Lubricant base oil synthesized from sugar alcohol esters

Abstract

The present invention provides a method for producing a saccharide-based saccharide comprising the steps of: 11 For esters with linear fatty acids, the sugar polyol is erythritol.

Description

[Technical field]

[0001] The present invention also relates to esters formed from sugar alcohols, particularly sugar polyols, and their use as lubricant bases, and methods for their preparation. [Background technology]

[0002] Currently, the lubricant basestock market is dominated by petroleum-derived mineral oils. In 2008, lubricant production in Europe reached 4.5 million tonnes per year. These lubricant basestocks are used in various industries, such as engine oils, cutting oils for chainsaw chains, offshore drilling oils, hydraulic fluids for heavy machinery and agricultural machinery.

[0003] These mineral oils, once used, are not always recycled and cause environmental pollution through discharge into land, sewers, lakes and rivers. Considering the potential impact of these lubricants on the environment, the development of ecological and biodegradable lubricant basestocks is essential, especially in applications where the lubricants are prone to leak into the environment.

[0004] Vegetable and animal oils, whose use as lubricants has been known for several years, can address this environmental concern, as they have the advantage of being environmentally friendly. However, these oils have lower thermal stability and oxidation resistance compared to mineral oils, and are prone to hydrolysis in the presence of water.

[0005] Polyol esters formed from fatty acids bound to alcohols have good oxidative stability, good hydrolytic stability, relatively high biodegradability and good low temperature performance. Biodegradable lubricant compositions of palm oil-derived polyol esters, including polyols such as neopentyl glycol or trimethylolpropane and palm oil-derived products, are described in European Patent Application No. 1533360. However, such compositions are only suitable for temperatures in the range of 15°C to 40°C.

[0006] Therefore, in this situation, there remains a need to develop alternative polyol esters whose structure can be derived entirely from components of renewable origin, which have excellent lubricating properties and which are also non-harmful to humans and the environment. Summary of the Invention

[0007] In the context of the present invention, sugar alcohols, in particular sugar polyols and C 6 -C 11 Esters with linear fatty acids have been observed to have superior properties for use in lubricants.

[0008] The present invention relates to a method for producing a sugar alcohol, particularly a sugar polyol, in particular erythritol, and a C 6 -C 11 This arises from the unexpected demonstration by the inventors that esters with linear fatty acids have superior properties for use in lubricants.

[0009] The present invention therefore provides a method for the preparation of a saccharide comprising at least one sugar alcohol, in particular a sugar polyol, and at least one C 6 -C 11 For esters with linear fatty acids, the sugar alcohol, in particular the sugar polyol, is erythritol.

[0010] The present invention also relates to a method for the preparation of a polyol comprising at least one sugar alcohol, in particular a sugar polyol, as defined above, and at least one C 6 -C 11 The present invention relates to the use of esters of linear fatty acids as lubricant base materials.

[0011] The present invention also relates to a method for the preparation of a polyol comprising at least one sugar alcohol, in particular a sugar polyol, as defined above, and at least one C 6 -C 11 The present invention relates to a lubricant base composition comprising an ester of a linear fatty acid.

[0012] The present invention also provides a method for producing at least one 6 -C 11Regarding the process for the preparation of esters comprising an esterification reaction of linear fatty acids with at least one sugar alcohol, in particular a sugar polyol, preferably the process comprises a step of removing excess acid and does not comprise at least one of the following steps: Downstream processing with the addition of additives; ·Addition of catalyst; Addition of organic solvents.

[0013] The present invention also relates to a method for producing a polyol comprising at least one sugar alcohol, in particular a sugar polyol, and at least one C 6 -C 11 It relates to esters with linear fatty acids. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The lubricant base composition according to the invention, which is synthesized from esters of at least one polyol and a fatty acid of renewable origin, for example erythritol and n-heptanoic acid (for example Oleris® C7 from Arkema), without the addition of catalysts and without downstream processing by the addition of additives, makes it possible to achieve properties with higher thermal stability than conventional esters of alcohols that are not biobased, for example trimethylolpropane, as will be described in detail in the examples below.

[0015] Thus, the present invention provides a lubricant base composition of renewable origin that has good oxidative stability, good thermal stability and very good lubricating properties.

[0016] Furthermore, the compositions have good flowability at low temperatures and are therefore particularly suitable for use at low temperatures, ie, typically below 0°C.

