Raw materials for grease, method for manufacturing raw materials for grease, method for manufacturing grease, and grease

Abstract

A method for manufacturing a raw material of a grease, wherein a first thickener raw material, a second thickener raw material, a first lubricating oil, a second lubricating oil, a first solvent having a boiling point lower than those of the first lubricating oil and the second lubricating oil and dissolving the first lubricating oil but not dissolving the generated thickener, and a second solvent having a boiling point lower than those of the first lubricating oil and the second lubricating oil and dissolving the second lubricating oil but not dissolving the generated thickener are prepared. The first lubricating oil is dissolved in the first solvent and the first thickener raw material is dissolved or dispersed therein to prepare a first mixed solution, and the second lubricating oil is dissolved in the second solvent and the second thickener raw material is dissolved or dispersed therein to prepare a second mixed solution. The first mixed solution and the second mixed solution are mixed, and the first thickener raw material and the second thickener raw material are reacted to generate a thickener.

Description

Technical Field

[0001] The present invention relates to raw materials for grease, a method for manufacturing raw materials for grease, a method for manufacturing grease, and grease.

[0002] This application claims priority based on Japanese Patent Application No. 2020-125473 filed on July 22, 2020, and incorporates by reference all the contents described in the above Japanese patent application. Background Art

[0003] Urea-based grease is usually manufactured through the following steps: reacting an amine compound with an isocyanate compound in a base oil to synthesize a urea compound as a thickener in the base oil, and then making the thickener particles finer by applying shear or the like.

[0004] In this manufacturing method, unreacted substances remaining in the base oil after the reaction cannot be completely removed and sometimes remain in the grease.

[0005] As a method for manufacturing urea-based grease, there is also known a method in which an amine compound and an isocyanate compound are reacted in a solvent to synthesize a urea compound, then the solvent is removed to manufacture a powdery urea compound, and then it is mixed with a base oil (for example, refer to Patent Document 1).

[0006] Patent Documents 2 and 3 disclose (poly)urea powders that can be used for urea-based grease and methods for manufacturing the same.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-81881

[0010] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2006-070262

[0011] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2006-070263 Summary of the Invention

[0012] One aspect of the present invention is a method for manufacturing raw materials for grease, wherein

[0013] a first thickener raw material, a second thickener raw material, a first lubricating oil, a second lubricating oil, a first solvent having a boiling point lower than those of the first lubricating oil and the second lubricating oil and dissolving the first lubricating oil but not dissolving the generated thickener, and a second solvent having a boiling point lower than those of the first lubricating oil and the second lubricating oil and dissolving the second lubricating oil but not dissolving the generated thickener are prepared.

[0014] Dissolve the above-mentioned first lubricating oil in the above-mentioned first solvent and dissolve or disperse the above-mentioned first thickener raw material to prepare a first mixed solution.

[0015] Dissolve the above-mentioned second lubricating oil in the above-mentioned second solvent and dissolve or disperse the above-mentioned second thickener raw material to prepare a second mixed solution.

[0016] Mix the above-mentioned first mixed solution with the above-mentioned second mixed solution to cause the first thickener raw material and the second thickener raw material to react to form a thickener.

[0017] Another aspect of the present invention is a method for manufacturing a raw material for a grease, wherein

[0018] Prepare a first thickener raw material, a second thickener raw material, a first lubricating oil, a first solvent having a boiling point lower than that of the first lubricating oil, dissolving the first lubricating oil and not dissolving the formed thickener, and a second solvent having a boiling point lower than that of the first lubricating oil and not dissolving the formed thickener.

[0019] Dissolve the above-mentioned first lubricating oil in the above-mentioned first solvent and dissolve or disperse the above-mentioned first thickener raw material to prepare a first mixed solution.

[0020] Dissolve or disperse the above-mentioned second thickener raw material in the above-mentioned second solvent to prepare a second mixed solution.

[0021] Mix the above-mentioned first mixed solution with the above-mentioned second mixed solution to cause the above-mentioned first thickener raw material and the above-mentioned second thickener raw material to react to form a thickener.

[0022] In the present invention, it also includes a raw material for a grease as another aspect, a method for manufacturing a raw material for another grease, a method for manufacturing a grease, and a grease. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a configuration diagram schematically showing an example of a double pinion type electric power steering device filled with the grease of the present invention.

[0024] Figure 2 is Figure 1 A-A cross-sectional view of

[0025] Figure 3 is Figure 1 B-B cross-sectional view of

[0026] Figure 4 is a configuration diagram schematically showing an example of a column type electric power steering device filled with the grease of the present invention.

[0027] Figure 5 is Figure 4 A-A cross-sectional view of

[0028] Figure 6 It is a cross-sectional view of a rolling bearing filled with the grease of the present invention.

[0029] Figure 7 It is a process chart for explaining the manufacturing method of the raw material of the grease of the first embodiment.

[0030] Figure 8 It is a process chart for explaining the manufacturing method of the raw material of the grease of the second embodiment.

[0031] Figure 9 It is a process chart for explaining the manufacturing method of the raw material of the grease of the third embodiment.

[0032] Figure 10 It is a process chart for explaining the manufacturing method of the raw material of the grease of the fourth embodiment.

[0033] Figure 11 It is a process chart for explaining the manufacturing method of the raw material of the grease of the fifth embodiment.

[0034] Figure 12 It is a process chart for explaining the manufacturing method of the raw material of the grease of the sixth embodiment.

[0035] Figure 13 It is a process chart for explaining the manufacturing method of the grease of the seventh embodiment.

[0036] Figure 14 It is a process chart for explaining the manufacturing method of the grease of the eighth embodiment.

[0037] Figure 15 It is a process chart for explaining the manufacturing method of the grease of the ninth embodiment.

[0038] Figure 16 It is a graph showing the evaluation results of the oil separation degree of the grease manufactured in Example 1 and Comparative Example 1.

[0039] Figure 17 It is a graph showing the evaluation results of the friction and wear test of the grease manufactured in Example 2, 3 and Comparative Example 2.

[0040] Figure 18 It is a graph showing the evaluation results of the friction and wear test of the grease manufactured in Example 4, 5 and Comparative Example 3. Detailed implementation manners

[0041] <Problems to be solved by the invention of the present disclosure>

[0042] The powdery urea compound synthesized in a solvent and from which the solvent has been removed can be used as a thickener, and grease can be manufactured by mixing it with a base oil.

[0043] In this case, before mixing with the base oil, unreacted amine compounds and isocyanate compounds can be removed by a cleaning treatment. Therefore, it is possible to suppress the remaining unreacted amine compounds and isocyanate compounds in the grease.

[0044] On the other hand, in the case of manufacturing a grease by synthesizing a urea compound in a solvent, removing the solvent, and then mixing with a base oil, there is a problem that the resulting grease is more likely to separate from the oil and has poor oil retention compared to a grease manufactured by synthesizing a urea compound in a base oil. One of the reasons for this is considered to be the large average particle size of the urea compound.

[0045] On the other hand, in the invention described in Patent Document 1, the particle size of the urea compound is controlled through a hard pulverization process and a classification process using a large pulverization mill such as a jet mill. Performing such a pulverization process and a classification process requires equipment investment, which is disadvantageous in this regard.

[0046] <Effect of the Invention of the Present Invention>

[0047] The raw material of the grease of the present invention can provide a grease capable of ensuring oil retention by mixing with a base oil.

[0048] The manufacturing method of the raw material of the grease of the present invention can manufacture a raw material of a grease containing a thickener and capable of providing a grease capable of ensuring oil retention by mixing with a base oil.

