Patent Publication Number: US-2021171855-A1

Title: Grease composition displaying improved adhesivity

Description:
The present invention relates to the field of greases, usable in particular in industrial applications, in particular grease compositions having good adhesivity properties. 
     Lubricating greases are solid or semi-fluid substances resulting from the dispersion of a thickener in a liquid lubricant, possibly including additives which confer particular properties on them. 
     Such greases are more particularly useful for lubrication in any industrial application, in particular for loaded applications and operating over a wide temperature range. In fact, for these applications, liquid lubricants are not suitable since they “drift” relative to the greasing point. 
     In the last few years, greases thickened with complex calcium sulfonate soaps have been widely developed and utilized since they display numerous properties such as resistance to extreme pressure and anti-wear, mechanical strength, corrosion resistance, water resistance and thermal stability, especially at elevated temperature. For example, the documents U.S. Pat. No. 5,126,062, US 2015/252283 or also WO 2015/071331 describe such compositions and methods for their preparation. 
     However, the complex calcium sulfonate soaps used in these greases are not naturally adhesive, as can be the case for certain complex lithium or aluminum soaps. Thus, these grease compositions do not make it possible to attain satisfactory levels of adhesivity. 
     In general, the use of additives to modify the properties of greases, for example in order to improve their anti-oxidant properties, is known to those skilled in the art. 
     It has thus also already been proposed to add additives, in particular polymers, such as polyolefins, polyisobutene (PIB), polyethylenes, polypropylenes, heavy PAOs, olefin copolymers (OCP) or also polymethacrylates (PMA), especially in order to increase the adhesivity of a grease, as is described for example in the document WO 2012/080940. 
     However, the majority of the polymers recommended are very viscous, which imposes considerable constraints on the process for preparation of the grease. In particular, it is necessary to preheat them before their incorporation into the grease mixture or to incorporate them during a grease heating step. Moreover, the properties in terms of adhesivity obtained with such polymers can still be improved. 
     There is thus a need for having available a grease utilizable in industrial applications, the adhesivity properties whereof are improved, by the selection of one or more additives not involving the aforesaid disadvantages, in particular not exhibiting excessively high constraints on the process for preparation of the grease. 
     There is also a need for having available a grease utilizable in industrial applications the properties whereof in terms of mechanical stability, anti-wear, load resistance, anticorrosion and heat resistance are otherwise conserved. 
     The present application aims precisely to propose a grease composition thickened with calcium sulfonate soaps, displaying improved adhesivity relative to the grease compositions of the prior art. 
     Another purpose of the present invention is to have available a grease the other properties whereof, in particular in terms of mechanical stability, especially at elevated temperature, are also maintained at a satisfactory level, or else are further improved relative to the grease compositions of the prior art. 
     More precisely, the inventors have discovered that it is possible to improve the adhesivity of a grease by including therein a very specific additive, namely a dicarboxylic acid ester. 
     Thus, in a first aspect thereof, the present invention relates to a grease composition comprising 
     (i) at least one base oil, 
     (ii) at least one calcium sulfonate soap, and 
     (iii) at least one dicarboxylic acid ester copolymer comprising constituent units deriving from (a) at least one α-olefin and (b) at least one ester formed by esterification of an α-β-ethylenically unsaturated dicarboxylic acid or a derivative thereof with an alcohol, the molar ratio (a)/(b) lying between 0.5 and 4. 
     In fact, the inventors have surprisingly discovered that the presence of such a dicarboxylic acid ester copolymer in a grease composition imparted to the grease excellent performance in terms of adhesivity, decreasing the loss of material during its use in the presence of water. The consistency of the grease, in the presence of a considerable quantity of water, is also conserved. Moreover, these properties are long-lasting. 
     Preferably, the presence of this particular ester further makes it possible to conserve the other properties of the grease, in particular their mechanical stability. Moreover, certain properties of the greases thus formulated can be found to be further improved, in particular their mechanical stability. 
     The present invention further relates to the utilization in a grease composition comprising: 
     (i) at least one base oil, and 
     (ii) at least one calcium sulfonate soap, 
     of at least one dicarboxylic acid ester copolymer comprising constituent units deriving from (a) at least one α-olefin and (b) at least one ester formed by esterification of an α-β-ethylenically unsaturated dicarboxylic acid or a derivative thereof with an alcohol, the molar ratio (a)/(b) lying between 0.5 and 4, to improve the adhesivity, measured according to the standard DIN 51807, of the said grease composition. 
     Finally, the present invention relates to a process for lubrication of a mechanical component, comprising at least one step of contacting the mechanical component with a grease composition as defined according to the present invention. 
     Other features, modifications and advantages of the implementation of a composition according to the invention will better emerge in the reading of the description, the examples and the diagrams which follow, given by way of illustration, and not restricting the invention. 
    
