JP6826651B2 - Grease composition - Google Patents

Description

The present invention relates to a grease composition.

Grease is a lubricant in which a fibrous thickener is dispersed in a base oil to form a semi-solid state. Compared to lubricating oil, grease is more likely to adhere to a lubricating portion and is less likely to flow out. Therefore, it is possible to make the lubrication system a simple structure, and it is mainly used for lubrication of mechanical elements such as rolling bearings, plain bearings, ball screws, linear motion guides, and gears, and is used for industrial machinery and transportation machinery systems. Widely used.

In recent years, with the demand for energy saving, reduction of energy loss of various mechanical systems has become an urgent issue. In the case of automobile engine oil, etc., in order to ensure fuel efficiency, the viscosity of the lubricating oil base oil is reduced as much as possible, energy loss due to the viscous resistance of the lubricating oil is reduced, and frictional resistance of sliding parts is reduced. Therefore, it is effective to optimally prescribe various additives such as a friction reducing agent (Patent Document 1).

On the other hand, in the case of grease which is a non-Newtonian fluid, it is necessary to consider not only the viscosity of the base oil but also the apparent viscosity including the structural viscosity caused by the fibrous thickener dispersed in the base oil. The apparent viscosity can be easily arranged by so-called consistency, and it is known that the higher the consistency (soft), the lower the viscous resistance (Non-Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-102281

Basics and Applications of Lubricating Grease, pp. 49-89, edited by Japan Tribology Society Grease Study Group, Yokendo, 2007

However, it is not always easy to secure an appropriate consistency when applied to a mechanical system while reducing the viscous resistance. That is, if the grease is too soft, it may scatter due to centrifugal force due to the rotational movement, or may flow out from the mechanical element. On the other hand, if it is too hard, it becomes sliding resistance and hinders the desired movement. In other words, in the case of conventional grease, there was no choice but to practice the optimum formulation while balancing the base oil composition and the amount of thickener.

An object to be solved by the present invention is to provide a grease composition having low sliding resistance and capable of significantly reducing the power consumption of mechanical elements, particularly the power consumption during bearing rotation.

As a result of diligent research to solve the above problems, the present inventors have used each base oil independently by mixing a predetermined amount of specific base oils having different properties as the base oil of grease. It was found that the power consumption during bearing rotation can be significantly reduced as compared with grease.

In order to reduce the energy required to rotate the bearing and save energy, it is necessary to reduce the rolling resistance and slip resistance between the bearing rolling element (ball, roller) and the raceway ring (inner ring and outer ring) as much as possible. It is important, and it is generally considered useful to reduce the viscosity of the base oil of a lubricating oil (lubricating oil or grease), or to add an oily agent having a friction reducing effect as an additive. However, in the case of grease, it is necessary to expose the base oil to high temperature conditions in the process of producing the thickener, and there is a limit to reducing the viscosity in terms of evaporation and safety of the base oil. Further, an additive that reduces friction has a problem that its effect is reduced with time of use. On the other hand, the present inventors have focused on the oil film forming ability of the bearing sliding portion and the viscosity change due to the temperature of the lubricating oil base oil, and formed a sufficient oil film between the bearing rolling element and the raceway ring by direct contact between them. to reduce energy loss, large molecular conformation to the components of the base oil, specifically be contained components (n-d-M ring analysis% C _a) containing an aromatic, and the temperature rise causing a high paraffin component viscosity index (n-d-M ring analysis% C _P) in order to avoid the viscosity reduction associated with contained good balance is found to be effective.

The present invention has been made based on the above findings, and provides the grease compositions described in the following [1] to [9].

[1] a lubricating base oil and, a grease composition comprising a thickener, wherein the lubricating oil base oil, n-d-M ring analysis value of% _{C A} is 2-8 by ASTM D3238, % _{C P} is the first and the lubricating oil base oil is 50~75, n-d-M ring analysis value of% _{C a} by ASTM D3238 of not more than 1,% _{C P} is 70 or more, the urea adduct value of 4 mass The content of the first lubricating oil base oil is 5 to 90% by mass based on the total amount of the lubricating oil base oil, and the content of the first lubricating oil base oil is 5 to 90% by mass. A grease composition having a lubricating oil base oil content of 10 to 95% by mass.
[2] The grease composition according to [1], which has a consistency of 220 to 300.
[3] The grease composition according to [1] or [2], which further contains an organic molybdenum compound.
[4] The grease composition according to [3], wherein the organic molybdenum compound contains at least one selected from molybdenum dithiocarbamate and molybdenum dithiophosphate.
[5] The grease composition according to any one of [1] to [4], wherein the first lubricating oil base oil has a kinematic viscosity of 10 to 700 mm ² / s at 40 ° C. and a viscosity index of 90 to 120. ..
[6] The grease composition according to any one of [1] to [5], wherein the second lubricating oil base oil has a kinematic viscosity of 10 to 5000 mm ² / s at 40 ° C. and a viscosity index of 110 to 150. Stuff.
[7] The grease composition according to any one of [1] to [6], wherein the second lubricating oil base oil contains at least one selected from mineral oils and synthetic hydrocarbons.
[8] The grease composition according to any one of [1] to [7], wherein the thickener contains at least one selected from a metallic soap-based compound and a urea compound.
[9] A grease composition containing a lubricating oil base oil, a thickener, and an organic molybdenum compound, wherein the lubricating oil base oil is% C of an nd-M ring analysis value by ASTM D3238. by _a 2 to 8,% _{C P} is the first and the lubricating oil base oil is 50~75, n-d-M ring analysis value of% _{C a} by ASTM D3238 of not more than 1,% _{C P} is 70 or more It contains a second lubricating oil base oil, and the content of the first lubricating oil base oil is 5 to 90% by mass based on the total amount of the lubricating oil base oil, and the second lubricating oil is contained. A grease composition having a base oil content of 10 to 95% by mass and a consistency of 220 to 300.

