JP2011529974A - Lubricating grease composition - Google Patents

Abstract

A lubricating grease composition comprising (i) a polyalkylene glycol base oil, (ii) a lithium complex thickener, and (iii) a carboxylic acid having 18 or more carbon atoms, particularly a friction reduction of a dual mass flywheel. Useful for.
[Selection figure] None

Description

FIELD OF THE INVENTION The present invention relates to a lubricating grease composition, particularly a lubricating grease composition used for flyholes, particularly for dual mass flywheels.

BACKGROUND OF THE INVENTION The main purpose of lubrication is to separate solid surfaces that move with each other to minimize friction and wear. The most frequently used materials for this purpose are oils and greases. The choice of lubricant is largely determined by the specific application.

  The dual mass flywheel eliminates excessive rattling gear shifting, reduces gear change / shift effort, and improves fuel economy. Dual mass flywheels are usually mounted on lightweight diesel trucks with standard manual transmissions or high-end luxury cars to damp vibrations in the drive train. As a result, the automobile can be operated for a long time without damage.

  It is known that greases based on lithium soap complexes are used for flywheels. Such greases have been found to provide sufficient lubrication characteristics. However, as the demand for high performance is increasing, it is desirable to provide a dual mass flywheel grease with improved lubrication properties, particularly friction reduction properties.

  According to the present invention, there is provided a lubricating grease composition comprising (i) a polyalkylene glycol base oil, (ii) a lithium complex thickener, and (iii) a carboxylic acid having 18 or more carbon atoms.

  Further in accordance with the present invention, there is provided a method of using the aforementioned lubricating grease composition for a dual mass flywheel.

  Further in accordance with the present invention, there is provided a method of using the lubricating grease composition described above to reduce friction.

  It was unexpectedly found that the grease composition of the present invention exhibits excellent friction reducing properties, as well as good stability, good wear resistance, high centrifugal resistance, and increased grease life. .

DETAILED DESCRIPTION OF THE INVENTION The lubricating grease of the present invention contains a polyalkylene glycol base oil as an essential component.
The polyalkylene glycol base oil used in the lubricating grease composition of the present invention is not particularly limited, and various conventional polyalkylene glycols can be conveniently used.
The polyalkylene glycol (PAG) used in the present invention can represent an alkylene oxide (—R—O—) having 1 to 6 carbon atoms as a monomer unit.

The polyalkylene glycol can exhibit hydrogen end groups, alkyl, aryl, alkylaryl, alkoxy, alkylaryloxy and / or hydroxy end groups. An alkylaryloxy group may also be understood to mean an arylalkyl (ene) group (eg, arylCH ₂ CH ₂ —, thus meaning an arylalkyl (ene) oxy group and an alkylaryl group. The terminal group of the type, or the terminal group of the alkylaryl type, aryloxy type and alkylaryloxy type preferably has 6 to 24 carbon atoms, particularly preferably 6 to 18 carbon atoms for the aryl type and carbon for the alkyl type. The number of atoms is preferably 1-12.

It is preferable that the density of the polyalkylene glycol used here is the same as the density of the lithium complex soap (for example, lithium sebacate, lithium azelate) used in the present composition. The density of the polyalkylene glycol used here is preferably 900 to 1400 kg / m ³ , more preferably 950 to 1100 kg / m ³ , and still more preferably 1000 to 1100 kg / m ³ .

  It may be a homogeneous polymer, ie, a polyalkylene glycol (and / or polypropylene oxide), or a copolymer, terpolymer, and the like. In the latter case, the monomer units may represent a random distribution or block structure. If the polyalkylene glycol is not a heterogeneous polymer, preferably 20% or more, preferably 40% or more of the total monomer units can be produced from polypropylene oxide (PO), and preferably the total monomer units of these polyalkylene glycols are preferably More than 20% can be produced using ethylene oxide (EO) (PO / EO copolymer). In a further embodiment, preferably more than 20%, preferably more than 40% of the total monomer units are obtained using butylene oxide (BO), more preferably more than 20% of the total monomer units of these polyalkylene glycols. , Obtained using ethylene oxide (EO) (BO / EO copolymer).

In a preferred embodiment here, preferably 50% or more, preferably 80% or more of the total monomer units can be produced from propylene oxide and the remainder can be produced from ethylene oxide.
In a particularly preferred embodiment here, the polyalkylene glycol is a homopolymer of propylene oxide. Examples of polypropylene homopolymers are commercially available from Dow Chemical under the trade name Synalox®, such as Synalox® 100-150B.

