JP3501443B2 - Lubrication method for using a water-resistant urea-based grease composition in an environment in contact with water - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating agent which is hardly broken when water is mixed into a urea grease and stable lubrication without impairing the inherent lubricating performance. The present invention relates to a lubrication method for using a water-resistant urea-based grease composition capable of maintaining a film and extending a lubrication life in an environment in which it comes into contact with water. 2. Description of the Related Art Grease used in a device driven in a use environment where a large amount of water is mixed therein, for example, various bucket pins of construction equipment used outdoors, sliding parts of cranes, water pumps Used in bearings for washing machines, washing machine bearings, and rolling mills in steel mills is in an environment where it comes into contact with water, and it is inevitable that water is mixed. [0003] Conventionally, water-resistant grease used in such a use environment has been improved in terms of adhesion and shear stability when containing water, so that the grease is less likely to flow from a lubricating part. Was. [0004] For example, with regard to the technology relating to water-resistant grease, Japanese Patent Publication No. 2-8639 discloses a grease composition in which a metal phenate is contained to improve the shear stability when containing water. Japanese Patent Publication No. 3-26717 discloses a grease composition in which a calcium salt or a magnesium salt of a fatty acid is added to a base grease to improve shear stability when containing water. However, many of these water-resistant greases have made it difficult for the grease to physically flow out, and have not yet achieved sufficient lubrication performance under an actual use environment. There are cases where poor lubrication may occur even when a large amount of grease is present in a lubricated portion under an actual use environment. This is because under relatively static conditions, such as rainwater, grease that is harder to flow than the lubricating part has a good effect, but these greases are often difficult to take in water, so it can be said that either This tends to be water repellent, which adversely affects the dynamic environment. When grease having a tendency to be water-repellent comes into contact with water in this dynamic environment, water existing on the surface is gradually taken into the grease by stirring as the grease flows. At this time, if the properties of the grease are extremely strong hydrophilic properties, water is present in a fine state and rarely affects the lubricating performance, but the grease having a water-repellent tendency as described above is mixed. Since the water particles are large and non-uniform, the oil film formed on the sliding surface of the lubricated portion is eliminated, resulting in poor lubrication. In this case, there is no correlation between the amount of grease around the lubricating portion and poor lubrication, and in these cases, poor lubrication is caused even if a large amount of grease is often present. [0005] As described above, even if a large amount of grease is present around the lubricated portion, large water particles are present in the grease interposed on the sliding surface of the lubricated portion. In such a case, satisfactory lubricity cannot be obtained. Of course, if the grease flows down from the lubricating part due to the influence of water, the original function of grease lubrication will not be fulfilled. Therefore, it is essential that the water-resistant grease has a property that it is hard to soften and flow away. Therefore, an object of the present invention is to provide a lubricating system by maintaining a stable lubricating film in which the grease structure is hard to be broken by water and water particles are present in a fine state even when water is mixed into the grease by stirring. A water-resistant urea-based grease composition that can extend the life, under the use environment where water is mixed into the grease,
Another object of the present invention is to provide a lubrication method characterized by using the lubrication method. The present invention relates to at least one urea-based grease selected from the group consisting of diurea-based grease, triurea-based grease and tetraurea-based grease; Formula 2 (Wherein, R is an alkyl group having 8 to 22 carbon atoms and M is a divalent metal). A urea grease containing 1 to 15% by weight of a metal salicylate represented by the following formula: The present invention relates to a method for lubricating, wherein the composition is used in an environment where the composition is in contact with water. [0007] A grease composition for a urea constant velocity joint in which an overbased calcium salt of salicylate is contained in grease is disclosed in JP-A-9-19487 and JP-A-9-324189. However, the grease composition for a constant velocity joint is not used in an environment that is absolutely in contact with water, and the invention relating to the grease composition for a constant velocity joint is intended to prevent the wear of the joint by the grease composition and prevent the grease composition from having a flare. It is intended to prevent kinging, and is completely different from the object of the present invention. The metal salicylate represented by the general formula (I) used in the present invention is well known mainly as a detergent and dispersant for engine oils and the like, and is partially used in grease. It is not known at all that grease imparts water resistance to grease, and much less that grease containing this grease exhibits excellent water resistance when it comes into contact with water in a dynamic state. is there. The present invention will be described specifically.