The grease composition of the present invention has a special effect that the amount of electric power consumed for bearing rotation is small.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The grease composition according to the embodiment of the present invention contains a lubricating oil base oil and a thickener. Lubricant base oil, the first and the lubricating oil base oil n-d-M ring analysis value of% _{C A} by ASTM D3238 there is 2 to 8,% _{C P} 50 to 75, according to ASTM D3238 n-d % of -M ring analysis value C _a is 1 or less,% C _P is 70 or more, containing a second lubricating base oil the urea adduct value is not more than 4 mass%, a. The mixing ratio of the first lubricating oil base oil and the second lubricating oil base oil is such that the content of the first lubricating oil base oil is 5 to 90% by mass based on the total amount of the lubricating oil base oil. The content of the lubricating oil base oil of No. 2 is 10 to 95% by mass.

In this embodiment, attention is paid to the oil film forming ability of the bearing sliding portion and the change in viscosity due to the temperature of the lubricating oil base oil, and a sufficient oil film is formed between the bearing rolling element and the raceway ring to reduce energy loss due to direct contact between them. In order to reduce the amount, the "wedge effect" that accompanies the rolling of the raceway ring and the bearing rolling element is used, and the base oil component has a large three-dimensional structure, and specifically contains an aromatic component (n-). it is effective to contain C _a)% by d-M ring analysis, based on the findings of the present inventors that, the first lubricating base oil is used.

Regard n-d-M ring analysis value by ASTM D3238, the% _{C A} of the first lubricating base oil 2-8, preferably 2-6, more preferably 4-6. % Reduction in energy loss and C _A is less than 2 becomes insufficient, also tends low content of relatively paraffinic components exceeds 8, the viscosity reduction at a high temperature becomes large, the oil film forming ability Is insufficient in terms of.

% _{C P} of the first lubricating base oil is 50 to 75, preferably 60 to 70. When% _CP is less than 50, the viscosity at high temperature is greatly reduced and the oil film forming ability is inferior, and when it exceeds 75, the content of components containing aromatic components tends to be relatively small, and the effect of reducing energy loss is achieved. Is insufficient.

The viscosity index of the first lubricating oil base oil is preferably 90 to 120, more preferably 95 to 115, and even more preferably 100 to 110. When the viscosity index is 90 or more, the decrease in viscosity due to the temperature rise can be suppressed, and the oil film forming ability is further improved.

The kinematic viscosity of the first lubricating oil base oil at 40 ° C. is not particularly limited, but is preferably 10 to 700 mm ² / s, more preferably 20 to 500 mm from the viewpoint of safely preparing a grease having excellent lubricity. ^{It is 2} / s, more preferably 25 to 70 mm ² / s.

The viscosity index and the kinematic viscosity at 40 ° C. in the present invention mean the viscosity index measured according to JIS K2283 and the kinematic viscosity at 40 ° C., respectively.

The first lubricating oil base oil is a lubricating oil fraction obtained by refining a distillate obtained by atmospheric distillation of crude oil or further vacuum distillation by various refining processes, and is nd according to ASTM D3238. % _{C a} is 2 to 8,% _{C P} of -M ring analysis value can be mentioned those 50 to 75. The refining process includes hydrorefining, solvent extraction, solvent desulfurization, and the like, and these can be combined and treated in an appropriate order to obtain the first lubricating oil base oil of the present embodiment. Mixtures of two or more refined oils with different properties obtained from different crude oils or distillates by different process combinations and sequences are also useful. As long as the properties of the obtained first lubricating oil base oil are adjusted so as to satisfy the above-mentioned physical properties, any of the first lubricating oil base oils obtained by any method can be preferably used.

In the present embodiment, it is effective to include a chain hydrocarbon component and a paraffin component having a low traction coefficient in the base oil at the closest portion between the bearing rolling element and the raceway ring, which are elastic fluid lubrication. Based on the findings of the present inventor, a second lubricating oil base oil is used.

On the other hand, the present inventors have found that even if the paraffin component in the lubricating oil base oil is large, if the paraffin component does not have an appropriate branch, the viscosity increase in the low temperature range becomes large, and the bearing starts at a low temperature. As a result of further studies, it was found that the urea adduct value is effective as an index of the paraffin content that causes the torque increase when starting the bearing at low temperature. I found it. Then, the present inventors found that urea adduct value,% of C _P and% C _A are each satisfy specific conditions the second lubricating base oil, by mixing the first lubricating base oil, starting at low temperatures We have found that it is possible to reduce the torque of bearings from normal temperature to high temperature while suppressing the rapid increase in torque.