When a (poly) alcohol is used, the starting compound is incorporated at the end of the polymer, also referred to as the end group of this polymer chain, according to the meaning of the present invention. Preferred starting groups consist of active hydrogen-containing compounds. Active hydrogen-containing compounds, for example water, n- butanol, propylene glycol, ethylene glycol, neopentyl glycols such as pentaerythritol, ethylene diamine, phenol, cresol or other (C ₁ ~C ₁₆ (mono-, di- or tri) alkyl) Aromatic, (hydroxyalkyl) aromatic, hydroquinone, aminoethanolamine, triethylenetetramine, polyamine, sorbitol or other sugars. Other CH acidic compounds such as carboxylic acids or carboxylic anhydrides can also be used as starting compounds. Examples of other suitable starting compounds include long chain alcohols such as C ₁₀ -C ₁₈ alcohol.

  The polyalkylene glycol has, for example, a group corresponding to an aryl group or heteroaromatic group inserted as a side group or terminal group into the polymer chain. These groups may be substituted with linear or branched alkyl groups or alkylene groups if necessary. These whole alkyl groups or alkylene groups preferably represent those having 1 to 18 carbon atoms.

  Cyclic ether alcohols such as hydroxyfurfuryl or hydroxytetrahydrofuran, nitrogen heterocyclic compounds or sulfur heterocyclic compounds can also be used as a starting compound group. Such polyalkylene glycols are disclosed in WO 01/57164. The teachings of this document are incorporated herein.

  The polyalkylene glycol of the present invention preferably has an average molecular weight (number average) of 200 to 6000 g / mol, more preferably 400 to 4000 g / mol, still more preferably 1000 to 3000 g / mol, and particularly 2000 to 3000 g / mol. It is.

  The polyalkylene glycol used in the present invention can be produced by reacting an alcohol containing a polyalcohol as a starting compound with an oxirane such as ethylene oxide, propylene oxide and / or butylene oxide. According to this reaction, the polyalkylene glycol has only one free hydroxyl group as a terminal group. Polyalkylene glycols having only one hydroxyl group are preferred over polyalkylene glycols having two free hydroxyl groups. For example, after further etherification steps, polyalkylene glycols which no longer contain free hydroxyl groups are particularly preferred in terms of stability, hygroscopicity and compatibility. Alkylation of the terminal hydroxyl group increases thermal stability. Thus, in a particularly preferred embodiment of the invention, the PAG base oil comprises a PAG that is end-capped, ie, free of free hydroxyl groups.

  The lubricating composition contains PAG base oil in an amount of 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more based on the total amount of the lubricating composition. It is even more preferred to use only the base oil (one or more) as the base oil.

In a preferred embodiment of the present invention, the PAG base oil has a kinematic viscosity at 40 ° C. (according to ASTM D445) of 32 to 690 mm ² / s, preferably 100 to 300 mm ² / s, more preferably 150 to 250 mm ² / s. is there.

  In addition to the polyalkylene glycol base oil, it may contain other base oils that may be any conventionally used mineral or synthetic source. However, in a preferred embodiment of the present invention, the base oil consists solely of one or more polyalkylene glycol base oils.

The mineral source base oil may be, for example, a mineral oil produced by solvent refining or hydroprocessing. The synthetic base oil may generally be a mixture of _C10-50 hydrocarbon polymers, such as a liquid polymer mixture of α-olefins. These may be conventional esters such as polyol esters. The base oil may be a mixture of these oils. The base oil is preferably a poly-α-olefin or a mixture of the two, as the mineral source base oil sold under the names “HVI” or “MVIN” by the Royal Dutch / Shell business group. Synthetic hydrocarbon base oils such as those sold under the name “XHVI” by the Royal Dutch / Shell corporate group can also be used. If there is a lubricating mineral oil base stock used in the manufacture of grease, this base stock can be any base stock derived from paraffinic, naphthenic and mixed base crudes and refined by conventional methods.

  The lubricating grease composition of the present invention further contains a lithium soap complex thickener in addition to the polyalkylene glycol base oil.

The amount of lithium soap complex present in the grease is preferably 2-30% by weight, preferably 5-20% by weight, based on the composition.
In a preferred embodiment, the lithium soap complex _contains C 12 _{-C 24} lithium hydroxy fatty acid soaps and lithium soaps of _C 2 _{-C 12} aliphatic dicarboxylic acids.

