LUBRICANT CONTAINING ORGANO SULFUR-CONTAINING NICKEL COMPLEXES

1088306 BACKGROUND OF THE INVENTION i0 Field of the Invention This invention relates to lubricant compositions, and relates more particularly to lubricant compositions normally subject to degradation by ultra-violet light present, for example in such sources of actinic radiation, as sunlight.

Still more particularly, in one of its aspects, the invention relates to lubricant compositions, such as oils of lubricating viscosity, hydrocracked lubricating oils, hydraulic oils, mineral oils or fractions thereof, automotive oils, gear oils, transmission fluids, waxes, greases and other forms of lubricants normally requirìng the presence of stabilizing agents against the degradation effects of ultra-violet light.

I Description of the Prior Art In general, the production of lubricant compositions, for example, lubricating oils produced by hydrocracking, affords a relatively high viscosity index and permits the use of certain stocks that would be unsuitable for other processes. On the other hand, however, hydrocracked lubricating oils tend toward poor stability against ultra-violet light degradation, rapidly forming suspended and/or precipitated insoluble material on exposure to ultra-violet light, such as sunlight, or other sources Of actinic radiation. Compounds capable of absorbing ultra-violet light, for example, hydroxybenzophenones, and hydroxyphenyl benzotriazoles, have afforded some improvement in the light stability of hydrocracked oils. Conventional antioxidants have also provided some benefit.

8S L ì :20 I • i L i S : i•¸ • In the literature, Heskins and Guillet in "Mechanism of Ultraviolet Stabilization of Polymers", Macromolecules I, 97 (1968) first proposed the energy transfer mechanism of ultra-violet protection. Commercially available ultra-violet stabilizers are also listed by class and function and identified as to structure in the Kirt-Othmer Encyclopedia in "Encyclopedia of Chemical Technology"; Second Edition, Vol. 21, pp. 115-122.

Uri in "Thermal and Photochemical Oxidation of Polymers and Its Prevention", Chemistry and Industry, March i, 1975, pp. 199-203, cites conventional antioxidant effects (hydroperoxide decomposition and free radical capture) of bis(stilbenedithiolato)nickel and its ultra-violet inhibiting properties. In British Patent Specification 1,263,910 (1972), there is disclosed bis(stilbenedithiolato)nickel as an antioxidant for plastic materials. The specification also cites superior hydroperoxide decomposition capability of this additive. U.S. patent 3,832,304, discloses the use of aromatic azo compounds for stabilizing hydrocracked oils. None of the foregoing disclosures show lubricant compositions containing the organo sulfur-containing nickel complexes described herein.

SUMMARY OF THE INVENTION In accordance with the present invention, we have found that degradation against ultra-violet light, present in sunlight or other sources of actinic radiation can be effectively imparted to lubricant compositions by the incorporation therein of organo sulfur-containing nickel complexes. These nickel complexes are particularly effective against ultra-viOlet degradation in such lubricating media as oils of lubricating "i f:

ï 1O883O6 viscosity, hydrocracked lubricating oils, hydraulic oils, mineral oils or factions thereof, automotive oils, gear oils, transmission fluids, waxes, greases and other forms of lubricant compositions normally requiring the presence of stabilizing agents against the degradation effect of ultra-violet light, In particular, there is provided by the present invention, a lubricant composition comprising a major proportion of a hydrocarbon oil lubricant and a minor proportion, sufficient to provide stability of said composition against degradation by ultra-violet radiation, of a nickel complex phenol sulfide complex.

The organo sulfur-containing nickel complexes can be effectively employed in any amount which is sufficient for imparting to the lubricant the desired degree of protection against ultra-violet degradation. In many instances, the nickel complex is effectively employed in an amount from about 0.01 to about 5%, by weight, and preferably in an amount from about 0.i to about 2%, by weight, of the total weight of the lubricant composition. The term "nickel complex", as used herein is intended to include nickel compounds having a chelate ring formation. As hereinbefore indicated, the organic sulfurcontaining nickel complexes may be incorporated in any lubricating media which can include oils of lubricatìng viscosity and also greases in which any of the aforementioned oils are employed as vehicles. In general, synthetic oils can also be effectively protected against ultra-violet degradation or may also be employed in combination with mineral oils, or as grease vehicles. Typical synthetic vehicles include polyìsobutylene, polybutenes, hydrogenated polydecenes, polypropylene glycol, polyethylene glycol, trìmethylol propane esters, neopentyl and pentaerythritol esters, di(2-ethyl hexyl) sebacate, di- (2-ethyl hexyl) adipate, dibutyl phthalate, fluorocarbons, silicate esters, silanes, esters of phosphorus-containing acids, liquid ureas, ferrocene derivatives, hydrogenated mineral oils, chain-type polyphenols, siloxanes and silicones (polysiloxanes), alkyl-substituted i0 !il • • ,i•¸ - 4a - t i; lO 1088S06 diphenyl ethers typified by a butyl-substituted bis-op-phenoxy phenyl) ether, phenoxy phenylether, etc.

