DE2249031A1 - ANTIOXIDANT FOR LUBRICATING OIL - Google Patents

Description

DR. BERG DIPL.-ING. STAPF

PATENT LAWYERS
8 MUNICH 8O, MAUERKIRCHERSTR. 45

Dr. Berg Dipl.-Ing. Slopf, 8 Munich 80, MouerkirchersfraSe 45

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date

Attorney's file 22 817
Be / Sch

Essο Eesearch and Engineering Company Linden, lew Jersey / USA

"Antioxidant for Lube Oil © '

This invention relates to a mixture of compounds which _s is suitable as an antioxidant especially in lubricants for aviation.

There have been many antioxidants for Sohmi © r- ■ oils, suggested for example for the lubrication of aircraft »

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(0811) 48 82 72 {98 82 72) 48 70 43 <Hä 70 43} 48 3310 (93 3310) Telegrams: BERGSTAPFPATENT Mönchen TELEX 05 24 560 SERG d Ban! :: Bavarian VcrChisbc-n't Munich 453100 Postscheck: Munich 653 43

The applicant was able now to find an improved antioxidant because · good entioxidative effect and also low Korroeionaneigung has.

According to this invention © contains an antioxidant, which is particularly suitable for turbine oil, "a Gemiaoh of (a) an alkylated N-Fhenylnaphthylainin eit wenigstene a Alkylaubstituenten containing 3 bi · 14 carbon atoms, and (b) an amino compound of the general formula

wherein X represents a hydrogen atom, a hydrocarbyl group having up to 20 carbon atoms or the group

ι rb, where the molar ratio of (a) to (b) is at least "i: 1 is,

.,:. i: 'Preferred alkylated N-phenylnaphthylamines are the mono · O' iü ::. ' • .Di- (C2-G ^^) - alkyl-W-phenylnephthylamiae · Sa can

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BAD ORtOlNAL

therefore Iaobutyl-, '-Heacyl-, Octyl-, Becyl- or Dodecyl-1-phenyl-α-oaphthylamine or similar, alkylated N-phenyl-β-naphthylamines or the dialkyl analogues are used. The Ükyl groups, of course, do not have to be the same for the dialkyl compounds. -Alkyl · - is substituted on the phenyl group, it is preferably in the pera position, although it is of course. ®b-en * ° so you can take the ortho or meta positions ₀

When there are two alkyl groups, the total number is of the carbon atoms in the two alkyl groups are preferred no more than 20 * There can of course other sub-substituents be in any of the aromatic rings, for example halogen atoms, nitro groups, etc. The preferred Elkylated Ϊί-Ehenylnaphthylamin is N- (tert-Quotylphenyl) -ß-naphthylamin.

Although it preferably Ehenylgruppe is that is alkylated, you identify one of the aromatic Hinge or both of Naphthylamint "ils of the molecule to be alkylated and the term" elkyliertes N-phenyl-naphthylamine "covers both possibilities" Suitable alkyl group substituent & »» N »phthyleminteils of Molecule; belong to those as mentioned epesially.

In order to avoid corrosion problems, it is preferred that component (a) should not contain any sulfur atoms

309815/1133

te acting as a substituent or part of a substituent group available.

The preferred component (b) is N.N -Tetramethyldiaminodiphenylmethane, i.e. when X is hydrogen. However, know it

/ ι
also for example .1.1-bis (NN -dimethylaminophenyl) -

1 1

heptane, N.N -Tetramethyldiaminotriphenylmethane or N.N .-

N -Hexamethyltriaminotriphenylmethane * If X is a Is hydrocarbyl group, it preferably contains 2 to 12 Carbon atoms.

The molar ratio of (a) to (b) must be at least 1: 1 and is preferably between 1: 1 and 13 * 1, in particular between 11 and 10: 1. A particularly preferred molar ratio is between 2: 1 and 4: 1 , and is, for example, about 2.3: 1.

The antioxidant mixture of the invention is in lubricating oils usable, especially with aviation turbine oils. When added to a lubricating oil, it should be in smaller proportions, preferably 0.001 to 10.0 wt. for example 0.1 to 5 »0 wt. ^, based on the weight of the lubricating oil, make up.

The lubricating oil to which the antioxidant mixture is added can, can any mineral ·, animal, fish, vegetable or synthetic oil, e.g. petroleum oil, fractions in the range from spindle oil to SAE 30, 40 or 50 lubricating oil,

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Here or I fish oils or oxidized mineral oil, for example Palm oil, lard oil, lalg oil, peanut oil or sperm oil ..