[0017] The term "biodegradable" is used herein to denote compounds formed from molecules that can be converted into smaller, less polluting molecules by microorganisms living in the natural environment, such as bacteria, fungi, and algae. The end result of this decomposition generally consists of water, carbon dioxide, or methane.

[0018] Materials or compounds or components that are "derived from renewable resources" or "bio-based" are understood to mean natural materials or compounds or components that are renewable, the stock of which can be reconstituted over a short period on the human time scale. These are in particular raw materials of animal or plant origin. The term "raw materials of renewable origin" or "bio-based raw materials" means materials that contain bio-based carbon or carbon of renewable origin. Specifically, unlike materials derived from fossil materials, materials that are composed of renewable raw materials contain no carbon-14 ( 14 "Renewable carbon content" or "bio-based carbon content" is determined by application of standards ASTM D 6866 (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04).

[0019] The viscosity of a fluid refers to the resistance its molecules withstand to the internal sliding of each other while it flows. Viscosity is given relative to a reference temperature. m / s 2 The kinematic viscosity, denoted by , is calculated using the following formula: υ = η / ρ, where: η is the dynamic viscosity in Pa s, ρ is the density of the fluid in kg / m3

[0020] Kinematic viscosity is also expressed in stokes (St) or centistokes (cSt).

[0021] The kinematic viscosity is measured according to standard ISO 3104.

[0022] Oxidative stability can be determined by two measurements: oxygen induction time and oxygen induction temperature, which can be measured with a differential scanning calorimeter (DSC) according to standard ISO 11357-6:2018.

[0023] The pour point of a product is the lowest temperature at which the product still flows. The pour point is measured according to standard ISO 3016.

[0024] Viscosity index (VI) (unitless) indicates the rate of change of viscosity of an oil over a given temperature range, usually 40°C to 100°C. Viscosity index can be defined as the kinematic viscosity gradient of a material from 40°C to 100°C. If the viscosity index is low (less than 100), the fluid exhibits a relatively large variation in viscosity with temperature. If the viscosity index is high (greater than 150), the fluid exhibits a relatively small change in viscosity with temperature. In various applications, a high or very high viscosity index is preferred. Viscosity index is measured according to the test method described in standard ASTM D 2270.

[0025] ester An alcohol is understood to mean a molecule having at least one hydroxyl (-OH) group. A polyol is understood to mean a molecule having at least two hydroxyl (-OH) groups.

[0026] Preferably, the polyol according to the invention is an organic compound containing several hydroxyl groups. Preferably, polyol does not refer to a compound containing functional groups other than hydroxyl groups. More preferably, the polyol according to the invention has the general chemical formula C n H 2n+2 O n and is a compound having at least two hydroxyl groups.

[0027] The ester according to the invention is a polysaccharide comprising at least one sugar alcohol, in particular a sugar polyol, and at least one C 6 -C 11 It is formed from fatty acids.

[0028] According to one embodiment, esters according to the present invention may be monoesters, diesters, triesters and tetraesters.

[0029] The sugar alcohols, in particular sugar polyols, according to the invention are preferably obtained from renewable resources. The sugar alcohols, in particular sugar polyols, according to the invention are preferably biodegradable.

[0030] Preferably, the sugar alcohols, in particular sugar polyols, according to the present invention are selected from the group consisting of monosaccharides, disaccharides, trisaccharides, and mixtures thereof.

[0031] Preferably, the monosaccharide according to the present invention is selected from the group consisting of erythritol, xylose, arabinose, ribose, sorbitol, sorbitan, glucose, sorbose, fructose, xylitol and mixtures thereof, more preferably selected from the group consisting of xylose, arabinose, ribose, glucose, sorbose, fructose and mixtures thereof.

[0032] Preferably, the disaccharide according to the present invention is selected from the group consisting of maltose, lactose, sucrose, and mixtures thereof.

[0033] The trisaccharide according to the present invention is preferably selected from the group consisting of raffinose, maltotriose, hydrogenated starch hydrolysates, and mixtures thereof.

[0034] More preferably, the sugar alcohol, in particular the sugar polyol, according to the present invention is erythritol.

[0035] According to one embodiment, the sugar polyol according to the invention is obtained by hydrogenation of a sugar.

[0036] The fatty acids according to the invention are preferably derived from renewable resources. The fatty acids according to the invention are preferably saturated or unsaturated, linear or branched, of vegetable or animal origin.