    
     In the text below, the expressions “lying between . . . and . . . ”, “ranging from . . . to . . . ” and “varying from . . . to . . . ” are equivalent and are intended to signify that the limits are included, unless otherwise stated. 
     Unless otherwise stated, the expression “comprising one” must be understood as “comprising at least one”. 
     Composition 
     Dicarboxylic Acid Ester Copolymer 
     As described above, a grease composition according to the invention comprises (iii) at least one dicarboxylic acid ester copolymer comprising constituent units deriving from (a) at least one α-olefin and (b) at least one ester formed by esterification of an α-β-ethylenically unsaturated dicarboxylic acid or a derivative thereof with an alcohol, the molar ratio (a)/(b) lying between 0.5 and 4. 
     (a) α-olefin 
     The α-olefins are compounds known to those skilled in the art and commonly utilized for the preparation of ester base oils. 
     The α-olefin utilized according to the invention preferably comprises between 8 and 24 carbon atoms, preferably between 10 and 18 carbon atoms, and in particular between 14 and 16 carbon atoms. 
     Preferably the α-olefin is linear. 
     According to one embodiment, the α-olefin, or the mixture of α-olefins, constituent of the dicarboxylic acid copolymer according to the invention, has a weight average molecular mass lying between 180 g/mol and 800 g/mol, in particular between 200 g/mol and 500 g/mol, preferably between 200 g/mol and 300 g/mol, more preferably between 220 g/mol and 260 g/mol. 
     (b) Ester 
     The α-β-ethylenically unsaturated dicarboxylic acid esters are compounds known to those skilled in the art and commonly utilized for the preparation of ester base oils. 
     According to the present invention, “α-β-ethylenically unsaturated dicarboxylic acid” designates an ester (b) obtained by an esterification reaction between an α-β-ethylenically unsaturated dicarboxylic acid or a derivative thereof and an alcohol. 
     The α-β-ethylenically unsaturated dicarboxylic acid utilized according to the present invention is preferably selected from maleic acid, fumaric acid, citraconic acid, mesaconic acid and itaconic acid, in particular from maleic acid and fumaric acid. 
     More particularly, an α-β-ethylenically unsaturated dicarboxylic acid derivative can be selected from maleic anhydride or itaconic anhydride. 
     The α-β-ethylenically unsaturated dicarboxylic acid ester utilized according to the present invention is preferably an α-β-ethylenically unsaturated dicarboxylic acid diester, in particular an α-β-ethylenically unsaturated dicarboxylic acid dioctyl ester or an α-β-ethylenically unsaturated dicarboxylic acid dibutyl ester. 
     Preferably, the alcohol utilized for the synthesis of the ester can be linear or branched and comprises between 3 and 10 carbon atoms, preferably between 4 and 8 carbon atoms. More preferably, it is butanol. 
     Alternatively, the alcohol can be selected from ethoxylated alcohols, linear or branched, having a degree of ethoxylation lying between 1 and 45, preferably between 1 and 20. 
     “Degree of ethoxylation” according to the present invention is understood to mean the number of ethene oxide units of a polyethylene oxide chain, which is etherified at one of its ends with an alcohol, whereas the hydroxyl group of the other end of the polyethylene oxide chain is esterified with an acid. 
     Preferably, the ethoxylated alcohol ester groups are the only ester groups of the α-β-ethylenically unsaturated dicarboxylic acid ester. 
     Preferably, the molar ratio (a) α-olefin/(b) ester formed by esterification of an α-β-ethylenically unsaturated dicarboxylic acid or a derivative thereof with an alcohol lies between 0.5 and 2. 
     According to one particular embodiment, a dicarboxylic acid ester copolymer according to the invention exhibits a pour point lying between −2° C. and −18° C., preferably lying between −3° C. and −10° C. 
     “Pour point” according to the invention is understood to mean the lowest temperature at which the dicarboxylic acid ester copolymer pours or flows when it is cooled. More particularly, the pour point is measured according to the standard ASTM D-97. 
     According to another particular embodiment, a dicarboxylic acid ester copolymer according to the invention exhibits a kinematic viscosity measured according to the standard ASTM D-445 at 100° C. lying between 20 mm 2 /s and 3000 mm 2 /s, preferably lying between 30 mm 2 /s and 50 mm 2 /s. 
     According to a still further particular embodiment, a dicarboxylic acid ester copolymer according to the invention exhibits a kinematic viscosity measured according to the standard ASTM D-445 at 40° C. lying between 200 mm 2 /s and 11000 mm 2 /s, preferably lying between 300 mm 2 /s and 500 mm 2 /s, still more preferably lying between 350 mm 2 /s and 450 mm 2 /s. 
     According to a still further particular embodiment, a dicarboxylic acid ester copolymer according to the invention exhibits a kinematic viscosity measured according to the standard ASTM D-445 at 40° C. lying between 350 mm 2 /s and 450 mm 2 /s and the α-olefin, or the mixture of α-olefins, constituent of the dicarboxylic acid copolymer according to the invention exhibits a weight average molecular mass lying between 220 g/mol and 260 g/mol. 
     According to a still further particular embodiment, a dicarboxylic acid ester copolymer according to the invention exhibits a flow point lying between −3° C. and −10° C. and a kinematic viscosity measured according to the standard ASTM D-445 at 40° C. lying between 350 mm 2 /s and 450 mm 2 /s. 
     According to a still further particular embodiment, a dicarboxylic acid ester copolymer according to the invention exhibits a flow point lying between −3° C. and −10° C., a kinematic viscosity measured according to the standard ASTM D-445 à 100° C. lying between 30 mm 2 /s and 50 mm 2 /and a kinematic viscosity measured according to the standard ASTM D-445 at 40° C. lying between 350 mm 2 /s and 450 mm 2 /s. 
     According to a still further particular embodiment, a dicarboxylic acid ester copolymer according to the invention comprises constituent units deriving from (a) at least one α-olefin of weight average molecular mass lying between 220 g/mol and 260 g/mol and (b) at least one ester formed by esterification of at least one fumaric acid with butanol. 
     The dicarboxylic acid ester copolymers according to the present invention can be prepared according to processes known to those skilled in the art. 
     Examples of dicarboxylic acid ester copolymers and processes for preparation of these copolymers are for example described in the documents CA 1,238,448, in particular in example 7, U.S. Pat. Nos. 4,931,197, 4,931,197, 5,435,928 and WO 94/19337. 
     In general, the dicarboxylic acid ester copolymer or copolymers are present in a grease composition according to the invention in a content ranging from 2% to 20% by weight, preferably from 5% to 15% by weight, more preferably from 8% to 10% by weight, relative to the total weight of the composition. 
     Base Oil 
     As previously stated, a grease according to the present invention comprises (i) at least one base oil. 
     The base oil or oils utilized in grease compositions according to the present invention can be oils of mineral, synthetic or natural origin and mixtures thereof. 
     In particular, the mineral or synthetic oils generally utilized for the preparation of grease belong to one of the groups I to V according to the classes defined in the API classification (or equivalents thereof according to the ATI EL classification) as summarized in table I below. 
     The API classification is defined in American Petroleum Institute 1509 “Engine Oil Licensing and Certification System” 17 th  edition, September 2012. 
     The ATI EL classification is defined in “The ATI EL Code of Practice”, Number 18, November 2012. 
     
