JP6072532B2 - Grease composition - Google Patents

Description

  The present invention relates to a grease composition. More particularly, the present invention relates to a lithium-containing calcium complex-based grease composition having a high dropping point and excellent shear stability, heat stability and a long bearing life.

  With the advancement of mechanical technology such as automobiles and electrical equipments year by year, the operating conditions have become high and severe due to the downsizing and weighting of various equipments and higher output. As a result, greases used in various devices are increasingly required to improve performance at high temperatures, and grease compositions having a high drop point and excellent thermal stability have been proposed.

  On the other hand, in recent years, not only the performance of greases at high temperatures has been improved, but also there has been a growing demand for materials that are less harmful to the environment and human safety in use. It has been. Under these requirements, a lithium complex soap with improved lithium soap and a grease composition using urea as a thickener are excellent in dropping point and heat resistance. Therefore, various proposals have been made for these types of grease compositions in order to further enhance these properties.

  Here, first, regarding a grease composition using a lithium soap system as a thickener, Patent Document 1 discloses lithium composed of an aliphatic monocarboxylic acid lithium salt, an aromatic dibasic acid lithium salt, and an aliphatic dibasic acid lithium salt. A grease that is a complex grease and has a higher dropping point than lithium grease and a wide operating temperature range has been proposed. However, lithium, which is a raw material for lithium grease, has a wide range of uses, not limited to grease, and due to the recent increase in demand, there is a concern about resource depletion and price increases. In addition, since lithium complex grease reacts two types of fatty acids in two stages, there is a problem that the manufacturing process is complicated and takes a long time.

  In addition, regarding a grease composition using urea as a thickener, Patent Document 2 proposes a diurea grease that can be used for a long time at a high temperature. However, amine compounds such as aniline used as a raw material are extremely toxic, and need to be handled with great care in manufacturing, which poses a problem in safety.

  Therefore, instead of lithium soaps and urea-based grease compositions that are not sufficient in terms of safety and environmental impact, calcium has advantages in terms of safety and environmental impact, as well as manufacturing costs. A grease composition using a thickener as a thickener has been studied.

  However, greases that use calcium soap as a thickener generally meet the demands of recent greases because they are inferior to lithium grease, lithium complex grease, or urea grease in terms of drip point and heat resistance. It is not a thing.

  In order to satisfy these requirements, a grease called calcium complex grease has been proposed that generally uses a calcium complex soap of a higher fatty acid and a lower fatty acid as a thickener.

  In particular, Patent Document 3 proposes a calcium complex grease having a high dropping point and a calcium soap composed of a calcium salt of a dibasic acid and a fatty acid as a thickener. However, there is a problem in that an appropriate consistency cannot be maintained if the amount of the thickener added is small, and there is a limitation on the shape of the dibasic acid, particularly terephthalic acid used as a raw material, and 120 ° C. There are also manufacturing problems in which terephthalic acid must be introduced at high temperatures.

JP 2006-131721 A JP 2008-231310 A JP2009-249419

  Therefore, the present invention is a grease equivalent to or higher than the heat resistance of a grease using lithium soap or urea as a thickener, and has a high dropping point and excellent shear stability, and is heat stable and long. It is an object to provide a grease composition having a bearing life.

  Under such circumstances, as a result of intensive studies by the inventors, the problem can be solved by using calcium soap and lithium soap containing a specific higher fatty acid, a specific lower fatty acid and a specific aromatic monocarboxylic acid. I found.

  The present invention relates to a grease composition containing a base oil and calcium complex soap and lithium soap as a thickener, wherein the calcium complex soap and the lithium carboxylic acid constituting the lithium soap are substituted or unsubstituted C18- A grease composition comprising 22 linear higher fatty acids, an aromatic monocarboxylic acid having a substituted or unsubstituted benzene ring, and C2-4 linear saturated lower fatty acids.

  Moreover, the said grease composition is 3-25 mass parts of linear higher fatty acids, and 0.5-3 masses of aromatic monocarboxylic acids on the raw material basis on the basis of 100 mass parts of the total compounding quantity of a grease composition. 1 to 5 parts by mass of a linear saturated lower fatty acid may be prepared.

  Further, in the grease composition, the linear higher fatty acid is at least one selected from stearic acid, oleic acid, 12-hydroxystearic acid and behenic acid, and the aromatic monocarboxylic acid is selected from benzoic acid and p-toluic acid. The linear saturated lower fatty acid may be one or more selected from acetic acid and butyric acid.