[0037] The fatty acids according to the invention are preferably obtained by grinding the seeds, kernels or fruits of plants, in particular oleaginous plants, for example linseed oil, rapeseed oil, sunflower oil, soybean oil, olive oil, palm oil, castor oil, wood oil, corn oil, pumpkin oil, grape seed oil, jojoba oil, sesame oil, walnut oil, hazelnut oil, almond oil, shea butter, macadamia oil, cottonseed oil, alfalfa oil, rye oil, safflower oil, peanut oil, copra oil, tall oil and argan oil, or from animal fats such as tallow.

[0038] The fatty acids according to the invention are preferably selected from the group consisting of the fatty acids of castor oil, coconut oil, cottonseed oil, dehydrated castor oil, soybean oil, tall oil, rapeseed oil, sunflower oil, linseed oil, palm oil, tung oil, oiticica oil, safflower oil, olive oil, wood oil, corn oil, pumpkin oil, grape seed oil, jojoba oil, sesame oil, walnut oil, hazelnut oil, almond oil, shea butter, macadamia oil, alfalfa oil, rye oil, peanut oil, copra oil and argan oil.

[0039] The fatty acids according to the invention contain from 6 to 11 carbon atoms.

[0040] Preferably, the fatty acids according to the present invention are selected from the group consisting of caproic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid, furandicarboxylic acid, tetrahydrofuran-2,5-dicarboxylic acid, tetrahydrofuran-3,5-dicarboxylic acid, azelaic acid, decanedioic acid, 10-undecylenic acid, undecanedioic acid, and dodecanedioic acid.

[0041] Preferably, the fatty acids according to the present invention are linear fatty acids.

[0042] Preferably, linear fatty acids can increase the viscosity index and improve the thermal stability of synthetic lubricant basestocks, and are more easily biodegradable than branched chain acids, which are primarily derived from the petroleum industry.

[0043] Preferably, the fatty acids according to the present invention are derived from castor oil.

[0044] Fatty acids derived from castor oil are understood to mean fatty acids present in the oil and / or fatty acids that can be obtained at the end of chemical transformation. For example, heptanoic acid and / or 10-undecylenic acid can be obtained from castor oil, typically by a step of pyrolysis of methyl ricinoleate resulting from transesterification of castor oil. The fatty acid according to the invention is preferably n-heptanoic acid. Also preferably, the fatty acid according to the invention is n-heptanoic acid Oleris® (Arkema).

[0045] Preferably, the n-heptanoic acid is derived from castor oil.

[0046] Preferably, the esters according to the invention are formed from sugar alcohols according to the invention, in particular sugar polyols, at least three alcohol groups, preferably four alcohol groups of which are esterified with fatty acids according to the invention.

[0047] Also preferably, the weight ratio of the fatty acid according to the present invention to the sugar alcohol according to the present invention, in particular the sugar polyol, is within the range of 4: 1 to 10: 1. More preferably, the weight ratio of the fatty acid according to the present invention to the sugar alcohol according to the present invention, in particular the sugar polyol, is about 5: 1.

[0048] Preferably, at least 50% by weight, preferably 75% by weight, of the esters, based on the total weight of the esters, are derived from renewable resources.

[0049] Preferably, the esters according to the invention have an oxygen induction time, measured by differential scanning calorimetry at 150° C., of greater than 2 hours.

[0050] Preferably, the esters according to the invention have an oxygen induction temperature, measured by differential scanning calorimetry, of greater than 200°C.

[0051] The esters according to the invention preferably have a pour point below -30°C, preferably between -50°C and -30°C, more preferably about -42°C.

[0052] The esters according to the invention preferably have a viscosity at 40° C. of 14 to 30 mm, measured according to standard ISO 3104. 2 / s, and / or 4.5 mm at 100°C 2 Includes kinematic viscosities less than / s.

[0053] method The process for preparing the esters according to the invention from sugar alcohols, in particular sugar polyols, according to the invention and fatty acids can be carried out according to the usual esterification techniques well known to those skilled in the art.

[0054] Preferably, the esterification process according to the invention comprises reacting at least one sugar alcohol, in particular a sugar polyol, according to the invention with at least one excess C 6 -C 11 The process includes esterifying in the presence of a linear fatty acid, with or without a catalyst.