       
         
           
               
               
               
               
             
               
                 TABLE I 
               
               
                   
               
               
                   
                 Saturateds content 
                 Sulfur content 
                 Viscosity index 
               
               
                   
               
             
            
               
                 Group I 
                 &lt;90% 
                 &gt;0.03% 
                 80 ≤ VI &lt; 120 
               
               
                 Mineral oils 
                   
                   
                   
               
               
                 Group II 
                 ≥90% 
                 ≤0.03% 
                 80 ≤ VI &lt; 120 
               
               
                 Hydrocracked oils 
                   
                   
                   
               
               
                 Group III 
                   
                   
                   
               
               
                 Hydrocracked or 
                 ≥90% 
                 ≤0.03% 
                 ≥120 
               
               
                 hydro- 
                   
                   
                   
               
               
                 isomerized oils 
                   
                   
                   
               
            
           
           
               
               
            
               
                 Group IV 
                 PAO (polyalphaolefins) 
               
               
                 Group V 
                 Esters and other bases not included in groups I to IV 
               
               
                   
               
            
           
         
       
     
     The mineral base oils include any type of bases obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreatment, hydrocracking and hydroisomerization, and hydrofinishing. 
     The synthetic base oils can be selected from esters, silicones, glycols, polybutene, polyalphaolefins (PAO), alkylbenzene or alkylnaphthalene. 
     The base oils can also be oils of natural origin, for example esters of alcohols and carboxylic acids, obtainable from natural resources such as the sunflower oil, rape oil, palm oil, soya oil etc. 
     More particularly, the base oil can be selected from synthetic oils, mineral oils and mixtures thereof. 
     According to one embodiment, a grease composition according to the invention contains a mixture of at least one mineral oil and at least one synthetic oil, for example at least one polyalphaolefin (PAO) and at least one white mineral oil. 
     According to another embodiment, a grease composition according to the invention contains a mixture of at least one naphthenic mineral oil and at least one paraffinic, in particular light, mineral oil. 
     In general, the base oil or oils are present in a grease composition according to the invention at a content ranging from 25% to 75% by weight, preferably from 30% to 60% by weight, more preferably from 40% to 60% by weight, relative to the total weight of the composition. 
     Calcium Sulfonate Soap 
     As previously stated, a grease according to the present invention comprises (ii) at least one calcium sulfonate soap. This compound is known to those skilled in the art as a detergent and is constituted of a calcium salt of a sulfonate. 
     The soap makes it possible to thicken the grease composition. 
     The calcium sulfonate soap can be prepared separately, or in situ during the manufacture of the grease. 
     These thickeners are products commonly used in the greases field, and are readily available and inexpensive. 
     Greases thickened with calcium sulfonate soaps exhibit very good mechanical stability, compared for example to greases comprising thickeners based on polyureas, which enables easy utilization in applications where the grease is in an unconfined enclosure. Furthermore, the polyureas are prepared from isocyanates, extremely toxic compounds, and it is therefore not desirable to utilize thickeners based on polyureas to obtain a biodegradable grease which is nontoxic and free from products classified under the CLP regulation (CE No. 1272/2008). 
     A grease according to the invention is thus preferably free from thickener(s) based on polyurea. 
     In particular, the calcium sulfonate can be overbased, that is to say the calcium is in excess (in a quantity greater than the stoichiometric quantity relative to the anionic group(s) of the soap). 
     The excess metal imparting the overbased nature to the detergent is in the form of metal salts insoluble in oil, for example carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate. 
     Preferably, the overbased calcium sulfonate is a calcium sulfonate overbased with calcium carbonate. 
     It is known that the BN (Base Number) of overbased calcium sulfonates is elevated, preferably greater than 150 mg KOH/g of detergent. The BN is measured according to the standard ASTM D-2896. 
     In one embodiment of the invention, the overbased calcium sulfonate has a BN of at least 300 mg KOH/g of detergent, preferably ranging from 300 to 500 mg KOH/g of detergent, advantageously from 300 to 400 mg KOH/g of detergent. 
     As examples of calcium sulfonate more particularly usable in a grease according to the present invention, those sold under the name SYNCAL® OB, in particular SYNCAL® OB 405 and SYNCAL® OB 408, by Kimes Technologies, those sold under the name LUBRIZOL® 75, in particular LUBRIZOL® 75M and LUBRIZOL® 75WO, by Lubrizol Corporation or also those sold under the name HYBASE®, in particular HYBASE® GF 400, by Chemtura, may be cited. 
     The content of calcium sulfonate soap(s) can be adjusted depending on the grade of grease that it is desired to obtain. Such an adjustment clearly falls within the abilities of those skilled in the art. 
