阅读说明：本技术 具有改善的粘合性的润滑脂组合物 (Grease composition with improved adhesion ) 是由 N·哥奈特 R·布鲁格曼 于 2018-12-07 设计创作，主要内容包括：本发明涉及一种润滑脂组合物,包含(i)至少一种基础油,(ii)至少一种磺酸钙皂,和(iii)至少一种二羧酸酯共聚物,其包含衍生自(a)至少一种α-烯烃和(b)至少一种通过α-β-烯键式不饱和二羧酸或其衍生物与醇的酯化反应而形成的酯的构成单元,摩尔比(a)/(b)在0.5和4之间。本发明还涉及至少一种二羧酸酯共聚物在润滑脂组合物中用于改善所述润滑脂组合物的根据标准DIN 51807测量的粘合性的用途,该润滑脂组合物包含(i)至少一种基础油,和(ii)至少一种磺酸钙皂,该至少一种二羧酸酯共聚物包含衍生自(a)至少一种α-烯烃和(b)至少一种通过α-β-烯键式不饱和二羧酸或其衍生物与醇的酯化反应而形成的酯的构成单元,摩尔比(a)/(b)在0.5和4之间。本发明最后还涉及一种润滑机械部件的方法,包括使用这种组合物。(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 derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, the molar ratio (a)/(b) being between 0.5 and 4. The present invention also relates to the use of at least one dicarboxylate ester copolymer comprising constituent units derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, in a grease composition comprising (i) at least one base oil, and (ii) at least one calcium sulfonate soap, in a molar ratio (a)/(b) between 0.5 and 4, for improving the adhesion of said grease composition as measured according to standard DIN 51807. The invention finally relates to a method for lubricating a mechanical part, comprising the use of such a composition.)

1. A grease composition comprising

(i) At least one base oil, at least one oil,

(ii) at least one calcium sulfonate soap, and

(iii) at least one dicarboxylate copolymer comprising constituent units derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, in a molar ratio (a)/(b) between 0.5 and 4.

2. The composition according to claim 1, wherein the α -olefin comprises from 8 to 24 carbon atoms, preferably from 10 to 18 carbon atoms, and in particular from 14 to 16 carbon atoms.

3. Composition according to any one of the preceding claims, in which the α - β -ethylenically unsaturated dicarboxylic acid is chosen from maleic acid, fumaric acid, citraconic acid, mesaconic acid and itaconic acid, in particular chosen from maleic acid and fumaric acid.

4. A composition according to any preceding claim, wherein the alcohol comprises from 3 to 10 carbon atoms, preferably from 4 to 8 carbon atoms.

5. Composition according to any one of the preceding claims, in which the alcohol is chosen from ethoxylated linear or branched alcohols having a degree of ethoxylation of between 1 and 45, preferably between 1 and 20.

6. Composition according to any one of the preceding claims, comprising from 2% to 20% by weight, preferably from 5% to 15% by weight, more preferably from 8% to 10% by weight, of at least one dicarboxylate copolymer, relative to the total weight of the composition.

7. Composition according to any one of the preceding claims, in which the base oil is chosen from oils of mineral, synthetic or natural origin and mixtures thereof.

8. Composition according to any one of the preceding claims, in which the base oil is chosen from synthetic oils, mineral oils and mixtures thereof, in particular a mixture of at least one polyalphaolefin and at least one white mineral oil, or a mixture of at least one naphthenic mineral oil and at least one paraffinic mineral oil.

9. The composition according to any one of the preceding claims, comprising from 25% to 75% by weight, preferably from 30% to 60% by weight, more preferably from 40% to 60% by weight, of at least one base oil, relative to the total weight of the composition.

10. The composition according to any of the preceding claims, wherein the calcium sulfonate is calcium sulfonate, preferably utilizing calcium carbonate overbase.

11. Composition according to any one of the preceding claims, comprising from 10% to 50% by weight, preferably from 15% to 40% by weight, more preferably from 25% to 35% by weight, of at least one calcium sulfonate soap, relative to the total weight of the grease composition.

