KR20150099565A - Grease composition - Google Patents

Abstract

A grease composition comprising calcium composite soap and lithium soap as base oil and thickener is disclosed. Higher fatty acids, aromatic monocarboxylic acids and lower fatty acids are used as carboxylic acid constituting calcium composite soap and lithium soap. The grease composition has high redness and excellent shear stability, and exhibits thermal stability and long bearing life.

Description

Grease composition {GREASE COMPOSITION}

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

As machine technology such as automobiles or electrical equipment advances, operating conditions use higher temperatures and are becoming increasingly harsh every year with minimized size and weight and increased output of various types of equipment. As a result, there is an increasing demand for improved performance of grease for use in various facilities at high temperatures. Grease compositions having high redness and excellent thermal stability have been proposed.

In addition to the improvement of grease performance under high temperature, there is an increasing need for materials that can be produced in a safe and environmentally friendly manner at the time of use, and as a result, grease is required to meet these requirements. In connection with the above requirements, a grease composition using lithium composite soap or urea as a thickener exhibits excellent redness and heat resistance. In order to improve the above properties, there are various proposals for this kind of grease composition.

First, as a grease composition using a lithium soap-based thickener, JP-A-2006-131721 discloses a lithium composite comprising a lithium salt of an aliphatic monocarboxylic acid, a lithium salt of an aromatic dibasic acid, and a lithium salt of an aliphatic dibasic acid. It is a grease that has a higher red point than lithium grease and allows a wider operating temperature range. However, lithium, a starting material for lithium grease, is not limited to use in Greece but is used in various fields in various fields. Therefore, there is a fear of resource depletion or a sharp rise in price in the future due to recent increase in demand. In addition, the lithium composite grease has a problem that the production procedure is complicated and requires a longer time because the reaction of the two kinds of aliphatic acids involves two steps.

Furthermore, JP-A-2008-231310 proposes a diurea grease which can be used at high temperature for a long time, as an oil composition using urea as a thickener. However, since amine compounds such as aniline used as a starting material are extremely toxic, special care is required when handling during production, and therefore safety problems exist.

Therefore, in place of the grease composition using lithium soap or urea as a thickener, which is not very satisfactory from the standpoint of safety and environmental burden, calcium, which is advantageous in terms of production cost in addition to safety and environmental burden, The grease composition used has been studied. However, since grease using calcium soap as a thickener usually has a poorer redness and heat resistance than lithium grease, lithium composite grease or urea grease, the grease using calcium soap satisfies the requirement as grease suitable for current operating conditions Do not.

As a grease satisfying such a requirement, a so-called calcium composite grease using a higher fatty acid or a lower fatty acid calcium composite soap is generally proposed as a thickener.

In particular, JP-A-2009-249419 proposes a calcium complex grease having a high redness using calcium soap containing a dibasic acid and a calcium salt of a fatty acid as a thickener. However, there is a limitation in the form of dibasic acid, particularly terephthalic acid, which is used as a starting material when the amount of the thickener to be added is small, and terephthalic acid is introduced at a high temperature of 120 DEG C during production There is a problem that should be.

It is therefore an object of the present invention to provide a heat-stable grease composition comprising a grease having a heat resistance equal to or higher than that of a grease using lithium soap or urea as a thickener, having a high red dot and an excellent shear stability, . As a result of intensive studies by the inventors, it has been found that the above-mentioned problems can be solved by using lithium soaps and calcium soaps to which certain higher fatty acids, certain lower fatty acids, and specific aromatic mono carboxylic acids are added.

Accordingly, the present invention relates to a grease composition comprising a base oil and as a thickener, a calcium composite soap and a lithium soap, comprising a C18-22 linear chain, a substituted or unsubstituted higher fatty acid, a substituted or unsubstituted aromatic monocarboxylic acid having a benzene ring, 4 straight chain saturated lower fatty acid is used as a carboxylic acid constituting calcium composite soap and lithium soap.

In addition, the grease composition comprises 3 to 25 parts by mass of a straight chain higher fatty acid, 0.5 to 3 parts by mass of an aromatic monocarboxylic acid, and 1 to 5 parts by mass of a linear saturated lower fatty acid based on the total amount of the grease composition of 100 parts by mass, ≪ / RTI >

In addition, the grease composition may be selected from straight-chain higher fatty acids which are at least one selected from stearic acid, oleic acid, 12-hydroxystearic acid and behenic acid, aromatic monocarboxylic acids which are at least one selected from benzoic acid and p-toluic acid, and acetic acid and butyric acid One or more straight chain saturated lower fatty acids.