More preferably, the hydroxy fatty acid lithium soap is a C ₁₆ -C ₂₀ hydroxy fatty acid. Particularly preferred hydroxy fatty acids are hydroxystearic acid, such as 9-hydroxy, 10-hydroxy or 12-hydroxystearic acid, more preferably the latter. Lisinolenic acid, an unsaturated form of 12-hydroxystearic acid with a double bond in the 9-10 position, can also be used. Other suitable hydroxy fatty acids include 12-hydroxybehenic acid and 10-hydroxypalmitic acid.

Dicarboxylic acid is preferably a _C 4 _{-C 12,} more preferably _C 6 _{-C 10} aliphatic dicarboxylic acids. Examples of suitable acids include succinic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, pimelic acid, azelaic acid, dodecanedioic acid and sebacic acid. Azelaic acid and sebacic acid are particularly preferred.

C ₁₂ -C ₂₄ hydroxy fatty acid and _C 2 _{-C 12} aliphatic dicarboxylic acid is 20: 1 to 1: 1, preferably 10: 1 to 1: 1, more preferably 8: 1 to 3: 1 by weight Preferably it is present.

  Another essential component of the lubricating grease composition of the present invention is a long chain carboxylic acid having 18 or more carbon atoms. The long chain carboxylic acid having 18 or more carbon atoms is preferably present in an amount of 0.1 to 10% by weight, preferably about 1 to about 10% by weight, more preferably about 1 to about 5% by weight, based on the composition.

The long chain carboxylic acid is selected from carboxylic acids having 18 to 90 carbon atoms. In a particularly preferred embodiment, the general formula R (COOH) _n , where n is 2 or 3, and R is a hydrocarbon residue of 24 to 90 carbon atoms, preferably 36 to 54, which may be saturated or unsaturated. ) Dimer acid and trimer acid. The linolenic acid dimer is formed by reacting two molecules of linolenic acid according to a normal Diels-Alder reaction. Linolenic trisodium mer is a C ₅₄ carboxylic acid that is formed by polymerization of three molecules of linolenic acid linked together by unsaturated groups of each linolenic acid. The dimers and trimers of linolenic acid are commercially available from Oleon Chemicals under the trade name Radiacid and from Arizona Chemicals under the trade name Unidyme. Particularly preferred linolenic acid dimers and trimers are Radiacid 0975 and Radiacid 0980 commercially available from Oleon Chemicals, Belgium, and Unidyme 12 (C ₁₈ dimer) commercially available from Arizona Chemicals, USA.

In the lubricating grease of the present invention, various conventional grease additives are used in the application field in order to impart desired properties such as oxidation stability, viscosity, extreme pressure and corrosion resistance to the grease. Can be taken in. Suitable additives include one or more extreme pressure / antiwear agents such as dialkyl or diaryldithiophosphates, borates, substituted thiadiazoles such as dialkoxyamines, and substituted organic phosphates, amine phosphates, sulfation of natural or synthetic sources. Whale oil, sulfated lard, sulfated esters, sulfated fatty acid esters, and similar sulfated materials such as organophosphates of the formula (OR) ₃ P = O, where R is an alkyl, aryl or aralkyl group, and triphosphoro Polymeric nitrogen / phosphorus compounds made by reaction with thionate; one or more overbased metal-containing detergents such as calcium or magnesium alkyl salicylates or alkylaryl sulfonates; polyisobutenyl succinic anhydride and One or more non-reactive products such as reaction products with amines or esters Minute dispersants; one or more antioxidants such as hindered phenols or amines such as phenyl α-naphthylamine; one or more rust inhibitors; one or more friction modifiers; one or more viscosity index improvements Agents; one or more pour point depressants; and one or more thickeners. Various polymers such as graphite, finely pulverized molybdenum disulfide, talc, metal powder, and polyethylene wax may also be added to impart special properties.

In order to reduce the friction level, those skilled in the art greatly expect the use of molybdenum-based formulations, and a large number of patent documents on such lubricating compositions have been proposed.
The invention will now be described with reference to the following examples.