12. The composition of any preceding claim, further comprising at least one additive selected from the group consisting of antioxidants, rust inhibitors, corrosion inhibitors, copper passivators, anti-wear agents, and extreme pressure additives.

13. The composition according to any of the preceding claims, further comprising at least one polymer, for example selected from polyolefins, Polyisobutylene (PIB), polyethylene, polypropylene, heavy Polyalphaolefins (PAO), Olefin Copolymers (OCP) such as diene-hydrogenated styrene and Polymethacrylate (PMA).

14. Composition according to any one of the preceding claims, having a consistency of between 220 and 340 tenths of a millimetre, preferably between 240 and 300 tenths of a millimetre, more preferably between 250 and 290 tenths of a millimetre, measured according to the standard ASTM D217.

15. Use of at least one dicarboxylate ester copolymer in a grease composition for improving the adhesion of said grease composition as measured according to standard DIN51807, the grease composition comprising:

(i) at least one base oil, and

(ii) at least one calcium sulfonate soap, wherein the calcium sulfonate soap,

the at least one dicarboxylate copolymer comprises constituent units derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, in a molar ratio (a)/(b) between 0.5 and 4.

16. Method for lubricating a mechanical component comprising at least one step of contacting the mechanical component with a composition as defined according to any one of claims 1 to 14.

Technical Field

The present invention relates to the field of greases (grasses) which are particularly useful in industrial applications, in particular grease compositions having good adhesion properties.

Background

Lubricating greases are solid or semi-fluid materials resulting from the dispersion of a thickener in a liquid lubricant, which optionally incorporates additives that impart special properties thereto.

Such greases are particularly suitable for lubrication in any industrial application, in particular for applications that are loaded and operate over a wide temperature range. This is because liquid lubricants are unsuitable for these applications because they can "drift" relative to the lubrication point.

Over the past few years greases thickened with complex calcium sulphonate soaps have been widely developed and utilised as they exhibit numerous properties such as extreme pressure and wear resistance, mechanical strength, corrosion resistance, water resistance and thermal stability, especially at high temperatures. Documents US 5126062, US 2015/252283 or WO2015/071331, for example, describe such compositions and a process for their preparation.

However, the complex calcium sulfonate soaps used in these greases are not naturally adhesive, as may be the case with some complex lithium or aluminum soaps. Therefore, these grease compositions do not achieve a satisfactory level of adhesion.

In general, it is known to the person skilled in the art to use additives to modify the properties of a grease, for example in order to improve its antioxidant properties.

It has therefore also been proposed to add additives, in particular polymers such as polyolefins, Polyisobutylene (PIB), polyethylene, polypropylene, heavy PAO, Olefin Copolymers (OCP) or Polymethacrylates (PMA), in order in particular to increase the adhesion, as described for example in document WO 2012/080940.

However, most of the proposed polymers are very viscous, which imposes great restrictions on the preparation process of the grease. In particular, it is necessary to preheat them before introducing them into the grease mixture, or to introduce them during the grease heating step. Furthermore, the properties in terms of adhesion obtained with such polymers still remain to be improved.

It is therefore desirable to provide a grease which can be used in industrial applications, the adhesion properties of which are improved by selecting one or more additives which do not involve the above-mentioned disadvantages and which, in particular, do not impose too great a limitation on the preparation process of the grease.

There is also a need to provide a grease useful for industrial applications which also maintains its properties in terms of mechanical stability, wear resistance, load resistance, corrosion resistance and heat resistance.

Disclosure of Invention

The present application in particular aims to propose a grease composition thickened with calcium sulphonate soaps having improved adhesion properties relative to prior art grease compositions.

Another object of the present invention is to provide a grease whose other properties, in particular in terms of mechanical stability (especially at high temperatures), are also maintained at a satisfactory level, even further improved with respect to the grease compositions of the prior art.

More particularly, the inventors have found that the adhesion of greases can be improved by incorporating therein very specific additives, namely dicarboxylic acid esters.