[0049] The manufacturing method of the grease of the present invention can provide a grease capable of ensuring oil retention.

[0050] According to the grease of the present invention, a grease capable of ensuring oil retention can be provided.

[0051] When such a grease is used for rolling bearings, gears, etc., sinter resistance and wear resistance can be ensured.

[0052] <Summary of the Embodiment of the Invention of the Present Disclosure>

[0053] Hereinafter, the summary of the embodiment of the invention of the present disclosure will be listed and described.

[0054] The inventor of the present invention conducted in-depth research to overcome the above problems and completed the invention of the present disclosure.

[0055] (1) The raw material of the grease of the present invention contains a thickener, a lubricating oil, and a solvent having a boiling point lower than that of the above lubricating oil, dissolving the above lubricating oil, and not dissolving the above thickener.

[0056] The raw material of the grease of the present invention can provide a grease capable of ensuring oil retention by mixing with a base oil.

[0057] (2) The manufacturing method of the raw materials of the grease of the present invention is as follows:

[0058] Prepare a first thickener raw material, a second thickener raw material, a first lubricating oil, a second lubricating oil, a first solvent with a boiling point lower than that of the above-mentioned first lubricating oil and the above-mentioned second lubricating oil, which can dissolve the first lubricating oil but not the generated thickener, and a second solvent with a boiling point lower than that of the above-mentioned first lubricating oil and the above-mentioned second lubricating oil, which can dissolve the second lubricating oil but not the generated thickener.

[0059] Dissolve the first lubricating oil in the above-mentioned first solvent and dissolve or disperse the first thickener raw material to prepare a first mixed solution.

[0060] Dissolve the second lubricating oil in the above-mentioned second solvent and dissolve or disperse the second thickener raw material to prepare a second mixed solution.

[0061] Mix the above-mentioned first mixed solution and the above-mentioned second mixed solution to cause the first thickener raw material and the second thickener raw material to react to generate a thickener.

[0062] In this case, raw materials of grease containing a thickener can be manufactured. The obtained raw materials of grease can provide a grease capable of ensuring oil retention by mixing with a base oil.

[0063] (3) In the manufacturing method of the raw materials of the grease described in the above (2), it is preferable to remove the above-mentioned first solvent and the above-mentioned second solvent after generating the above-mentioned thickener.

[0064] (4) In the manufacturing method of the raw materials of the grease described in the above (2) or (3), it is preferable that at least one of the above-mentioned first lubricating oil and the above-mentioned second lubricating oil is a poly-α-olefin.

[0065] (5) The manufacturing method of the raw materials of the grease of the present invention is the manufacturing method of the raw materials of the grease described as follows:

[0066] Prepare a first thickener raw material, a second thickener raw material, a first lubricating oil, a first solvent with a boiling point lower than that of the above-mentioned first lubricating oil, which can dissolve the first lubricating oil but not the generated thickener, and a second solvent with a boiling point lower than that of the above-mentioned first lubricating oil and not dissolving the generated thickener.

[0067] Dissolve the first lubricating oil in the above-mentioned first solvent and dissolve or disperse the first thickener raw material to prepare a first mixed solution.

[0068] Dissolve or disperse the second thickener raw material in the above-mentioned second solvent to prepare a second mixed solution.

[0069] Mix the above-mentioned first mixture with the above-mentioned second mixture to react the above-mentioned first thickener raw material with the above-mentioned second thickener raw material to form a thickener.

[0070] In this case, it is also possible to manufacture a raw material for grease containing a thickener. The obtained raw material for grease can be mixed with a base oil to provide a grease capable of ensuring oil retention.

[0071] (6) In the method for manufacturing the raw material for grease described in the above (5), it is preferable to remove the above-mentioned first solvent and the above-mentioned second solvent after forming the above-mentioned thickener.

[0072] (7) In the method for manufacturing the raw material for grease described in the above (5) or (6), it is preferable that the above-mentioned first lubricating oil is poly-α-olefin.

[0073] (8) Another method for manufacturing the raw material for grease of the present invention is as follows:

[0074] Prepare a first thickener raw material, a second thickener raw material, a first lubricating oil, a first solvent having a boiling point lower than that of the above-mentioned first lubricating oil and not dissolving the formed thickener, and a second solvent having a boiling point lower than the boiling point of the above-mentioned first lubricating oil and not dissolving the formed thickener.

[0075] Dissolve or disperse the above-mentioned first thickener raw material in the above-mentioned first solvent to form a first mixture.

[0076] Dissolve or disperse the above-mentioned second thickener raw material in the above-mentioned second solvent to form a second mixture.

[0077] Mix the above-mentioned first mixture, the above-mentioned second mixture and the above-mentioned first lubricating oil to react the above-mentioned first thickener raw material with the above-mentioned second thickener raw material to form a thickener.

[0078] In this case, it is also possible to manufacture a raw material for grease containing a thickener. The obtained raw material for grease can be mixed with a base oil to provide a grease capable of ensuring oil retention.

[0079] (9) In the method for manufacturing the raw material for grease described in the above (8), it is preferable to remove the above-mentioned first solvent and the above-mentioned second solvent after forming the above-mentioned thickener.

[0080] (10) In the method for manufacturing the raw material for grease described in the above (8) or (9), it is preferable that the above-mentioned first lubricating oil is poly-α-olefin.

[0081] (11) Another method for manufacturing the raw material for grease of the present invention is as follows:

[0082] Prepare a thickener, a first lubricating oil, and a first solvent having a boiling point lower than that of the above-mentioned first lubricating oil, dissolving the above-mentioned first lubricating oil and not dissolving the above-mentioned thickener.

[0083] Dissolve the first lubricating oil in the above-mentioned first solvent to form a first solution, and immerse the obtained first solution in the above-mentioned thickener.

[0084] In this case, it is also possible to manufacture a raw material for grease containing a thickener. The obtained raw material for grease can be mixed with a base oil to provide a grease capable of ensuring oil retention.

[0085] (12) In the method for manufacturing a raw material for grease described in the above (11), it is preferable to remove the first solvent after immersing the first solution in the thickener.

[0086] (13) Another method for manufacturing a raw material for grease of the present invention is as follows:

[0087] Prepare a thickener, a first lubricating oil, and a first solvent having a boiling point lower than that of the first lubricating oil, dissolving the first lubricating oil and not dissolving the thickener,

[0088] Disperse the thickener in the first solvent to form a first mixed liquid, and add the first lubricating oil to the obtained first mixed liquid.

[0089] In this case, it is also possible to manufacture a raw material for grease containing a thickener. The obtained raw material for grease can be mixed with a base oil to provide a grease capable of ensuring oil retention.

[0090] (14) In the method for manufacturing a raw material for grease described in the above (13), it is preferable to remove the first solvent after adding the first lubricating oil to the first mixed liquid.

[0091] (15) The method for manufacturing grease of the present invention is as follows:

[0092] Add a third lubricating oil to the raw material for grease manufactured by the manufacturing method described in the above (2), (5), or (8),

[0093] Then, remove the first solvent and the second solvent.

[0094] According to this manufacturing method, a grease capable of ensuring oil retention can be provided. In addition, the obtained grease can ensure good seizure resistance and good abrasion resistance when used for rolling bearings and sliding members.

[0095] (16) Another method for manufacturing grease of the present invention is as follows:

[0096] Add a third lubricating oil to the raw material for grease manufactured by the manufacturing method described in the above (3), (6), (9), (12), or (14).