  The mass ratio (Li / Ca) of the lithium metal to the calcium metal in the thickener raw material may be 1/100 to 5/100.

  In addition, as a method for producing the grease composition, a linear higher fatty acid, an aromatic monocarboxylic acid and a linear saturated lower fatty acid, calcium hydroxide and lithium hydroxide are added to the base oil. The method may include a step of producing a lithium-containing calcium composite soap.

  The lithium-containing calcium complex grease composition according to the present invention has a high dropping point and can maintain an appropriate consistency, so that it can be used in a high-temperature environment where only lithium grease and urea grease can be used. In addition to this, there is an effect that safety, environmental performance, and further low cost can be exhibited. Furthermore, the lithium-containing calcium complex grease composition according to the present invention has an excellent shear stability, an effect of being stable to heat and having a long bearing life.

  Hereinafter, although one aspect of the present invention will be described in detail, the technical scope of the present invention is not limited to the one aspect.

  The grease composition of this embodiment contains “base oil” and “thickener” as essential components. Hereinafter, each component contained in the grease composition, the amount (mixing amount) of each component in the grease composition, the manufacturing method of the grease composition, the properties of the grease composition, and the use of the grease composition will be described in order.

≪Grease composition (component) ≫
[Base oil]
The base oil used for the grease composition of this embodiment is not particularly limited. For example, mineral oils, synthetic oils, animal and vegetable oils, and mixed oils thereof used in ordinary grease compositions can be appropriately used. As specific examples, base oils belonging to Group 1, Group 2, Group 3, Group 4, etc. in the API (American Petroleum Institute) base oil category may be used alone or as a mixture.

  For Group 1 base oils, for example, paraffin obtained by applying a suitable combination of solvent refining, hydrorefining, dewaxing, etc. to lubricating oil fractions obtained by atmospheric distillation of crude oil There are mineral oils. For Group 2 base oils, for example, paraffinic mineral oil obtained by applying a suitable combination of hydrocracking, dewaxing and other refining means to a lubricating oil fraction obtained by atmospheric distillation of crude oil There is. Group 2 base oils refined by hydrorefining methods such as the Gulf Company method have a total sulfur content of less than 10 ppm and an aroma content of 5% or less, and can be suitably used in the present invention. Group 3 base oil and Group 2 plus base oil include, for example, a paraffinic mineral oil produced by advanced hydrorefining and a dewaxing process for a lubricating oil fraction obtained by atmospheric distillation of crude oil. There are base oils refined by the ISODEWAX process for converting and dewaxing the produced wax to isoparaffin, and base oils refined by the mobile WAX isomerization process, and these can also be suitably used in this embodiment.

  Synthetic oils include, for example, polyolefins, dibasic acid diesters such as dioctyl sebacate, polyol esters, alkylbenzenes, alkylnaphthalenes, esters, polyoxyalkylene glycols, polyoxyalkylene glycol esters, polyoxyalkylene glycol ethers, polyphenyls. Examples include ether, dialkyldiphenyl ether, fluorine-containing compounds (perfluoropolyether, fluorinated polyolefin, etc.), silicone and the like. The polyolefin includes polymers of various olefins or hydrides thereof. Any olefin may be used, and examples thereof include ethylene, propylene, butene, and α-olefin having 5 or more carbon atoms. In the production of polyolefin, one of the above olefins may be used alone, or two or more may be used in combination. Particularly preferred are polyolefins called poly-α-olefins (PAO), which are group 4 base oils.

  Oil obtained by GTL (Gas Liquid) synthesized by the Fischer-Tropsch method of natural gas liquid fuel technology has extremely low sulfur and aromatic content compared to mineral base oil refined from crude oil. Since it is low and has a very high paraffin constituent ratio, it has excellent oxidation stability and very low evaporation loss. Therefore, it can be suitably used as the base oil of this embodiment.

[Thickener]
The thickener used in this form is a lithium-containing calcium composite soap obtained by reacting a plurality of carboxylic acids with a specific base (typically calcium hydroxide and lithium hydroxide). Here, “composite” in the lithium-containing calcium composite soap according to the present embodiment means that a plurality of carboxylic acids are used. As the carboxylic acid source of the lithium-containing calcium composite soap according to the present embodiment, (1) higher fatty acid, (2) aromatic monocarboxylic acid, and (3) lower fatty acid are used. Hereinafter, the carboxylic acid part (anion part) of the lithium-containing calcium composite soap will be described in detail.