A water-resistant urea-based grease composition for use in an environment contacting water containing at least (a) a base oil, (b) a urea-based thickener, and (c) a metal salicylate represented by the general formula (I). It is. As the base oil (a), all lubricating oils generally used as grease base oils can be used, and there is no particular limitation. For example, paraffinic mineral oils can be used. Mineral oil, naphthenic mineral oil, poly-α-olefin of hydrocarbon synthetic oil, alkylene glycol-based polyethylene glycol or polypropylene glycol or ester-based diester, polyol ester, silicate ester or ether-based alkyl diphenyl ether, or silicon-based dimethyl silicone And mixtures thereof. The urea thickener (b) used in the present invention refers to any thickener containing a urea bond, and this urea bond is generally obtained by reacting an isocyanate with an amine. Examples of the urea thickener include monourea, monourea monourethane, diurea compounds, diurea monourethane, diurea compounds such as diurea diurethane, triurea, triurea monourethane, triurea diurethane, triurea triurethane, tetraurea, tetraurea And polyurea-based compounds such as tetraureamonourethane, tetraureadiurethane, tetraureatriurethane, and tetraureatetraurethane, but are not particularly limited thereto. The diurea-based compound is obtained, for example, by reacting a diisocyanate with a monoamine. Examples of the diisocyanate include tolylene diisocyanate, vitriylene diisocyanate, m-xylene diisocyanate, phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate. Examples include amine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, aniline, p-chloroaniline, benzylamine, m-xylidine, p-toluidine, o-toluidine, cyclohexylamine, furfurylamine and the like. The polyurea compound is obtained, for example, by reacting a diisocyanate with a diamine and a monoamine. Diisocyanates and monoamines include those similar to those used for producing diurea compounds.Examples of diamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, phenylenediamine, tolylenediamine, Xylene diamine and the like. Further, as a compound containing a urethane bond in addition to a urea bond, it is necessary to react an isocyanate with an alcohol. Examples of the alcohol include octyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, and eicosin alcohol. The reason why the present invention is limited to urea compounds as thickeners is that even if a metal salicylate is added to a general metal soap grease, no special effect can be obtained, the urea compound is used. This is because the object of the present invention is achieved only for grease using a thickener. The metal salicylate (c) used in the present invention is widely used mainly as a detergent and dispersant for engine oils and the like, and has a chemical composition of the general formula (I) , R in the above is an alkyl group having 8 to 22 carbon atoms,
M represents a divalent metal, and usually, magnesium or calcium is used as the metal. These metal salicylates have an effect of appropriately dispersing the water mixed in the grease without softening the urea-based grease, and minimizing a decrease in lubrication performance due to mixing of water. Further, the amount of the metal salicylate to be added is effective in the range of 1 to 15% by weight, and it is particularly preferable to add 1 to 5% by weight. If the amount of the metal salicylate is less than 1 % by weight, the effect of dispersing water is weak and the life cannot be prolonged. If the amount is more than 15% by weight, the grease is easily softened, and the oxidation stability and other properties are reduced. It can have a negative impact on performance. In addition, the price becomes expensive and the economy is impaired, which is not preferable. Further, in order to add various properties of the grease, an antioxidant, a corrosion inhibitor, a rust inhibitor, an oiliness improver, an antiwear agent, an extreme pressure agent, a solid lubricant and the like are added as required. be able to. The present invention will now be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto. The urea thickeners of Examples 1 to 5 and Comparative Example 1 used diurea, and the urea thickeners of Examples 6 to 7 and Comparative Example 2 used triurea monourethane, and further compared with Example 8. Example 3 used tetraurea. EXAMPLES 1-5, COMPARATIVE EXAMPLE 1 (1) Preparation of base grease 10.71 g at 2.5 ° C. at 100 ° C.