[0097] According to this manufacturing method, a grease capable of ensuring oil retention can be provided. In addition, the obtained grease can ensure good seizure resistance and good abrasion resistance when used in rolling bearings and sliding members.

[0098] (17) Another manufacturing method of the grease of the present invention is as follows:

[0099] Add a third lubricating oil to the raw material of the grease manufactured by the manufacturing method described in the above (11) or (13),

[0100] Then, remove the above first solvent.

[0101] According to this manufacturing method, a grease capable of ensuring oil retention can be provided. In addition, the obtained grease can ensure good seizure resistance and good abrasion resistance when used in rolling bearings and sliding members.

[0102] (18) In the manufacturing method of the grease according to any one of the above (15) to (17), it is preferable that the above third lubricating oil is at least one selected from ester oil, ether oil, poly-α-olefin (PAO), and mineral oil.

[0103] (19) The grease of the present invention contains a thickener, a base oil, and an additive. The above thickener is a biurea compound, and the above base oil is poly-α-olefin and trimellitate,

[0104] In the above grease, relative to the total amount of the above thickener and the above base oil, the amount of the above thickener is 20.0 to 40.0% by mass, the amount of poly-α-olefin is 0.1 to 5.0% by mass, and the amount of trimellitate is 59.9 to 75% by mass.

[0105] The above grease has sufficient oil retention. In addition, according to the above grease, excellent abrasion resistance can be ensured when used in rolling bearings and sliding members.

[0106] <Details of the embodiments of the invention of the present disclosure>

[0107] Hereinafter, embodiments of the invention of the present disclosure will be described with reference to the drawings.

[0108] It should be noted that in the present invention, the embodiments of the invention should be considered illustrative in all respects and not restrictive. The scope of the rights of the present invention is shown by the claims, including all changes within the meaning equivalent to the claims and within the scope.

[0109] First, devices using the grease of the present invention will be described, and then, the raw materials of the grease of the present invention, the manufacturing method of the raw materials of the grease, the manufacturing method of the grease, and the embodiments of the grease will be described.

[0110] In this specification, the concept of the grease of the present invention includes, in addition to the grease of the present invention, greases using the raw materials of the grease of the present invention, greases using the raw materials of the grease obtained by the manufacturing method of the raw materials of the grease of the present invention, and greases obtained by the manufacturing method of the grease of the present invention.

[0111] The grease of the present invention can be used for, for example, a dual pinion type electric power steering device, a column type electric power steering device, a rolling bearing, etc.

[0112] (Dual pinion type electric power steering device)

[0113] Figure 1 FIG. is a configuration diagram schematically showing an example of a dual pinion type electric power steering device 1 including a steering gear device 3.

[0114] Figure 2 is a partial view showing the Figure 1 A - A cross - sectional view of. Figure 2 In, the lower side of the drawing corresponds to the lower side in the vertical direction when mounted on a vehicle.

[0115] Figure 3 is a partial view showing the Figure 1 B - B cross - sectional view of. Figure 3 In, the lower side of the drawing corresponds to the lower side in the vertical direction when mounted on a vehicle.

[0116] The dual pinion type electric power steering device 1 includes a steering wheel 10, a steering shaft 2, a first pinion shaft 32, a rack shaft 31, a housing 33, two rack bushings 30, 34, two bearings 35, 36, a first rack guide mechanism 39, and a steering assist device 5. The steering assist device 5 includes a controller 50, a torque sensor 51, an electric motor 52, a reduction mechanism 53, a second pinion shaft 54, two bearings 55, 56, a worm gear box housing 57, and a second rack guide mechanism 59. The reduction mechanism 53 includes a worm 531 and a worm gear 532.

[0117] A driver driving a vehicle equipped with the dual pinion type electric power steering device 1 performs a steering operation by rotating the steering wheel 10. The steering shaft 2 includes a column shaft 21, a first universal joint 23, an intermediate shaft 22, and a second universal joint 24. The first universal joint 23 includes a first yoke (not shown), a plurality of first rolling elements (not shown), a first cross shaft (not shown), a plurality of second rolling elements (not shown), and a second yoke (not shown). The second universal joint 24 includes a third yoke (not shown), a plurality of third rolling elements (not shown), a second cross shaft (not shown), a plurality of fourth rolling elements (not shown), and a fourth yoke (not shown).

[0118] One end of the column shaft 21 in the extending direction is fixed to the steering wheel 10. The other end of the column shaft 21 in the extending direction is fixed to the first yoke of the first universal joint 23. The column shaft 21 can rotate about the central axis in the extending direction. The first yoke is swingably fitted via a plurality of first rolling elements on a first pair of trunnions located on the same central axis of the first cross shaft. The second yoke is swingably fitted via a plurality of second rolling elements on a second pair of trunnions located on the same central axis of the first cross shaft. The central axis of the first pair of trunnions intersects the central axis of the second pair of trunnions at an angle of 90 degrees.

[0119] The second yoke of the first universal joint 23 is fixed to one end of the intermediate shaft 22 in the extending direction. The other end of the intermediate shaft 22 in the extending direction is fixed to the third yoke of the second universal joint 24. The third yoke is swingably fitted via a plurality of third rolling elements on a third pair of trunnions located on the same central axis of the second cross shaft. The fourth yoke is swingably fitted via a plurality of fourth rolling elements on a fourth pair of trunnions located on the same central axis of the second cross shaft. The central axis of the third pair of trunnions intersects the central axis of the fourth pair of trunnions at an angle of 90 degrees. The fourth yoke of the second universal joint 24 is fixed to one end of the first pinion shaft 32 in the extending direction. Thus, when the driver rotates the steering wheel 10, the column shaft 21 rotates about its central axis in the extending direction, the intermediate shaft 22 also rotates about its central axis in the extending direction, and the first pinion shaft 32 also rotates about its central axis in the extending direction.

[0120] In the double pinion type electric power steering device 1, the first pinion shaft 32, the rack shaft 31, the housing 33, the two rack bushings 30, 34, the first bearing 35, the second bearing 36, the first rack guide mechanism 39, the electric motor 52, the reduction mechanism 53, the second pinion shaft 54, the third bearing 55, the fourth bearing 56, the worm gear housing 57, and the second rack guide mechanism 59 constitute the steering gear device 3 as a rack and pinion type steering device. In Figure 1 In it, the housing 33 is represented by an imaginary line (double-dot dash line), and its interior is shown.

[0121] The first pinion shaft 32 extends from the upper side to the lower side in the vertical direction of the vehicle. The first pinion shaft 32 has a serrated portion 324, a first shaft portion 322, a first pinion tooth portion 320, and a first boss portion 323 along the extending direction from one end side to the other end. Serrations are formed in the serrated portion 324. The serrations of the serrated portion 324 fix the fourth yoke of the second universal joint 24. The first shaft portion 322 has a cylindrical shape. The first pinion tooth portion 320 is formed with first pinion teeth 321 on the entire circumferential surface. The extending direction of the first pinion teeth 321 has an angle other than 90 degrees with respect to the extending direction of the central axis of the first pinion shaft 32. The first boss portion 323 has a cylindrical shape.

