant Change in weight in mg / cm Ti / Cu Cu / Ni / Si 1 Pb-Brünzc Steel with Pb- Ni / Cr-cin- Fast Cu middle ΛΙ FluBslahl high ge Mcssing salt hardened jobless hold on stole C and Cr zero -1.2 -1.2 -3.7 -2.1 -0.27 -0.03 -1.5 D. zero zero -1.8 1-8.9 -4.3 -16 -6.4 -21 -6.3 -2.0 E. zero zero -0.94 -36 -0.86 -2.9 -1.8 -2.6 -0.23 -1.5 G zero -6.1

From this table it can be seen that the corrosion caused by triphenyl phosphorothionate is significantly reduced at high temperatures by the addition of triphenyl phosphate.

The only danger when using triphenyl phosphate in an ester is that the phosphate increases an acidic phosphate can be hydrolyzed, which in turn causes partial hydrolytic decomposition of the ester catalyzed to the half ester. This half ester has a corrosive effect while at the same time alcohol formed lowers the flash point. This behavior was determined using two well-known tests checked, namely by means of the Rolls-Royce Hydrolysestabililätslesles and using the S.O.D. Lead Corrosion Storage Stability Test.

In the Rolls-Royce test, 250 ml of the to

Table IV

^{The lubricant to be tested is heated to 90 °} C. together with 25 ml of distilled water until the acidity has risen by 1.5 mg KOH / g. In the SOD test, a test piece made of lead is placed on a stirrer together with a copper piece acting as a catalyst, and this stirrer is immersed in the lubricant mixture to be tested and rotated at a predetermined speed. Simultaneously, air is blown through the lubricant at a fixed rate for one hour at a temperature of 166.8 ° C.

These measures are applied both with the fresh lubricant and after storage for 7 days IIO ° C carried out. The results obtained are summarized in Table IV.

lubricant
DE

“Rolls-Roycew Hydrolysis Stability Test
(Number of hours until the acid value rises by 1.5 mg KOH / g)

Weight loss of the lead sample after 1 hour at 162.8 ° C. in mg / 6.45 cm ² before storage
After 7 days of storage at 110 ° C

134

-0.19
-1.86

124

-0.67
-0.56

126

zero
-0.49

These results confirm that the triphenyl phosphate does not appear in the lubricants of the present invention has an adverse hydrolytic effect on the ester lubricant.

Finally, there is the action of triphenyl phosphate on common esters, such as di-isooctyl azelate, has been determined.

The results summarized in Table V confirm that a lubricant containing only 1% Contains triphenyl phosphate but no triphenyl phosphorothionate, gives rise to higher lead corrosion, i. H., that a stronger hydrolysis takes place than when the the same ester contains both 1% of the phosphate and 1% of the phosphorothionate.

Table V

50 lubricants

Ester

+ 1% TPP

Ester

+1% TPP

+ 1% TPPT

Weight loss of the lead specimen after 7 days Storage at 110 ⁰ C and
1 hour treatment at
162.8 C

5.45

0.19

Claims (7)

Claims: IO 15 1. Lubricant consisting of a larger one Portion of an ester lubricant and minor portions each of a triarylphosphorothionate and a triaryl phosphate and optionally other known additives. 2. Lubricant according to claim I _1, characterized in that it contains a triaryl phosphorothionate having 6 to 10 carbon atoms in each aryl group, in particular triphenyl phosphorothionate 3. Lubricant according to Claims 1 and 2, characterized in that it is a triaryl phosphate containing 6 to 10 carbon atoms in each aryl group, especially triphenyl phosphate 4. Lubricant according to Claims 1 to 3, characterized in that it is the triaryl phosphate and the triaryl phosphorothionate in a ratio of 0.25: 1 5. Lubricant according to claims 1 to 3, characterized in that it is the triaryl phosphate and the triaryl phosphorothionate in a ratio of 0.5: 1 6. Lubricant according to claims 1 to 5, characterized in that it is used as a lubricating oil base contains a simple ester, a complex ester and / or a polyester 7. Lubricant according to claims 1 to 6, characterized in that there is also a Contains thickening agent, preferably in a concentrated form trations up to 50 percent by weight, based on the finished lubricant.