Thus, the present invention according to a first aspect thereof relates to a grease composition comprising

(i) At least one base oil, at least one oil,

(ii) at least one calcium sulfonate soap, and

(iii) at least one dicarboxylate copolymer comprising constituent units derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, in a molar ratio (a)/(b) between 0.5 and 4.

This is because the inventors have surprisingly found that the presence of such dicarboxylate ester copolymers in the grease composition gives excellent performance in: adhesiveness, reducing the loss of material during its use in the presence of water. The consistency of the grease in the presence of large amounts of water is also maintained. Moreover, these properties are also durable over time.

Preferably, the presence of this specific ester also makes it possible to maintain the other properties of the grease, in particular its mechanical stability. It was furthermore found that certain properties of the greases thus formulated are further improved, in particular their mechanical stability.

The present invention further relates to the use of at least one dicarboxylate ester copolymer in a grease composition for improving the adhesion of said grease composition as measured according to standard DIN51807, the grease composition comprising:

(i) at least one base oil, and

(ii) at least one calcium sulfonate soap, wherein the calcium sulfonate soap,

the at least one dicarboxylate copolymer comprises constituent units derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, in a molar ratio (a)/(b) between 0.5 and 4.

The invention finally also relates to a method of lubricating a machine part comprising at least one step of contacting the machine part with a grease composition as defined according to the invention.

Other characteristics, variations and advantages of the use of the composition according to the invention will become more apparent from reading the description, examples and figures given by way of illustration and not of limitation of the invention.

In the following, the expressions "between", "from.

Unless otherwise indicated, the expression "component un (e) (comprising …)" is to be understood as "component audions un (e) (comprising at least one (or one) …)".

Composition comprising a metal oxide and a metal oxide

Dicarboxylic acid ester copolymers

As mentioned above, the grease composition according to the present invention comprises (iii) at least one dicarboxylate ester copolymer comprising constituent units derived 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 derivative thereof with an alcohol, the molar ratio (a)/(b) being between 0.5 and 4.

(a) Alpha-olefins

Alpha-olefins are compounds known to those skilled in the art and commonly used to prepare ester base oils.

The alpha-olefins used according to the invention preferably contain from 8 to 24 carbon atoms, preferably from 10 to 18 carbon atoms, and in particular from 14 to 16 carbon atoms.

Preferably, the alpha-olefin is linear.

According to one embodiment, the alpha-olefin or alpha-olefin mixture constituting the dicarboxylic acid copolymer according to the invention has a weight average molecular weight of between 180g/mol and 800g/mol, in particular between 200g/mol and 500g/mol, preferably between 200g/mol and 300g/mol, more preferably between 220g/mol and 260 g/mol.

b) Esters

Alpha-beta-ethylenically unsaturated dicarboxylic acid esters are compounds known to those skilled in the art and commonly used to prepare ester base oils.

According to the present invention, "α - β -ethylenically unsaturated dicarboxylic acid" means an ester (b) obtained by an esterification reaction between an α - β -ethylenically unsaturated dicarboxylic acid or a derivative thereof and an alcohol.

The alpha-beta-ethylenically unsaturated dicarboxylic acids used according to the invention are preferably selected from maleic acid, fumaric acid, citraconic acid, mesaconic acid and itaconic acid, in particular from maleic acid and fumaric acid.

The alpha-beta-ethylenically unsaturated dicarboxylic acid derivative may more particularly be selected from maleic anhydride or itaconic anhydride.

The alpha-beta-ethylenically unsaturated dicarboxylic acid esters used according to the invention are preferably alpha-beta-ethylenically unsaturated dicarboxylic acid diesters, in particular dioctyl alpha-beta-ethylenically unsaturated dicarboxylic acids or dibutyl alpha-beta-ethylenically unsaturated dicarboxylic acids.

Preferably, the alcohol used to synthesize the ester may be linear or branched and contain 3 to 10 carbon atoms, preferably 4 to 8 carbon atoms. More preferably, it is butanol.

Alternatively, the alcohol may be selected from linear or branched alcohols with ethoxylation degrees between 1 and 45, preferably between 1 and 20.