[0122] The housing 33 has a first opening 332 on the side of the steering wheel 10, and the side opposite to the first opening 332 is sealed. The first pinion shaft 32 is received inside the housing 33. The first pinion shaft 32 is supported by two bearings 35, 36 rotatably with respect to the housing 33. The first bearing 35 is a ball bearing. The first bearing 35 includes an inner ring, an outer ring, and balls. The inner ring is fixed to the first shaft portion 322, and the outer ring is fixed to the housing 33, and the balls roll between the inner ring and the outer ring. The second bearing 36 is a roller bearing. The second bearing 36 includes rollers and an outer ring. The outer ring is fixed to the housing 33, and the rollers roll on the outer peripheral surface of the first boss portion 323 and the outer ring.

[0123] In a state where the first pinion shaft 32, the first bearing 35, and the second bearing 36 are inserted into the housing 33, a cover 37 through which the first pinion shaft 32 passes is fixed to the first opening 332 of the housing. A seal is fixed to the cover 37, and the seal can slide on the outer peripheral surface 322b of the first shaft portion 322 of the first pinion shaft 32. A cover member 38 is also fixed to the housing 33. The cover member 38 covers a part of the first shaft portion 322 of the first pinion shaft 32 from the outer side in the radial direction.

[0124] The rack shaft 31 has a first cylindrical portion 316, a first rack tooth portion 310, a second cylindrical portion 317, a second rack tooth portion 314, and a third cylindrical portion 318 from one end to the other end in the extending direction. The first rack tooth portion 310 has first rack teeth 311 formed on a part in the circumferential direction, and another part in the circumferential direction is a cylindrical surface 312 centered on the extending direction of the rack shaft 31. The second rack tooth portion 314 has second rack teeth 315 formed on a part in the circumferential direction, and another part in the circumferential direction is a cylindrical surface 313 centered on the extending direction of the rack shaft 31. The outer peripheral surfaces of the first cylindrical portion 316, the second cylindrical portion 317, and the third cylindrical portion 318 are cylindrical surfaces centered on the extending direction of the rack shaft 31 respectively. The extending direction of the first rack teeth 311 has an angle other than 90 degrees with respect to the extending direction of the rack shaft. The extending direction of the second rack teeth 315 has an angle other than 90 degrees with respect to the extending direction of the rack shaft 31. When the angle of the first rack teeth 311 with respect to the extending direction of the rack shaft 31 is set as X, the angle of the second rack teeth 315 with respect to the extending direction of the rack shaft 31 is π - X.

[0125] The housing 33 extends in a direction different from that of the first opening 332 on the side of the steering wheel 10, and has a second opening 333 at one end in the extending direction and a third opening 334 at the other end. The rack shaft 31 is accommodated inside the housing 33 along the extending direction of the housing 33. The first cylindrical portion 316 at one end in the extending direction of the rack shaft 31 projects from the second opening 333 at one end in the extending direction of the housing 33. The third cylindrical portion 318 at the other end in the extending direction of the rack shaft 31 projects from the third opening 334 at the other end in the extending direction of the housing 33. The housing 33 has a fourth opening 335. The fourth opening 335 is located on the other end side in the extending direction of the housing, closer to the other end than the first opening 332. The housing 33 also has a fifth opening 336 and a sixth opening 337. The fifth opening 336 is located in the radial direction centered on the extending direction of the housing 33 and in a direction perpendicular to the first opening 332, at a position substantially the same as that of the first opening 332 in the extending direction of the housing 33. The sixth opening 337 is located in the radial direction centered on the extending direction of the housing 33 and in a direction perpendicular to the fourth opening 335, at a position substantially the same as that of the fourth opening 335 in the extending direction of the housing 33.

[0126] The first rack bushing 30 is fixed to one end in the extending direction of the housing 33. The first rack bushing 30 is fixed to the housing 33 adjacent to the second opening 333. The first rack bushing 30 can slide on the outer peripheral surface of the first cylindrical portion 316 of the rack shaft 31. The second rack bushing 34 is fixed to the other end in the extending direction of the housing 33. The second rack bushing 34 is fixed to the housing 33 adjacent to the third opening 334. The second rack bushing 34 can slide on the outer peripheral surface of the third cylindrical portion 318 of the rack shaft 31.

[0127] The first pinion teeth 321 formed on the first pinion tooth portion 320 of the first pinion shaft 32 and the first rack teeth 311 formed on the first rack tooth portion 310 of the rack shaft 31 are in rollable and slidable contact via the grease G. The first pinion teeth 321 and the first rack teeth 311 are meshed via the grease G. When the first pinion shaft 32 rotates relative to the housing 33 about the central axis in its extending direction, the rack shaft 31 moves linearly in the extending direction of the housing 33 relative to the housing 33.

[0128] The first rack guiding mechanism 39 is fixed to the housing 33. The first rack guiding mechanism 39 is fixed to the fifth opening 336. The fifth opening 336 is located on the side of the cylindrical surface 312, which is the other part of the circumferential direction of the first rack tooth portion 310 of the rack shaft 31, at the position where the first pinion shaft 32 meshes with the rack shaft 31 in the extending direction of the housing 33.

[0129] The first rack guide mechanism 39 includes a first support yoke 391, a first sheet member 392, a first helical spring 393, and a first plug 394. The first sheet member 392 is clamped between the cylindrical surface 312, which is the other circumferential part of the first rack tooth portion 310 of the rack shaft 31, and the cylindrical surface of the first support yoke 391. The first sheet member 392 is fixed to the first support yoke 391. The first sheet member 392 and the cylindrical surface 312, which is the other circumferential part of the first rack tooth portion 310 of the rack shaft 31, are in slidable contact via the grease G. The first plug 394 is fixed to the fifth opening 336 of the housing 33. The first plug 394 contacts one end of the first helical spring 393. The first support yoke 391 contacts the other end of the first helical spring 393. The first helical spring 393 is shorter than its free length in a state where the first plug 394 is fixed to the fifth opening 336. Therefore, the first sheet member 392 is pressed against the rack shaft 31 relative to the housing 33.

[0130] The second pinion shaft 54 extends from the upper side to the lower side in the vertical direction of the vehicle. The second pinion shaft 54 has a fitting portion 544, a second shaft portion 542, a second pinion tooth portion 540, and a second boss portion 543 along the extending direction from one end side to the other end side. The fitting portion 544 has a cylindrical shape. The second shaft portion 542 has a cylindrical shape. The second pinion tooth portion 540 is formed with second pinion teeth 541 on the entire circumferential surface. The extending direction of the second pinion teeth 541 has an angle other than 90 degrees with respect to the extending direction of the central axis of the second pinion shaft 54. The second boss portion 543 has a cylindrical shape.

[0131] The worm gear 532 is fitted to the fitting portion 544. The worm 531 is fixed to the output shaft 521 of the electric motor 52. The electric motor 52 is fixed to the worm gear housing 57. The worm gear housing 57 has a seventh opening 571. The output shaft 521 of the electric motor 52 is disposed in the inner space of the worm gear housing 57 via the seventh opening 571. The electric motor 52 is fixed to the worm gear housing 57 so as to block the seventh opening 571 of the worm gear housing 57.

[0132] The worm 531 is disposed in the inner space of the worm gear housing 57. The worm gear 532 is disposed in the inner space of the worm gear housing 57. The worm gear housing 57 has an eighth opening 572 vertically above, and the assembly of the second pinion shaft 54 and the worm gear 532 is inserted into the inner space of the worm gear housing 57 from the eighth opening 572. The eighth opening is closed by a cover 58. The worm gear housing 57 has a ninth opening 573 on the side opposite to the eighth opening 572. A part of the second shaft portion 542, the second pinion tooth portion 540, and the second boss portion 543 of the second pinion shaft 54 protrude from the ninth opening 573 of the worm gear housing 57.

