2-OCTANOL MONOESTER AS LUBRICANT

- ARKEMA FRANCE

The present invention relates to a lubricating composition comprising: from 0.1% to 30% by weight, with respect to the total weight of the composition, of at least one 2-octanol monoester of formula R1-C(═O)OR2, in which R1 denotes an alkyl group comprising from 8 to 36 carbon atoms and R2 denotes 1-methylheptyl, and at least one base oil. The invention also relates to the use of the 2-octanol monoester as additive in a lubricating composition.

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Description

The present invention relates to a lubricating composition comprising a 2-octanol monoester and to the use of this ester as an additive in a lubricating composition.

Lubricating compositions, also known as lubricants, are commonly employed in order to reduce the frictional forces between different moving metal parts, whether in an engine, on an industrial production line, or also the frictional forces generally between a tool and a part, as is the case in particular for cutting oils (metalworking fluids) or calendering (rolling). These oils can in particular take up the heat formed by the friction and the deformation of the metal parts. They thus makes it possible to ensure the corrosion protection of the tools, parts and machines. They make it possible to clean the treated surfaces in order to ensure correct roughness of these treated surfaces. They are in addition effective in preventing premature wear of, indeed even damage to, these parts and in particular their surface.

To do this, a lubricating composition is conventionally composed of a base oil, with which are generally combined one or more additives dedicated to stimulating the lubricating performance qualities of the base oil, such as, for example, friction-modifying additives, but also to providing additional performance qualities. For example, detergent additives are very often considered in order to prevent the formation of deposits at the surface of the metal parts by dissolution of the secondary oxidation and combustion products.

In point of fact, it turns out that it is still advantageous to improve the lubricating compositions, by improving the coefficients of friction, in particular under shear forces. This is because, in order to reduce friction to a desired and suitable level, it is advantageous to retain a relatively low viscosity between the elements to be lubricated. However, this viscosity has a tendency to increase under pressure and shear forces.

An overall increase in the friction is often observed in contact, particularly in the “boundary lubrication” range according to the Stribeck curve, thus showing that lubricating formulations can act less effectively.

In point of fact, increases in frictional actions are harmful in the various industrial applications because they can reduce productivity, increase energy consumption and cause defects, to mention only the disadvantages most frequently encountered.

There thus exists a real need for lubricating compositions which make it possible to further reduce the frictional forces of metal parts, in particular under shear forces.

BRIEF DESCRIPTION OF THE INVENTION

Thus, a subject matter of the present invention is a lubricating composition comprising:

    • from 0.1% to 30% by weight, with respect to the total weight of the composition, of at least one 2-octanol monoester of following formula:


R1—C(═O)OR2

    • in which:
      • R1 denotes an alkyl group comprising from 8 to 36 carbon atoms and
      • R2 denotes the 1-methylheptyl group, and
        at least one base oil.

It has been observed that the 2-octanol monoester defined above makes it possible to reduce, surprisingly, the frictional forces when it is present in a lubricating composition.

Thus, it has been observed that 2-octanol monoesters make it possible, by their hydrodynamic properties under shearing, but also by better physical wetting, to improve the effectiveness of the lubricating composition, in particular in the zone of “boundary” lubrication (strong contact between surfaces, very slight lubricating films).

Moreover, it exhibits the advantage of being able to be obtained from renewable starting material. This is because 2-octanol, the precursor of the ester of use in the composition according to the invention, can advantageously be obtained by pyrolysis of natural vegetable oil and in particular of castor oil.

The invention also relates to the use of the ester as defined above as additive in a lubricating composition.

BRIEF DESCRIPTION OF THE FIGURE

FIG. 1 is a graph representing the change in the coefficient of friction of the exemplified compositions as a function of the temperature.

 DETAILED DESCRIPTION OF THE INVENTION

Other characteristics, aspects, subject matters and advantages of the present invention will become even more clearly apparent on reading the description which follows.

It is specified that the expressions “from . . . to . . . ” and “of between . . . and . . . ” used in the present description should be understood as including each of the limits mentioned.