(1) The higher fatty acid used in this embodiment is a C18-22 linear higher fatty acid (monocarboxylic acid). Here, the linear higher fatty acid may be unsubstituted or may have one or more substituents (for example, a hydroxyl group). The linear higher fatty acid may be a saturated fatty acid or an unsaturated fatty acid, but is preferably a saturated fatty acid. Specific examples of the saturated fatty acid include stearic acid (octadecanoic acid, C18), tuberculostearic acid (nonadecanoic acid, C19), arachidic acid (icosanoic acid, C20), heicosanoic acid (C21), behenic acid (docosanoic acid, C22), hydroxystearic acid (C18, castor hydrogenated fatty acid oil), unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid (C18), gadoleic acid, eicosadienoic acid, mead acid (C20), erucic acid, docosadienoic acid (C22). These may be used alone or in combination. For example, when an unsaturated fatty acid is used, it is preferably used in combination with a saturated fatty acid.

(2) The aromatic monocarboxylic acid used in this embodiment is an aromatic monocarboxylic acid having a substituted or unsubstituted benzene ring. Here, the aromatic monocarboxylic acid may be unsubstituted or may have one or more substituents (for example, o-, m- or p-alkyl group, hydroxy group, alkoxy group, etc.). Specific examples include benzoic acid, methylbenzoic acid {toluic acid (p-, m-, o-)}, dimethylbenzoic acid (xylylic acid, hemelitonic acid, mesityleneic acid), trimethylbenzoic acid {prenicylic acid, jurylic acid, isodilyl Acid (α-, β-, γ-)}, 4-isopropylbenzoic acid (cumic acid), hydroxybenzoic acid (salicylic acid, etc.), dihydroxybenzoic acid {pyrocatechuic acid, resorcylic acid (α-, β-, γ-) , Gentisic acid, protocatechuic acid}, trihydroxybenzoic acid (gallic acid), hydroxy-methylbenzoic acid {crestic acid (p-, m-, o-)}, dihydroxy-methylbenzoic acid (orceric acid), methoxybenzoic acid {Anisic acid (p-, m-, o-)}, dimethoxybenzoic acid (veratormic acid), trimethoxybenzoic acid (asarone acid), hydroxy - methoxybenzoic acid (vanillic acid, isovanillin acid), hydroxy - dimethoxybenzoic acid (syringic acid) and the like. These may be used alone or in combination. In addition, the alkyl part of the "substituent" in this specification and the alkyl part of alkoxy are 1-4 linear or branched alkyl, for example.

(3) The lower fatty acid (monocarboxylic acid) used in this embodiment is a C2-4 linear saturated lower fatty acid. Specific examples include acetic acid (C2), propionic acid (C3), and butyric acid (C4). These may be used alone or in combination.

  Among these, from the viewpoints of good grain, viscoelasticity, ease of production, etc., the linear higher fatty acid is stearic acid or behenic acid, the aromatic monocarboxylic acid is benzoic acid or paratoluic acid, lower A combination of acetic acid or butyric acid is most preferred as the fatty acid.

(Other thickeners)
In the grease composition of this embodiment, other thickeners can be used in combination with the above lithium-containing calcium composite soap. Such other thickeners include tricalcium phosphate, alkali metal soap, alkali metal composite soap, alkaline earth metal soap, alkaline earth metal composite soap (other than calcium composite soap), alkali metal sulfonate, alkaline earth Metal sulfonate, other metal soap, terephthalate metal salt, triurea monourethane, diurea, tetraurea, other polyurea, or silica (silicon oxide) such as clay or silica airgel, fluorine resin such as polytetrafluoroethylene, etc. 1 type, or 2 or more types can be used together. In addition to these, any substance that can impart a viscosity effect to a liquid substance can be used.