The preferred lubricating oil is a synthetic ester and suitable diesters include the diesters of the general formula

HOOGH ¹ GQQE. and RGOOE ¹ OQGE ₁

wherein E is a Gg to G ^ alkyl group, while E ^ is a Gn to C [Q saturated aliphatic hydrocarbon group or an ether-interrupted saturated aliphatic hydrocarbon group is. The types of esters given above can be selected from alcohols and dicarboxylic acids or glycols Monocarboxylic acids are produced.

Another suitable class of ester lubricants are the EoIyester, which by reacting polyhydric alcohols, for example with 2 to 12 hydroxyl groups per molecule and 2 to 40 carbon atoms per molecule., such as trimethylolpropane, Pentaerythritol and dipentaerythritol with mono- and / or dicarboxylic acids such as butyric acid, caproic acid, caprylic acid and pelergonic acid or with adipic, sebagic or Azelaic acids can be produced.

The complex esters that can be used as base oils are by teresterification reactions .. ·. ".. ...., a dicarboxylic acid a glycol and an alcohol and / or a monocarboxylic acid manufactured «These esters correspond to the

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- 6 - 'the following general formulas

R ₄ COO-R ₅ -C0OCR ₂ COO-R ₅ ) _n -00CR ₄ R ₁ -OOCK ₂ COO-CR ₃ -OOCR ₂ COO) _n -R ₁ R ₁ -C0OCR ₂ COO-R ₃ ) _n 00CR ₄ ,

where R _{1 is} alkyl radicals derived from a monohydric alcohol, R _{2 is derived} from a dicarboxylic acid, for example alkanedioic acids, hydrocarbon radicals derived from} R? divalent hydrocarbon or hydrocarbonoxy radicals such as "" 0H ₂ COHg) _n - or -CH ₂ GH ₂ COCH ₂ CH ₂ ) _n - or CH ₂ CHCCH ₅ ) (OGH ₂ GHCGH ₅ )) _n radicals derived from an alkylene glycol or polyalkylene glycol while R ^ represents the alkyl group derived from a monocarboxylic acid, "n" in the complex ester molecule is an integer, usually from 1 to 6 depending on the desired viscosity of the product, which is increased by the relative molar ratio of the glycol or polyglycol the dicarboxylic acid is controlled. During the preparation of the complex ester, a somewhat simple ester, ie n = 0, is always formed, but this will generally take up a small proportion. In general, these complex esters will have a total number of carbon atoms between 15 and 80, for example between 20 and 65 carbon atoms per molecule.

Particularly suitable lubricants are eaters of polyhydric alcohols of the general formula below

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CHpOH

β- 0 -OH ₂ OH

OB ₂ OH

wherein R is a -CH ₂ OH- group or an alkyl group, for example an alkyl group having 1 to 6 carbon atoms. Suitable esters of this type are therefore the lieopentyl polyol esters of trimethylolethane, trimethylolpropane, l'rimethylolbutän and of pentaerythritol or dipentaerythritol.

The preferred acids which are used for the esterification of trimethylolpropane are the G ^ - to 0>, ^ monocarboxylic acids. Particularly preferred are the C 1 -C 4 esters, for example Co (caprylic) and Cq (elargonic) acid esters. Mixtures of these Cr ₇ to G ^ ₂ acids can be used. When such a mixture of acids is used, it is preferred that the average of the mixture have between 8 and 9 carbon atoms. Although more difficult to manufacture, it is even more preferred that one methylol group esterify with a neoheptanoic acid, for example 2,2-dimethylpentanoic acid, and the remaining methylol groups with non-hindered acids, for example pelargonic acid. sincL ·. This particular ester is essentially as thermally stable as the fully hindered ester, but has superior volatility and low temperature properties.

The preferred- ·

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th acids are the C ^, - to C ^ Q-monocarboxylic acids, where the more preferred esters those of Cc to Cg acids, for example η-valerian, isovalerian, 2-ethylbutter, capron, n-heptyl, n-octanoic or 2-ethylhexoic acids or a mixture from Cc to Cq acids.

Geraische the diester with smaller proportions of one or more thickening agents can also be used as lubricants be used. So you can use mixtures that contain up to 50 Vol. ^ Of one or more water-insoluble polyoxyalkylene glycols, for example polyethylene or polypropylene glycol or mixed oxyethylene-z-oxypropylene glycol contain.