     In particular, the calcium sulfonate soap(s) are generally present in a grease composition according to the invention in a content ranging from 10% to 50% by weight, preferably from 15% to 40% by weight, preferably from 25% to 35% by weight, relative to the total weight of the grease composition. 
     According to one particular embodiment, a grease composition according to the invention comprises: 
     (i) 25% to 75% by weight of at least one base oil, in particular of a mixture of at least one mineral base oil and at least one PAO base oil or of a mixture of at least one naphthenic mineral oil and at least one paraffinic mineral oil, 
     (ii) 10% to 50% by weight of at least one calcium sulfonate soap, in particular overbased with calcium carbonate, and 
     (iii) 2% to 20% by weight of at least one dicarboxylic acid ester copolymer comprising constituent units deriving from (a) at least one α-olefin and (b) at least one ester formed by esterification of an α-β-ethylenically unsaturated dicarboxylic acid or a derivative thereof with an alcohol, the molar ratio (a)/(b) lying between 0.5 and 4. 
     According to another particular embodiment, a grease composition according to the invention comprises: 
     (i) 40% to 60% by weight of at least one base oil, in particular of a mixture of at least one mineral base oil and at least one PAO base oil or a mixture of at least one naphthenic mineral oil and at least one paraffinic mineral oil, 
     (ii) 25% to 35% by weight of at least one calcium sulfonate soap, in particular overbased with calcium carbonate, and 
     (iii) 8% to 10% by weight of at least one dicarboxylic acid ester copolymer comprising constituent units deriving from (a) at least one α-olefin and (b) at least one ester formed by esterification of an α-β-ethylenically unsaturated dicarboxylic acid or a derivative thereof with an alcohol, the molar ratio (a)/(b) lying between 0.5 and 4. 
     Other Additives 
     A grease composition according to the invention can also contain any types of additives suitable for its subsequent uses. 
     Thus, a grease composition according to the invention can also contain antioxidant additives, for example antioxidants of the phenolic or amine type, anti-rust additives such as for example oxygen-containing compounds such as esters, for example sorbitan mono-oleate and oxidized waxes, or amine phosphates, anti-corrosion additives such as tolyltriazoles or also copper passivating agents. 
     A grease composition according to the present invention can also contain anti-wear and extreme pressure additives, in particular phosphorus-containing, such as for example alkyl phosphates or alkyl phosphonates, phosphoric acid, phosphorous acid, mono, di and triesters of phosphorous acid and phosphoric acid, and salts thereof. 
     A grease composition according to the present invention can also contain sulfur-containing anti-wear and extreme pressure additives, for example dithiocarbamates, thiadiazoles and benzothiazoles, and olefin sulfides. 
     As examples of antioxidant agents more particularly utilizable in a grease according to the present invention, those sold under the name IRGANOX®, in particular IRGANOX® L57, by BASF may be cited. 
     As examples of anticorrosion agents more particularly utilizable in a grease according to the present invention, those sold under the name INFINEUM®, in particular INFINEUM® M7121, by INFINEUM may be cited. 
     These different compounds are generally present in contents lower than 2%, or also 0.5% by weight, relative to the total weight of the grease composition. 
     A grease according to the invention can also contain at least one polymer, for example selected from polyolefins, polyisobutene (PIB), polyethylenes, polypropylene, heavy polyalphaolefins (PAO), olefin copolymers (OCP) for example diene-hydrogenated styrene and polymethacrylates (PMA). 
     These polymers are utilized to improve the cohesivity of greases, which thus better withstand centrifugation. These polymers also result in better adhesivity (especially the PIB) of the grease to surfaces, and increase the viscosity of the base oil fraction, and thus the thickness of the oil film between the friction parts. The quantity incorporated varies depending on the molar mass, the viscosity and the effect desired. 
     As examples of polymers more particularly utilizable in a grease according to the present invention, those sold under the name INDOPOL®, in particular INDOPOL® H300, by Ineos Oligomers and those sold under the name FUNCTIONAL V® by Functional Products may be cited. 
     These polymer(s) are generally comprised in a grease composition according to the invention at contents lying between 1% and 35% by weight, relative to its total weight. 
     For example PIBs of molar mass lying between 15,000 and 25,000 Daltons will be utilized at contents lying between 1% and 10% by weight, relative to the total weight of the composition, to increase the adhesivity of the grease to metallic surfaces. 
     The nature of the aforesaid additives, and in particular the polymers, and the quantity thereof will be adjusted by those skilled in the art, in such a manner as to conserve the properties imparted to the grease composition by the presence of at least one dicarboxylic acid ester copolymer as defined above. 
     Grease Grades 
     The consistency of a grease is a measure of its hardness or its fluidity at rest. It is expressed numerically by the depth of penetration of a cone of given dimensions and mass. The grease subjected to kneading beforehand. The conditions for measurement of the consistency of a grease are defined by the standard ASTM D 217. 
     According to their consistency, greases are divided into 9 classes or 9 NLGI (National Lubricating Grease Institute) grades commonly utilized in the greases field. These grades are shown in table II below. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE II 
               