[0133] The worm gear housing 57 is fixed to the housing 33. The ninth opening 573 of the worm gear housing 57 communicates with the fourth opening 335 of the housing 33, sealing the internal space from the external space.

[0134] The third bearing 55 is a ball bearing. The bearing 55 includes an inner ring, an outer ring, and balls. The inner ring is fixed to the second shaft portion 542, and the outer ring is fixed to the worm gear housing 57. The balls roll between the inner ring and the outer ring. The bearing 56 is a roller bearing. The bearing 56 includes rollers and an outer ring. The outer ring is fixed to the housing 33, and the rollers roll between the outer peripheral surface of the second boss portion 543 and the outer ring.

[0135] The second pinion teeth 541 formed on the second pinion tooth portion 540 of the second pinion shaft 54 and the second rack teeth 315 formed on the second rack tooth portion 314 of the rack shaft 31 are in rollable and slidable contact via the grease G. The second pinion teeth 541 and the second rack teeth 315 are meshed via the grease G. When the second pinion shaft 54 rotates relative to the housing 33 about the central axis in its extending direction, the rack shaft 31 moves linearly in the extending direction of the housing 33 relative to the housing 33.

[0136] The housing 33 is fixed to the second rack guiding mechanism 59. The second rack guiding mechanism 59 is fixed to the sixth opening 337. The sixth opening 337 is located on the cylindrical surface 313 side, which is the other part of the circumferential direction of the second rack tooth portion 314 of the rack shaft 31, at the position where the second pinion shaft 54 and the rack shaft 31 mesh in the extending direction of the housing 33.

[0137] The second rack guiding mechanism 59 has a second support yoke 591, a second sheet member 592, a second helical spring 593, and a second plug 594. The second sheet member 592 is clamped between the cylindrical surface 313, which is the other part of the circumferential direction of the second rack tooth portion 314 of the rack shaft 31, and the cylindrical surface of the second support yoke 591. The second sheet member 592 is fixed to the second support yoke 591. The second sheet member 592 and the cylindrical surface 313, which is the other part of the circumferential direction of the second rack tooth portion 314 of the rack shaft 31, are in slidable contact via the grease G. The second plug 594 is fixed to the sixth opening 337 of the housing 33. The second plug 594 contacts one end of the second helical spring 593. The second support yoke 591 contacts the other end of the second helical spring 593. The second helical spring 593 is shorter than its free length in the state of fixing the second plug 594 to the sixth opening 337. Therefore, the second sheet member 592 is pressed against the rack shaft 31 relative to the housing 33.

[0138] The torque sensor 51 detects the steering torque applied by the driver to the steering wheel 10 through the column shaft 21. The reduction mechanism 53 is an assembly formed by the meshing of a worm 531 that rotates integrally with the output shaft 521 of the electric motor 52 and a worm gear 532 that rotates integrally with the second pinion shaft 54. Motor current is supplied from the controller 50 to the electric motor 52. The controller 50 controls the electric motor 52 based on the steering torque, vehicle speed, etc. detected by the torque sensor 51, and transmits the rotational force of the output shaft 521 of the electric motor 52 decelerated by the reduction mechanism 53 to the second pinion shaft 54. The rotational force of the second pinion shaft 54 is applied as a steering assist force from the second pinion teeth 541 to the second rack teeth 315.

[0139] The housing 33 is fixed to an unillustrated vehicle such that the extending direction of the housing 33 coincides with its vehicle width direction. Ball joint seats 11, 11 are respectively fixed to one end and the other end of the rack shaft 31, and tie rods 12, 12 respectively connected to these ball joint seats 11, 11 are connected via knuckle arms 13, 13 to the raceway rings of rolling bearings that rotatably support a pair of left and right front wheels 14, 14. The rack shaft 31 moves linearly in the extending direction of the housing 33, thereby steering the left and right front wheels 14, 14 that are the steering wheels.

[0140] Grease G is enclosed in the housing 33. Grease G exists between the rolling and sliding surfaces of the first pinion teeth 321 and the first rack teeth 311 that come into contact through mutual meshing, thereby lubricating between the two rolling and sliding surfaces. Grease G exists between the sliding surface of the first sheet member 392 and the cylindrical surface 312 that is the circumferential other part of the first rack tooth portion 310 of the rack shaft 31, which come into contact through mutual pressing of the first sheet member 392 and the rack shaft 31, thereby lubricating between the two sliding surfaces. Grease G exists between the rolling and sliding surfaces of the second pinion teeth 541 and the second rack teeth 315 that come into contact through mutual meshing, thereby lubricating between the two rolling and sliding surfaces. Grease G exists between the sliding surface of the second sheet member 592 and the cylindrical surface 313 that is the circumferential other part of the second rack tooth portion 314 of the rack shaft 31, which come into contact through mutual pressing of the second sheet member 592 and the rack shaft 31, thereby lubricating between the two sliding surfaces.

[0141] The steering gear device 3 configured in this way encloses the grease of the present invention as grease G. The grease of the present invention can ensure oil retention property, so the steering gear device 3 has good anti-seizure property and anti-wear property.

[0142] (Column-type Electric Power Steering Device)

[0143] Figure 4 is a configuration diagram schematically showing an example of a column-type electric power steering apparatus 601 including a steering gear device 603.

[0144] Figure 5 is a Figure 4 A-A cross-sectional view showing a part of the steering gear device 603. Figure 5 In [the figure], the lower side of the drawing corresponds to the lower side in the vertical direction when mounted on a vehicle.

[0145] The column-type electric power steering apparatus 601 includes a steering wheel 610, a steering shaft 602, a pinion shaft 632, a rack shaft 631, a housing 633, two rack bushings 630, 634, two bearings 635, 636, a rack guide mechanism 639, and a steering assist device 4. A driver driving a vehicle equipped with the column-type electric power steering apparatus 601 performs a steering operation by rotating the steering wheel 610. The steering shaft 602 includes a column shaft 621, a first universal joint 623, an intermediate shaft 622, and a second universal joint 624. The first universal joint 623 includes a first yoke (not shown), a plurality of first rolling elements (not shown), a first cross shaft (not shown), a plurality of second rolling elements (not shown), and a second yoke (not shown). The second universal joint 624 includes a third yoke (not shown), a plurality of third rolling elements (not shown), a second cross shaft (not shown), a plurality of fourth rolling elements (not shown), and a fourth yoke (not shown).

[0146] The column shaft 621 fixes the steering wheel 610 at one end in the extending direction. The column shaft 621 fixes the first yoke of the first universal joint 623 at the other end in the extending direction. The column shaft 621 can rotate about the central axis in the extending direction. The first yoke is swingably fitted via a plurality of first rolling elements on a first pair of trunnions located on the same central axis of the first cross shaft. The second yoke is swingably fitted via a plurality of second rolling elements on a second pair of trunnions located on the same central axis of the first cross shaft. The central axis of the first pair of trunnions intersects the central axis of the second pair of trunnions at an angle of 90 degrees.

[0147] The second yoke of the first universal joint 623 fixes one end of the intermediate shaft 622 in the extending direction. The other end of the intermediate shaft 622 in the extending direction fixes the third yoke of the second universal joint 624. The third yoke is swingably fitted via a plurality of third rolling elements on a third pair of trunnions located on the same central axis of the second cross shaft. The fourth yoke is variably fitted via a plurality of fourth rolling elements on a fourth pair of trunnions located on the same central axis of the second cross shaft. The central axis of the third pair of trunnions intersects the central axis of the fourth pair of trunnions at an angle of 90 degrees. The fourth yoke of the second universal joint 624 fixes one end of the pinion shaft 632 in the extending direction. Thus, when the driver rotates the steering wheel 610, the column shaft 621 rotates about the central axis in its extending direction, the intermediate shaft 622 also rotates about the central axis in its extending direction, and the pinion shaft 632 also rotates about the central axis in its extending direction.