Regard n-d-M ring analysis value by ASTM D3238,% _{C A} of the second lubricating base oil, 1 or less, preferably 0.8 or less. % C if _A is greater than 1, can not be sufficiently supplied to low suitable paraffinic components of traction coefficient at the closest site of the bearing rolling elements and the bearing ring comprising an elastic fluid lubrication.

% _{C P} of the second lubricating base oil is 70 or more, preferably 75 or more, more preferably 80 or more. When% _CP is less than 70, the effect of reducing the traction coefficient at the closest portion between the bearing rolling element and the raceway ring, which is the elastic fluid lubrication, becomes insufficient.

The urea adduct value of the second lubricating oil base oil is 4% by mass or less, preferably 3.5% by mass, from the viewpoint of suppressing the increase in viscosity in the low temperature region and suppressing the torque increase in bearing start-up at low temperature. % Or less, more preferably 3% by mass or less. The urea adduct value of the second lubricating oil base oil may be 0% by mass, but it is possible to obtain a lubricating oil base oil having a higher viscosity index while sufficiently suppressing the torque increase when the bearing is started at a low temperature. Further, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, in that the dewaxing condition is relaxed and the economical efficiency is excellent.

The urea adduct value in the present invention is measured by the following method. 100 g of the weighed sample oil (lubricating oil base oil) is placed in a round bottom flask, 200 g of urea, 360 ml of toluene and 40 ml of methanol are added, and the mixture is stirred at room temperature for 6 hours. As a result, white granular crystals are generated as a urea adduct in the reaction solution. The reaction solution is filtered through a 1 micron filter to collect the produced white granular crystals, and the obtained crystals are washed 6 times with 50 ml of toluene. The recovered white crystals are placed in a flask, 300 ml of pure water and 300 ml of toluene are added, and the mixture is stirred at 80 ° C. for 1 hour. The aqueous phase is separated and removed with a separating funnel, and the toluene phase is washed 3 times with 300 ml of pure water. A desiccant (sodium sulfate) is added to the toluene phase for dehydration treatment, and then toluene is distilled off. The ratio (mass percentage) of the urea adduct thus obtained to the sample oil is defined as the urea adduct value.

In the measurement of the urea adduct value, as the urea adduct, the component of isoparaffin that causes a torque increase at low temperature bearing start-up, and the normal paraffin when normal paraffin remains in the lubricating oil base oil. Is excellent as an index of the content ratio of normal paraffin and the above-mentioned specific isoparaffin because it can collect the oil accurately and surely. According to the analysis using GC and NMR, the present inventors have found that the main component of the urea adduct is normal paraffin and isoparaffin urea adduct having 6 or more carbon atoms from the end of the main chain to the branch position. Is confirmed.

The viscosity index of the second lubricating oil base oil is 110 to 150, preferably 115 to 140, and more preferably 125 to 140. When the viscosity index is 110 or more, the decrease in viscosity at high temperature can be suppressed, and the oil film forming ability is further improved. When the viscosity index is 150 or less, it is excellent in terms of manufacturing cost when obtaining a lubricating oil base oil.

The kinematic viscosity of 40 ° C. of the second lubricating base oil is preferably 10~5000mm ² / s, more preferably 20~3000mm ² / s, more preferably 25~70mm ² / s. When the kinematic viscosity at 40 ° C. is 10 mm ² / s or more, the decrease in flash point can be suppressed and grease can be safely produced. When the kinematic viscosity at 40 ° C. is 5000 mm ² / s or less, the increase in viscous resistance can be suppressed, which is further excellent in terms of energy saving characteristics.

The second lubricating oil base oil is preferably one or more selected from mineral oils and synthetic hydrocarbon oils having the above properties. A base oil in which a mineral oil and a synthetic hydrocarbon oil are mixed may be used as the second lubricating oil base oil.

The mineral oil of the second lubricating oil base oil is a lubricating oil distillate obtained by refining the distillate obtained by atmospheric distillation of crude oil or further reduced pressure distillation by various refining processes, according to ASTM D3238. n-d-M ring analysis value of% _{C a} is 1 or less,% _{C P} is 75 or more, the urea adduct value include the 4 wt% or less. The refining process includes hydrocracking, hydrorefining, solvent extraction, solvent dewaxing, hydrodesulfurization, etc., and these are combined and processed in an appropriate order to obtain the second lubricating oil base oil component of the present invention. Obtainable. Mixtures of two or more refined oils with different properties obtained from different crude oils or distillates by different process combinations and sequences are also useful. As long as the properties of the obtained second lubricating oil base oil are adjusted so as to satisfy the above-mentioned physical properties, any of the second lubricating oil base oils obtained by any method can be preferably used.

Examples of the synthetic hydrocarbon oil of the second lubricating oil base oil include polyolefins such as poly-α-olefin, polybutene and copolymers of two or more kinds of olefins, alkylbenzene, alkylnaphthalene and the like, according to ASTM D3238. n-d-M ring analysis value of% _{C a} is 1 or less,% _{C P} is 75 or more, the urea adduct value include the 4 wt% or less. Among these, poly-α-olefin is preferable in terms of availability, cost, viscosity characteristics, oxidation stability, and compatibility with system members. As the poly-α-olefin, polymers such as 1-dodecene and 1-decene are more preferable in terms of cost.