According to the invention, "degree of ethoxylation" is understood to mean the number of ethylene-oxygen units of the polyethylene oxide chain, which are etherified with an alcohol at one end and the hydroxyl group at the other end of the polyethylene oxide chain is esterified with an acid.

Preferably, the ethoxylated alcohol ester group is the only ester group 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 derivative thereof with an alcohol is between 0.5 and 2.

According to a particular embodiment, the dicarboxylate copolymers according to the invention have a pour point of between-2 ℃ and-18 ℃, preferably between-3 ℃ and-10 ℃.

"pour point" according to the present invention is understood to mean the lowest temperature at which the dicarboxylate copolymer pours or flows on cooling. The pour point is more particularly measured according to the standard ASTM D-97.

According to another particular embodiment, the dicarboxylate copolymers according to the invention have a value of 20mm measured at 100 ℃ according to standard ASTM D-445²S and 3000mm²Between/s, preferably 30mm²S and 50mm²Kinematic viscosity between/s.

According to yet another particular embodiment, the dicarboxylate copolymers according to the invention have a value of 200mm measured at 40 ℃ according to standard ASTM D-445²S and 11000mm²A/s, preferably between 300mm²S and 500mm²Between/s, more preferably 350mm²S and 450mm²Kinematic viscosity between/s.

According to yet another particular embodiment, the dicarboxylate copolymer according to the invention has a value of 350mm measured according to standard ASTM D-445 at 40 ℃²S and 450mm²A kinematic viscosity of between/s and the α -olefin or α -olefin mixtures constituting the dicarboxylic acid copolymer according to the invention have a weight-average molecular weight of between 220g/mol and 260 g/mol.

According to yet another particular embodiment, the dicarboxylate copolymer according to the invention has a pour point between-3 ℃ and-10 ℃ and a pour point of 350mm measured at 40 ℃ according to standard ASTM D-445²S and 450mm²Kinematic viscosity between/s.

According to yet another particular embodiment, the dicarboxylate copolymer according to the invention has a pour point between-3 ℃ and-10 ℃, measured according to standard ASTM D-445 at 100 ℃ of 30mm²S and 50mm²Kinematic viscosity between/s and measured at 40 ℃ according to the standard ASTM D-445 of 350mm²S and 450mm²Kinematic viscosity between/s.

According to yet another particular embodiment, the dicarboxylate copolymer according to the present invention comprises constituent units derived from (a) at least one alpha-olefin having a weight average molecular weight between 220g/mol and 260g/mol and (b) at least one ester formed by esterification of at least one fumaric acid with butanol.

The dicarboxylate copolymers according to the present invention may be prepared according to methods known to those skilled in the art.

Examples of dicarboxylate copolymers and methods of preparing these copolymers are described, for example, in the following documents: CA 1238448 (in particular example 7), US 4931197, US 4931197, US 5435928 and WO 94/19337.

Typically, the one or more dicarboxylate ester copolymers are present in the grease composition of the present invention in a content of from 2 to 20% by weight, preferably 5 to 15% by weight, more preferably 8 to 10% by weight, relative to the total weight of the composition.

Base oil

As previously mentioned, the grease according to the present invention comprises (i) at least one base oil.

The one or more base oils used in the grease composition according to the present invention may be oils of mineral, synthetic or natural origin and mixtures thereof.

In particular, the mineral or synthetic oils usually used for preparing greases belong to one of groups I to V according to the categories defined in the API classification (or their equivalents according to the ATI EL classification), as summarized in table I below.

API classifications are defined in the following documents: the American Petroleum institute 1509 "Engine Oil Licensing and monitoring System", 17 th edition, 9 months 2012.

The ATI EL classification is defined in "The ATI EL Code of Practice" No. 18 of month 11, 2012.

TABLE I

Mineral base oils include all types of base oils obtained by: the crude oil is distilled at atmospheric pressure and vacuum, and then subjected to refining operations such as solvent extraction, desalting (dewaxing), solvent deparaffinization, hydrotreating, hydrocracking and hydroisomerization, and hydrofinishing.