Further, the mass ratio (Li / Ca) of the lithium metal content to the calcium metal content in the thickener starting material may be 1 part per 100 parts to 5 parts per 100 parts.

The method of producing the grease composition can be a process comprising the step of forming a lithium-containing calcium composite soap by adding a straight chain higher fatty acid, an aromatic monocarboxylic acid, a straight chain saturated lower fatty acid, calcium hydroxide and lithium hydroxide to the base oil .

The lithium-containing calcium composite grease composition according to the present invention, in addition to the fact that the composition of the present invention can be used under a high temperature environment, which has high redness and maintains proper orientation and which was previously only possible with lithium-based grease or urea grease, The compositions of the present invention exhibit safety, environmental and cost effectiveness. In addition, the lithium-containing calcium composite grease composition according to the present invention has excellent shear stability, and exhibits thermal stability and long bearing life.

Hereinafter, embodiments of the present invention will be described, but the technical scope of the present invention is not limited by embodiments in any way.

The grease composition of this embodiment includes "base oil" and "thickener" as essential structural components. Hereinafter, the components included in the grease composition, the amount of each component (amount of mixing) in the grease composition, the production method of the grease composition, the characteristics of the grease composition and the use of the grease composition will be described in this order.

Base oil

The base oil used in the grease composition of this embodiment is not particularly limited. For example, oils used in common grease compositions such as mineral oils, synthetic oils, animal and vegetable oils or mixtures thereof can be appropriately selected. As a specific example, base oils belonging to Group 1, Group 2, Group 3, Group 4 and the like in the American Petroleum Institute (API) base oil category may be used alone or as a mixture.

Examples of group 1 base oils include paraffin-based mineral oils which can be obtained by purifying a lubricating oil distillate obtained from atmospheric distillation of crude oil by appropriately combining means such as solvent refining, hydrotreating, dewaxing and the like. Examples of group 2 base oils include paraffin-based mineral oils which can be obtained by purifying a lubricating oil distillate obtained from atmospheric distillation of crude oil by properly combining means such as hydrotreating, dewaxing and the like. Group 2 base oils which can be purified by Gulf hydrotreating or the like have a sulfur content of less than 10 ppm and an aroma content of less than 5% and can be preferably used in the present invention. Examples of Group 3 base oils and Group 2 + base oils are paraffin-based mineral oils which can be prepared by applying a lubricating oil distillate obtained from atmospheric distillation of crude oil to high hydrogenated refining, the wax produced by the dewaxing process being converted to isoparaffin / Base oil refined by the ISODEWAX process to be dewaxed, and a base oil refined by the Mobil wax isomerization process, which oils may also preferably be used in this embodiment.

Examples of synthetic oils are polyolefins, diesters of dibasic acids such as dioctyl sebacate, polyol esters, alkylbenzenes, alkylnaphthalenes, esters, polyoxyalkylene glycols, polyoxyalkylene glycol esters, polyoxyalkylene glycol ethers, poly Phenyl ether, dialkyl diphenyl ether, fluorine-containing compound (perfluoropolyether, fluorinated polyolefin, etc.), silicone and the like. The above-mentioned polyolefins include various olefin polymers and their hydrogenation products. Any olefin may be used, and examples thereof include ethylene, propylene, butene,? -Olefins having 5 or more carbon atoms, and the like. The polyolefin may be produced using one or a combination of two or more of the olefins mentioned above. Particularly, so-called poly-a-olefin (PAO) is preferably used as a polyolefin which is a group 4 base oil.

Oils synthesized using GTL (gas to liquid) by the Fischer-Tropsch process, a technique for obtaining liquid fuels from natural gas, have significantly lower sulfur and aromatics content than the mineral base oils obtained by refining crude oil And significantly higher paraffin component ratios, and therefore exhibit excellent oxidation stability and extremely low evaporative loss. Therefore, the oil can be preferably used as a base oil in this embodiment.