Particularly desirable organic sulfur-contalning nickel complexes in accordance with the present ìnvention include commercially available nickel phenol sulfides, nickel alkylthioamines, nickel dithiophosphates and nickel dìthiocarb tes.

Nickel phenol sulfides may be employed having, for example, the structure:

in which R is either hydrogen or an alkyl group having up to carbon atoms.

Representative of the nickel phenol sulfides are nickel bis(octylphenol) sulfide having the structure:

3H17 and nickel bisphenol sulfide having the structure:

1.088506 The sulfur-containing nickel phenol-phenolates are useful materials. They are described, for example, in U.S.

Patents Nos. 2971940 and 2971941. They comprise nickel salts of bisphenol sulfides in which only a portion of the total phenolic hydrogen has been replaced by nickel. They may have formulae such as the following:

H R s I I / I / I Ni R R f J f f I I o/ t s F• i / i s R R f -, OH R OH F (a) where R is H or an alkyl group, suitably of up to 30 carbon at oms.

A mixture of these two compounds (designated here as "Mixture A"), where R is octyl, is a good ultra-violet stabiliser.

Sulfur-contalnlng nickel amine complexes are described in U.S. Patents Nos. 3215717 and 3313770.

5(b) Representative of the nickel alkylamines is [2,2'-thio-bis(4-tert-octylphenolato)]-n-butylamine nickel having the structure C8H17 O NH2C4H9 Representative of the nickel thiophosphates is nickel di(4-methyl-2-pentyl) dìthiophosphate having the structure - - NiS- P 613o octa13 !i i' Representative of the nickel dithiocarbamates is nickel dibutyl dithiocarbamate having the structure C4H9 18SSS DESCRIPTION OF SPECIFIC EMBODIMENTS In order to evaluate the effectiveness of the organo sulfur-containing nickel complexes of the present invention against ultra-violet degradation in lubricant media, the following test was employed:

This test utilized a base oil, viz. a hydrofinished hydrocracked i00" oil obtained by dewaxing 725°F bottoms from a first-stage product of a fuel hydrocracker. Blends of additives with the aforementioned hydrocracked base oil were tested by subjecting 20 grams of the test oil in a capped fourounce tall form bottle to daylight on a window sill with a southeast exposure. The test oil was observed each day for suspended insoluble products, which usually progress from a haze to a suspended floc and precipitates, which generally are preceded by hazes or floes, and often consist of settled haze or floc. In the following Table I are recorded the results obtained employing 0.1 weight percent additives in the aforementioned hydrocracked base oil. From the table, it will be noted that the nickel complexes of the present inventìon are much more markedly effective against ultra-violet degradation (Examples 2-6) than the best of the commercially available conventional antioxidants and ultra-violet absorbers (Examples 7-11).

I Ex. Additive 1 None (Base Oil) 2 Mixture A 3 Nickel bisphenol sulfide [2,2'-thio-bis(4-tertoctylphenolato)]-nbutylamine nickel Nickel dibutyl dithio carbamate Nickel di(4-methyl-2pentyl)dithiophosphate Di-t-butyl para cresol Phenyl alpha-naphthylamine Zinc di(4-methyl 2-pentyl) dithiophosphate 2,2'-dihydroxy-4-methoxybenzophenone 2-(2'-hydroxy-5'-methylphenyl) benzotriazole TABLE I Daylight Exposure Tests of Hydrocracked Base StOck Containing 0.i Wt. % Additives Number of Days/Condition 1 4 8 Slightly hazy Hazy, heavy Ppt.

Clear Very slightly hazy Slightly hazy Clear, light Ppt.

Very slightly hazy, Lt Ppt.

Slightly hazy, Lt Ppt.

Clear Hazy Clear Clear Clear Clear Clear Clear Clear Slightly hazy, Medium Ppt.

Lt suspended Floc, hvy Ppt.

Suspended Floc, Medium Ppt.

Suspended Floc, Medium Ppt.

Slightly hazy, Trace Ppt.

Slightly hazy Hazy Suspended Floc, Heavy Ppt.

Slightly hazy, heavy Ppt.

Suspended Floc heavy Ppt.

Suspended Floc, heavy Ppt.

Suspended Floc, heavy Ppt.

Suspended Floc, heavy Ppt.

Hazy, heavy Ppt.

Hazy, heavy Ppt.

Lt suspended Floc, hvy Ppt.

1 883 In the following Table II are recorded the results obtained employing 0.5 weight percent additives in the abovedescribed hydrocracked base oil of Table I. Here, also, it will be noted from the table that, when subjected to the above-described test, the organo sulfur-containing nickel complexes in the lubricant compositions of the present invention are much more markedly effective against ultra-violet degradation (Example 2-4) than the best of the aforementioned commercially available conventional antioxidants and ultraviolet absorbers (Example 5-9).