The synthetic base oil may be selected from esters, silicones, glycols, polybutenes, Polyalphaolefins (PAO), alkylbenzenes or alkylnaphthalenes.

The base oil may also be an oil of natural origin, such as an ester of an alcohol and a carboxylic acid, which may be obtained from natural sources, such as sunflower oil, rapeseed oil, palm oil, soybean oil, and the like.

The base oil may more particularly be selected from synthetic oils, mineral oils and mixtures thereof.

According to one embodiment, the grease composition according to the present invention comprises a mixture of at least one mineral oil and at least one synthetic oil, for example a mixture of at least one Polyalphaolefin (PAO) and at least one white mineral oil.

According to another embodiment, the grease composition according to the invention comprises a mixture of at least one naphthenic mineral oil and at least one (in particular light) paraffinic mineral oil.

Typically, the one or more base oils are present in the grease composition of the present invention in 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 mentioned above, the grease according to the present invention comprises (ii) at least one calcium sulfonate soap. Such compounds are known to the person skilled in the art as detergents (tergents) and consist of calcium sulphonates.

The soap enables thickening of the grease composition.

The calcium sulfonate soap can be prepared independently or in situ in the process of manufacturing the lubricating grease.

These thickeners are products commonly used in the grease art and are readily available and inexpensive.

Compared to greases comprising, for example, a thickener based on polyurea, greases thickened with calcium sulphonate soaps have very good mechanical stability, which enables easy use in applications where the grease is in an unenclosed space. Furthermore, polyureas are prepared from isocyanates, which are an extremely toxic compound, and it is therefore not desirable to use thickeners based on polyureas to obtain a polyurea which is non-toxic and free from compliance with the CLP regulations (CE n)^o1272/2008) to the classified products.

The grease according to the present invention is thus preferably free of polyurea-based thickeners.

In particular, the calcium sulfonate may be overbased, that is to say the calcium is in excess (greater than stoichiometric amounts relative to the anionic group or groups of the soap).

The excess metal which renders the detergent overbased is in the form of an oil-insoluble metal salt, for example a carbonate, hydroxide, oxalate, acetate, glutamate, preferably a carbonate.

Preferably, the overbased calcium sulfonate is calcium sulfonate that utilizes the overbased nature of calcium carbonate.

Overbased calcium sulfonates are known to have an elevated BN (base number), preferably greater than 150mg KOH/g detergent. 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 300mg KOH/g detergent, preferably from 300 to 500mg KOH/g detergent, advantageously from 300 to 400mg KOH/g detergent.

As an example of a calcium sulphonate that can be used more particularly in the grease according to the invention, mention may be made of the calcium sulphonate by the company Kimes technologies under the nameOB, especiallyOB 405 andthose sold by OB408, under the name of Lubrizol Corporation75. In particular75M andthose sold under the name 75WO or by the company ChemturaIn particularThose sold under GF 400.

The content of calcium sulfonate soap may be adjusted according to the grade of grease desired to be obtained. Such adjustments are well within the ability of those skilled in the art.

In particular, the one or more calcium sulphonate soaps are generally present in the grease composition of the present invention in a content of from 10% to 50% by weight, preferably from 15% to 40% by weight, more preferably from 25% to 35% by weight, relative to the total weight of the grease composition.

According to a particular embodiment, the grease composition according to the invention comprises:

(i) 25% to 75% by weight of at least one base oil, in particular 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) from 10% to 50% by weight of at least one calcium soap sulfonate, in particular calcium soap sulfonate overbased using calcium carbonate, and

(iii) 2% to 20% by weight of at least one dicarboxylate copolymer comprising constituent units derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, the molar ratio (a)/(b) being between 0.5 and 4.

According to another particular embodiment, the grease composition according to the present invention comprises:

(i) from 40 to 60% by weight of at least one base oil, in particular 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 calcium sulfonate soap using calcium carbonate overbase; and

(iii) from 8% to 10% by weight of at least one dicarboxylate copolymer comprising constituent units derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, the molar ratio (a)/(b) being between 0.5 and 4.