In the present embodiment, the second lubricating oil base oil may consist of only one of the mineral oil and the synthetic hydrocarbon oil, or may be a mixture of both. That is, as a preferable combination of the first lubricating oil base oil and the second lubricating oil base oil, the first lubricating oil base oil (mineral oil), the second lubricating oil base oil (mineral oil), and the first Lubricating oil base oil (mineral oil) and second lubricating oil base oil (synthetic hydrocarbon oil), or first lubricating oil base oil (mineral oil) and second lubricating oil base oil (mineral oil and synthetic carbide) (Mixed base oil with hydrogen) can be exemplified. The first lubricating oil base oil (mineral oil), the second lubricating oil base oil (mineral oil), and the second lubricating oil base oil (synthetic hydrocarbon oil) may be one or more. There may be.

The content of the first lubricating oil base oil is 5 to 90% by mass, preferably 10 to 80% by mass, and more preferably 30 to 60% by mass, based on the total amount of the lubricating oil base oil. The content of the second lubricating oil base oil is 10 to 95% by mass, preferably 20 to 90% by mass, and more preferably 40 to 70% by mass, based on the total amount of the lubricating oil base oil. If the contents of the first and second lubricating oil base oils are out of the above range, the desired power consumption reduction effect may not be obtained.

The content of the lubricating oil base oil is preferably 70 to 98% by mass, particularly preferably 80 to 97% by mass, based on the total amount of the grease composition.

The thickener preferably contains at least one selected from a metal soap-based compound (also referred to as "metal soap-based thickener") and a urea compound (also referred to as "urea-based thickener").

Examples of the metallic soap-based thickener include single soap and complex soap. A single soap is a metal soap obtained by saponifying fatty acids or fats and oils with alkali metal hydroxides, alkaline earth metal hydroxides, or the like. Complex soap is a complex of fatty acids used in a single soap and an organic acid having a different molecular structure. The fatty acid may be a fatty acid derivative having a hydroxy group or the like. The fatty acid may be an aliphatic carboxylic acid such as stearic acid or an aromatic carboxylic acid such as terephthalic acid. As the fatty acid, a monovalent or divalent aliphatic carboxylic acid, for example, an aliphatic carboxylic acid having 6 to 20 carbon atoms is used, and in particular, a monovalent aliphatic carboxylic acid having 12 to 20 carbon atoms or 6 to 14 carbon atoms. The divalent aliphatic carboxylic acid of No. 1 is preferably used. As the fatty acid, a monovalent aliphatic carboxylic acid containing one hydroxyl group is preferable. As the organic acid to be combined with the fatty acid in the complex soap, acetic acid, dibasic acids such as azelaic acid and sebacic acid, and benzoic acid are suitable.

As the metal of the metal soap-based thickener, an alkali metal such as lithium and sodium, an alkaline earth metal such as calcium, and an amphoteric metal such as aluminum are used. Among these, alkali metals, particularly lithium, are preferably used.

As the metal soap-based thickener, one type may be used alone, or two or more types may be used in combination. The content of the metal soap-based thickener is, for example, preferably 2 to 30% by mass, more preferably 3 to 20% by mass, and further preferably 10 to 20% by mass based on the total amount of the grease composition.

As the urea-based thickener, for example, a diurea compound obtained by a reaction of diisocyanate with a monoamine, a polyurea compound obtained by a reaction of diisocyanate with a monoamine, or a diamine can be used.

Examples of the diisocyanate include aliphatic diisocyanates and aromatic diisocyanates. Aliphatic diisocyanates include, for example, saturated and / or unsaturated linear, branched, or alicyclic hydrocarbon groups. For example, phenylenediisocyanate, tolylene diisocyanate, diphenyldiisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decandiisocyanate, hexanediisocyanate and the like are preferable. Examples of monoamines include aliphatic monoamines and aromatic monoamines. Aliphatic monoamines include, for example, saturated and / or unsaturated monoamines having linear, branched, or alicyclic hydrocarbon groups. For example, octylamine, dodecylamine, hexadecylamine, stearylamine, oleylamine, aniline, p-toluidine, cyclohexylamine and the like are preferable. Examples of the diamine include aliphatic diamines and aromatic diamines. Aliphatic diamines include, for example, diamines having saturated and / or unsaturated linear, branched, or alicyclic hydrocarbon groups. For example, ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, diaminodiphenylmethane and the like are preferable.

One type of urea-based thickener may be used alone, or two or more types may be used in combination. The content of the urea-based thickener is, for example, preferably 2 to 30% by mass, more preferably 3 to 20% by mass, and further preferably 10 to 20% by mass based on the total amount of the grease composition.

The grease composition preferably contains an organic molybdenum compound. This makes it possible to extend the life of the bearing. Examples of the organic molybdenum compound include molybdenum dithiocarbamate, molybdenum dithiophosphate, an amine complex of molybdenum, an imide complex of succinic acid of molybdenum, a molybdenum salt of an organic acid, and a molybdenum salt of an alcohol. Among these, molybdenum dithiocarbamate and molybdenum dithiophosphate are preferable from the viewpoint of extending the life of the bearing.