Thickener

The thickener used in this embodiment is a lithium-containing calcium complex soap obtained by reacting a plurality of carboxylic acids with specific bases (typical examples are calcium hydroxide and lithium hydroxide). Herein, the term "composite" in the lithium-containing calcium composite soap according to this embodiment means that a plurality of carboxylic acid is used. There are three sources of carboxylic acid in the lithium-containing calcium composite soap according to this embodiment, which are (1) higher fatty acids, (2) aromatic monocarboxylic acids and (3) lower fatty acids. Hereinafter, the carboxylic acid residue (anion residue) in the lithium-containing calcium composite soap will be described.

(1) The higher fatty acid used in this embodiment is C18-22 straight chain higher fatty acid (monocarboxylic acid). Here, the straight chain higher fatty acid may be substituted or unsubstituted with one or more substituents (e.g., hydroxyl group, etc.). The straight chain higher fatty acid may be a saturated or unsaturated fatty acid, but is preferably a saturated fatty acid. Specific examples of saturated fatty acids include stearic acid (octadecanoic acid, C18), tobacco stearic acid (nonadecanoic acid, C19), arachidic acid (icosanic acid, C20), henonic acid (C21), behenic acid Examples of unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid (C18), valoleic acid, eicosadienic acid, mead acid (C18), and hydroxystearic acid (C18, hydrogenated castor oil fatty acid) acid (C20), erucic acid, docosadienoic acid (C22), and the like. These acids may be used alone, or a plurality of them may be used in combination. For example, when containing an unsaturated fatty acid, the saturated fatty acid is preferably used in combination.

(2) The aromatic monocarboxylic acid used in this embodiment is a substituted or unsubstituted aromatic monocarboxylic acid having a benzene ring. Here, the aromatic monocarboxylic acid may be substituted or unsubstituted with one or more substituents (e.g., o-, m- or p-alkyl groups, hydroxy groups, alkoxy groups, etc.). Specific examples are benzoic acid, methylbenzoic acid {toluenic acid (p-, m-, o-)}, dimethylbenzoic acid (xylyl acid, hemelitic acid, mesitylene acid), trimethylbenzoic acid { (Α-, β-, γ-)}, 4-isopropylbenzoic acid (cuminic acid), hydroxybenzoic acid (salicylic acid), dihydroxybenzoic acid {pyrocatecholic acid, resorcinic acid (P-, m-, o-)}, dihydroxy-methylbenzoic acid (orthosylenes such as orthohexanoic acid, p-toluenesulfonic acid, Acid), methoxybenzoic acid (p-, m-, o-), dimethoxybenzoic acid (veratric acid), trimethoxybenzoic acid (asaronic acid), hydroxy-methoxybenzoic acid Vanillic acid), hydroxy-dimethoxybenzoic acid (sicinic acid), and the like. These may be used alone, or a plurality of them may be used in combination. In this specification, the alkyl and the alkyl residue in the alkoxy in the "substituent" are, for example, 1-4 linear or branched alkyl.

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

Among them, a combination of stearic acid or behenic acid as a straight chain higher fatty acid, benzoic acid or p-toluic acid as an aromatic monocarboxylic acid and acetic acid or butyric acid as a lower fatty acid is most preferable in view of good texture, viscosity (body) It is a desirable combination.

Other thickener

In the grease composition of this embodiment, another thickener may also be used in combination with the above-mentioned lithium-containing calcium composite soap. Examples of the other thickener include tricalcium phosphate, alkali metal soap, alkali metal complex soap, alkaline earth metal soap, alkaline earth metal compound soap (other than calcium complex soap), alkali metal sulfonate, alkaline earth metal sulfonate, Tetra-urea, other polyurea, clay, silica (silicon oxide) such as silica airgel, or fluorine resin such as polytetrafluoroethylene and the like. These may be used alone or in combination of two or more kinds. In addition to the listed examples, any material capable of imparting a buildup effect to the liquid material may be used.