[Arbitrary ingredients]
The grease composition of this embodiment further includes any antioxidant, rust inhibitor, oiliness agent, extreme pressure agent, antiwear agent, solid lubricant, metal deactivator, polymer, metal detergent, and nonmetal Additives such as detergents, colorants, and water repellents can be added in an amount of about 0.1 to 20 parts by mass based on 100 parts by mass of the entire grease composition. For example, as an antioxidant, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylparacresol, p, p′-dioctyldiphenylamine, N-phenyl-α-naphthylamine And phenothiazine. Examples of the rust preventive include oxidized paraffin, carboxylic acid metal salt, sulfonic acid metal salt, carboxylic acid ester, sulfonic acid ester, salicylic acid ester, succinic acid ester, sorbitan ester, various amine salts, and the like. For example, oily agents, extreme pressure agents and antiwear agents include zinc sulfide dialkyldithiophosphate, zinc sulfide diallyldithiophosphate, zinc sulfide dialkyldithiocarbamate, zinc sulfide diallyldithiocarbamate, sulfurized dialkyldithiophosphate molybdenum, sulfide diallyldithiophosphate molybdenum. , Sulfurized dialkyldithiocarbamate molybdate, diallyldithiocarbamate molybdate, organic molybdate complex, sulfurized olefin, triphenyl phosphate, triphenyl phosphorothioate, tricresin phosphate, other phosphate esters, sulfurized oils and fats, and the like. Examples of the solid lubricant include molybdenum disulfide, graphite, boron nitride, melamine cyanurate, PTFE (polytetrafluoroethylene), tungsten disulfide, and graphite fluoride. For example, the metal deactivator includes N, N′disalicylidene-1,2-diaminopropane, benzotriazole, benzimidazole, benzothiazole, thiadiazole and the like. For example, examples of the polymer include polybutene, polyisobutene, polyisobutylene, polyisoprene, and polymethacrylate. For example, examples of the metal detergent include metal sulfonate, metal salicylate, and metal finate. For example, succinimide etc. can be mentioned as a nonmetallic detergent.

≪Grease composition (mixing amount of each component) ≫
Next, the blending amount in the grease composition according to this embodiment will be described.

[Base oil]
As a compounding quantity of a base oil, the whole grease composition is 100 mass parts, Preferably it is 50-95 mass parts, More preferably, it is 60-90 mass parts, More preferably, it is 70-85 mass parts.

[Thickener]
(Lithium-containing calcium composite soap)
The lithium-containing calcium composite soap in the thickener is preferably 1 to 40 parts by weight, more preferably 3 to 25 parts by weight, still more preferably 5 to 20 parts by weight, based on the raw material, with the total grease composition being 100 parts by weight. Especially preferably, 15 to 20 parts by mass can be blended.

  The higher fatty acid in the lithium-containing calcium composite soap can be blended in an amount of 1 to 30 parts by weight, more preferably 3 to 25 parts by weight, and still more preferably 5 to 20 parts by weight, based on 100 parts by weight of the entire grease composition.

  The aromatic monocarboxylic acid in the lithium-containing calcium complex soap is 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and still more preferably 0.75 to 100 parts by mass of the entire grease composition. 2.5 parts by mass can be blended.

  The lower fatty acid in the lithium-containing calcium composite soap is 0.15 to 7 parts by mass, more preferably 0.5 to 6 parts by mass, still more preferably 1 to 5 parts by mass, especially 100 parts by mass of the grease composition. Preferably 2 to 4 parts by weight can be blended.

  The calcium content in the lithium-containing calcium composite soap may be 3 to 15 parts by mass, more preferably 5 to 14 parts by mass, and still more preferably 8 to 12 parts by mass, with the total amount of the thickener raw material being 100 parts by mass. it can.

  The lithium content in the lithium-containing calcium composite soap is 0.05 to 1 part by mass, more preferably 0.1 to 0.6 part by mass, still more preferably 0.15, with the total amount of the thickener raw material being 100 parts by mass. -0.5 mass part can be mix | blended.

  The mass ratio of the lithium-containing calcium composite soap to the base oil is preferably about 99: 1 to 60:40, more preferably about 95: 5 to 65:35, and still more preferably about 90:10 to 70:40. 30.

  The mass ratio of higher fatty acids to the amount of total carboxylic acid is preferably about 50-90%, more preferably about 60-80%, and even more preferably about 65-75%.

  The mass ratio of aromatic monocarboxylic acid to the total amount of carboxylic acid is preferably about 1-30%, more preferably about 3-20%, and even more preferably about 5-15%. If the ratio of the aromatic monocarboxylic acid exceeds 30%, a grease structure is not formed, and if it is less than 1%, heat resistance is not imparted.