The Lubricating Composition

The invention relates to a lubricating composition comprising:

    • from 0.1% to 30% by weight, with respect to the total weight of the composition, of at least one 2-octanol monoester of following formula:


R1—C(═O)OR2

    • in which:
      • R1 denotes an alkyl group comprising from 8 to 36 carbon atoms, preferably from 10 to 36 carbon atoms, more preferentially from 10 to 26 carbon atoms, advantageously from 11 to 26 carbon atoms and more particularly from 12 to 24 carbon atoms, and
      • R2 denotes the 1-methylheptyl group, and
        at least one base oil.

The term “alkyl group” is understood to mean a saturated, linear or branched, hydrocarbon chain originating, for example, from saturated, linear- or branched-chain, fatty acids, or also from unsaturated, linear- or branched-chain, fatty acids converted into saturated fatty acids by hydrogenation (according to techniques well known to a person skilled in the art), and/or also hydroxylated, linear- or branched-chain, fatty acids converted into saturated fatty acids by dehydration (according to techniques well known to a person skilled in the art).

The 2-octanol monoester

The 2-octanol monoester can be easily obtained by esterification of a saturated fatty acid as defined above with 2-octanol. The fatty acid can be chosen from lauric acid, myristic acid, palmitic acid, stearic acid and arachidic acid. Thus, the ester can be chosen from 2-methylheptyl laurate, 2-methylheptyl myristate, 2-methylheptyl palmitate, 2-methylheptyl stearate and 2-methylheptyl arachidate. Preferably, 2-methylheptyl palmitate is included in the composition according to the invention.

According to one embodiment of the invention, the lubricating composition can comprise several 2-octanol monoesters.

The composition according to the invention comprises from 0.1% to 30% by weight, with respect to the total weight of the composition, of at least one 2-octanol monoester, preferably between 0.1% and 25%, more particularly between 0.1% and 20%, and entirely preferably between 0.1% and 20%, for example between 0.1% and 15%. According to a preferred aspect, the composition according to the invention preferably comprises between 0.5% and 25%, more particularly between 1% and 20%, and entirely preferably between 2% and 20%, for example between 3% and 15%.

Base Oil

The lubricating composition according to the invention comprises at least one base oil. The base oils particularly suitable for the requirements of the invention are advantageously chosen from the base oils conventionally used in the field of lubricating oils, among which may be mentioned mineral, synthetic or natural, animal or vegetable oils, and also the mixtures of two or more of them in all proportions.

The base oils, in particular those used in the metalworking or rolling field, generally belong to one of the following four classes:

    • “straight oils”, also known as “cutting oils” or “neat oils”: these oils are, for example, mineral (petroleum), animal, marine, vegetable or synthetic oils and can be refined, by means of solvents or by hydrotreating, in order to reduce the amount of polyaromatic hydrocarbons (PAHs); straight oils are generally used as such, optionally with additives, and are rarely diluted with water;
    • “soluble oils” (emulsifiable oils), which generally comprise from 30% to 85% of refined petroleum oils, and also, if appropriate, emulsifiers in order to promote the emulsion of the oil in water;
    • “semisynthetic fluids”, which generally comprise from 5% to 30% of refined petroleum oils, from 30% to 50% water, and additives;
    • “synthetic fluids”, which generally do not comprise petroleum oils but detergent-type compounds and other additives intended to “wet” the part to be treated.

In the context of the present invention, the term “base oil” is understood to mean an oil having a lubricating viscosity. The base oil can be natural oils, synthetic oils, semisynthetic oils or their mixtures.

The natural base oils can be animal oils and vegetable oils, such as castor oil, mineral lubricating oils, liquid petroleum oils, solvent- or acid-treated mineral lubricating oils of paraffinic, naphthenic or mixed paraffinic-naphthenic type, oils based on coal or on oil shale having a lubricating viscosity.