Optional ingredient

The grease composition of this embodiment also includes optional additives such as antioxidants, rust inhibitors, oil improvers, extreme pressure additives, abrasion inhibitors, solid lubricants, metal deactivators, polymers, metal-based detergents, non-metal detergents, And the total amount of the optional components is about 0.1 to 20 parts by mass based on 100 parts by mass of the total grease composition. Examples of the antioxidants are 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-para-cresol, p, p'-dioctyldiphenylamine, - naphthylamine, phenothiazine, and the like. Examples of rust inhibitors include paraffin oxide, metal salts of carboxylic acids, carboxylic acid esters, sulfonic acid esters, salicylic acid esters, succinic acid esters, sorbitan esters and various other amine salts. Examples of oil repellents, extreme pressure additives and abrasion inhibitors include zinc sulfide dialkyldithiophosphate, zinc sulfide diallyl dithiophosphate, zinc sulfide dialkyldithiocarbamate, zinc sulfide diallyl dithiocarbamate, molybdenum sulfide Dodecyldithiocarbamate, dodecyldithiocarbamate, dodecyldithiocarbamate, dodecyldithiocarbamate, dodecyldodecyldithiophosphate, molybdenum disulfide diallyldithiophosphate, molybdenum disulfide dialkyldithiocarbamate sulfide, molybdenum disulfide diallyldithiocarbamate sulfide, organic molybdenum complex, Triphenylphosphorothionate, tricresine phosphate, other phosphate esters, sulfurized fats and oils, and the like. Examples of solid lubricants include molybdenum disulfide, graphite, boron nitrides, melamine cyanurate, PTFE (polytetrafluoroethylene), tungsten disulfide, graphite fluoride, and the like. Examples of the metal deactivators include N, N'-disalicylidene-1,2-diaminopropane, benzotriazole, benzimidazole, benzothiazole, thiadiazole and the like. Examples of the polymer include polybutene, polyisobutene, polyisobutylene, polyisoprene, polymethacrylate and the like. Examples of metal-based detergents include metal sulfonates, metal salicylates, metal phenates, and the like. Examples of non-metal detergents include succinic acid imides and the like.

The grease composition (miscibility of each component )

Next, the blend amount for the grease composition according to this embodiment will be described.

Base oil

The blending amount of the base oil is preferably 50 to 95 parts by mass, more preferably 60 to 90 parts by mass, still more preferably 70 to 85 parts by mass, based on 100 parts by mass of the total grease composition.

Thickener

(Lithium-containing calcium composite soap)

The lithium-containing calcium complex soap as a thickener is preferably added in an amount of 1 to 40 parts by mass, more preferably 3 to 25 parts by mass, and still more preferably 5 to 20 parts by mass in terms of the starting material base with respect to 100 parts by mass of the total amount of the grease composition Particularly preferably 15 to 20 parts by weight, based on 100 parts by weight of the composition.

The higher fatty acid in the lithium-containing calcium composite soap may be mixed in an amount of 1 to 30 parts by mass, more preferably 3 to 25 parts by mass, and still more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the whole grease composition.

The aromatic monocarboxylic acid in the lithium-containing calcium composite soap may be blended in an amount of 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and still more preferably 0.75 to 2.5 parts by mass based on 100 parts by mass of the total grease composition .

The lower fatty acid in the lithium-containing calcium complex soap is added in an amount of 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, particularly preferably 2 to 5 parts by mass, 4 parts by mass.

The calcium content in the lithium-containing calcium composite soap is 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 respect to 100 parts by mass of the total thickener starting material.

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, and even more preferably 0.15 to 0.5 part by mass with respect to 100 parts by mass of the total thickener starting material.

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

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

The mass ratio of the aromatic monocarboxylic acid to the total amount of carboxylic acid is preferably about 1 to 30%, more preferably about 3 to 20%, even more preferably about 5 to 15%. It is believed that a grease form can not be obtained with an aromatic monocarboxylic acid ratio of more than 30% and a heat resistance can not be provided at a ratio of less than 1%.

The mass ratio of the lower fatty acid to the total carboxylic acid amount is preferably about 7 to 35%, more preferably about 10 to 30%, and still more preferably about 15 to 25%. Grease form can not be obtained with a lower fatty acid ratio of more than 35%, and it is considered that a ratio of less than 7% can not provide heat resistance.

The mass ratio of the aromatic monocarboxylic acid to the higher fatty acid is preferably about 3:97 to 30:70, more preferably about 5:95 to 25:75, and even more preferably about 7:93 to 16:84. When the proportion of the aromatic monocarboxylic acid exceeds 30% based on the total amount of the higher fatty acid and the aromatic monocarboxylic acid, a grease form can not be obtained, and when the ratio is less than 3%, heat resistance can not be provided.