[0055] The esterification step according to the present invention is preferably carried out at a temperature of 140° C. to 250° C. for a period of 0.5 to 12 hours, preferably 1 to 10 hours, more preferably 2 to 9 hours.

[0056] The esterification step according to the present invention is preferably carried out under an inert atmosphere.

[0057] Preferably, the process for preparing the ester according to the present invention is carried out under a controlled reduced pressure to remove excess acid. The esterification process according to the present invention may include the step of adding an absorbent such as alumina, silica gel, zeolite, activated carbon, and clay.

[0058] The process according to the invention may further comprise the step of adding water and a base to simultaneously neutralise the residual organic and inorganic acids and / or hydrolyse the catalyst, in which case the process according to the invention may comprise the step of removing the water used by heating and applying a reduced pressure.

[0059] The process according to the invention may also include a step of filtering the solids of the ester mixture, which contains most of the excess acid mixture used in the esterification reaction.

[0060] The process according to the invention may include the step of removing excess acid by steam extraction or by any other distillation method and recycling the acid in the reactor.

[0061] According to one embodiment, the process of the present invention includes a step of removing excess acid, preferably performed by vacuum distillation.

[0062] Preferably, the compound obtained by the method according to the invention is freed of unreacted acid by vacuum distillation. The distillation is preferably carried out under reduced pressure for 15 minutes to 2 hours. The distillation is more preferably carried out at a temperature of 140°C to 180°C. The amount of free acid remaining after the distillation step can be reduced by treatment with epoxy ester, neutralization with any suitable alkaline material such as lime, alkali metal hydroxide, alkali metal carbonate or basic alumina. If treatment with epoxy ester is carried out, a second vacuum distillation may be carried out to remove excess epoxy ester. If alkali treatment is carried out, washing with water may be carried out to remove excess unreacted alkaline material.

[0063] The process according to the invention may include the step of removing any residual solid material from the extracted ester during a final filtration.

[0064] Preferably, the fatty acids according to the invention are present in an excess of about 10-50 mol %, preferably about 10-30 mol %, relative to the amount of sugar alcohol, particularly sugar polyol, used in the reaction to form the esters according to the invention.

[0065] The process according to the invention can be carried out in the presence of a catalyst. The catalyst can be any catalyst for esterification reactions known to those skilled in the art. Preferably, the catalyst is selected from the group consisting of tin chloride, sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid, sulfosuccinic acid, hydrochloric acid, phosphoric acid, zinc-, copper-, tin-, titanium-, zirconium- or tungsten-based catalysts; alkali metal salts, such as sodium or potassium hydroxide, sodium or potassium carbonate, sodium or potassium ethoxide, sodium or potassium methoxide, zeolites and acidic ion exchangers, or mixtures thereof.

[0066] Preferably, no downstream processing steps by addition of additives are carried out during the process for the preparation of the esters according to the invention.

[0067] The term "downstream processing by addition of additives" is understood to mean one or more of the steps typically carried out at the end of the esterification step, as described above, of adding an absorbent, of adding water and a base, of filtering solids from the mixture of esters and / or of removing excess acid.

[0068] Preferably, the process for preparing the ester is carried out without a catalyst.

[0069] Preferably, the process for preparing the ester is carried out without the addition of organic solvents.

[0070] Preferably, the process for preparing the ester comprises: -Downstream processing with the addition of additives Catalyst addition process · Organic solvent addition process At least one, preferably at least two, and more preferably none of the above is performed.

[0071] Preferably, the reaction is carried out for a time sufficient to obtain a tetraester content of 80% or more by weight, based on the total amount of esters, more preferably, the reaction is carried out for a time sufficient to obtain a tetraester content of 93% or more by weight, based on the total amount of esters.

[0072] use The esters according to the invention are preferably used as such as lubricant base stocks or lubricant base oils.

[0073] The esters according to the invention can also be used as mixtures with other base oils, such as mineral oils, highly refined mineral oils, polyalphaolefins (PAOs), polyalkylene glycols (PAGs), phosphate esters, silicone oils, diesters, polyisobutylenes and polyol esters.

[0074] In particular, the esters according to the invention are useful for the preparation of lubricant base compositions which can be used in all kinds of industries, in particular as automotive lubricants, as metal working oils, as hydraulic oils, as turbine oils or as aviation oils.