Examples 1 to 3 and Comparative Example A
The lubricating greases of Examples 1 to 3 and Comparative Example A were produced by the following procedure.
50% of the base oil was charged to the autoclave with 12-hydroxystearic acid, sebacic acid and lithium hydroxide monohydrate and 100 ml of water. The autoclave was closed and heated to 145 ° C. After reaching the venting temperature, the vent valve was opened and water vapor was released for 30 minutes. When the water vapor pressure reached 0 bar, heating was started with the degassing valve still open, and the temperature was 215 ° C. After reaching a temperature of 215 ° C., the jacket was used to cool to 165 ° C. at a cooling rate of 1 ° C./min. After reaching 165 ° C., the remaining 50% of the base oil was charged to the container. The product was then cooled to 80 ° C. and the additive was charged to the container. The product was then homogenized on a three roll mill.
The composition of the manufactured grease is shown in Table 1 below. Example 1 contains 4% of a specific dimer of unsaturated C18 fatty acids. Example 2 contains 4% of a specific trimer of unsaturated C18 fatty acids. Example 3 contains saturated C18 fatty acids. Comparative Example A does not contain a dimer or trimer of C18 fatty acids.

1. 1. Polypropylene glycol homopolymers available from Dow Chemical 2. Dimer of _C18 fatty acid commercially available from Oleon Chemicals. 3. Trimers of _C18 fatty acids commercially available from Oleon Chemicals 4. _C18 saturated fatty acids commercially available from Oleon Chemicals 5. Commercial product of Chemtura, USA 6. Commercial products from Ludwigshafen, Chemtura, Germany 7. Swiss commercial product of CIBA Geigy Specialties. Commercial products from Belgium, Belgium.

Example 4
Measurement of Friction Coefficient The friction coefficients of Examples 1 to 3 and Comparative Example A were measured using the following test method.

  The friction test of the mass flywheel was performed using a rig equipped with a dynamic torsion test. It is necessary to use completely new all internal parts of the mass flywheel that must meet the material standards. The mass flywheel is first conditioned in a dynamic torsion test rig to obtain a constant surface condition. Mass flywheels are filled with grease (in the examples and comparative examples) according to the test part filling guidelines and then tested at a temperature of 120 ° C., 2000 rpm, and 0.25 Hz with an angle of +/− 30 °. The mass flywheel friction value corresponds to the torque required for a complete cycle. The friction coefficient is calculated by subtracting the minimum torque after displacement in each direction at zero crossing from the maximum torque after displacement in each direction at zero crossing and dividing by 2. Is done. The friction coefficients of Examples 1 to 3 and Comparative Example A are shown in Table 2 below.

From the results in Table 2, it can be seen that the addition of dimer (C ₃₆ ) acid or trimer (C ₅₄ ) acid to the PAG + lithium soap complex significantly reduces the coefficient of friction.

WO 01/57164

Claims (11)

  A lubricating grease composition comprising (i) a polyalkylene glycol base oil, (ii) a lithium complex thickener, and (iii) a carboxylic acid having 18 or more carbon atoms.   The lubricating grease composition according to claim 1, wherein the carboxylic acid has 18 to 54 carbon atoms. The carboxylic acid is derived from dimer acid and trimer acid of the general formula R (COOH) _n (where n is 2 or 3 and R is a hydrocarbon residue having 36 to 54 carbon atoms). The lubricating grease composition according to claim 1 or 2, which is selected.   The lubricating grease composition according to any one of claims 1 to 3, wherein the carboxylic acid is selected from a dimer or trimer of linolenic acid. Wherein the lithium complex _thickener, lubricating grease composition according to claim 1 comprising a C 12 _{-C 24} lithium soap of a hydroxy carboxylic acid and lithium soaps of _C 2 _{-C 12} dicarboxylic acids . The lubricating grease composition according to claim 5, wherein the C ₁₂ -C ₂₄ hydroxycarboxylic acid lithium soap is lithium 12-hydroxystearate. The C ₂ -C ₁₂ dicarboxylic acids, azelaic acid, lubricating grease composition according to claim 5 or 6 selected from sebacic acid and mixtures thereof.   The lubricating grease composition according to any one of claims 1 to 7, wherein the polyalkylene glycol base oil is a homogeneous polymer of polypropylene glycol. The lubricating grease composition according to any one of claims 1 to 8, wherein the density of the polyalkylene glycol base oil is 900 to 1400 kg / m ³ .   A method of using the lubricating grease composition according to any one of claims 1 to 9 for a dual mass flywheel.   A method of using the lubricating grease composition according to any one of claims 1 to 10 to reduce friction.