[0148] In the column type electric power steering apparatus 601, the pinion shaft 632, the rack shaft 631, the housing 633, two rack bushings 630, 634, two bearings 635, 636, and the rack guide mechanism 639 constitute a steering gear device 603 as a rack and pinion type steering device. Figure 4 In the figure, the housing 633 is represented by an imaginary line (double-dot dash line), and its interior is shown.

[0149] The pinion shaft 632 extends from the upper side to the lower side in the vertical direction of the vehicle. The pinion shaft 632 has a serrated portion 724, a shaft portion 722, a pinion tooth portion 720, and a boss portion 723 along the extending direction from one end side to the other end. Serrations are formed in the serrated portion 724. The serrations of the serrated portion 724 fix the fourth yoke of the second universal joint 624. The shaft portion 722 has a cylindrical shape. The pinion tooth portion 720 is formed with pinion teeth 721 on the entire circumferential surface. The extending direction of the pinion teeth 721 has an angle other than 90 degrees with respect to the extending direction of the central axis of the pinion shaft 632. The boss portion 723 has a cylindrical shape.

[0150] The housing 633 has a first opening 732 on the steering wheel 610 side and is sealed on the side opposite to the first opening 732. The pinion shaft 632 is housed inside the housing 633. The pinion shaft 632 is supported by two bearings 635, 636 rotatably with respect to the housing 633. The bearing 635 is a ball bearing. The bearing 635 includes an inner ring, an outer ring, and balls. The inner ring is fixed to the shaft portion 722, and the outer ring is fixed to the housing 633, and the balls roll between the inner ring and the outer ring. The bearing 636 is a roller bearing. The bearing 636 includes rollers and an outer ring. The outer ring is fixed to the housing 633, and the rollers roll between the outer peripheral surface of the boss portion 723 and the outer ring.

[0151] With the pinion shaft 632 and two bearings 635, 636 inserted into the housing 633, a cover 637 through which the pinion shaft 632 passes is fixed to the first opening 732 of the housing. A seal is fixed to the cover 37, and the seal can slide on the outer peripheral surface 722b of the shaft portion 722 of the pinion shaft 632. A cover member 638 is also fixed to the housing 633. The cover member 638 covers a part of the shaft portion 722 of the pinion shaft 632 from the outer side in the radial direction.

[0152] The rack shaft 631 has a first cylindrical portion 716, a rack tooth portion 710, and a second cylindrical portion 717 from one end to the other end in the extending direction. The rack tooth portion 710 has rack teeth 711 formed on a part in the circumferential direction, and a cylindrical surface 712 centered on the extending direction of the rack shaft 631 on the other part in the circumferential direction. The outer peripheral surfaces of the first cylindrical portion 716 and the second cylindrical portion 717 are each a cylindrical surface centered on the extending direction of the rack shaft 631. The extending direction of the rack teeth 711 has an angle other than 90 degrees with respect to the extending direction of the rack shaft 631.

[0153] The housing 633 extends in a direction different from the first opening 732 on the side of the steering wheel 610, and has a second opening 733 at one end in the extending direction and a third opening 734 at the other end. The rack shaft 631 is housed inside the housing 633 along the extending direction of the housing 633. One end in the extending direction of the rack shaft 631 protrudes from the second opening 733 at one end in the extending direction of the housing 633. The other end in the extending direction of the rack shaft 631 protrudes from the third opening 734 at the other end in the extending direction of the housing 633.

[0154] The first rack bushing 630 is fixed to one end in the extending direction of the housing 633. The first rack bushing 630 is fixed to the housing 633 adjacent to the second opening 733. The first rack bushing 630 can slide on the outer peripheral surface of the first cylindrical portion 716 of the rack shaft 631. The second rack bushing 634 is fixed to the other end in the extending direction of the housing 633. The second rack bushing 634 is fixed to the housing 633 adjacent to the third opening 734. The second rack bushing 634 can slide on the outer peripheral surface of the second cylindrical portion 717 of the rack shaft 631.

[0155] The gear teeth 721 formed on the pinion tooth portion 720 of the pinion shaft 632 and the rack teeth 711 formed on the rack tooth portion 710 of the rack shaft 631 are in rolling and sliding contact via the grease G. The pinion teeth 721 and the rack teeth 711 are meshed via the grease G. When the pinion shaft 632 rotates relative to the housing 633 about the central axis in its extending direction, the rack shaft 631 moves linearly in the extending direction of the housing 633 relative to the housing 633.

[0156] Housing 633 is fixed to a vehicle (not shown) so that its extension direction aligns with the vehicle's width. Ball joint sockets 11, 11 are fixed to one end and the other end of rack shaft 631, respectively. Tie rods 12, 12, connected to these ball joint sockets 11, 11, are connected via knuckle arms 13, 13 to the raceways of rolling bearings that rotatably support a pair of left and right front wheels 14, 14. Rack shaft 631 moves linearly in the direction housing 633 extends, steering left and right front wheels 14, 14, which serve as steerable wheels.

[0157] The rack guide mechanism 639 is fixed to the housing 633. The housing 633 has a fourth opening 736 on the cylindrical surface 712 side of the rack tooth portion 710 of the rack shaft 631 at the position where the pinion shaft 632 and the rack shaft 631 mesh in the extending direction.

[0158] The rack guide mechanism 639 includes a support yoke 791, a sheet-like member 792, a coil spring 793, and a plug 794. The sheet-like member 792 is sandwiched between the cylindrical surface 712, which is another portion of the circumference of the rack teeth portion 710 of the rack shaft 631, and the cylindrical surface of the support yoke 791. The sheet-like member 792 is fixed to the support yoke 791. The sheet-like member 792 and the cylindrical surface 712, which is another portion of the circumference of the rack teeth portion 710 of the rack shaft 631, are in slidable contact via grease G. The plug 794 is fixed to the fourth opening 736 of the housing 633. The plug 794 contacts one end of the coil spring 793. The support yoke 791 contacts the other end of the coil spring 793. When the plug 794 is fixed to the fourth opening 736, the coil spring 793 is shorter than its free length. Therefore, the sheet-like member 792 is pressed against the rack shaft 631 relative to the housing 633.

[0159] The steering assist device 4 includes a controller 40, a torque sensor 41 that detects the steering torque applied by the driver to the steering wheel 610, an electric motor 42, and a reduction mechanism 43 that reduces the rotational force of the output shaft 421 of the electric motor 42 and transmits it to the column shaft 621. The reduction mechanism 43 is an assembly consisting of a worm 431 that rotates integrally with the output shaft 421 of the electric motor 42 and a worm wheel 432 that rotates integrally with the column shaft 621. The controller 40 supplies motor current to the electric motor 42. The controller 40 controls the electric motor 42 based on the steering torque detected by the torque sensor 41, the vehicle speed, and other factors, and applies the rotational force of the output shaft 421 of the electric motor 42, reduced by the reduction mechanism 43, to the column shaft 621 as a steering assist force.