The synthetic base oils can be chosen from hydrocarbon oils and oils based on halogenated hydrocarbons, such as homopolymerized and copolymerized olefins, for example polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1-hexene), poly(1-octene) and poly(1-decene) and their mixtures, alkylbenzenes, such as dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes and di(2-ethylhexyl)benzenes, polyphenyls, such as biphenyls, terphenyls or polyphenyls which are alkylated, alkylated diphenyl ethers and alkylated diphenyl sulfides and their derivatives, alkylene oxide polymers and copolymers and their derivatives, in which the terminal hydroxyl groups have been modified by esterification or etherification. The products of the polymerization of ethylene oxide or of propylene oxide, and the alkyl and aryl ethers of these polyoxyalkylene polymers, may also be suitable.

Another class of synthetic base oils are dicarboxylic acid esters, in particular those chosen from phthalic acid, succinic acid, alkylsuccinic acids and alkenylsuccinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acids or alkenylmalonic acids with various alcohols, such as butanol, hexanol, dodecyl alcohol, ethyl alcohol, ethylene or propylene glycol. Specific examples of such esters are dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the sebacic acid ester prepared with 2 mol of tetraethylene glycol and 2 mol of 2-ethylcaproic acid.

The synthetic oils can also be esters of monocarboxylic acids of C5-C12 type, dicarboxylic acids, tricarboxylic acids or tetracarboxylic acids and polyols or polyol ethers, such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol or tripentaerythritol.

The synthetic oils can also be silicone oils, such as polyalkyl-, polyaryl-, polyalkoxy- or polyaryloxysiloxane oils and silicate oils. The silicone oils can be chosen from tetraethyl silicate, tetraisopropyl silicate, tetra(2-ethylhexyl) silicate, tetra(4-methylhexyl) silicate, tetra(p-tert-butylphenyl) silicate, hexyl(4-methyl-2-pentoxy) silicate, disiloxane, poly(methyl)siloxanes and poly(methylphenyl)siloxanes.

The synthetic oils can also be liquid esters of phosphorus-containing acids, such as tricresyl phosphate, trioctyl phosphate and the diethyl ester of decylphosphonic acid, and polymeric tetrahydrofurans.

Unrefined, refined and double refined natural or synthetic oils and mixtures of two or more of these oils can be used in the lubricating compositions according to the invention.

The unrefined oils can be obtained directly from natural or synthetic sources without other purification, for example petroleum oil directly from the distillation and ester oils directly from the esterification.

Preferably, the base oil included in the composition according to the invention is a diester, a triester, a tetraester or their mixture.

The composition of the present invention generally comprises from 70% to 99.9% by weight of at least one base oil, with respect to the total weight of the composition, preferably from 75% to 99.9% by weight, more preferably from 80% to 99.9% by weight, more generally from 85% to 99.9% by weight, for example from 90% to 99.9% by weight.

In another embodiment, the composition of the present invention comprises from 75% to 99.9% by weight of at least one base oil, with respect to the total weight of the composition, preferably from 75% to 99.5% by weight, more preferably from 80% to 99.5% by weight, more generally from 85% to 99.5% by weight, for example from 90% to 99.5% by weight.

The lubricating composition can additionally contain one or more additives well known to a person skilled in the art and, for example and in a nonlimiting way, those chosen from sulfur-comprising or chlorine-comprising compounds, corrosion inhibitors (for example calcium sulfonate, sodium sulfonates, fatty acid soaps, amines, boric acid), metal passivators, extreme-pressure additives (for example sulfur-comprising compounds having a fatty chain, chlorinated paraffins, phosphorus derivatives), antihaze additives (for example polyisobutylene), antiweld additives, viscosity index improvers, deposition inhibitors, detergents, dispersants, antiwear additives and friction modifiers, emulsifiers (for example triethanolamine, petroleum sodium sulfonates, fatty acid salts and nonionic surfactants), alkanolamines, biocides (for example compounds of triazine type, compounds of oxazolidine type), antioxidants, preservatives, stabilizers, antifoaming agents, dyes, pigments, scents and fragrances, to mention only the best known of them.

In particular, the additives can advantageously be chosen from antioxidants, metal passivators, corrosion inhibitors, viscosity index improvers, deposition inhibitors, detergents, dispersants, antiwear additives and friction modifiers.