The mass ratio of higher fatty acid to lower fatty acid is preferably about 85:15 to 65:35, more preferably about 83:17 to 70:30, even more preferably about 81:19 to 76:24. Grease form can not be obtained when the lower fatty acid ratio exceeds 35% based on the total amount of higher fatty acid and lower fatty acid, and it is considered that when the ratio is less than 15%, heat resistance can not be provided.

The weight 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 even more preferably about 45:55 to 23:77. It is considered that when the ratio of the lower fatty acid is more than 90% by mass based on the total amount of the aromatic monocarboxylic acid and the lower fatty acid, there is a weakening effect and a grease form can not be obtained.

The mass ratio (Li / Ca) of the lithium metal content to the calcium metal content in the thickener starting material is preferably from 0.3 parts per 100 parts to 100 parts per 100 parts, more preferably 0.5 parts per 100 parts to 100 parts per 100 parts, Preferably from 1 part per 100 parts to 5 parts per 100 parts by weight. When the value is less than 0.3 parts per 100 parts, the heat resistance or the shear stability is not improved, and the extension of the bearing life at high temperature can not be expected, which is therefore undesirable. When the value is more than 10 parts per 100, the grease softens, the body is lost, and poor rolling stability (shear stability) is brought about; Therefore, it is not preferable.

Method of producing grease composition

The grease composition of this embodiment can be produced according to the methods commonly used in grease production. The production method is not particularly limited, and examples include a method involving mixing base oil, higher fatty acid, lower fatty acid, and aromatic monocarboxylic acid in a grease production vessel and dissolving the content at a temperature of 60 to 120 캜. Here, subsequently, calcium hydroxide and lithium hydroxide, which are preliminarily dissolved and dispersed in an appropriate amount of distilled water, are filled in the vessel. The various carboxylic acids undergo a saponification reaction with basic calcium and basic lithium (typically, calcium hydroxide and lithium hydroxide), soap is slowly formed in the base oil and the resulting product is further heated and dehydrated to form a grease thickener do. After completion of the dewatering, the resulting product is heated to a temperature above 200 ° C, thoroughly stirred and mixed, and cooled to room temperature. A mill (e. G., 3-roll mill or the like) is then used to obtain a uniform grease composition.

Characteristics of grease composition

Dropping point

In the case of the grease composition of the present invention, a composition having a melting point of 180 ° C or higher is used, more preferably a composition having a melting point of 220 ° C or higher is used, and particularly preferably a composition having a melting point of 260 ° C or higher is used. When the grease composition has an admission point of 180 DEG C or higher (which is usually 50 DEG C higher than the melting point of the calcium grease), the lubricating problems such as loss of viscosity at high temperatures and the resulting spills, burns, Is likely to be suppressed. Here, the red dot refers to the temperature at which the viscous grease loses the thickener structure as the temperature increases. Here, the redness is measured according to JIS K 2220 8.

Consistency

The lead of the grease of this embodiment is preferably Nos. 1 to 4 (175 to 340), more preferably Nos. 2 to 3 (220 to 295). The lead indicates the nominal grease hardness. The lead is measured by carrying out the developed penetration measurement according to JIS K 2220 7.

Thermal stability

The grease composition of this embodiment preferably exhibits an evaporation amount of less than 5% based on a thin film oven test (at 150 占 폚 for 24 hours). The thin film oven test method is described as follows. In other words, 3.0 g +/- 0.1 g (0.04 g) was added to the center portion (50 mm x 70 mm) of one side of the specimen, which is an SPCC steel sheet described in the humidity cabinet test according to JIS K 2246 having dimensions of 1.0 mm thickness x 60 mm length x 80 mm width , The heat test is performed at 150 ° C for 24 hours, the weight of the SPCC steel sheet is measured before and after the heat test, and the amount of evaporation is determined using the formula shown below. For the thin film oven test, 0.5 parts by mass of p, p'-dioctyldiphenylamine < RTI ID = 0.0 > And the test is carried out.