[0160] The housing 633 is filled with a grease G. The grease G exists between the rolling and sliding surfaces of the pinion teeth 721 and the rack teeth 711 that come into contact with each other through meshing, so as to lubricate between the two rolling and sliding surfaces. The grease G exists between the sliding surface of the sheet member 792 and the sliding surface of the cylindrical surface 712, which is another part of the circumferential direction of the rack tooth portion 710 of the rack shaft 631, that come into contact with each other through pressing of the sheet member 792 against the rack shaft 631, so as to lubricate between the two sliding surfaces.

[0161] The steering gear device 603 configured in this way is filled with the grease of the present invention as the grease G. The grease of the present invention can ensure oil retention property, so the steering gear device 603 has good seizure resistance and wear resistance.

[0162] (Rolling bearing)

[0163] Figure 6 It is a cross-sectional view of a ball bearing 801 as an example of a rolling bearing.

[0164] The ball bearing 801 includes an inner ring 802, an outer ring 803 provided on the radially outer side of the inner ring 802, a plurality of balls 804 as rolling elements provided between the inner ring 802 and the outer ring 803, and an annular retainer 805 for holding these balls 804. In addition, seals 806 are provided on one side and the other side in the axial direction of the ball bearing 801.

[0165] In addition, the annular region 807 between the inner ring 802 and the outer ring 803 is filled with the grease G.

[0166] The inner ring 802 forms an inner raceway surface 821 on its outer circumference for the balls 804 to roll.

[0167] The outer ring 803 forms an outer raceway surface 831 on its inner circumference for the balls 804 to roll.

[0168] A plurality of balls 804 are interposed between the inner raceway surface 821 and the outer raceway surface 831 and roll on these inner raceway surface 821 and outer raceway surface 831.

[0169] The grease G filled in the region 807 also exists at the contact portions between the balls 804 and the inner raceway surface 821 of the inner ring 802 and at the contact portions between the balls 804 and the outer raceway surface 831 of the outer ring 803. It should be noted that the grease G is filled in such a way that it accounts for 20 to 40% by volume of the volume of the space obtained by removing the balls 804 and the retainer 805 from the space surrounded by the inner ring 802, the outer ring 803 and the seals 806.

[0170] The seal 806 is an annular member having an annular mandrel 806a and an elastic member 806b fixed to the mandrel 806a. The radially outer portion is fixed to the outer ring 803, and the radially inner portion is slidably mounted on the inner ring 802. The seal 806 prevents the enclosed grease G from leaking to the outside.

[0171] The ball bearing 801 thus configured encloses the grease of the present invention as the grease G. Since the grease of the present invention can ensure oil retention, the ball bearing 801 has good seizure resistance and wear resistance.

[0172] The grease of the present invention can be enclosed in the above-described double pinion type electric power steering device, column type electric power steering device, rolling bearing, etc. for use.

[0173] In the invention of the present disclosure, the raw material of the grease refers to a mixture containing at least a thickener and a lubricating oil, and the grease can be manufactured by mixing with the lubricating oil as the base oil.

[0174] Here, the lubricating oil contained in the raw material of the above grease may be the same as or different from the lubricating oil as the base oil.

[0175] In an embodiment of the raw material of the grease of the present invention, in addition to containing a thickener and a lubricating oil, it may further contain a solvent having a boiling point lower than that of the above lubricating oil, dissolving the above lubricating oil and not dissolving the above thickener. Such a raw material of the grease can be manufactured, for example, by a method of synthesizing a thickener not in the base oil but in the solvent.

[0176] Specifically, for example, it can be manufactured by using the manufacturing method of the raw material of the grease of the present invention.

[0177] In the following description of the first to tenth embodiments, the manufacturing method of the raw material of the grease of the present invention, the manufacturing method of the grease, and the embodiment of the grease will be described by taking a urea-based grease having a thickener of a biurea compound as an example.

[0178] (First Embodiment)

[0179] Figure 7 It is a process chart for explaining the manufacturing method of the raw material of the grease of the first embodiment.

[0180] (1) In the present embodiment, first, a predetermined amount of an amine compound, a diisocyanate compound, lubricating oil A, lubricating oil B, solvent A, and solvent B are respectively prepared.

[0181] The above amine compound may be any known substance as an amine compound for synthesizing a biurea compound which is a thickener for a urea-based grease.

[0182] The above amine compounds can be aliphatic amines, aromatic amines, or alicyclic amines.

[0183] There is no particular limitation on the above aliphatic amines. For example, aliphatic amines having 4 to 22 carbon atoms can be cited, etc. The carbon chain can be straight-chain or branched-chain.

[0184] There is no particular limitation on the above aromatic amines. For example, 4-amino-1-methylbenzene (p-toluidine), 2-amino-1-methylbenzene (o-toluidine), 4-amino-1-dodecylbenzene, 2-amino-1-dodecylbenzene, aniline, naphthylamine, etc. can be cited.

[0185] There is no particular limitation on the above alicyclic amines. For example, cyclohexylamine, 1-amino-2-methylcyclohexane, 1-amino-3-methylcyclohexane, 1-amino-4-methylcyclohexane, etc. can be cited.

[0186] The above diisocyanate compound only needs to be a publicly known substance of a diisocyanate compound for synthesizing a biurea compound known as a thickener for urea-based grease.

[0187] There is no particular limitation on the above diisocyanate compound. For example, hexamethylene diisocyanate (HDI), 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), a mixture of 2,4-TDI and 2,6-TDI, 4,4'-diphenylmethane diisocyanate (MDI), etc. can be cited.

[0188] As the above lubricating oil A and the above lubricating oil B, for example, substances used as base oils in grease can be cited. The above lubricating oil A and the above lubricating oil B can be the same or different.

[0189] As the above base oils (lubricating oil A, lubricating oil B), for example, ether oils such as alkyl diphenyl ether (ADE), ester oils, poly-α-olefins (PAO), polyalkylene glycols, fluorine oils, silicone oils, mineral oils, etc. can be cited.

[0190] As the above lubricating oil A and the above lubricating oil B, poly-α-olefins (PAO) are preferred. More preferred poly-α-olefins are PAO6 and PAO8.

[0191] The solvent A only needs to be a substance having a boiling point lower than that of the prepared lubricating oil A and lubricating oil B and dissolving the prepared lubricating oil A.

[0192] Regarding the above-mentioned solvent A, it is sufficient to satisfy the above requirements considering the amine compound, the diisocyanate compound, and the lubricating oil A. As specific examples of the above-mentioned solvent A, for example, toluene, hexane, ethyl acetate, tetrahydrofuran, p-xylene, m-xylene, o-xylene, methyl acetate, etc. can be used. It should be noted that it is preferable to avoid using substances that react with the isocyanate group-containing substances, such as substances having an amino group and substances having a hydroxyl group, and substances that react with the amino group-containing substances as the above-mentioned solvent A.

[0193] In addition, the above-mentioned solvent A preferably has a lower viscosity than the prepared lubricating oil A.

[0194] In the present invention, the viscosities of the solvent and the lubricating oil are measured using a Cannon-Fenske viscometer by the method of JIS Z 8803:2011.

[0195] The solvent B only needs to have a boiling point lower than the prepared lubricating oil A and lubricating oil B and dissolve the prepared lubricating oil B.

[0196] Regarding the above-mentioned solvent B, it is sufficient to satisfy the above requirements considering the amine compound, the diisocyanate compound, and the lubricating oil B. As specific examples of the above-mentioned solvent B, for example, toluene, hexane, ethyl acetate, tetrahydrofuran, p-xylene, m-xylene, o-xylene, methyl acetate, etc. can be used. It should be noted that, similarly to the above-mentioned solvent A, it is preferable to avoid using substances that react with the isocyanate group-containing substances, such as substances having an amino group and substances having a hydroxyl group, and substances that react with the amino group-containing substances as the above-mentioned solvent B.