[0075] Preferably, the composition according to the invention may contain a tetraester content of 80% by weight or more relative to the total amount of esters, more preferably, the composition may contain a tetraester content of 93% by weight or more relative to the total amount of esters.

[0076] The composition according to the invention may contain, in addition to the ester according to the invention, one or more additives, preferably selected from the group consisting of antioxidants, thermal stability improvers, corrosion inhibitors, metal deactivators, lubricity additives, viscosity index improvers, pour point depressants, detergents, dispersants, antifoam agents, antiwear agents, and extreme pressure additives.

[0077] Preferably, the amount of additive in the composition according to the invention does not exceed 10% by weight, preferably 8% by weight, more preferably 5% by weight, based on the total weight of the lubricant base composition.

[0078] Preferably, the amount of antioxidant used is from 0.01% to 5% based on the total weight of the lubricant base composition.

[0079] Preferably, the amount of corrosion inhibitor is from 0.01% to 5% by weight, based on the total weight of the lubricant base composition.

[0080] Preferably, the amount of metal deactivator is from 0.001% to 0.5% by weight, based on the total weight of the lubricant base composition.

[0081] Preferably, the amount of lubricant additive is from 0.5% to 5% by weight, based on the total weight of the lubricant base composition.

[0082] Preferably, the amount of viscosity index improver is from 0.01% to 2% by weight, based on the total weight of the lubricant base composition.

[0083] Preferably, the amount of pour point depressant is from 0.01% to 2% by weight, based on the total weight of the lubricant base composition.

[0084] Preferably, the amount of detergent is from 0.1% to 5% by weight, based on the total weight of the lubricant base composition.

[0085] Preferably, the amount of dispersant is from 0.1% to 5% by weight, based on the total weight of the lubricant base composition.

[0086] Preferably, the amount of antifoaming agent is from 0.01% to 2% by weight, based on the total weight of the lubricant base composition.

[0087] Preferably, the amount of antiwear agent is from 0.01% to 2% by weight, based on the total weight of the lubricant base composition.

[0088] Preferably, the amount of extreme pressure additive is from 0.1% to 2% by weight, based on the total weight of the lubricant base composition.

[0089] The antioxidant and thermal stability enhancer can be selected from any antioxidant and thermal stability enhancer known to those skilled in the art. By way of example, the antioxidant and thermal stability enhancer can be selected from the group consisting of: diphenylamine, dinaphthylamine, phenylnaphthylamine, in which the phenyl or naphthyl group may be replaced, for example, by N,N'-diphenylphenylenediamine, p-octyldiphenylamine, p,p-dioctyldiphenylamine, N-phenylnaphthylamine, N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2-naphthylamine, di-1-naphthylamine and di-2-naphthylamine groups; Phenothiazines, such as N-alkylphenothiazines; Imino(bisbenzyl); and Hindered phenols, such as 6-(t-butyl)phenol, 2,6-di-(t-butyl)phenol, 4-methyl-2,6-di-(t-butyl)phenol, 4,4'-methylenebis(2,6-di-(t-butyl)phenol).

[0090] The metal deactivator may be selected from any metal deactivator known to those skilled in the art. By way of example, the metal deactivator may be selected from the group consisting of imidazole, benzamidazole, 2-mercaptobenzthiazole, 2,5-dimercaptothiadiazole, salicylidene-propylenediamine, pyrazole, benzotriazole, tolutriazole, 2-methylbenzamidazole, 3,5-dimethylpyrazole, and methylenebis(benzotriazole). Other examples of metal deactivators or corrosion inhibitors include: · organic acids and their esters, metal salts and anhydrides, for example, N-oleyl sarcosine, sorbitan monooleate, lead naphthenate, dodecenyl succinic acid and its partial esters and amides, and 4-nonylphenoxyacetic acid; Aliphatic and alicyclic primary, secondary and tertiary amines, and amine salts of organic and inorganic acids, e.g. oil-soluble alkylammonium carboxylates; Nitrogen-containing heterocyclic compounds, such as thiadiazoles, substituted imidazolines, and oxazolines; Quinolines, quinones and anthraquinones; ·Propyl gallate; · Barium dinonylnaphthalenesulfonate; · Derivatives of esters and amides of alkenylsuccinic anhydrides or acids, dithiocarbamates, dithiophosphates; ·Amine salts of alkyl acid phosphates and their derivatives.