Evaporation rate (%) = {(Weight before heat test g - Weight after heat test g / Weight before heat test g) × 100

Oxidation stability

In the case of the grease composition of this embodiment, the oxygen pressure loss due to the oxidation reaction according to the oxidation stability test (99 DEG C, 100 hours) is preferably not more than 40 kPa, more preferably not more than 30 kPa, even more preferably not more than 20 kPa . The oxidation stability of the grease shows resistance to oxidation of the grease caused by the reaction with oxygen in the air. The deterioration of the grease composition due to oxidation affects the base oil, and particularly the oxidative decomposition of the thickener. The basic function of the thickener is to retain the base oil and to maintain the physical hardness of the grease to allow the base oil to remain in the lubricating part of the machine while at the same time the thickener is used to properly supply the base oil component retained by the thickener to the sliding surface . When such thickener is destroyed by oxidation, the hardness originally retained by the grease can not be maintained and the ability to retain the base oil is lost, at which time the base oil slips in the lubrication part and the proper lubrication can not be maintained. This occurrence is greatly influenced by the environment of use, and in particular, the oxidative decay accelerates with increasing temperature. As the oxidation of grease progresses due to heat, oxidation products form, the viscosity of the base oil content increases, the formation of sludge, the destruction of the network structure, etc., which leads to hardening or softening of the grease and to the end of its lubrication life Lt; / RTI > The use of such greases in machinery can eventually develop into a reduction in the service life of the machine or loss of operational reliability. Therefore, the high oxidation stability of the grease composition is very important in order to maintain the lubricating part in a suitable lubrication state and to improve the lubrication life. Here, the oxidation stability is measured according to JIS 222012.

Shear stability

After the rolling stability test (room temperature, 24 hours), the greencidity of the grease composition of this embodiment is preferably not more than 340, more preferably not more than 330, still more preferably not more than 320. The rolling stability test is used to evaluate the shear stability of the grease by measuring the leadness (hardness) of the grease after mixing 50 g of test grease with the apparatus for a predetermined period of time in advance. The shear stability of the grease composition is an important factor in maintaining the lubricating ability and physical behavior of the grease. Poor shear stability causes grease to easily escape from the lubrication portion of the machine, and the required lubrication can not be provided, which leads to a shortening of life and also to the scattering of grease, And deteriorate the working environment. Here, the rolling stability test used for evaluating the shear stability is carried out according to ASTM D 1831.

Bearing life

In the case of the grease composition of this embodiment, the service life according to the grease bearing life test (150 DEG C) is preferably 200 hours or more, more preferably 300 hours or more, and even more preferably 400 hours or more. For the bearing life test, 6.0 g of test grease is applied to a 6306 depth-groove radial ball bearing, and the test grease-placed bearing is operated at a temperature of 150 캜 for 20 hours of operation and 4 hours of stop. The device has a mechanism in which the power supply current of the motor driving the bearing exceeds a certain level due to subsequent loss of grease lubrication function and consequently stops when a bad bearing rotation occurs. The time at which the device stops is understood and recorded as the life of the grease. Lubrication life of grease greatly affects the physical behavior and chemical degradation of grease, and loss in each function greatly affects lubrication life. For example, when the grease changes from a high temperature to a liquid or is heavily softened by shearing in the bearing, the grease is removed from the bearing and lost, and if the lubricant replenishment is not made, the life is shortened. Furthermore, when there is excess self-heating of grease or when the environment of use is high, the grease is heavily influenced by the thermal and oxidative decay processes, thereby increasing the viscosity of the base oil content, the formation of sludge, Causes the hardening or softening of the grease and the premature termination of the lubrication life. Hence, higher grease mechanical reliability and extended maintenance life can be expected with greases having a long lubrication life that allow for reduced chemical degradation with the physical behavior of the grease and maintain a stable lubrication condition. In addition, such greases can be used in high temperature environments and thus will be widely desired in the market. Here, the grease lubrication lifetime is measured in accordance with ASTM D1741 for bearing life test.

Use of grease composition

The grease composition of this embodiment can, of course, be used in commonly used machines, bearings, gears and the like and exhibits excellent performance under harsh conditions, for example, at high temperature. For example, the grease composition preferably comprises various components in an automobile such as engine peripherals such as starting devices, alternators and various actuators, power transmission devices such as propeller shafts, constant velocity joints (CVJ), wheel bearings and clutches , Electric power steering (EPS), brake units, ball joints, door hinges, steering wheels, cooling fan motors, brake extenders and the like. In addition, the grease composition is also preferably used in a variety of high temperature / heavy duty components such as power shovels, bulldozers and crane trucks, steel industry, paper industry, recruitment machinery, agricultural machinery, chemical plants, power plants, Railway vehicles, screw joints of seamless pipes, and the like. For other purposes, the grease composition may also preferably be used in hard disk bearings, plastic lubrication, cartridge grease, and the like.