Suitable for the Gesturbinenschmiermittel formulations include from 65 to 90% by volume of one or more diesters of azelaic acid or sebacic acid and a C ₆ - to C ^. | ₆ -branched-chain alcohol, especially 2-ethylhexanol, or "oxo" alcohols, which predominantly consist of Oq, Cg or CjQ alcohols or of mixtures of such alcohols and 55 to Λ0% polyoxyalkylene glycol ethers of the general formula

RO

0H ₀ CH-O

—Q— 309815/1133

_ 9 -

in which the radicals R *, E and R _{2 are} hydrogen atoms, or CL- to CLp-alkyl groups and in which no more than two of these groups are hydrogen and η is an integer greater than 1. » Particularly useful compounds are polyoxypropylene glycol monoethers and the corresponding diethers «

The thermal stability of such diesters / polyoxyalkylene glycol ethers can be improved by adding a small proportion of a complex ester of three or more Carboxylic acids or alcohols, two of which are difunctional acids or alcohols, incorporates. Such Complex esters can have a glycol or a diacid center have, wherein a monohydroxy or monocarboxylic acid compound is terminal «A particularly preferred complex ester of this type comes from an ethylene glycol with a molecular weight of 2QO, 2 molecules of sebaoic or azelaic acid and 2 molecules of a Gg to CLiQ branched chain aliphatic monohydric alcohol, especially 2-ethylhexanol, from.

Further additives that can be incorporated into the lubricating oil include corrosion inhibitors, for example sebacic acid, a metal deactivator such as quinizarin, a foam inhibitor, for example a silicone polymer such as dimethyl silicone or an anti-abrasion additive, for example neutral alkyl phosphates such as l'ricresyl phosphate _? neutral alkylaryl phosphates or neutral phosphonates «,

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The following examples illustrate the invention.

example 1

Various antioxidant products were produced by mixing N- (tert-octylphenyl) -ß-naphthylamine (abbreviated Cq-FBNI.) And Li. N -tetramethyldiaminodiphenylmethane (abbreviated TMDDPM).

Each mixture was added separately to a synthetic Esterbasisöl which further contained 1.0 wt.% Tricreeylphosphat. The base oil was a mixture of complete esters obtained by esterifying 90 $ pentaerythritol and 10 $ dipentaerythritol with a mixture of (O ^ -C ^ q) fatty acids.

The mixture of oil plus antioxidant was subjected to the Rolls-Royce oxidation test (R-R1001) (D. Eng RD 2497 supplement method Wo.12) and the results obtained are summarized in the table below. For comparison purposes, tests were carried out in which G _Q - PBNA alone and TMDDPM alone and a mixture in which the molar ratio Co - PBNA to THDDPM is less than 1: 1, ie 0.77: 1.

In tests (1) and (2) relating to antioxidants, which are not in the area of the present invention. fall, the vapor deposition was called varnish

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found in the test tube, from which it can be seen that these two antioxidants are too dirty to use.

In experiments (5) and (6), which also concern antioxidants that are not within the scope of the present Invention fall, it should be noted that the A KV (increase in the kinematic viscosity), the! Volatility too high and the induction time too low compared to experiments (7) to (10) with the antioxidants within the scope of the present invention.

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Tabel

attempt

(D (2) (3) (4)

Rolls Royoe test (temp. 215 ⁰ C, 72 hours continuous) Antioxidant molar ratio $ Flüchtig- induction ΔKV about ΔΤΑΝ

and $ sentence, referring to
the oil

(a)

(b) speed

(a)

(b)

1. OZ C - PBHA

IZ TMDDPM IZ TMDDPM

1.5Σ Cg-PBNA 0.5Z TMDDPM

2Z C ₀ PBNA
ο

(10)

2Z Cg - PBNA

3Z C ₀ - PBNA
ο

3.0ZC ₀ -PBNA 1.OZ TMDDPM 8

3.0ZC ₀ -PBNA O.75Z TMDDPM

3.0ZC ₀ -PBNA 0.60Z TMDDPM ο

3.0Z Cg-PBHA 0.50Z TWDPM period h

KV c

99 ⁰ C

0.77: 1 2.31: 1 37.5 28.4 23.4 31.6

0 24 36 24

125

.

149

4.70 5.59 4.5

Benzene Insoluble % (c)

0.03 0.03 0.01

Temp. 215 ⁰ G, duration increased to 192 h

' ] [solidified after

56.6 24

2.31: 1 3.07: 1 3.84: 1 4.61: 1 54.7 28.9 34.7 37.1 40.0

48 192 84 82 89

428 64 131 142 118

4.32

2.50 4.34

4.22 3.75

168 h) *?

0.03

0.04 0.04

0.03 0.02

(c) Maximum acceptable value 0.05 wt .;

Example 2 . '

An antioxidant mixture of TMDDEM and G ₈ - EBNA- was prepared and added to a synthetic ester mixture, which consisted of complete esters, which consisted of mixed Gg- to C -.- fatty acids and a mixture of 80% by weight of eentaerythritol, 10 * Weight .% Dipentaerythritol, and 10 wt $ Triraethylolpropan were prepared containing 1 wt The Estergemisch ° J> tricresyl phosphate, and the antioxidant components were in the synthetic ester than 1 wt # TMDDEM and 3.0 wt ^ C ₈ -..., Based on EBEA the weight of the ester (molar ratio (a) :( b) = 2.3i1) is present.