[0091] The lubricity additive can be selected from any lubricity additive known to those skilled in the art. Examples of lubricity additives include long chain derivatives of fatty acids and natural oils, such as esters, amines, amides, imidazolines and borates.

[0092] The viscosity index improver may be selected from any viscosity index improver known to those skilled in the art. Examples of viscosity improvers include polymethacrylates, copolymers of vinylpyrrolidone and methacrylate, polybutene and styrene-acrylate copolymers.

[0093] The pour point depressant can be selected from any pour point depressant known to those skilled in the art. Examples of pour point depressants include polymethacrylates, such as methacrylate-ethylene-vinyl acetate terpolymers; alkylated naphthalene derivatives; and products of urea-catalyzed Friedel-Crafts condensation with naphthalene or phenols.

[0094] The detergent and dispersant can be selected from any detergent and dispersant known to those skilled in the art.Examples of detergent and dispersant can include polybutenyl succinamide; polybutenyl phosphonic acid derivatives; aromatic sulfonic acids and their salts substituted with long alkyl chains; and metal salts of alkyl sulfides, alkyl phenols, and condensation products of alkyl phenols and aldehydes.

[0095] The antifoaming agent can be selected from any antifoaming agent known to one of ordinary skill in the art. Examples of antifoaming agents include polymers of silicones and certain acrylates.

[0096] The antiwear and extreme pressure additives may be selected from any antiwear and extreme pressure additive. Examples of antiwear and extreme pressure additives include: Sulfurized fatty acids and fatty acid esters, such as sulfurized octyl tallowate; Sulfurized terpenes; Sulfurized olefins; Organic polysulfides; amine phosphates, alkyl acid phosphates, dialkyl phosphates, amine dithiophosphates, trialkyl and triaryl phosphorothioates, trialkyl and triaryl phosphines, and dialkyl phosphites, e.g., amine salts of monohexyl phosphoric acid ester, amine salts of dinonylnaphthalene sulfonate, triphenyl phosphate, trinaphthyl phosphate, diphenyl cresyl phosphate, and organophosphorus derivatives including phenyl phenyl phosphate, naphthyl diphenyl phosphate, triphenyl phosphorothioate; Dithiocarbamates, such as antimony dialkyldithiocarbamates; Chlorinated and / or fluorinated hydrocarbons and xanthates.

[0097] The invention is further illustrated by the following non-limiting examples. EXAMPLES

[0098] The inventors have investigated the properties of the esters according to the invention for lubricant applications.

[0099] 1. Preparation of Esters Two samples are prepared. esters of erythritol and n-heptanoic acid (esters according to the invention); and Ester of trimethylolpropane and n-heptanoic acid (Comparative Example 1).

[0100] Synthesis of esters of erythritol and n-heptanoic acid (esters according to the invention): Erythritol (14.7 g, 0.12 mol) and n-heptanoic acid (81.7 g, 0.62 mol) are placed in a 250 ml three-neck flask equipped with a stirrer, thermometer, condenser and nitrogen inlet. The reaction mixture is heated at 210° C. for 7 hours and 30 minutes under nitrogen until the theoretical amount of water stabilizes. The crude product is then distilled at a temperature of 180° C. and maximum vacuum for 1 hour and 30 minutes to remove excess n-heptanoic acid, in order to obtain 66.5 g of product with an acid value of 0.1 mg KOH / g.

[0101] The kinematic viscosity, viscosity index (VI) and pour point of the product were evaluated and are reported in Table 2.

[0102] The chemical composition of the product was established by gas chromatography as 94.1% tetraester of erythritol and n-heptanoic acid, 2.2% triester of erythritol and n-heptanoic acid, and 2.9% anhydroester of erythritol and n-heptanoic acid.

[0103] Synthesis of ester of trimethylolpropane and n-heptanoic acid (Comparative Example 1) Trimethylolpropane (53.8 g, 0.4 mol) and n-heptanoic acid (181.5 g, 1.38 mol) are placed in a 500 ml three-neck flask equipped with a stirrer, thermometer, condenser and nitrogen inlet. The reaction mixture is heated under nitrogen atmosphere at 185 °C for 3 h until the theoretical amount of water stabilizes. Zirconium tetrabutanolate (1.5 g, 80% in butanol, 0.5 wt.% of the total weight of reactants) is then added batchwise to the reactor. The assembly is gradually placed under maximum vacuum at 150 °C for 3 h 30 min to distill off excess unreacted acid, yielding 187.4 g of product. Downstream treatment with activated basic alumina is performed on the crude reaction product to obtain an oil with an acid value of 0.1 mg KOH / g.