/i i !L Ex. Additive 1 None (Base oil) 2 Mixture A ' 4 O Nickel di(4-methyl-2pentyl)dithiophospha e [2,2 '- thio-bis ( - te rtoctylphenolato) ]-nbutylamlne nicke I Di-t-butyl para c esol Phenyl alpha-naphthylamine Zinc di(4-methyl 2-pentyl) dithlophosphate 2,2'-d% hydroxy-4-methoxybenzophenone 2-(2'-hydroxy-5'-methylphenyl)benzotriazole TABLE II Daylight Exposure Tests of Hydrocracked Base Stock Containing 0.5 Wt. % Additives Number of Da s/Condit.ipn 4 8 Slightly Hazy, hvy ppt.

Clear Clear Clear Clear Clear Clear Slightly hazy Slightly hazy Slightly hazy, medium ppt.

Suspended floc, hvy ppt.

Clear Suspended floc, medium ppt.

Clear Suspended floc, medium ppt.

Clear Very slightly hazy Clear Slightly hazy Hazy, medium ppt.

Hazy, hvy ppt.

Clear Hazy Hazy, hvy ppt.

Slightly haz medium ppt.

Lt. suspended floc, hvy ppt.

'fABLE II CONTINUED J ,7 Daylight Exposure Tests of Hydrocracked Base Stock Containing 0.5 Wtt Additives Additive Number of Dav/Condition 1'8 s5 None (Base oil) Hazy, Lt. ppt.

Mixture A Clear Clear Nickel di(l -methyl-2pentyl)dithiophosphate Lt. suspended floc, hvy ppt.

[2,2'-thio-bis(4-tertoctylphenolato)]-nbutylamine nickel Di-t-butyl para cresol Phenyl alpha-naphthylamine Zinc di(4-methyl 2-pentyl) dlthiophosphate 2,2'-dlhydroxy-4-methoxy benzophenone 2-(2'-Çydroxy-5'-methylphenyl)benzotriazole 1088S06 In the following Table III is shown the effectiveness of a typically representative nickel complex of the present invention viz. nickel bis(octylphenol)sulfide in a 200" hydrocracked base oil (Base oil i) and also in another base oil (Base oil 2) riz. a heavy vacuum gas oil. As shown in the table, the nickel (octylphenol)sulfide of the present invention was markedly effective in reducing the ultra-violet degradation of the respective base oils.

....... ...... I x i • : • : » i:% « i J : :. " " TABLE III Daylight Exposure Tests of Hydrocracked Oils Containing Nickel(octylphenol)sulfide EX.

Additive None (Base oil l) 0.5% Nickel(octylphenol)sulfide 0.1% Nickel(octylphenol)sulfide None (Base oil 2) 0.5% Nickel(octylphenol)sulflde Number of aFs/Condition Clear Slightly hazy, hvy ppt.

Hazy, hvy ppt.

Clear Very slightly Very slightly hazy hazy Clear Very slightly Very slightly hazy hazy I Hazy, suspended floc, hvy ppt.

Very slightly hazy, trace ppt.

Very slightly hazy, trace ppt.

Slightly hazy, trace ppt.

TABLE III CONTINUED Daylight Exposure Tests of }lydrocracked Oils Contalnin6 Nickel(octy!phenol)sulfide Ex. Additive 12 None (Base oil l) 0.5%Nickel(octylVery slightly phenol)sulfide hazy 3 O.1% Nickel(octylVery slightly Suspended floc, phenol)sulfíde hazy hvy ppt« None (Base oil 2) 0.5% Nickel(octylHazy, trace phenol)sulfide ppt.

Number of Days/Condltion Very slightly hazy, trace ppt.

Very slightly hazy, trace ppt.

o l0 1 S8506 in %he following Table iV is shown %he effectiveness of ç3 ica!!3r representative nicke! complexes of the present invention, as antioxìdants in lubricant composltions. The representative additives were individually blended in 150" solvent-refined paraffinic minerai oil and were subjected to the standard Rotary Bomb Oxidation Test in accordance with test method ASTM D-2272.

As will be noted from the table, the oxidation lire of the base oll was markedly increased by the antioxidant effect imparted by the nickel complexes of the present invention.

i TABLE IV Ant!oxidant Effects of Nickel Complexes A None (Base Oil) 1% [2,2'-th!o-bis(h-tertoctylphenolato)]-nbutylamine nickel I% Mixture A 1% Nickel di(4-methyl-2pentyl) dithiophosphate 0.25% Nickel dibutyldithiocarbamate RBOT Lifer minutes 6o 8o !i i[hile his invention has been described with reference to preferred compositions nd components therefor, iz »:ill be OEnderstood by those skilled in the art that departure from the preferred embodiments can be effectively made and are within the scope of the specification.

i i / i , 1088506 J t i iï! • The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

i. A lubricant composition comprising a major proportion of a hydrocarbon oil lubricant and a minor proportion, sufficient to provide stability of said composition against degradation by ultraviolet radiation, of sulfur-containing nickel phenol-phenolates and mixtures thereof having the following formulae:

R R / i111 R I I I t ! Ho I ç ' ,, Si R f 0 Oit OH wherein R is hydrogen or an alkyl group containing up to carbon atoms.