Lubricating Compositions

Abstract

Lubricating compositions, particularly useful for manufacturing multigrade oils, hydraulic fluids, oils for industrial gears and cutting oils, comprising 5 - 95 percent by weight of a hydrocarbon oil produced according to a conventional process and 5-95 percent by weight of a compound selected from the group consisting of the esters of polyalkyleneglycol ethers complying with the general formula: ##SPC1## Wherein R.sub.1 is a divalent hydrocarbon radical having from one to 34 carbon atoms, R.sub.2 and R'.sub.2 are divalent aliphatic radicals having from two to five carbon atoms, R.sub.3 and R'.sub.3 are monovalent hydrocarbon radicals having from one to twenty-five carbon atoms and n.sub.1 and n.sub.2 are integers from two to 50, and those complying with the general formula: ##SPC2## Wherein R.sub.4 is a hydrocarbon radical of valency m, having from three to 15 carbon atoms, R.sub.5 is a monovalent hydrocarbon radical having from one to 25 carbon atoms, R.sub.2 is a divalent aliphatic radical having from two to five carbon atoms, n is an integer from two to 50 and m is an integer from two to four.

Description

This invention relates to new lubricating compositions consisting of mixtures of conventional hydrocarbon oils and derivatives of polyalkyleneglycols.

The conventional base oils are prepared according to different methods. The main processes for manufacturing these oils are the acid or solvent refining of vacuum distillates or deasphalted vacuum residues from crude oils, the hydrotreatment of the same petroleum cuts and the oligomerization of olefinic hydrocarbons.

In the first of these processes, a vacuum distillate or deasphalted vacuum residue can be subjected to a solvent extraction for example by means of furfurol or phenol, so as to eliminate from the petroleum cut the aromatic compounds contained therein, then to a series of treatments such as dewaxing, clay bleaching and moderate hydrogenation, at a temperature of from 250.degree. to 350.degree.C, under a hydrogen pressure of 20 to 80 kg/cm.sup.2 in the presence of a catalyst.

In the case of certain crude oils containing a small proportion of aromatic compounds, it is possible to replace the solvent extraction by an acid treatment, generally with sulfuric acid.

The second process, the hydrotreatment of the abovementioned petroleum cuts, may be achieved, for example, according to the teaching of U.S. Pat. No. 3,560,370, in the name of the applicant.

In this Patent, the hydrotreatment is conducted at a temperature of from 350.degree. to 450.degree.C, under a hydrogen pressure of from 80 to 240 kg/cm.sup.2 and in the presence of a catalyst.

In the third process, the oil is manufactured by oligomerizing olefinic hydrocarbons having from two to 20 and preferably from nine to 16 carbon atoms per molecule.

This oligomerization may be achieved by the action of catalysts consisting of aluminium halides, or by the action of heat, in the presence of organic peroxides acting as initiators.

The oils prepared according to the above-described processes generally exhibit viscosity indexes of from 50 to 160 and, more particularly, from 50 to 110 for solvent refined oils, from 50 to 150 for the hydrorefined oils and from 110 to 160 for the oligomerization oils.

It can be observed that the oils obtained in the two last above-described processes already exhibit much better characteristics than those obtained by the first process. For their various uses, all these oils require the addition, besides the conventional additives such as detergents or antioxidants, of more or less substantial amounts of viscosity additives, which however, exhibit inherent disadvantages such as poor thermal and/or mechanical stability.

Moreover, these conventional oils necessitate a compromise between a low cold viscosity, a sufficient viscosity at high temperature (100.degree.- 150.degree.C) and a low volatility.

It is known that the above mentioned drawbacks have been partly avoided by adding to the conventional base oils a certain amount of synthetic oils consisting of esters of polycarboxylic acids or of polyols. The improvement achieved by the use of these products is however very limited, with respect to the viscosity index.

It is an object of this invention to provide new lubricating compositions exhibiting viscosity-temperature characteristics so improved that the amount of viscosity additives that must be incorporated thereto is very substantially decreased (or even nullified). Consequently, their thermal stability and mechanical resistance to shearing are also improved and their volatility is reduced. Moreover, they exhibit such an exceptional lubricating power that their use makes it possible to avoid mechanical difficulties such as seizing and pitting, as well as to reduce the wear of the machines lubricated therewith. These qualities are particularly useful for lubricating engines operating under severe conditions, hydraulic circuits, gears of various types as well as in machining metals.

The present invention relates to new lubricating compositions which contain generally a compound (A) consisting of a hydrocarbon oil and a compound (B) selected amongst the esters of polyalkyleneglycol ethers.

The hydrocarbon oil (A) is selected among the mineral oils obtained either by solvent refining or by acid treatment, or by severe hydrotreatment of vacuum distillates or deasphalted vacuum residues from crude oils and the synthetic oils obtained by oligomerizing olefinic hydrocarbons having from two to 20 carbon atoms per molecule.