Next, the present invention will be described in more detail using examples and comparative examples, but the present invention is not limited in any way by them.

The starting material used in the composition of the present invention

The starting materials used in Examples and Comparative Examples of the present invention are as follows. Unless specifically stated otherwise, the amounts set forth in Table 1A were used in Examples 1-6, and the amounts set forth in Table 1B were used in Comparative Examples 1-4. The amount of the starting materials listed in Table 1 {in particular, calcium hydroxide, lithium hydroxide and various carboxylic acids (higher fatty acids, aromatic monocarboxylic acids and lower fatty acids)} is the amount of the reagent. Therefore, the actual amount of components in the composition can be calculated based on the values in Tables 1A and 1B and the purity described below.

Thickener starting material

Calcium hydroxide: Exceptional reagent with a purity of 96.0%

Lithium hydroxide: lithium hydroxide monohydrate of a special grade reagent having a purity of 98.0%

Stearic acid: C18 straight chain alkyl saturated fatty acid, which is provided as a premium reagent with a purity of 95.0%

Behenic acid: C22 straight chain alkyl saturated fatty acid, provided as a reagent with a purity of 99.0%

Benzoic acid: a special grade reagent with a purity of 99.5%

Para-toluic acid: benzoic acid in which the hydrogen at the p-position is substituted with a methyl group, which is provided as an exclusive reagent with a purity of 98.0%

Acetic acid: alkyl fatty acid having 2 carbon atoms, which is provided as a special grade reagent with a purity of 99.7%.

Butyric acid: alkyl fatty acid with 4 carbon atoms, which is provided as a special grade reagent with a purity of 98.0%

Formic acid: alkyl fatty acid with 1 carbon atom, which is provided as a special grade reagent with a purity of 98.0%

Base oils A to D

Base oil A: Paraffin-based mineral oil obtained by refining the tanning agent belonging to Group 1 had a kinematic viscosity at 100 DEG C of 11.25 mm < 2 > / s and a viscosity index of 97

Base oil B: poly-a-olefin belonging to group 4, kinematic viscosity at 100 DEG C of 6.34 mm < 2 > / s and viscosity index of 136

Base oil C: paraffin-based mineral oil produced by high hydrogen addition refining belonging to group 3, the kinematic viscosity at 100 ° C was 7.603 mm 2 / s and the viscosity index was 128

Base oil D: GTL (gas liquefied) oil synthesized by the Fischer-Tropsch process belonging to Group 3 had a kinematic viscosity at 100 ° C of 7.77 mm 2 / s, a kinematic viscosity at 40 ° C of 43.88 mm 2 / s, 148

Example 1

The starting materials, base oil A, stearic acid, benzoic acid and acetic acid, were mixed in a grease preparation vessel, the mixture was heated to 90 DEG C and the contents were dissolved. The vessel was then filled with calcium hydroxide and lithium hydroxide preliminarily dissolved and dispersed in an appropriate volume of distilled water. At this time, the various carboxylic acids underwent a saponification reaction with calcium hydroxide and lithium hydroxide, the soap slowly formed in the base oil, and the resulting product was further heated and dehydrated to form a grease thickener. After completion of the dewatering, the grease was heated to a temperature above 200 ° C, thoroughly stirred and mixed, and cooled to room temperature. Then, using a 3-roll mill, A homogeneous grease with 2.5 lead was obtained.

Example 2

The starting materials, base oil A, stearic acid, p-toluic acid and acetic acid, were mixed in a grease preparation vessel. A homogeneous grease having three main ratios was obtained in the same manner as in Example 1.

Example 3

The starting materials, base oil A, behenic acid, benzoic acid and acetic acid, were mixed in a grease preparation vessel. A homogeneous grease having three main ratios was obtained in the same manner as in Example 1.