877.5 g of a naphthenic mineral oil of mm ² / sec and 70.61 g of diphenylmethane diisocyanate were taken and heated to 60 ° C. while stirring. Next, 31.56 mm at 100 ° C.
300 g of a ² / sec paraffinic mineral oil and 57.04 g of octylamine were weighed and mixed, and charged into the kettle. At this time, the temperature of the contents is increased to 80 at a stretch by the heat of reaction.
° C. After maintaining this temperature for 20 minutes, a solution in which 172.5 g of the same paraffinic mineral oil and 22.35 g of octylamine were dissolved at 80 ° C. was further added, and heating was continued while thoroughly stirring and mixing the contents. The temperature was raised to 180 ° C. Thereafter, the contents were gradually cooled, and the contents were taken out of the kettle and treated with three rolls. This diurea base grease has a consistency of 280 and a dropping point of 242 ° C.
Met. The thickener amount of this grease is 10%.
And the base oil viscosity is 225.7 mm ² / sec at 40 ° C.
At 100 ° C. is 15.86 mm ² / sec. (2) Mixing of metal salicylate Commercially available metal salicylates shown in Tables 1 and 2 were added to the base grease in amounts shown in Tables 1 and 2,
After mixing and stirring, the mixture was kneaded with three rolls to obtain a urea grease composition. The amount of metal salicylate in the table but the addition amount of the upper is commercially available, for commercial products in the form of metal salicylate is dissolved in a mineral oil such as overbased calcium <br/> Umusarishireto in commercially available 1 minute to about 38 wt%, calcium salicylate content in the commercial product 2 is about 34 wt%, excessive in commercially available 3
Since the basic magnesium salicylate content is about 30% by weight, the numbers in parentheses at the bottom are the net metal salicylate content. Example 6 , Comparative Example 2, Comparative Example 6 (1) Formulation of base grease 11.13 at 100 ° C. in a 2.5 g g prototype grease pot.
900 g of paraffinic mineral oil of mm ² / sec, 60.6 g of toluene diisocyanate and 46.95 g of stearyl alcohol were taken and heated to 70 ° C. with stirring. Next, 420 g of the same paraffinic mineral oil and ethylenediamine 10.
5 g and 61.95 g of stearylamine are weighed to 70
What was heated and melted to ° C was filled in the kettle. At this time, the temperature of the contents rose to 85 ° C at a stretch due to the heat of reaction. The heating was continued while the contents were stirred and mixed well, the temperature was raised to 120 ° C., and the temperature was maintained for 1 hour.
Thereafter, the contents were gradually cooled, and the contents were taken out of the kettle and treated with three rolls. The consistency of the base grease of this triurea monourethane is 311 and the drop point is 24
1 ° C. The thickener amount of this grease is 1
1%, and the base oil viscosity is 99.05 mm ² / s at 40 ° C.
ec at 100 ° C. is 11.13 mm ² / sec. (2) Mixing of metal salicylate Commercially available metal salicylates shown in Tables 1 and 2 were added to the base grease in amounts shown in Tables 1 and 2,
After mixing and stirring, the mixture was kneaded with three rolls to obtain a urea grease composition. The amount of metal salicylate in the table but the addition amount of the upper is commercially available, for commercial products in the form of metal salicylate is dissolved in a mineral oil such as overbased calcium <br/> Umusarishireto in commercially available 1 minute to about 38 wt%, calcium salicylate content in the commercial product 2 is about 34 wt%, excessive in commercially available 3
Since the basic magnesium salicylate content is about 30% by weight, the numbers in parentheses at the bottom are the net metal salicylate content. Example 7 , Comparative Examples 3 to 5 (Comparative Examples 4 and 5 are commercially available products) A 2.5 kg grease prototype pot was placed at 11.degree.