  The mass ratio of the lower fatty acid to the total amount of carboxylic acid is preferably about 7 to 35%, more preferably about 10 to 30%, and still more preferably about 15 to 25%. If the ratio of the lower fatty acid exceeds 35%, the grease structure is not formed, and if it is less than 7%, heat resistance is not imparted.

  The mass ratio of aromatic monocarboxylic acid to higher fatty acid is preferably about 97: 3 to 70:30, more preferably about 95: 5 to 75:25, and still more preferably about 93: 7 to 84: 16. If the ratio of aromatic monocarboxylic acid exceeds 30% of the total amount of higher fatty acid and aromatic monocarboxylic acid, the grease structure is not formed, and if it is less than 3%, heat resistance is not imparted.

  The mass ratio of the lower fatty acid to the higher fatty acid is preferably about 85:15 to 65:35, more preferably about 83:17 to 70:30, and still more preferably about 81:19 to 76:24. . If the ratio of the lower fatty acid in the total amount of the higher fatty acid and the lower fatty acid exceeds 35%, the grease structure is not formed, and if it is less than 15%, heat resistance is not imparted.

  The mass ratio of the lower fatty acid to the aromatic monocarboxylic acid is preferably about 55:45 to 15:85, more preferably about 50:50 to 20:80, and still more preferably about 45:55 to 23: 77. If the proportion of the lower fatty acid in the total amount of the aromatic monocarboxylic acid and the lower fatty acid exceeds 90% by mass, it is considered that the thickening effect is weak and the grease structure is not formed.

  The mass ratio (Li / Ca) of the lithium metal to the calcium metal in the thickener raw material is preferably about 0.3 / 100 to 100/100, more preferably about 0.5 / 100. ˜7 / 100, more preferably about 1/100 to 5/100. Here, when the numerical value is less than 0.3 / 100, the heat resistance and the shear stability are not improved, and the extension of the bearing life at a high temperature cannot be expected. If it exceeds 1, the grease becomes soft and the strength of the stiffness cannot be felt, and the roll stability (shear stability) is deteriorated.

≪Grease composition manufacturing method≫
The grease composition of this embodiment can be manufactured by a generally-used method for manufacturing grease. Although the manufacturing method is not specifically limited, For example, a base oil, a higher fatty acid, a lower fatty acid, and an aromatic monocarboxylic acid are mixed in a grease manufacturing kettle, and the contents are dissolved at a temperature of 60 to 120 ° C. Next, calcium hydroxide and lithium hydroxide previously dissolved and dispersed in an appropriate amount of distilled water are placed in the kettle. Various carboxylic acids, basic calcium and basic lithium (typically calcium hydroxide and lithium hydroxide) undergo a saponification reaction, so that soap is gradually formed in the base oil and dehydration is completed by further heating. Forming a grease thickener. After completion of dehydration, the mixture is heated to a temperature exceeding 200 ° C., sufficiently stirred and mixed, and then cooled to room temperature. Thereafter, a homogenous grease composition is obtained using a disperser (for example, a three roll mill).

≪Physical properties of grease composition≫
The grease composition of the drip point form preferably has a drip point of 180 ° C. or higher, more preferably 220 ° C. or higher, and particularly preferably 260 ° C. or higher. If the dropping point of the grease composition is 180 ° C. or higher (a temperature higher by 50 ° C. or more than that of normal calcium grease), lubrication problems such as loss of viscosity at high temperatures and associated leakage and seizure occur. The possibility is thought to be suppressed. The dropping point refers to a temperature at which the viscous grease loses the thickener structure as the temperature increases. Here, the measurement of the dropping point can be carried out according to JIS K 22208.

Grease consistency this embodiment, the consistency test, preferably a consistency of No. 1 to 4 No. (175-340), more preferably penetration of No. 2 to 3 No. (220-295). The consistency indicates the external hardness of the grease. Here, the consistency measurement method can measure the penetration consistency according to JIS K 22207.