Example 4

The starting materials which are the mixed oil, behenic acid, benzoic acid and acetic acid obtained by mixing base oils A, B, C and D were mixed in a grease production vessel. A homogeneous grease having three main ratios was obtained in the same manner as in Example 1.

Example 5

The starting materials, base oil A, behenic acid, benzoic acid and acetic acid, were mixed in a grease preparation vessel. A homogeneous grease having two turns was obtained in the same manner as in Example 1.

Example 6

The starting materials, base oil A, behenic acid, benzoic acid and butyric acid, were mixed in a grease preparation vessel. A homogeneous grease having a consistency of 2.5 was obtained in the same manner as in Example 1.

Comparative Example 1

The starting materials, base oil C, stearic acid, benzoic acid and acetic acid, were mixed in a grease preparation vessel, the mixture was heated to 90 占 폚 and the contents were dissolved. The vessel was then filled with calcium hydroxide which was preliminarily dissolved and dispersed in an appropriate amount of distilled water. At this time, the various carboxylic acids underwent saponification with calcium hydroxide, soap was formed slowly in the base oil, and the resulting product was further heated and dehydrated to form a grease thickener. After completion of the dewatering, the grease was heated to a temperature above 200 ° C, thoroughly stirred and mixed, and cooled to room temperature. Then, using a 3-roll mill, A homogeneous grease with two turns was obtained.

Comparative Example 2

The starting materials, base oil A, stearic acid, p-toluic acid and acetic acid, were mixed in a grease preparation vessel. A homogeneous grease having a consistency of 1.5 was obtained in the same manner as in Comparative Example 1.

Comparative Example 3

The starting materials, base oil A, stearic acid, benzoic acid and formic acid, were mixed in a grease preparation vessel and greases were similarly prepared using the amount of admixture shown in the table based on the production method of Comparative Example 1. The grease showed separation and fluidized material was obtained.

Comparative Example 4

Showa Shell Sekiyu K.K. Lt; RTI ID = 0.0 > commercially available < / RTI > The thickener was lithium 12-hydroxystearate soap, and the base oil was a mineral oil-based lubricant. At 100 ℃, the viscosity of the base oil was 12.2 mm2 / s.

The oxidation resistance, the thermal stability (thin film oven test), the shear stability (rolling stability test), and the bearing life were measured for each of the prepared grease compositions using the starting materials combinations and production methods mentioned above according to the previously described method . The results are presented in Tables 2A and 2B. In Comparative Example 3, the term "not measurable" indicates that the base oil and the thickener were separated and the grease structure was not obtained, so that the redness point could not be measured. The results show that the grease composition according to this embodiment exhibits low shear stability / rolling stability and significantly improved bearing life while ensuring high redness, heat resistance and the like. With such a composition, it is possible to greatly improve the grease function and increase the reliability in improving the maintenance of the machine.

Table 1A

Table 1B

Table 2A

Table 2B

Claims (5)

A grease composition comprising a calcium complex soap and a lithium soap as a base oil and a thickener, the composition comprising a C18-22 linear chain, a substituted or unsubstituted higher fatty acid, a substituted or unsubstituted aromatic monocarboxylic acid having a benzene ring, and a C2-4 linear saturated lower Wherein the fatty acid is used as a carboxylic acid constituting the calcium composite soap and the lithium soap. 2. The lubricating composition according to claim 1, which comprises 3 to 25 parts by mass of a straight chain higher fatty acid, 0.5 to 3 parts by mass of an aromatic monocarboxylic acid and 1 to 5 parts by mass of a linear saturated lower fatty acid based on 100% ≪ / RTI > The process according to claim 1 or 2, wherein the straight chain 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 at least one selected from benzoic acid and p- And the straight chain saturated lower fatty acid is at least one selected from acetic acid and butyric acid. 4. The grease composition according to any one of claims 1 to 3, wherein the mass ratio (Li / Ca) of the lithium metal content to the calcium metal content in the thickener starting material is from 1 part per 100 parts to 5 parts per 100 parts. The method of any one of claims 1 to 4, comprising the step of forming a calcium complex soap and a lithium soap by adding a straight chain higher fatty acid, an aromatic monocarboxylic acid, a linear saturated lower fatty acid, calcium hydroxide and lithium hydroxide to the base oil A method for producing a grease composition according to one of the preceding claims.