               
                   
                   
               
               
                   
                   
                 Consistency according to 
               
               
                   
                 NLGI Grade 
                 ASTM D 217 (1/10 mm) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 000 
                 445-475 
               
               
                   
                 00 
                 400-430 
               
               
                   
                 0 
                 355-385 
               
               
                   
                 1 
                 310-340 
               
               
                   
                 2 
                 265-295 
               
               
                   
                 3 
                 220-250 
               
               
                   
                 4 
                 175-205 
               
               
                   
                 5 
                 130-160 
               
               
                   
                 6 
                  85-115 
               
               
                   
                   
               
            
           
         
       
     
     A grease according to the invention preferably has a consistency lying between 220 and 340 tenths of a millimeter, preferably between 240 and 300 tenths of a millimeter, more preferably between 250 and 290 tenths of a millimeter, measured according to the standard ASTM D217. Preferably, it is of NLGI grade 1, 2 or 3. 
     As stated above, a grease composition according to the invention exhibits excellent performance in term of adhesivity. Further, the consistency of the grease is maintained during the use of the grease composition in presence of large quantities of water. 
     In particular, the adhesivity is measured by the standard DIN 51807. This consists in determining the percentage by mass of grease lost during its use in presence of water. 
     The examples below make it possible to demonstrate that the adhesivity of a grease according to the invention, incorporating at least one quite specific dicarboxylic acid ester copolymer as defined above, is much superior to the adhesivity of a grease not incorporating such a copolymer. 
     In particular, it is considered that the adhesivity of a grease composition is improved when its loss of grease, measured according to the standard DIN 51807, is lower by at least 5%, preferably at least 10%, more preferably at least 20% relative to the loss of grease of the same composition free from dicarboxylic acid ester copolymer defined according to the present invention. 
     The present invention thus relates to the utilization, in a grease composition comprising: 
     (i) at least one base oil, and 
     (ii) at least one calcium sulfonate soap, 
     of at least one dicarboxylic acid ester copolymer comprising constituent units deriving from (a) at least one α-olefin and (b) at least one ester formed by esterification of an α-β-ethylenically unsaturated dicarboxylic acid or a derivative thereof with an alcohol, the molar ratio (a)/(b) lying between 0.5 and 4, to improve the adhesivity, measured according to the standard DIN 51807, of the said grease composition. 
     Processes for Preparation of Greases 
     A grease according to the invention can be manufactured according to processes known to those skilled in the art by forming the metal soap in situ or by utilizing a preformed soap. 
     First Process 
     According to a first alternative, one process for preparation of the grease, taking place in two steps, forming the metal soap in situ, is as follows. 
     The first step implements the stages which comprise:
         introducing into a reactor, capable of being hermetically closed and resistant to certain pressures defined in advance:       

     (1) a mixture, generally liquid, containing an inert liquid carrier in the form of a volatile liquid and/or a non-volatile liquid or mixtures compatible therewith, in particular corresponding to a fraction of at least one base oil as defined above; 
     (2) a sulfonic acid having or containing an aliphatic chain having in principle at least 12 carbon atoms; 
     (3) calcium hydroxide and/or calcium oxide; and 
     (4) a small proportion of a promoter selected from the group constituted of water, C 1 -C 4  aliphatic alcohols soluble in water, readily miscible with water or readily dispersible in water, alkoxyalkanols soluble in water, readily miscible with water or readily dispersible in water and mixtures thereof; and
         hermetically closing this reactor, stirring the contents of this aforesaid reactor, while maintaining these contents at a temperature in the range from about 15° C. to 177° C. and introducing carbon dioxide into these contents in quantities making it possible to regulate the pressure in this reactor in the range from about 172 kPa to about 551 kPa (25 to 80 psi) during a time making it possible to transform this reaction mixture into a thixotropic composition thickened by a calcium sulfonate complex containing an excess of the desired base.       