For comparative purposes the procedure was repeated exactly, except .that instead of the TMDDEM Estergemisch was used containing 1.0 wt. ° / o Ii ₀ N -Tetraäthyldiaminodiphenylmethan (TEDDEM abbreviated.) (Molar ratio (a) :( b) = 2 , 8: 1).

When the mixtures were subjected to the Rolls-Royce oxidation test at 215 ° C for 192 hours, the following were obtained Results:

Antioxidant ^ Volatile Induc- AKV 210 ⁰ F A Benzene-

medium (99 ⁰ O) 'TAN insoluble'

time fo. Fabrics (hours) '. . ° / o

^: 1.0 wt. # TMDDEM

3.0 wt. # Cq-EBNA. 36.2 74-80 3.28 0

1.0 wt. ^ TEDDEM

48.2 48 182 4.33 0, Q7

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From the results it can be seen that it is much more advantageous to use TMDDPR instead of TEDDPM. to use.

Example 3

An antioxidant mixture of TMDDPM and N- (n-heptylphenyl) -ß-naphthylamine (abbreviated CU - PBNA) was prepared and added to a synthetic ester mixture containing complete esters made from mixed Og-G ^ Q fatty acids and a mixture of 90 Weight # pentaerythritol and $ 10 dipentaerythritol were produced. The ester mixture contained 1 wt. ⁰ Jo l'ricresyl phosphate and the antioxidation components were in the synthetic ester as 1.0 wt. # I ¹ MDDEM and 3.0 wt. # Cn PBNA, based on the weight of the ester (molar ratio (a ) :( b) - 2.4: 1) available.

Another iintioxidationsgemisch was prepared in the same manner, so that the synthetic ester 1.0 wt $> K. E .N -Hexameth; yltriamintriphenylmethan (HMTATPM) and 3.0% by weight C ₈ - PBNA (molar ratio (a)..: (b) = 3.14: 1).

These mixtures were included in the Rolls-Hoyoe Oxidation Test Subjected to 215 ° 0 for 192 hours, the was obtained

following results:

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Antioxidants -

Flüchtig- Indukkeit% TION,

time (hours)

1.0 wt % TMDDPM

3.0 wt % C ₇ PBNA. 28.9 192

1.0 wt % HMT-ATPM

3.0 wt % O ₈ EBNA. 3 ^, 3 192

(99 ⁰ O)

64

99

21O ⁰ P

Δ BenzolTAN insol. Fabrics

2.50 0.04

3.7Q 0.03

From the results it can be seen that with the two antioxidants included in the range of the present Invention fall, good results are achieved.

-Patent claims-

309815/1133 -16-

Claims (7)

-Ib claims; 1. Antioxidant blend, labeled
with at least one alkyl substituent, each of said bubstituenten ~ i> to 14 carbon atoms by (a) an alkylated IJ-phen ^ lnaplithylorain and (b) a Aininoverbindung of formula where α is a hydrogen atom having an ilydrocarbyl group up to 20 carbon atoms or the group and the pick ratio (e) to (b) is at least 1: 1. 2. Mixture according to claim 1, characterized in that the component (ε) is a hono- ouor di- (U ^ -C ^^,) -alk _c > li ^ -phen _l ylnBphth ^ lürain, vorzuKsweiue ij - (tert-Gctylphen, yl) -ii-naphth _< yl8min. -V- 309815/1133 t t t t 22A9031 - 17 - 3. Mixture according to one of the preceding claims, characterized in that the component (a) has two alkyl groups and the total number of Carbon atoms in the two alkyl groups no more than 2Q is. 4. Geraisch according to one of the preceding claims, characterized in that the molar ratio from (a) to (b) is between 1: 1 and 13: 1, preferably between 2: 1 and 4: 1. 5. Mixture according to one of the preceding claims characterized in that the component 1 11 1 (b) N.N.W -hexamethyltriaminotriphenyl methane or N.N tetramethyldiaminodiphenyl methane is", 6. Labeled lubricating oil preparation by a larger weight share. of a lubricating oil and a lesser proportion by weight of the antioxidant mixture / according to one of claims 1 to 5 ° 7. lubricating oil preparation according to claim 6 thereby characterized in that the lubricating oil is an aviation turbine oil, preferably an Esteu ¥ on pentaerythritol; is", 309815/1113