As the molybdenum dithiocarbamate, for example, a compound represented by the following general formula (1) can be used.

In formula (1), R ¹ , R ² , R ³ and R ⁴ may be the same or different, and each has an alkyl group having 2 to 24 carbon atoms, preferably an alkyl group having 4 to 13 carbon atoms or 6 to 24 carbon atoms, respectively. It preferably represents a hydrocarbon group such as an aryl group having 8 to 15 carbon atoms (including an alkylaryl group). X ¹ , X ² , X ³ and X ⁴ may be the same or different and represent sulfur or oxygen atoms, respectively. The alkyl group referred to here includes a primary alkyl group, a secondary alkyl group and a tertiary alkyl group. These may be linear or branched.

Preferred examples of the alkyl group include ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, Hexadecyl group, heptadecyl group, octadecyl group and the like can be mentioned. These may be a primary alkyl group, a secondary alkyl group or a tertiary alkyl group, and may be linear or branched. Preferred examples of the (alkyl) aryl group include phenyl group, trill group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group and un. Examples thereof include a decylphenyl group and a dodecylphenyl group. The alkyl group in the (alkyl) aryl group may be a primary alkyl group, a secondary alkyl group or a tertiary alkyl group, and may be linear or branched. The (alkyl) aryl group includes all substituted isomers having different substitution positions of the alkyl group with respect to the aryl group.

More preferable molybdenum dithiocarbamate, specifically, molybdenum sulfide diethyl dithiocarbamate, molybdenum sulfide dipropyl dithiocarbamate, molybdenum dibutyl dithiocarbamate, molybdenum sulfide dipentyl dithiocarbamate, molybdenum sulfide dihexyl dithiocarbamate, molybdenum sulfide dioctyl dithiocarbamate, sulfurization Molybdenum didecyl dithiocarbamate, molybdenum sulfide didodecyl dithiocarbamate, molybdenum sulfide di (butylphenyl) dithiocarbamate, molybdenum sulfide di (nonylphenyl) dithiocarbamate, oxymolybdenum diethyldithiocarbamate, oxymolybdenum sulfide dipropyldithiocarbamate, oxymolybdenum sulfide dibutyldithiocarbamate, Oxymolybdenum sulfide dipentyldithiocarbamate, oxymolybdenum sulfide dihexyldithiocarbamate, oxymolybdenum sulfide dioctyldithiocarbamate, oxymolybdenum sulfide didecyldithiocarbamate, oxymolybdenum sulfide didodecyldithiocarbamate, oxymolybdenum sulfide di (butylphenyl) dithiocarbamate, oxymolybdenum sulfide di (nonyl) Examples thereof include phenyl) dithiocarbamate and mixtures thereof. The alkyl group in these molybdenum dithiocarbamate may be linear or branched, and the bonding position of the alkyl group in the alkylphenyl group is arbitrary. As these molybdenum dithiocarbamates, compounds having hydrocarbon groups having different carbon numbers and / or structures in one molecule can also be preferably used.

As the molybdenum dithiophosphate, those commercially available as a lubricating oil additive can be used, and for example, a compound represented by the following general formula (2) can be used.

In formula (2), R ⁵ and R ⁶ may be the same or different from each other, and each represents a hydrocarbon group having 1 or more carbon atoms. X ⁵ , X ⁶ , X ⁷ , X ⁸ and X ⁹ may be the same or different from each other and represent oxygen or sulfur atoms, respectively. a, b and c each represent an integer of 1 to 6. However, at least one of X ⁵ , X ⁶ , X ⁷ , X ⁸ and X ⁹ represents a sulfur atom. Examples of the hydrocarbon group represented by R ⁵ and ^{R 6,} for example, an alkyl group having 1 to 24 carbon atoms, cycloalkyl group having 5 to 7 carbon atoms, alkylcycloalkyl group having 6 to 11 carbon atoms, 6 carbon atoms Examples thereof include an aryl group having an amount of 18 to 18, an alkylaryl group having 7 to 24 carbon atoms, and an arylalkyl group having 7 to 12 carbon atoms.

From the viewpoint of extending the life of the bearing, the content of the organic molybdenum compound is preferably 300 mass ppm or more, more preferably 500 mass ppm or more, still more preferably 600 mass ppm or more in terms of molybdenum element amount based on the total amount of the grease composition. It is ppm or more, particularly preferably 700 mass ppm or more. The content of the organic molybdenum compound is preferably 50,000 mass ppm or less, more preferably 40,000 mass ppm or less, and further preferably 40,000 mass ppm or less in terms of the amount of molybdenum element, based on the total amount of the grease composition, from the viewpoint of the effect of addition to the bearing performance and the manufacturing cost. It is preferably 30,000 mass ppm or less. The content of the organic molybdenum compound is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and further preferably 1% by mass or more as the weight of the molybdenum compound based on the total amount of the grease composition. .. The content of the organic molybdenum compound is preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 10% by mass or less, based on the total amount of the grease composition, from the viewpoint of the effect of addition to the bearing performance and the manufacturing cost. Is 5% by mass or less.