     Such a process step is described in particular in the document FR 2,626,277. 
     The second step consists in adding 12-hydroxystearic acid, lime and boric acid to a thixotropic composition thickened with a calcium sulfonate complex obtained in the previous step, preferably in the same reactor. 
     The mixture thus obtained is heated slowly to a temperature lying between 100° C. and 120° C. then heated more rapidly to a temperature greater than 120° C. 
     The boric acid is thus converted to calcium borate. 
     The reaction mixture is cooled to a temperature less than or equal to 80° C. 
     During the cooling, the remainder of the base oil is added. 
     Finally, the various additives desired in the grease composition are added at a temperature lying between 60° C. and 90° C. 
     Such a process can further comprise subsequent grinding and grease recovery steps. 
     Second Process 
     Alternatively, a grease according to the present invention can be manufactured according to a process in a single step, which represents an improvement compared to the first process described above, and which is for example described in the document WO 2015/071331. 
     Such a process comprises at least the following steps:
         a) preparing, in a reactor, a calcium sulfonate soap,   b) closing the reactor,   c) increasing the temperature in the reactor to a temperature of at least 130° C. and under a pressure of at least 400 kPa,   d) decompression, and removing the water contained in the reactor,   e) cooling the reactor.       

     The process can further comprise an implementation step 0 after step e) and comprising the addition of at least one supplementary additive, optionally followed by a step of grinding the product obtained. 
     These processes for preparation of a grease according to the invention are well known and it is among the general abilities of those skilled in the art to adapt the conditions thereof in order to obtain a grease the consistency and properties whereof are suitable for the intended use. 
     Use 
     A grease composition as defined above finds uses in many industrial fields, in particular wind power, automotive, steel-making, mining, papermaking or also the foodstuffs industry, in particular when the load is high and the temperature range is wide. 
     A grease according to the invention is quite especially useful for the lubrication of roller and slide bearings, open gears, metal cables and chain drives, and more generally uses not comprising a sealing system. 
     The present invention thus relates to a process for lubrication of a mechanical component, comprising at least one step of contacting the mechanical component with a grease composition as defined according to the present invention. 
     EXAMPLES 
     Method for Evaluation of Physical and Chemical Properties 
     This involves the evaluation of the physical and chemical properties of greases, and more particularly their grade. 
     The grade is determined according to the standard ASTM D217 after 60 strokes. 
     Method for Evaluation of the Mechanical Stability Properties of Greases 
     The mechanical stability of greases is evaluated by the penetrability measurement (P100000) and by the “Shell Roller” test. 
     The penetrability is measured according to the standard ISO 2137 after 100000 strokes and is expressed in 1/10 mm. 
     The “Shell Roller” test is performed according to the standard ASTM D1831 after 100 hours at 80° C. and the results are expressed in 1/10 mm. This test in principle consists in lamination of the grease by means of rollers and enables evaluation of the stability of a grease when the latter is laminated. 
     Method for Evaluation of the Heat Resistance Properties of Greases 
     The heat resistance of greases is evaluated by measurement of the drop point and by evaluation of the oil separation. 
     The drop point is measured according to the standard NF T60-627 and is expressed in degrees Celsius. 
     The oil separation after 50 hours at 100° C. is evaluated according to the standard ASTM D6184 and is expressed as a percentage corresponding to a mass percentage oil loss. 
     The oil separation after 168 hours at 40° C. is evaluated according to the standard NF T60-191 and is expressed as a percentage corresponding to a mass percentage oil loss. 
     More particularly, the oil separation makes it possible to evaluate the thermal stability of a grease. The lower the percentage obtained, the better is the heat resistance and the evaluation of the oil separation well reflects the quality of a thickener for retaining the oil present in a grease. 
     Method for Evaluation of the Extreme Pressure Properties 
     The 4 ball EP test is performed according to the standard DIN 51350/4 and the extreme pressure is expressed in daN. 
     Method for Evaluation of the Anti-Corrosion Properties 
     This involves the evaluation, by the Emcor test, of the anti-corrosion properties of greases. The Emcor test is evaluated according to the standard ISO 11007. 
     Method for Evaluation of the Anti-Wear Properties 
     This involves the evaluation of the anti-wear properties of greases by performing the 4 ball test according to the standard ASTM D2266. 
     The 4 ball test is performed under the following conditions:
         duration: 1 hour,   load: 40 kg,   temperature: 75° C.       