Thermal stability The grease composition of the present embodiment preferably has an evaporation loss of less than 5% in a thin film heating test (at 150 ° C. for 24 hours). Here, the method of the thin film heating test is as follows. In other words, the SPCC steel sheet specified in the wet test method of JIS K 2246 has a thickness of 1.0 g × 60 mm × 80 mm in width. The coating was applied, a heating test at 150 ° C. for 24 hours was performed, the weight of the SPCC steel plate before and after the heating test was measured, and the evaporation amount was obtained by the following equation. In the thin film heating test, 99.5 parts by mass of each of the grease compositions described in Examples 1 to 6 and Comparative Examples 1 to 4 were used based on 100 parts by mass of the total amount of the grease composition. -The test was carried out with the addition of 0.5 parts by weight of dioctyldiphenylamine.
Evaporation amount (%) = {(weight before heating test, g-weight after heating test, g) / weight before heating test, g} × 100

Oxidation stability The grease composition of the present embodiment preferably has a reduction amount of oxygen pressure consumed by an oxidation reaction of 40 kPa or less, preferably 30 kPa or less in an oxidation stability test (99 ° C., 100 hours). More preferably, it becomes 20 kPa or less. The oxidation stability of grease refers to resistance to oxidation of grease due to reaction with oxygen in the air. The deterioration of the grease composition due to oxidation is also affected by the base oil, but the oxidative decomposition of the thickener is particularly significant. The basic function of the thickener is to retain the base oil and maintain the physical hardness of the grease so that it stays at the lubrication part of the machine, and the base oil content retained by the thickener is properly slid. Also plays a role of supplying to the moving surface. If this thickener is destroyed by oxidation, it will not be possible to maintain the original hardness of the grease, and it will not be possible to maintain a proper lubrication state by flowing from the lubrication site by losing the retention function of the base oil. . This behavior is greatly affected by the use environment, but oxidative degradation occurs particularly at an accelerated rate as the temperature rises. When the grease is oxidized by heat, an oxidation product is generated, and the grease is hardened or softened due to increase in the viscosity of the base oil, generation of sludge, breakage of the network structure, etc., resulting in a lubricating life. Eventually, these may lead to a loss in the life and operating reliability of the machine in which they are used. Therefore, high oxidation stability of the grease composition is extremely important for maintaining an appropriate lubrication state at the lubrication site and improving the lubrication life. Here, the measurement of the oxidation stability can be performed according to JIS222012.

Shear Stability The grease composition of the present embodiment is preferably such that the consistency of the grease after the test is 340 or less, more preferably 330 or less, in the roll stability test (room temperature, 24 hours), 320 More preferred are: The roll stability test evaluates the shear stability of grease by measuring the consistency (hardness) of the grease after kneading 50 g of the test grease for a certain period of time with this equipment. The shear stability is an important factor for maintaining the lubrication function and the physical behavior of the grease. If the shear stability is inferior, the grease will easily flow out from the lubrication point of the machine, the desired lubrication cannot be applied, the service life will be shortened, and the grease will scatter and contaminate the surroundings of the machine. Or worsen the working environment. Here, the measurement of the roll stability test used for evaluation of shear stability can be performed according to ASTM D1831.

Bearing life In the grease composition of this embodiment, in the grease bearing life test (150 ° C.), the life time is preferably 200 hours or more, more preferably 300 hours or more, and even more preferably 400 hours or more. . In the bearing life test, 6.0 g of the test grease is sealed in a 6306 type deep groove ball bearing, and the test grease-filled bearing is operated in a cycle operation of 20 hours operation and 4 hours stop at a temperature of 150 ° C. After that, the lubrication function of the grease is lost, the rotation of the bearing becomes defective, and the device stops when the current of the motor driving the bearing exceeds a certain level. The grease life is read as the time when it stopped and recorded as the grease life time. The lubrication life of grease is greatly related to the physical behavior and chemical deterioration of grease, and in either case, loss of function greatly affects the lubrication life. For example, if the grease becomes liquid at high temperatures or becomes extremely soft due to shearing in the bearing, the grease will be washed away from the bearing, making it impossible to supply lubricating oil and shortening the life time. In addition, if the grease itself is excessively self-heating or the usage environment is high, the grease is greatly affected by heat and the oxidation deterioration progresses, increasing the viscosity of the base oil, generating sludge, or a thickener structure. With this change, the grease hardens or softens and reaches the lubrication life early. Therefore, grease with a long lubrication life that can maintain a stable lubrication state with little physical behavior and chemical degradation of grease can be expected to improve the reliability of the machine and extend the maintenance period. Since it can be used, it is widely desired in the market. Here, the grease lubrication life can be measured according to the bearing life test of ASTM D1741.