In addition to the above components, the grease composition may contain additives generally used for lubricating oils and greases, if necessary. Examples of such additives include cleaning agents, dispersants, abrasion inhibitors, viscosity index improvers, antioxidants, extreme pressure agents, rust inhibitors, corrosion inhibitors, metal deactivators, solid lubricants and the like. Can be mentioned. The content of these additives is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of the grease composition.

The consistency of the grease composition is preferably 220 to 300, more preferably 225 to 295, further preferably 230 to 290, and particularly preferably 230 to 285. When the consistency of the grease composition is within the above range, the amount of electric power consumed for bearing rotation can be significantly reduced. As a method for adjusting the consistency of the grease composition, the above-mentioned first lubricating oil base oil, the second lubricating oil base oil and the thickener type and mixing ratio, and the grease composition described later are produced. Examples thereof include a method of adjusting the mixing method of each component (for example, the number of times of mixing, heating temperature, cooling rate, roll condition) and the like.

Consistency in the present invention means an admixture consistency measured in accordance with JIS K2220. The specific measurement conditions are as follows. The sample is packed in a pot for measuring consistency, kept at 25 ° C., and then mixed 60 times in 1 minute using a specified mixer. Next, the excess sample is removed with a spatula, the surface of the sample is flattened, and then the specified cone is dropped into the sample for 5 seconds, and the mixing density is 10 times the depth of penetration (mm). ..

Another embodiment of the present invention is a grease composition containing a lubricating oil base oil, a thickener, and an organic molybdenum compound, wherein the lubricating oil base oil is nd-m according to ASTM D3238. the first and the lubricating oil base oil% _{C a} is 2 to 8,% _{C P} of the ring analysis value of 50~75, n-d-M ring analysis value of% _{C a} by ASTM D3238 is 1 or less,% C _P is contained, and a second lubricating base oil is 70 or more, based on the lubricating base oils the total amount, the content of the first lubricating base oil is 5 to 90 wt%, A grease composition having a content of the second lubricating oil base oil of 10 to 95% by mass and a consistency of 220 to 300. This embodiment has a special effect of reducing power consumption during rotation of the bearing and extending the life of the bearing.

The method for producing a grease composition according to the present embodiment includes a step of mixing a first lubricating oil base oil, a second lubricating oil base oil, and a thickener to obtain a grease composition. The first lubricating oil base oil and the second lubricating oil base oil have a content of the first lubricating oil base oil of 5 to 90% by mass and a second lubricating oil base based on the total amount of the lubricating oil base oil. The oils are mixed so that the oil content is 10 to 95% by mass.

In the present embodiment, the thickener prepared in advance may be mixed with the first and second lubricating oil base oils, or the first lubricating oil base oil or the second lubricating oil base oil or these. A thickener raw material may be mixed with the mixed base oil, and the raw materials may be reacted with each other in the base oil to obtain a thickener. For example, when a metal soap-based thickener is used, it may be mixed with the lubricating oil base oil in the form of metal soap, but the carboxylic acid and the metal source (metal salt, metal salt hydroxide, etc.) are separately added to the lubricating oil. It may be blended with a base oil and reacted with a carboxylic acid and a metal source at the time of preparing grease to form a metal soap thickener. When a urea-based thickener is used, it may be blended with the lubricating oil base oil in the form of a urea compound, but diisocyanate and amines (monoamine, diamine, etc.) are blended with the lubricating oil base oil, and the grease is mixed with the diisocyanate during grease preparation. It may be used as a urea-based thickener by reacting with an amine.

The grease composition obtained by mixing the first lubricating oil base oil, the second lubricating oil base oil, and the thickener can be dispersed by a roll or a mill, if necessary. ..

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples.

[Base oil A]
The lubricating oil base oil having the following properties obtained by solvent refining the distillate obtained by distilling the atmospheric distillation residue under reduced pressure was used as the base oil A.
Kinematic viscosity at 40 ° C: 37.6 mm ² / s
Viscosity index: 107
Flash point: 220 ° C
% _CP : 66
% _C A: 5.2

[Base oil B]
The bottom fraction obtained from the fuel oil hydrocracking apparatus was used as a raw material for the lubricating oil base oil, and hydrogenation treatment was carried out using a hydrogenation treatment catalyst. At this time, the reaction temperature and the liquid space velocity were adjusted so that the decomposition rate of normal paraffin in the raw material oil was 10% by mass or less. Further, the object to be treated obtained by the hydrogenation treatment is dehydrogenated in a temperature range of 315 to 325 ° C. using a zeolite-based hydrogenation dewaxing catalyst adjusted to have a noble metal content of 0.1 to 5% by mass. And obtained dewax oil. Further, this desulfurized oil was hydrorefined using a hydrorefining catalyst. Then, the lubricating oil base oil having the following properties obtained by distillation was used as the base oil B.
Kinematic viscosity at 40 ° C: 36.8 mm ² / s
Viscosity index: 130
Flash point: 240 ° C
% _CP : 79
% _C A: 0
Urea adduct value: 2% by mass

[Base oil C]
Poly-α-olefin (Durasin 166 manufactured by INEOS), which is a synthetic hydrocarbon having the following properties, was used as the base oil C.
Kinematic viscosity at 40 ° C: 30.8 mm ² / s
Viscosity index: 135
Flash point: 250 ° C
% _CP : 91
% _C A: 0
Urea adduct value: 0% by mass