     Method for Evaluation of the Adhesivity of Greases 
     This involves measuring the quantity of grease lost in presence of water. This behavior of the grease is measured according to the standard DIN 51807. 
     Compounds Used 
     Base oil 1 is a polyalphaolefin. 
     Base oil 2 is a white mineral oil. 
     Base oil 3 is a naphthenic mineral oil. 
     Base oil 4 is a light paraffinic base oil, described as “Bright Stock Solvent”. 
     The dicarboxylic acid ester copolymer according to the invention exhibits the properties shown in the following table 1: 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                 Kinematic viscosity at 100° C. (mm 2 /s) 
                 ASTM D-445 
                 30 to 50 
               
               
                 Kinematic viscosity at 40° C. (mm 2 /s) 
                 ASTM D-445 
                 350 to 450 
               
               
                 Pour point (° C.) 
                 ASTM D-97 
                  −3 to −10 
               
               
                   
               
            
           
         
       
     
     The antioxidant agent is an alkylated diphenylamine. 
     The polymer is a polybutene. 
     The anticorrosion agent is a salicylate detergent. 
     Example 1: Grease Compositions According to the Invention 
     The compositions of greases according to the invention are detailed in table 2 below, in percentage by weight: 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Grease A 
                 Grease B 
                 Grease C 
               
               
                   
                 According 
                 According 
                 According 
               
               
                   
                 to the 
                 to the 
                 to the 
               
               
                 Composition 
                 invention 
                 invention 
                 invention 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Base oil 1 
                 27.9 
                 29.9 
                   
               
               
                 Base oil 2 
                 14.5 
                 15.5 
                   
               
               
                 Base oil 3 
                 — 
                 — 
                 27.8 
               
               
                 Base oil 4 
                 — 
                 — 
                 27.1 
               
               
                 Dicarboxylic acid ester 
                 8.3 
                 8.8 
                 8.3 
               
               
                 copolymer according to the 
                   
                   
                   
               
               
                 invention 
                   
                   
                   
               
               
                 Calcium sulfonate soap 
                 32.8 
                 29.9 
                 25.1 
               
               
                 Sulfonic acid 
                 2.1 
                 1.9 
                 1.6 
               
               
                 12-hydroxystearic acid 
                 2.5 
                 2.3 
                 1.9 
               
               
                 Lime 
                 1.9 
                 1.7 
                 1.4 
               
               
                 70% acetic acid 
                 0.6 
                 0.6 
                 0.5 
               
               
                 Calcium carbonate 
                 — 
                 1.5 
                 1.5 
               
               
                 Water 
                 2.9 
                 2.9 
                 2.9 
               
               
                 Anti-oxidant agent 
                 0.5 
                 0.5 
                 0.5 
               
               
                 Polymer 
                 6 
                 6 
                 — 
               
               
                 Anticorrosion agent 
                 — 
                 — 
                 1.4 
               
               
                   
               
            
           
         
       
     
     The greases A, B and C according to the invention are prepared according to the following procedure:
         The base oil 1, a major part of the base oil 2 and calcium sulfonate soap are taken at ambient temperature,   The mixture is heated to 75° C.,   During this heating, the 12-hydroxystearic acid and the antifoaming agent are added, then the sulfonic acid, next the water and finally the acetic acid drop by drop,   The pilot plant is closed and the mixture is heated to 90° C.,   The reactor is opened and the start of the conversion into calcite is monitored by infrared,   The lime is added and the reactor is closed,   The mixture is heated to 140° C.;   The system is decompressed slowly,   The remainder of base oil 2 is added slowly,   The calcium carbonate is added, if necessary,   The mixture is cooled to 80° C.,   The rest of the additives are added, still at 80° C.       

     The performance of greases A, B and C according to the invention, measured according to the methods defined above, is summarized in table 3 below: 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                 Grease A 
                 Grease B 
                 Grease C 
               
               
                   
                   
                 According 
                 According 
                 According 
               
               
                   
                   
                 to the 
                 to the 
                 to the 
               
               
                 Property 
                 Standard 
                 invention 
                 invention 
                 invention 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Grade (1/10 mm) 
                 ASTM D217 
                 258 
                 276 
                 281 
               
               
                 P100000 (1/10 mm) 
                 1S0 2137 
                 +18 
                 +23 
                 +17 
               
               
                 “Shell Roller” (1/10 
                 ASTM D1831 
                 +8 
                 +11 
                 +14 
               
               
                 mm) 
                   
                   
                   
                   
               
               
                 Drop point (° C.) 
                 NF T 60-627 
                 &gt;300 
                 &gt;300 
                 &gt;300 
               
               
                 Oil separation at 
                 ASTM D 6184 
                 1.2 
                 1.9 
                 ≤0.6 
               
               
                 100° C. (%) 
                   
                   
                   
                   
               
               
                 Oil separation at  
                 NF T 60-191 
                 0.4 
                 0.4 
                 0.6 
               
               
                 40° C. (%) 
                   
                   
                   
                   
               
               
                 Extreme pressure 
                 DIN 51350/4 
                 360-380 
                 360-380 
                 400-420 
               
               
                 (daN) 
                   
                   
                   
                   
               
               
                 Anti-corrosion 
                 ISO 11007 
                 — 
                 0-0 
                 0-0 
               