Generally, compound (B) results from the esterification of a dicarboxylic acid by at least one ether of polyalkyleneglycol and of monoalcohol or by the esterification of an ether of polyalkyleneglycol and of polyol by at least one monocarboxylic acid. More particularly, compound (B) complies with the general formula : ##SPC3## (1)

wherein R.sub.1 is a divalent hydrocarbon radical having from one to 34 carbon atoms, R.sub.2 and R'.sub.2 are divalent aliphatic radicals having from two to five carbon atoms, R.sub.3 and R'.sub.3 are monovalent hydrocarbon radicals having from one to 25 carbon atoms, and n.sub.1 and n.sub.2 are integers from two to 50, or with the general formula : ##SPC4## (2)

wherein R.sub.4 is a hydrocarbon radical of valency m, having from three to 15 carbon atoms, R.sub.5 is a monovalent hydrocarbon radical having from one to 25 carbon atoms, R.sub.2 is a divalent aliphatic radical having from two to five carbon atoms, n is an integer from two to 50 and m is an integer from two to four, with the provision that radicals R.sub.2 and R.sub.5 and integer n may be different from one chain to another.

Compound (B) may also result from the esterification of an ether of polyalkyleneglycol and of polyol having the formula : ##SPC5##

wherein R.sub.2, R.sub.4, n and m are defined as above, by means of a mixture of monocarboxylic acids ##SPC6##

and dicarboxylic acids ##SPC7##

wherein R.sub.1 and R.sub.5 are defined as above.

Most of the esters of polyalkeneglycol ethers contemplated according to this invention are miscible with mineral or synthetic oils in rather large proportions, their miscibility with fluid oils being better than with more viscous oils, and better with naphthenic oils than with paraffinic oils.

Moreover, since the polyethyleneglycol derivatives, for a given oil, are less easily miscible than those of polypropyleneglycol, there are used preferably polypropyleneglycol derivatives or still mixed derivatives of poly (ethylene-propylene)glycol in which the ratio ethylene oxide/propylene oxide is kept lower than or equal to 1/1.

In this latter case, it is preferred to make use of mixed derivatives complying with formulae (1) and (2) wherein the radicals R.sub.3 and R'.sub.3 on the one hand and the radicals R.sub.5 on the other hand are relatively heavy and contain for example from 10 to 25 carbon atoms.

As examples of compounds (B) that can be used in the compositions according to the invention, there can be mentioned :

the dodecanedioate of the ether obtained by condensation of propylene oxide with isobutanol;

the decanedioate of the ether obtained by condensation of a mixture of ethylene and propylene oxides (25/75 by weight) with 2-ethyl hexanol;

the didodecanoate of the ether obtained by condensation of propylene oxide with neopentylglycol;

the diisotridecanoate of the ether obtained by condensation of propylene oxide with 1,6-hexanediol;

the trinonanoate of the ether obtained by condensation of propylene oxide with trimethylolpropane;

the triethylhexanoate of the ether obtained by condensation of propylene oxide with glycerol;

the trioleate of the ether obtained by condensation of a mixture of ethylene and propylene oxides (50/50 by weight) with trimethylolhexane;

the tetraheptanoate of the ether obtained by condensation of propylene oxide with pentaerythritol;

the ester resulting from the simultaneous treatment of the ether obtained by condensation of propylene oxide with trimethylolpropane by a mixture, in a molar ratio of 2/1, of heptanoic acid and dodecanoic acid;

the ester resulting from the simultaneous treatment of the ether obtained by condensation of propylene oxide with trimethylolpropane by a mixture, in a molar ratio of 4/1, of dodecanoic acid and azelaic acid; and

the ester resulting from the simultaneous treatment of the ether obtained by condensation of propylene oxide with trimethylolpropane by a mixture, in a molar ratio of 8/1, of dodecanoic acid and isononadecanedioic acid.

The compositions according to the invention may contain the hydrocarbon oil (A) in a major proportion (50 to 95 percent by weight) as compared with the ester of polyalkyleneglycol ether (B) (5 to 50 percent by weight), or, on the contrary, the compound (B) may be present in a major proportion (50 to 95 percent by weight) as compared with the compound (A) (5 to 50 percent by weight). More generally, the compositions containing from 5 to 95 percent by weight of each of the compounds (A) and (B) are to be considered.

In order to increase the miscibility of compounds (A) and (B), it may be contemplated to add to their mixture an amount of about 2 to 20 percent by weight of a third solvent such as an ester of dicarboxylic acid or of polyol, e.g., isodecyl adipate, trimethylhexyl azelate, neopentylglycol pelargonate, ethylhexyl sebacate, trimethylolpropane tripelargonate.

The compositions of the invention may be used for manufacturing motor oils and particularly multigrade oils; they are also advantageously used for manufacturing hydraulic fluids, oils for gear-boxes, oils for industrial gears or oils for the cut or the forming of metals. In all these applications, the lubricating and anti-wear properties of the compositions according to the invention appear of particular interest since they permit a good working security and an extended life for the mechanisms lubricated therewith.