Use may be made, as antioxidants, for example of phenolic or amine antioxidants, diphenylamines, aliphatic and aromatic phosphites, thiodipropionic acid esters, butylated hydroxyanisole, butylated hydroxytoluene, methoxyhydroquinone, tocopherol or mixtures of these.

The metal passivators can be chosen, for example, from benzotriazoles and their derivatives, salicylaminoguanidine, toluotriazoles and their derivatives, 2-mercaptobenzothiazole, 2-mercaptobenzotriazole, salicylidenepropylenediamine or their mixtures.

The corrosion inhibitors optionally used can be chosen from organic acids, their esters, the metal salts and anhydrides, in particular n-oleoylsarcosine, alkenylsuccinic anhydrides, from nitrogenous compounds, in particular primary, secondary or tertiary nitrogenous compounds, aliphatic or cycloaliphatic amines, and amine salts of organic and inorganic acids, of heterocyclic compounds, in particular substituted imidazolines and oxazolines, of phosphorus-comprising compounds, in particular amine salts of partial phosphoric acid esters, or their mixtures.

The lubricating composition can contain, for example, polyacrylates, polymethacrylates, vinylpyrrolidone-(meth)acrylate copolymers, polyisoprenes, polyethers or mixtures of these as viscosity index improvers.

If the lubricating composition contains a dispersant as additive, the latter can be chosen from polybutenyl succinic acid amides or imides, polybutenyl phosphoric acid derivatives, guanidine derivatives and/or salicylates.

Antiwear additives, for example, concern sulfur-comprising and/or phosphorus-comprising compounds, such as sulfur-comprising vegetable oils, metal dithiophosphates, in particular zinc dialkyldithiophosphates, nitrogen-comprising dithiophosphates, phosphoric acid esters, phosphites, phosphonites or the mixtures of these.

As already indicated above, the lubricating composition can contain antifoaming additives as additive.

These are chosen, for example, from silicone oils, in particular dimethylpolysiloxane being used.

Polyethylene glycol ethers, amino alcohols or mixtures of the abovementioned substances can also be used as antifoaming additives.

If the lubricating composition contains friction modifiers, these can be chosen from organic and/or inorganic friction modifiers.

Examples of suitable organic friction modifiers are esters, fatty acid amides, fatty esters which comprise sulfur and fatty acid amides, alkoxylated amine esteramides, long-chain 1,2-alkanediols borates, polycarboxylic acid esters or their mixtures. Typical inorganic friction modifiers are compounds comprising a molybdenum-amine complex, Mo(VI)-dithiocarbamates, phosphoric acid esters and partial esters, phosphorous acid esters and partial esters, dithiophosphoric acid esters and partial esters or their mixtures. Some of these compounds also have antiwear additive properties.

The lubricant composition can also contain detergents as additives.

These can be chosen from alkaline earth sulfonates, salicylates or phenoxides or their mixtures, in particular from superbased magnesium or calcium sulfonate, salicylate or phenoxide or their mixtures. Superbased calcium and magnesium sulfonates and their production are described, for example, in the patent application EP 0 515 062.

According to one embodiment of the invention, the lubricating composition comprises from 0.01% to 30% by weight, preferably between 0.1% and 25% by weight, of additives, with respect to the total weight of the composition.

According to the targeted application, the composition according to the invention can be used directly. According to another embodiment, it can be used in the form of an emulsion.

Finally, the invention relates to the use of 2-octanol monoester as additive in a lubricating composition.

Preferably, the monoester according to the invention makes it possible to reduce the coefficient of friction.

The examples which follow make it possible to illustrate the present invention but are not in any way limiting.

EXAMPLES Example 1: Synthesis of 2-octanol palmitate

2-Octanol (191 g), palmitic acid (199 g) and 0.3 g of tin oxalate are heated under a nitrogen atmosphere. The esterification reaction begins at 170° C. with the formation of water. After 3 hours, the water produced is extracted under vacuum from the reaction medium and the vacuum is reduced over 4 hours down to approximately 15 mbar. The final temperature is 230° C. After having reached an acid number of less than 1, the excess alcohol is distilled off and the ester is cooled to a temperature of 90° C. It is then washed in 300 ml of water in order to remove the catalyst, dried and filtered, and 198 g of ester are obtained.