≪Use of grease composition≫
The grease composition of the present embodiment can be used for generally used machines, bearings, gears, and the like, and can exhibit excellent performance under more severe conditions, for example, high temperature conditions. For example, in automobiles, the engine periphery of starters, alternators and various actuators, propeller shafts, constant velocity joints (CVJ), power trains such as wheel bearings and clutches, electric power steering (EPS), braking devices, ball joints, door hinges It can be suitably used for lubricating various parts such as a handle part, a cooling fan motor, and a brake expander. In addition, construction machines such as excavators, bulldozers, cranes, steel industry, paper industry, forestry machinery, agricultural machinery, chemical plants, power generation equipment, drying furnaces, copying machines, railway vehicles, seamless pipe screw joints, etc. -It is also preferable to use for a high load site. Other applications include hard disk bearings, plastic lubrication, cartridge grease, etc., which are also suitable for these applications.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these examples.

≪Raw materials used in this composition≫
The raw materials used in the examples and comparative examples are as follows. The amounts of Examples 1 to 6 and Comparative Examples 1 to 4 are as shown in Table 1 below unless otherwise specified. The amounts of raw materials described in Table 1 {particularly calcium hydroxide, lithium hydroxide and various carboxylic acids (higher fatty acids, aromatic monocarboxylic acids and lower fatty acids)} are amounts of reagents. Therefore, the actual component amount in the composition is calculated based on the numerical values in Table 1 and the purity described below.

Thickener raw material , calcium hydroxide: a special grade reagent with a purity of 96.0%.
Lithium hydroxide: Lithium hydroxide monohydrate, a special grade reagent with a purity of 98.0%.
-Stearic acid: C18 linear alkyl saturated fatty acid and 95.0% pure reagent.
Behenic acid: C22 linear alkyl saturated fatty acid with a purity of 99.0%.
Benzoic acid: a special grade reagent with a purity of 99.5%.
Paratoluic acid: a benzoic acid in which the hydrogen at the p-position is substituted with a methyl group, and is a special grade reagent with a purity of 98.0%
Acetic acid: A special grade reagent having a purity of 99.7% and having 2 carbon atoms.
Butyric acid: A special grade reagent of 98.0% purity with alkyl fatty acids having 4 carbon atoms.
Formic acid: A special grade reagent of 98.0% purity with alkyl fatty acids having 1 carbon.

Base oils A to D
Base oil A: A paraffinic mineral oil obtained by dewaxing solvent refining and belonging to Group 1, having a kinematic viscosity at 100 ° C. of 11.25 mm ² / s and a viscosity index of 97.
Base oil B: Poly-α-olefin, belonging to group 4, having a kinematic viscosity at 100 ° C. of 6.34 mm ² / s and a viscosity index of 136.
Base oil C: a paraffinic mineral oil produced by advanced hydrorefining, belonging to Group 3, having a kinematic viscosity at 100 ° C. of 7.603 mm ² / s and a viscosity index of 128.
Base oil D: GTL (Gas Liquid) synthesized by the Fischer-Tropsch method and belonging to Group 3, 100 ° C. kinematic viscosity 7.77 mm ² / s, 40 ° C. kinematic viscosity 43.88 mm ² / s and a viscosity index of 148.

Example 1
The base oil A, stearic acid, benzoic acid and acetic acid were mixed as raw materials in the grease production kettle and heated to 90 ° C. to dissolve the contents. Next, calcium hydroxide and lithium hydroxide previously dissolved and dispersed in an appropriate amount of distilled water were placed in the kettle. At this time, various carboxylic acids reacted with calcium hydroxide and lithium hydroxide, and soap was gradually generated in the base oil. Further heating was performed to complete dehydration and form a grease thickener. . After completion of dehydration, the grease was heated to a temperature exceeding 200 ° C., sufficiently stirred and mixed, and then cooled to room temperature. Thereafter, a three-roll mill was used to obtain a homogeneous No. 2.5 consistency grease.

Example 2
A base oil A, stearic acid, p-toluic acid and acetic acid were mixed as raw materials in the grease production kettle, and a homogeneous No. 3 consistency grease was obtained in the same manner as in Example 1.