Other additives

The grease composition according to the present invention may further comprise any type of additive suitable for its subsequent use.

Thus, the grease composition according to the present invention may further comprise an antioxidant additive, such as a phenol or amine type antioxidant; rust-inhibiting additives, such as oxygen-containing compounds, for example esters, such as sorbitan monooleate and oxidized waxes, or amine phosphates; anti-corrosion additives such as tolyltriazole or copper passivators.

The grease composition according to the present invention may also comprise antiwear and extreme pressure additives, in particular phosphorus-containing additives, such as alkyl phosphates or phosphonates, phosphoric acid, phosphorous acid, mono-, di-and triesters of phosphorous acid and phosphoric acid, and salts thereof.

The grease composition according to the present invention may also comprise sulphur-containing anti-wear and extreme pressure additives, such as dithiocarbamates, thiadiazoles and benzothiazoles, and olefin sulphides.

As an example of an antioxidant which can be used more particularly in the grease according to the invention, mention may be made of the company BASF under the nameIn particularThose sold by L57.

As an example of an anti-corrosion agent which can be used more particularly in the grease according to the invention, mention may be made of the company INFINUM under the nameIn particularThose sold by M7121.

These different compounds are generally present in a content of less than 2% or less than 0.5% by weight relative to the total weight of the grease composition.

The grease according to the present invention may further comprise at least one polymer, for example selected from polyolefins, Polyisobutylene (PIB), polyethylene, polypropylene, heavy Polyalphaolefins (PAO), Olefin Copolymers (OCP) such as diene-hydrogenated styrene and Polymethacrylates (PMA).

These polymers serve to improve the cohesion (cohsivit) of the grease, which is thus better able to withstand centrifugal forces. These polymers also result in better adhesion of the grease to the surface (especially PIB) and increase the viscosity of the base oil fraction, thereby increasing the thickness of the oil film between the friction parts. The amount introduced varies depending on the molar mass, the viscosity and the desired effect.

As an example of a polymer which can be used more particularly in the grease according to the invention, mention may be made of the polymers known by the company IneosOligomers under the nameIn particularThose sold by H300 and under the name Functional by the Functional Products companyThose sold.

The polymer(s) is/are typically comprised in the grease composition in a content of 1 to 35% by weight, relative to the total weight of the grease composition of the present invention.

For example PIB having a molar mass between 15000 and 25000 daltons, used in a content ranging from 1% to 10% by weight relative to the total weight of the composition, for improving the adhesion of the grease to the metal surface.

The above additives and in particular the polymers will have their properties and their amounts adjusted by the person skilled in the art in order to maintain the properties imparted to the grease composition by the presence of at least one dicarboxylate ester copolymer as defined above.

Grade of grease:

the consistency of a grease may be a measure of its hardness or its fluidity at rest. It is represented numerically by the skin depth of a cone of given size and mass. The grease was stirred in advance. The measurement conditions for grease consistency are defined by the standard ASTM D217.

Greases are classified, according to their consistency, into 9 classes or 9 grades nlgi (national Lubricating great institute) that are commonly used in the field of greases. These ratings are shown in table II below.

NLGI grade	Consistency according to ASTM D217 (1/10mm)
		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

TABLE II

The grease according to the present invention preferably has a consistency of 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 standard ASTM D217. Preferably, it is NLGI grade 1, 2 or 3.

As described above, the grease composition according to the present invention has excellent properties in terms of adhesion. Furthermore, the consistency of the grease is maintained during use of the grease composition in the presence of a large amount of water.

In particular, the adhesion was measured by the standard DIN 51807. This consists in determining the mass percentage of grease lost during its use in the presence of water.

The following examples demonstrate that the adhesion of the greases of the present invention incorporating at least one very specific dicarboxylate ester copolymer as defined above is far superior to the adhesion of greases not incorporating such a copolymer.

In particular, it is believed that the adhesion of the grease composition is improved when: when the grease loss, measured according to standard DIN51807, is at least 5% lower, preferably at least 10% lower, more preferably at least 20% lower, than the grease loss of the same composition without the dicarboxylate ester copolymer as defined according to the present invention.