810 g of paraffinic mineral oil of 10 mm ² / sec and 102.9 g of diphenylmethane diisocyanate were taken and heated to 60 ° C. with stirring. Next, 100
In a 0 ml beaker, 510 g of the same paraffinic mineral oil, 12.4 g of ethylenediamine, and 26.6 g of octylamine
And 38.1 g of laurylamine were weighed, dissolved by heating, and charged into the kettle. At this time, the temperature of the contents rose to 80 ° C. at once by the reaction heat. Furthermore, heating was continued while the contents were well stirred and mixed, the temperature was raised to 170 ° C, and the temperature was maintained for 30 minutes. Thereafter, the contents were gradually cooled, and the contents were taken out of the kettle and treated with three rolls. The consistency of this tetraurea base grease is 2
92 and the dropping point was 258 ° C. The thickener amount of this grease was 12%, and the base oil viscosity was 40 ° C.
At 99.05 mm ² / sec at 100 ° C.
3 mm ² / sec. Grease of Comparative Example 3 is obtained by directly subjected to test this base grease, performed
The grease of Example 7 was obtained by adding 3.0% by weight of a commercially available overbased calcium salicylate to this tetraurea base grease.
After adding, mixing and stirring, it is finished by three-roll processing. [Test Method] The water resistance of the greases described in the examples and comparative examples was evaluated by using a large-size flushing water resistance life tester shown in FIG. This large-size flushing water resistance life tester is a tester for evaluating the lubrication life of a bearing while pouring water into a housing. This method is based on JIS
K2220 This is an improvement of the water resistance test specified in 5.12. However, as in JIS, circulating water is sprayed onto a test ball bearing outer ring retainer (seal plate) (300 ml / mi).
n) Instead of injecting distilled water directly into the housing, it is possible to inject a more precise amount of water in a clean and reliable manner, improving the reliability of the test and improving the accurate lubrication life. It is improved so that it can be measured. As a specific method, a grease obtained by mixing grease with 30% by weight of water in advance is used as a test grease, and a test bearing is filled with 5.0 g of grease. After assembling the bearings into the housing, 3,0,0 ml of distilled water heated to 40 ° C was injected into the shaft box at a rate of 50 ml / min.
Operate at 00 rpm. The injected water is discharged outside through the test bearing. The life of the grease was evaluated as the life time when the bearing became high torque due to poor lubrication of the test grease, the current of the drive motor reached 250% or more of that during stable rotation, and the control device was activated and the motor stopped. . (Test conditions) Test bearing: No. 22208 (Spherical roller bearing) Grease filling amount: 5.0 g (30% water content) Rotation speed: 3,000 rpm Radial load: 15 Kgf Water temperature: 40 ° C. Water volume: 50 ml / min [Table 2] According to the present invention, it is a surprising effect that the life of the grease composition is improved by 2 to 10 times or more as compared with the case where the conventional grease composition is used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an outline of a measuring device used in a life test of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10N 10:04 C10N 30:00 C 30:00 40:02 40:02 50:10 50:10 (56) References JP 8-225793 (JP, A) JP-A-9-104889 (JP, A) JP-A-9-194871 (JP, A) JP-A-9-324189 (JP, A) JP-A-9-324190 (JP, A) A) European Patent Application Publication 227182 (EP, A2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10M 169/06 C10M 115/08 C10M 129/54 C10M 159/20-159/22 C10N 10:04 C10N 30:00 C10N 40:02 C10N 50:10

Claims (1)

(57) [Claim 1] At least one urea grease selected from the group consisting of diurea grease, triurea grease and tetraurea grease is added to the following general formula (I): ] (Wherein, R is an alkyl group having 8 to 22 carbon atoms and M is a divalent metal). A urea grease containing 1 to 15% by weight of a metal salicylate represented by the following formula: A method of lubricating, wherein the composition is used in an environment in which it comes into contact with water.