               
                 (cote) 
                   
                   
                   
                   
               
               
                 Anti-wear (mm) 
                 ASTM D2266 
                 0.45 
                 0.69 
                 0.55 
               
               
                 Adhesivity 
                 DIN 51807 
                 43 
                 63 
                 43 
               
               
                 (% losses) 
               
               
                   
               
            
           
         
       
     
     Example 2: Grease Compositions not According to the Invention 
     The compositions of greases outside the invention are detailed in table 4 below, as a percentage by weight: 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                   
                 Grease D 
                 Grease E 
                 Grease F 
               
               
                   
                   
                 Outside 
                 Outside 
                 Outside 
               
               
                   
                 Compound 
                 invention 
                 invention 
                 invention 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Base oil 1 
                 23.7 
                 28.5 
                 — 
               
               
                   
                 Base oil 2 
                 23.7 
                 28.5 
                 — 
               
               
                   
                 Base oil 3 
                   
                   
                 27.8 
               
               
                   
                 Base oil 4 
                   
                   
                 35.3 
               
               
                   
                 Dicarboxylic acid ester 
                 — 
                 — 
                 — 
               
               
                   
                 copolymer 
                   
                   
                   
               
               
                   
                 Calcium sulfonate soap 
                 31.3 
                 27.4 
                 25.1 
               
               
                   
                 Sulfonic acid 
                 1.6 
                 1.8 
                 1.6 
               
               
                   
                 12-hydroxystearic acid 
                 1.9 
                 2.4 
                 1.9 
               
               
                   
                 Lime 
                 2.7 
                 1.6 
                 1.4 
               
               
                   
                 70% acetic acid 
                 0.6 
                 0.5 
                 0.5 
               
               
                   
                 Calcium carbonate 
                 — 
                 — 
                 1.5 
               
               
                   
                 Water 
                 6.6 
                 2.9 
                 2.9 
               
               
                   
                 Antioxidant agent 
                 0.5 
                 0.5 
                 0.5 
               
               
                   
                 Polymer 
                 5.7 
                 6 
                 — 
               
               
                   
                 Boric acid 
                 1.7 
                 — 
                   
               
               
                   
                 Anticorrosion agent 
                 — 
                 — 
                 1.4 
               
               
                   
                   
               
            
           
         
       
     
     Grease D is prepared according to a standard process for grease preparation in two step, as described in the present application. Greases E and F outside invention are prepared according to the procedure of example 1. 
     The performance of greases D to F outside invention, measured according to the methods defined above, are summarized in table 5 below: 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
                   
                 Grease D 
                 Grease E 
                 Grease F 
               
               
                   
                   
                 Outside 
                 Outside 
                 Outside 
               
               
                 Property 
                 Standard 
                 invention 
                 invention 
                 invention 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Grade (1/10 mm) 
                 ASTM D217 
                 291 
                 284 
                 302 
               
               
                 P100000 (1/10 mm) 
                 ISO 2137 
                 +17 
                 +12 
                 +8 
               
               
                 “Shell Roller” (1/10 
                 ASTM 
                 +26 
                 +2 
                 +4 
               
               
                 mm) 
                 D1831 
                   
                   
                   
               
               
                 Drop point (° C.) 
                 NF T 60-627 
                 &gt;300 
                 &gt;300 
                 &gt;300 
               
               
                 Oil separation at 
                 ASTM D 
                 5.1 
                 — 
                 1.37 
               
               
                 100° C. (%) 
                 6184 
                   
                   
                   
               
               
                 Oil separation at 
                 NF T 60-191 
                 1.2 
                 — 
                 1.1 
               
               
                 40° C. (%) 
                   
                   
                   
                   
               
               
                 Extreme pressure 
                 DIN 51350/4 
                 440-460 
                 320-340 
                 420-440 
               
               
                 (daN) 
                   
                   
                   
                   
               
               
                 Anti-corrosion 
                 ISO 11007 
                 — 
                 — 
                 0-0 
               
               
                 (cote) 
                   
                   
                   
                   
               
               
                 Anti-wear (mm) 
                 ASTM 
                 0.37 
                 0.37 
                 0.37 
               
               
                   
                 D2266 
                   
                   
                   
               
               
                 Adhesivity (% 
                 DIN 51807 
                 91 
                 71 
                 94 
               
               
                 losses) 
               
               
                   
               
            
           
         
       
     
     The performance of greases A and B according to the invention is more particularly to be compared with that of greases D and E outside invention and the performance of the grease C according to the invention is more particularly to be compared with that of the grease F outside invention. 
     Greases A, B and C according to the invention exhibit a lower level of water lost on contact with water, and thus greatly improved adhesivity, compared to greases D to F outside invention. 
     This demonstrates the beneficial effect of the presence of at least one specific ester copolymer according to the present invention on the adhesivity performance of greases according to the invention. 
     Further, the other effects of greases A, B and C are of the same order of magnitude, or even better, compared to the effects of greases D to F. 
     In particular, their mechanical stability is maintained and their oil separation is improved.