[0104] The kinematic viscosity, viscosity index (VI) and pour point of the product were evaluated and are reported in Table 2.

[0105] The chemical composition of the product was established by gas chromatography to be 98.8% trimethylolpropane triheptanoate and 0.03% trimethylolpropane diheptanoate.

[0106] 2. Measurement of oxidation resistance Oxidative stability is determined by measuring two things: oxygen induction time and oxygen induction temperature, which are measured by differential scanning calorimetry (DSC).

[0107] To measure the oxygen induction time, a sample is heated to 150°C and then held at a constant temperature. It is then exposed to an oxidizing atmosphere. The time from contact with oxygen until oxidation begins is the oxygen induction time.

[0108] To measure the oxygen induction temperature, a sample is heated in an oxidizing atmosphere at a constant heating rate until the reaction begins. The oxygen induction temperature is the temperature at which the oxidation reaction begins.

[0109] The results are shown in Table 1 below. TIFF0007620555000001.tif37170

[0110] The measurements show that the oxygen induction times at 150° C. of the two samples are comparable. The ester according to the invention has a higher oxygen induction temperature than the comparative example. Thus, the ester according to the invention has better oxidation resistance properties than the conventional esters synthesized from non-bio-based alcohols.

[0111] 4.Kinematic Viscosity Measurement The kinematic viscosity was measured according to standard ISO 3104 at 40°C and 100°C.

[0112] Results in mm 2 The values ​​are expressed in units of / s and are shown in Table 2 below.

[0113] 5. Viscosity index measurement The viscosity index (unitless) is measured according to the test method described in standard ASTM D 2270. The results are shown in Table 2 below.

[0114] 6. Pour point measurement The pour point, expressed in °C, is measured according to standard ISO 3016. The results are shown in Table 2 below.

[0115] TIFF0007620555000002.tif65170

[0116] These results show that, unlike the comparative example, the esters according to the invention, which were synthesised exclusively from materials of renewable origin, without the addition of catalysts and without downstream processing by the addition of additives, have kinematic viscosities at 40° C. and 100° C. close to those of the comparative example. The esters according to the invention show a higher viscosity index, which means that the lubricant basestocks according to the invention have a more stable viscosity depending on the temperature.

[0117] The lubricant basestock of the present invention exhibits a higher pour point, which correlates with the higher melting point of erythritol (120° C.) compared to the melting point of trimethylolpropane (60° C.) in the comparative example, but this value is still relatively low and advantageous for lubricant applications.

Claims

1. A sugar polyol and at least one C ６ -C １１ A lubricant base composition comprising an ester composition with a linear fatty acid, wherein the sugar polyol is erythritol.

2. C ６ -C １１ 2. The lubricant base composition of claim 1, wherein the linear fatty acid is n-heptanoic acid.

3. C ６ -C １１ 3. The lubricant base composition of claim 1, wherein the weight ratio of linear fatty acid to sugar polyol is at least 5:

1.

4. C ６ -C １１ The lubricant base composition according to any one of claims 1 to 3, wherein the linear fatty acid is derived from renewable resources.

5. A sugar polyol which is erythritol and at least one C ６ -C １１ Use of an ester composition with a linear fatty acid as a lubricant base.

6. An excess of at least one C ６ -C １１ preparing an ester comprising the steps of esterifying a sugar polyol in the presence of a linear fatty acid, the sugar polyol being erythritol; preparing a lubricant base composition comprising an ester.

7. The method of claim 6, further comprising removing excess acid.

8. downstream processing steps by the addition of additives; Catalyst addition process Organic solvent addition process The method according to claim 6 or 7, wherein the method is carried out without including at least one of the following:

9. The method of claim 6, wherein the esterification step is carried out for a time sufficient to obtain a tetraester content of 80% by weight or more based on the total amount of esters.

10. C ６ -C １１ 10. The method according to any one of claims 6 to 9, wherein the linear fatty acid is n-heptanoic acid.

11. C ６ -C １１ The method of any one of claims 6 to 10, wherein the linear fatty acid is derived from a renewable resource.

12. C ６ -C １１ 12. The method according to any one of claims 6 to 11, wherein the weight ratio of linear fatty acid to sugar polyol is at least 5:1.

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