The present invention thus relates to the use of at least one dicarboxylate ester copolymer in a grease composition for improving the adhesion of said grease composition as measured according to standard DIN51807, the grease composition comprising:

(i) at least one base oil, and

(ii) at least one calcium sulfonate soap, wherein the calcium sulfonate soap,

the at least one dicarboxylate copolymer comprises constituent units derived from (a) at least one alpha-olefin and (b) at least one ester formed by esterification of an alpha-beta-ethylenically unsaturated dicarboxylic acid or derivative thereof with an alcohol, in a molar ratio (a)/(b) between 0.5 and 4.

Preparation method of lubricating grease

The grease according to the present invention may be manufactured according to methods known to the skilled person, by forming metal soaps in situ or by using preformed soaps.

First method

According to a first alternative, the preparation of the grease in two steps by in situ formation of the metal soap is as follows.

The first step is carried out in stages comprising:

-introducing, in a reactor that can be sealed and withstands a predetermined certain pressure:

(1) a normally liquid mixture comprising, or a mixture compatible with, an inert liquid carrier in the form of a volatile liquid and/or a non-volatile liquid, in particular corresponding to a portion of at least one base oil as defined above;

(2) sulfonic acids having or comprising in principle an aliphatic chain having at least 12 carbon atoms;

(3) calcium hydroxide and/or calcium oxide; and

(4) a small amount of a promoter selected from water, C soluble, miscible or dispersible in water₁-C₄Aliphatic alcohols, alkoxyalkanols soluble, miscible or dispersible in water and mixtures thereof; and is

-sealing the reactor, agitating the contents of the reactor as described above while maintaining the contents at a temperature in the range of about 15 ℃ to 177 ℃, and introducing carbon dioxide into the contents in an amount such that the pressure in the reactor can be adjusted in the range of about 172kPa to about 551kPa (25 to 80psi) during a time period such that the reaction mixture can be converted 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 document FR 2626277.

The second step consists in adding 12-hydroxystearic acid, lime and boric acid to the thixotropic composition thickened with the calcium sulphonate complex obtained in the preceding step, preferably in the same reactor.

The mixture thus obtained is slowly heated to a temperature of 100 ℃ to 120 ℃ and then more rapidly heated to a temperature of more than 120 ℃.

Boric acid is thus converted to calcium borate.

The reaction mixture is cooled to a temperature of less than or equal to 80 ℃.

During cooling, the remaining base oil was added.

Finally, the various additives required in the grease composition are added at a temperature of 60 ℃ to 90 ℃.

Such a process may further comprise subsequent grinding and grease recovery steps.

Second method

Alternatively, the grease according to the invention may be manufactured according to a single-step process, which represents an improvement over the first process described above and is described, for example, in document WO 2015/071331.

Such a method comprises at least the following steps:

a) preparing calcium sulfonate soap in a reactor,

b) the reactor was closed and the reaction mixture was allowed to cool,

c) the temperature in the reactor is raised up to a temperature of at least 130 ℃ and at a pressure of at least 400kPa,

d) the pressure was reduced and the water contained in the reactor was removed,

e) the reactor was cooled.

The method may further comprise an implementation step f) after step e) and comprising the addition of at least one additional additive, optionally followed by a step of grinding the resulting product.

These methods of preparation of the greases of the present invention are well known and it is within the general ability of the person skilled in the art to adjust their conditions to obtain greases of adjusted consistency and properties according to the intended application.

Applications of

The grease composition as defined above may be used in numerous industrial fields of application, in particular in the fields of wind power generation, automotive, ferrous metallurgy, mining, paper or food, in particular when the load is high and the temperature range is wide.

The grease according to the invention is particularly useful for lubricating rolling bearings and sliding bearings, open gear transmissions (engreages), metal cables and chain transmissions, and more generally applications that do not include a sealing system.

The present invention thus relates to a method for lubricating a mechanical part comprising at least one step of contacting the mechanical part with a grease composition as defined according to the present invention.

Detailed Description