Example 3
Base oil A, behenic acid, benzoic acid and acetic acid were mixed as raw materials in the grease production kettle, and a homogeneous No. 3 consistency grease was obtained in the same manner as in Example 1.

Example 4
A base oil mixed with base oils A, B, C and D as raw materials, behenic acid, benzoic acid and acetic acid are mixed in the grease production kettle, and in the same manner as in Example 1, homogeneous No. 3 A degree of grease was obtained.

Example 5
A base oil A, behenic acid, benzoic acid and acetic acid were mixed as raw materials in the grease production kettle, and a homogeneous No. 2 consistency grease was obtained in the same manner as in Example 1.

Example 6
Base oil A, behenic acid, benzoic acid and butyric acid were mixed as raw materials in the grease production kettle, and a homogeneous No. 2.5 consistency grease was obtained in the same manner as in Example 1.

Comparative Example 1
Base oil C, stearic acid, benzoic acid and acetic acid as raw materials were mixed in the grease production kettle and heated to 90 ° C. to dissolve the contents. Next, calcium hydroxide dissolved and dispersed in an appropriate amount of distilled water in advance was placed in the kettle. At this time, various carboxylic acids and calcium hydroxide reacted with each other to gradually produce soap in the base oil, and further heated to complete dehydration and form a grease thickener. After completion of dehydration, the grease was heated to a temperature exceeding 200 ° C., sufficiently stirred and mixed, and then cooled to room temperature. Thereafter, using a three-roll mill, a homogeneous No. 2 consistency grease was obtained.

Comparative Example 2
The base oil A, stearic acid, p-toluic acid and acetic acid were mixed as raw materials in the grease production kettle, and a homogeneous No. 1.5 consistency grease was obtained in the same manner as in Comparative Example 1.

Comparative Example 3
In the grease production kettle, base oil A, stearic acid, benzoic acid and formic acid were mixed as raw materials, and in accordance with the production method of Comparative Example 1, grease was produced in the same manner with the blending amounts shown in the table. Separated to obtain a fluid substance.

Comparative Example 4
This is a commercial general-purpose lithium grease. Thickener is lithium 12 hydroxystearate soap and mineral oil is used as the base oil. The viscosity of the base oil is 12.2 mm ² at 100 ° C. / S.

  For the grease composition prepared by the above raw material composition and manufacturing method, the consistency, drop point, oxidation stability, thermal stability (thin film heating test), shear stability (roll stability test), and bearing life are as described above. And the results are shown in Table 2. Incidentally, “impossible to measure” in Comparative Example 3 means that the base oil and the thickener were separated to obtain a grease structure, and the dropping point could not be measured. From this result, it can be seen that the grease composition according to the present example has low shear stability / roll stability and significantly improved bearing life while ensuring high drop point and heat resistance. As a result, it is possible to greatly increase the reliability of the grease function itself and the improvement of machine maintenance.

Claims (4)

In a grease composition containing a base oil and calcium complex soap and lithium soap as a thickener, a substituted or unsubstituted C18-22 linear chain as the carboxylic acid constituting the calcium complex soap and lithium soap A higher fatty acid, an aromatic monocarboxylic acid having a substituted or unsubstituted benzene ring, and a C2-4 linear saturated lower fatty acid, where the linear higher fatty acid is stearic acid, oleic acid, 12- One or more selected from hydroxystearic acid and behenic acid, one or more aromatic monocarboxylic acids selected from benzoic acid and paratoluic acid, and one selected from linear saturated lower fatty acids from acetic acid and butyric acid A grease composition characterized by the above .   Based on 100 parts by mass of the total amount of the grease composition, 3 to 25 parts by mass of linear higher fatty acid, 0.5 to 3 parts by mass of aromatic monocarboxylic acid, and linear saturated lower fatty acid on a raw material basis The grease composition according to claim 1, wherein 1 to 5 parts by mass is added. The grease composition according to claim 1 or 2 , wherein a mass ratio (Li / Ca) of a lithium metal component to a calcium metal component in the thickener raw material is 1/100 to 5/100. It is a manufacturing method of the grease composition as described in any one of Claims 1-3 , Comprising: In a base oil, a linear higher fatty acid, aromatic monocarboxylic acid, a linear saturated lower fatty acid, and calcium hydroxide And lithium hydroxide are added to produce calcium composite soap and lithium soap.