[Base oil D]
The fraction separated by vacuum distillation of the solvent-refined base oil was solvent-extracted with furfural, hydrotreated, and then solvent-desorbed with a mixed solvent of methyl ethyl ketone and toluene. The wax component removed during solvent dewaxing and obtained as slack wax was used as a raw material for the lubricating oil base oil and subjected to hydrogenation treatment. At this time, the reaction temperature and the liquid space velocity were adjusted, and the temperature condition for hydrodesulfurization of the object to be treated obtained by the hydrogenation treatment was adjusted as low as about 300 ° C., and the obtained dehydrogenated oil was hydrorefined. did. Then, a lubricating base oil having the following properties and a urea adduct value of 5% by mass obtained by distillation was used as the base oil D.
Kinematic viscosity at 40 ° C: 32.0 mm ² / s
Viscosity index: 130
Flash point: 240 ° C
% _CP : 75
% _C A: 0
Urea adduct value: 5% by mass

[Test oil 1-1-1-10]
The base oils A, B, C and D were placed in a stainless steel container in the blending amounts (indicated by mass%) shown in Tables 1 and 2. When a urea compound is used as the thickener, amine and isocyanate, which are the raw materials of the urea compound, are added to the lubricating oil base oil in the container, heated to 150 ° C., and stirred with a magnetic stirrer to remove amine and diisocyanate. It was reacted. Then, after dehydration, it was cooled to room temperature to obtain a semi-solid composition. When a metallic soap-based compound was used as the thickener, lithium stearate was added to the lubricating oil base oil, heated to 200 ° C., and then cooled to obtain a semi-solid composition. Further, di-t-butyl-p-cresol, which is a phenolic antioxidant, is added to each of the obtained semi-solid compositions, and dispersion treatment is carried out with three rolls to obtain the compositions shown in Tables 1 and 2. A grease composition was obtained.

[Evaluation test 1]
The power consumption during bearing rotation when each grease composition was used was measured by the following method. As the bearing, NTN's double-row tapered roller bearing 4T-CRI-0868 was used. Before the test, the inside of the bearing was thoroughly washed with an organic solvent, and then an experimental oil (grease composition) was injected into the gap between the bearing, the raceway ring, and the cage with a syringe. In the experiment, a total of 4 bearings (2 bearings x 2 sets) filled with the same oil agent were used. The inner ring of the bearing is fixed and rotated in a certain direction by an electric motor (manufactured by Yasukawa Electric Co., Ltd., TYPE: FEQ, 2.2 kW) via a pulley, and the power consumption of the motor is measured by a power meter (manufactured by HIOKI Co., Ltd., CE3169, CLAMP ON POWER). It was measured by HiTESTER). The integrated power consumption (kW) in continuous rotation for 2 hours was compared with the bearing rotation speed set to 1300 rpm and the temperature set to room temperature. The number of repeated experiments was set to 3. The results obtained are shown in Tables 1 and 2. The bearing power consumption and power reduction rate (%: test oil 1-6 standard) in Tables 1 and 2 are the average values of the three experiments. The power reduction rate in this embodiment is indicated by a negative value when the power consumption is less than the standard.

[Test oil 2-1 to 2-12]
The base oils A, B, C and D, and the thickener were placed in a stainless steel container in the amounts shown in Tables 3 to 5 (indicated by mass%). When a metallic soap compound (single soap) is used as the thickener, lithium stearate is added to the lubricating oil base oil, and the mixture is heated to 200 ° C. and then cooled to obtain a semi-solid composition. .. When a metal soap compound (complex soap) is used as the thickener, 12-hydroxystearic acid, azelaic acid, and lithium hydroxide are added to the lubricating oil base oil and heated to 200 ° C. to react to form a complex soap. By cooling, a semi-solid composition was obtained. When a urea compound is used as the thickener, amine and isocyanate, which are the raw materials of the urea compound, are added to the lubricating oil base oil in the container, heated to 150 ° C., stirred with a magnetic stirrer, and the amine and isocyanate are added. The diisocyanate was reacted. Then, after dehydration, it was cooled to room temperature to obtain a semi-solid composition. Further, di-t-butyl-p-cresol, which is a phenolic antioxidant, is added to each of the obtained semi-solid compositions, and dispersion treatment is carried out with three rolls to have the compositions shown in Tables 3 to 5. A grease composition was obtained. In addition, the consistency (mixing consistency) of the obtained grease composition was measured according to JIS K2220.

[Evaluation test 2-1]
The power consumption during bearing rotation when each grease composition was used was measured by the following method. As the bearing, a double row ball bearing 7008A-DF manufactured by NSK Co., Ltd. was used. Before the test, the inside of the bearing was thoroughly washed with an organic solvent, and then an experimental oil (grease composition) was injected into the gap between the bearing ball, the raceway ring, and the cage with a syringe. In the experiment, a total of 4 bearings (2 bearings x 2 sets) filled with the same oil agent were used. The inner ring of the bearing is fixed and rotated in a certain direction by an electric motor (manufactured by Yasukawa Electric Co., Ltd., TYPE: FEQ, 2.2 kW) via a pulley, and the power consumption of the motor is measured by a power meter (manufactured by HIOKI Co., Ltd., CE3169, CLAMP ON POWER). It was measured by HiTESTER). The integrated power consumption (kW) in continuous rotation for 2 hours was compared with the bearing rotation speed set to 1300 rpm and the temperature set to room temperature. The number of repeated experiments was set to 3. The results obtained are shown in Tables 3-5. The bearing power consumption and power reduction rate (%: test oil 2-11 standard) in Tables 3 to 5 are average values of three experiments.