Example 2: Preparation of the Compositions

Lubricating compositions are prepared. The constituents of the compositions tested appear in the following table 1. The contents of the constituents are expressed as percentages by weight. The compositions A and B are comparative compositions. The composition C is according to the invention.

TABLE 1 A B C (comparative) (comparative) (invention) Mineral oil1 100 99.5 99.5 2-Ethylhexyl palmitate —  0.5 — 2-Methylheptyl palmitate — —  0.5 1Torilis HC1850 oil, sold by Total

Example 3: Evaluation of the Compositions

The coefficients of friction of these compositions are evaluated on a pendulum in frictional action between 40° C. and 120° C.

The pendulum used is of the Shincos brand. The parameters of the apparatus are as follows:

    • Maximum angle: 0.7°;
    • Period of 4 seconds;
    • Maximum pressure 150 kN;
    • M1=40 g and M2=80 g, giving a constant C of 3.2,
      test carried out with a minimum of 15 swings and an average of 5 successive identical measurements.

The coefficient of friction is calculated according to the following formula:


F=C·Ao−An/n

where C represents the constant, Ao represents the initial angle, in this instance 0.5°, An represents the last angle measured >0.1°, and n represents the number of oscillations.

The results obtained appear in the graph of FIG. 1.

In this graph, the straight line located at the top of the graph corresponds to the values obtained with the composition A. The intermediate straight line corresponds to the values obtained with the composition B. The straight line located at the bottom of the graph corresponds to the values obtained with the composition C.

Thus, the lubricating composition according to the invention makes it possible to lower the level of friction with respect to the pure base oil, this being the case whether at 40° C. or at 120° C. The same situation applies in comparison with a branched C8 alcohol monoester.

Consequently, the specific structure of the 2-octanol monoester confers entirely advantageous and surprising lubricating properties.

Claims

1.-7. (canceled)

8. A lubricating composition comprising:

0.1% to 30% by weight of the total weight of the composition, of at least one 2-octanol monoester having the formula R1-C(═O)OR2, wherein: R1 is an alkyl group of 8 to 36 carbons; R2 is 1-methylheptyl; and
at least one base oil.

9. The composition of claim 1, wherein R1 is an alkyl group of 10 to 36 carbons.

10. The composition of claim 1, wherein R1 is an alkyl group of 10 to 26 carbons.

11. The composition of claim 1, wherein R1 is an alkyl group of 11 to 26 carbons.

12. The composition of claim 1, wherein R1 is an alkyl group of 12 to 24 carbons.

13. The composition of claim 1, wherein the 2-octanol monoester is 2-octanol palmitate.

14. The composition of claim 5, wherein the 2-octanol monoester is 2-octanol palmitate.

15. The composition of claim 1, wherein the base oil is selected from the group consisting of diesters, triesters, tetraesters, and mixtures thereof.

16. The composition of claim 6, wherein the base oil is selected from the group consisting of diesters, triesters, tetraesters, and mixtures thereof.

17. The composition of claim 7, wherein the base oil is selected from the group consisting of diesters, triesters, tetraesters, and mixtures thereof.

18. The composition of claim 1, further comprising an additive chosen from the group consisting of: antioxidants, metal passivators, corrosion inhibitors, viscosity index improvers, deposition inhibitors, detergents, dispersants, additives for protection against wear, and friction modifiers.

19. The composition of claim 1, wherein the composition is an emulsion.

Patent History
Publication number: 20240343987
Type: Application
Filed: Jul 13, 2022
Publication Date: Oct 17, 2024
Applicant: ARKEMA FRANCE (Colombes)
Inventors: Olivier MARTOS (Colombes Cedex), Jean-Philippe GILLET (Pierre-Benite Cedex)
Application Number: 18/579,121
Classifications
International Classification: C10M 101/02 (20060101); C10M 129/70 (20060101); C10N 50/00 (20060101);