The esters of polyalkyleneglycol ethers used in the lubricating compositions of the invention may be prepared by direct esterification of the ether obtained by condensing at least one alkylene oxide with the suitable monoalcohol or polyol, by means of one or more convenient mono or dicarboxylic acids, in the presence of a convenient catalyst, the water produced being removable by azeotropic entrainement by means of a solvent.

After the end of the reaction, the remaining acidic products may be removed either by washing with a hydroalcoholic potash solution and then with water or by clay treatment. The solvent is then expelled under vacuum and the residue, consisting of the ester of polyalkyleneglycol ether, may be recovered without having to be distilled.

The following examples illustrate the invention but are not to be considered in any way as limiting the scope thereof.

EXAMPLES 1 to 13

In these examples, various compositions according to the invention have been prepared by determining the proportions of hydrocarbon oil and of polyalkyleneglycol compound so as to obtain multigrade oils having given viscosity characteristics.

By way of comparison, an attempt has been made to prepare multigrade oils exhibiting the same viscosity characteristics from pure hydrocarbon oils (examples 3, 5, 7, 9, 11 and 13).

The desired characteristics are indicated in Table I, below : ##SPC8##

To each of the base mixtures indicated in Table II, 6 percent by weight of an anti-oxidant and detergent additive has been added. The amount of viscosity additive (polymethacrylate) required for obtaining the desired characteristics have been reported. TABLE II ##SPC9##

Test of Lubricating Power

A lubricating composition consisting of 50 percent by weight of 150 neutral mineral oil and 50 percent by weight of trioleate of the ether obtained by condensation of a 50--50 mixture of ethylene oxide and propylene oxide with trimethylolpropane, has been tested for its anti-wear properties and its load capacity.

By way of comparison, a pure 150 neutral mineral oil and the same oil containing 1 percent by weight of zinc dialkyldithiophosphate of a commercial quality, have been also tested.

The tests have been carried out with a four balls E.P. machine.

The conditions of the anti-wear test are :

running speed : 1,500 runs per minute,

constant load : 30 kgf,

duration : 1 hour.

The average diameter of the three lower balls is an indication of the anti-wear power under limit lubrication conditions.

The properties of load capacity have been tested according to the standardized method ASTMD 2596 or federal test method standard 791 D No. 6503 - I

The results of the tests are given in Table III below : ##SPC10##

These results show that, in addition to the improved viscosity performances, the lubricating compositions of the invention exhibit anti-wear properties and a charge capacity particularly satisfactory, which permit, if desired, to avoid the use of specific additives, which otherwise may result in some drawbacks such as :

an insufficient resistance to hydrolysis ;

a relatively low thermal stability.

Claims

What we claim is :

1. A lubricating composition containing from 5 to 95 percent by weight of a compound (A) consisting of a hydrocarbon oil selected among the solvent-refined mineral oils, from acid-refined mineral oils, the hydrorefined oils and the synthetic oils obtained by oligomerization of olefinic hydrocarbons having from two to 20 carbon atoms per molecule and from 5 to 95 percent by weight of a compound (B) selected among the esters of polyalkyleneglycol ethers resulting from the esterification of a polyalkyleneglycol and polyol ether having the formula : ##SPC11##

wherein R.sub.4 is an aliphatic hydrocarbon radical of valency m, having from three to 15 carbon atoms, R.sub.2 is a divalent aliphatic radical having from two to five carbon atoms, n is an integer from two to 50, and m is an integer from two to four, by a mixture of monocarboxylic acids of the formula ##SPC12##

wherein

R.sub.5 is a monovalent aliphatic hydrocarbon radical having from one to 25 carbon atoms and of dicarboxylic acids of the formula ##SPC13##

wherein R.sub.1 is a divalent aliphatic hydrocarbon radical having from one to 34 carbon atoms.

2. A composition according to claim 1, in which compound (B) is an ester of polypropyleneglycol ether.

3. A composition according to claim 1, further containing from 2 to 20 percent by weight of a third solvent selected from the group consisting of: (a) esters of dicarboxylic acids and aliphatic monoalcohols, and (b) esters of monocarboxylic acids and aliphatic polyols.

4. A composition as defined by claim 1, wherein compound (B) is selected from the group consisting of the esters resulting from the simultaneous esterification of an ether obtained by condensation of propylene oxide with trimethylol propane with a mixture, in a molar ratio of 4/1, of dodecanoic acid and azelaic acid, and the esters resulting from the simultaneous esterification of an ether obtained by condensation of propylene oxide with trimethylolpropane with a mixture, in a molar ratio of 8/1, of dodecanoic acid and isononadecanedioic acid.

5. A composition according to claim 1, wherein R.sub.4, R.sub.2, R.sub.5, and R.sub.1 are saturated aliphatic hydrocarbyl groups.

6. A lubricating composition as defined by claim 1, wherein compound (B) is an ester of poly(ethylene-propylene) glycol ether, said glycol having a ratio of ethylene oxide:propylene oxide of not more than 1:1 respectively.