[Evaluation test 2-2]
The same test as in the evaluation test 1 was carried out for each grease composition. The results obtained are shown in Tables 3-5. The bearing power consumption and power reduction rate (%: test oil 2-11 standard) in Tables 3 to 5 are average values of three experiments.

[Test oil 3-1 to 3-8]
Base oils A and B, thickeners, and organic molybdenum compounds include molybdenum dithiocarbamate (molybdenum element content 29% by mass, sulfur element content 28% by mass) and molybdenum dithiophosphate (molybdenum element content 8% by mass). %, Phosphorus element content is 6% by mass, Sulfur element content is 12% by mass) in a stainless steel container at the blending amounts shown in Tables 6 to 7 (indicated by mass%. Molybdenum element amount conversion value is also shown). .. When a metallic soap compound (single soap) is used as the thickener, lithium stearate is added to the lubricating oil base oil, and the mixture is heated to 200 ° C. and then cooled to obtain a semi-solid composition. .. When a metal soap compound (complex soap) is used as the thickener, 12-hydroxystearic acid, azelaic acid, and lithium hydroxide are added to the lubricating oil base oil and heated to 200 ° C. to react to form a complex soap. By cooling, a semi-solid composition was obtained. When a urea compound is used as the thickener, amine and isocyanate, which are the raw materials of the urea compound, are added to the lubricating oil base oil in the container, heated to 150 ° C., stirred with a magnetic stirrer, and the amine and isocyanate are added. The diisocyanate was reacted. Then, after dehydration, it was cooled to room temperature to obtain a semi-solid composition. Further, other additives (phenolic antioxidant, corrosion inhibitor, etc.) are added to each of the obtained semi-solid compositions, and dispersion treatment is performed with three rolls to carry out grease having the compositions shown in Tables 6 to 7. The composition was obtained. In addition, the consistency (mixing consistency) of the obtained grease composition was measured according to JIS K2220.

[Evaluation test 3-1 (bearing life)]
Each grease composition was subjected to a high temperature grease bearing life test. Specifically, in accordance with ASTM-D3336, the bearing (6204ZZ) is filled with 2 g of sample grease, and the bearing is continuously operated at a temperature of 150 ° C. at a rotation speed of 10000 rpm and a thrust load of 66 N, resulting in abnormal operation due to poor lubrication. The time to reach was recorded as the bearing life (hr).

[Evaluation test 3-2 (bearing power consumption)]
The same test as the evaluation test 2-1 was carried out for each grease composition. The results obtained are shown in Tables 6-7. The bearing power consumption and power reduction rate (%: test oil 3-7 standard) in Tables 6 to 7 are the average values of the three experiments.

The grease composition of the present invention has a special effect that the amount of electric power consumed for bearing rotation is small. Therefore, the grease of the present invention can be suitably used for lubrication of mechanical elements such as rolling bearings, slide bearings, ball screws, linear motion guides, and gears, and is useful in industrial machines, transportation machine systems, and the like.

Claims (5)

A grease composition containing a lubricating oil base oil, a thickener, and an organic molybdenum compound containing at least one selected from molybdenum dithiocarbamate and molybdenum dithiophosphate .
The first and the lubricating oil base oil n-d-M ring analysis value of% _{C A} by ASTM D3238 there is 2 to 8,% _{C P} 50 to 75,
ASTM D3238 is n-d-M ring analysis value of% _{C A} by 1 or less,% _{C P} is 70 or more, the urea adduct value of 4% by mass or less, is kinematic viscosity at 40 ° C. is 20 mm ² / s or more Second lubricating oil base oil and
Contains,
The basis of the lubricating base oils the total amount, the content of the first lubricating base oil is 5 to 90 wt%, the content of the second lubricating base oil Ri 10-95% by mass ,
The total content of the first lubricating oil base oil and the second lubricating oil base oil is 70% by mass or more based on the total amount of the lubricating oil base oil.
Butterfly degree of Ru der 220 to 300, the grease composition. The grease composition according to claim 1, wherein the first lubricating oil base oil has a kinematic viscosity of 10 to 700 mm ² / s at 40 ° C. and a viscosity index of 90 to 120. The grease composition according to claim 1 or 2 , wherein the second lubricating oil base oil has a kinematic viscosity of 20 to 5000 mm ² / s at 40 ° C. and a viscosity index of 110 to 150. The grease composition according to any one of claims 1 to 3 , wherein the second lubricating oil base oil contains at least one selected from mineral oils and synthetic hydrocarbons. The grease composition according to any one of claims 1 to 4 , wherein the thickener contains at least one selected from a metallic soap-based compound and a urea compound.