[0197] In addition, the above-mentioned solvent B preferably has a lower viscosity than the prepared lubricating oil B.

[0198] The above-mentioned solvent B may be the same as or different from the above-mentioned solvent A, and the same is preferred.

[0199] In the subsequent process, when the mixed liquid containing solvent A and the mixed liquid B containing solvent B are mixed, the two can be reliably mixed, so it is suitable for the reaction of the amine compound and the diisocyanate compound. In addition, in the subsequent process, when removing solvent A and solvent B, the selection of the removal method and removal conditions is easy.

[0200] (2) Next, a mixed liquid A (S11) is obtained by adding the lubricating oil A and the amine compound to the solvent A.

[0201] At this time, the timing of adding the lubricating oil A and the amine compound to the solvent A is not particularly limited.

[0202] (a) The lubricating oil A can be dissolved in the solvent A to prepare a solution, and then the amine compound can be dissolved or dispersed in the obtained solution to form the mixed liquid A.

[0203] (b) The amine compound may be dissolved or dispersed in solvent A to prepare a mixed solution, and then lubricating oil A may be dissolved in the obtained mixed solution to prepare mixed solution A;

[0204] (c) Alternatively, the amine compound and the lubricating oil A may be added to the solvent A simultaneously, and then all the components may be mixed to prepare the mixed liquid A.

[0205] In this case, the amount of the amine compound can be set to about 5% by mass to about 60% by mass relative to 100% by mass of the solvent A.

[0206] The amount of the lubricating oil A can be set to about 0.3% by mass to about 30% by mass relative to 100% by mass of the solvent A.

[0207] (3) Separately from the step (2) above, lubricating oil B and a diisocyanate compound are added to solvent B to obtain a mixed liquid B (S12).

[0208] At this time, the timing of adding the lubricating oil B and the diisocyanate compound to the solvent B is not particularly limited.

[0209] (a) Lubricating oil B may be dissolved in solvent B to prepare a solution, and then the diisocyanate compound may be dissolved or dispersed in the obtained solution to prepare a mixed solution B;

[0210] (b) The diisocyanate compound may be dissolved or dispersed in solvent B to prepare a mixed solution, and then lubricating oil B may be dissolved in the obtained mixed solution to prepare mixed solution B;

[0211] (c) Alternatively, the diisocyanate compound and the lubricating oil B may be added to the solvent B simultaneously, and then all the components may be mixed to prepare a mixed solution B.

[0212] In this case, the amount of the diisocyanate compound can be set to approximately 5% by mass to 60% by mass relative to 100% by mass of the solvent B.

[0213] The amount of the lubricating oil B can be set to about 0.3% by mass to about 30% by mass relative to 100% by mass of the solvent B.

[0214] (4) Next, the mixed solution A and the mixed solution B are mixed to react the amine compound with the diisocyanate compound to synthesize a diurea compound (S13).

[0215] Here, the mixed solution B may be added dropwise to the mixed solution A while stirring the mixed solution A to mix the two, or the mixed solution A may be added dropwise to the mixed solution B while stirring the mixed solution B to mix the two.

[0216] The mixing of the mixed solution A and the mixed solution B can be carried out at room temperature or under heating.

[0217] When carried out under heating, the heating temperature can be set to about 40°C to about 110°C.

[0218] The time for the reaction of the amine compound and the diisocyanate compound is not particularly limited and can be the time for the reaction to proceed sufficiently. Specifically, for example, it can be set to about 0.2 hours to about 5 hours.

[0219] In the above steps (2) to (4), the mixing of the amine compound, the diisocyanate compound, and the lubricating oil in the solvent respectively, and the mixing of the mixed liquid A and the mixed liquid B can be carried out using, for example, a mechanical stirrer, a magnetic stirrer, etc. Among them, from the viewpoint of easily mixing each component uniformly, a mechanical stirrer is preferred.

[0220] By going through the above steps (1) to (4), a mixture containing a biurea compound (thickener), lubricating oil A and lubricating oil B, and solvent A and solvent B, that is, the raw material of the grease of the present invention, can be obtained.

[0221] (5) Remove solvent A and solvent B (S14) from the mixture obtained in the above step (4).

[0222] The method for removing solvent A and solvent B is not particularly limited, and solvent A and solvent B can be vaporized at room temperature or while appropriately heating, reducing pressure, stirring, etc. as needed. The specific method can be appropriately selected according to the types of solvent A and solvent B, and the following methods can be cited, for example.

[0223] For example, a method of allowing the above mixture to stand at room temperature and atmospheric pressure to vaporize solvent A and solvent B can be cited.

[0224] In addition, for example, a method of heating the above mixture at a temperature lower than the boiling points of solvent A and solvent B under atmospheric pressure to vaporize solvent A and solvent B can be cited. In this case, as the heating conditions, for example, heating in a constant temperature bath at 40°C for 5 to 10 hours under atmospheric pressure can be exemplified.

[0225] These methods can be combined.

[0226] (6) Next, wash the mixture remaining after removing solvent A and solvent B (S15).

[0227] By performing this washing step, unreacted amine compounds and diisocyanate compounds remaining in the mixture can be removed.

[0228] Here, as specific examples of the washing method, the following methods can be cited, for example.

[0229] First, the mixture after removing solvent A and solvent B is mixed with water and filtered through a membrane filter to recover the residue. The residue is then heated at a temperature lower than the boiling point of water and lower than the boiling points of lubricating oils A and B to vaporize the water adhering to the residue and remove the water from the residue. Heating conditions include, for example, heating in a high-temperature bath at 80°C under atmospheric pressure for 5 to 10 hours.

[0230] In this embodiment, the order of step S14 of removing the solvent A and the solvent B and step S15 of washing the remaining mixture may be reversed.

[0231] In this case, for example, the following method can be adopted.

[0232] The mixture containing the diurea compound dispersed in solvent A and solvent B is placed in a separatory funnel. Water is then added to the separatory funnel to transfer the unreacted amine compound and diisocyanate compound into the aqueous phase. The water containing the unreacted amine compound and diisocyanate compound is then removed from the separatory funnel. Solvent A and solvent B are then removed from the mixture after washing with the separatory funnel using the method described in step S14.

[0233] (7) The washed mixture is recovered to obtain a raw material of grease containing a diurea compound, lubricating oil A, and lubricating oil B (S16).

[0234] The obtained grease raw material may be subjected to a pulverization treatment as needed. By performing the pulverization treatment, the particle size of the thickener can be made finer and uniform.

[0235] When the pulverization treatment is performed, it is preferable to use a small pulverizer (for example, Labo Miller manufactured by OSAKA CHEMICAL) because it can be performed at low cost with a simple device.

[0236] The raw material of grease produced through the above steps (1) to (4) and the raw material of grease produced through the above steps (5) to (7) can be used in the grease production method described below.

[0237] (Second embodiment)

[0238] Figure 8 It is a process diagram for explaining the method for producing a raw material of grease according to the second embodiment.

[0239] The method for producing a raw material for grease according to the second embodiment differs from the first embodiment in the mixed liquid containing the diisocyanate compound.

[0240] (1) In this embodiment, first, a predetermined amount of an amine compound, a diisocyanate compound, lubricating oil A, solvent A, and solvent B are separately prepared.

[0241] As each of these components, for example, the same substances as those in the first embodiment can be used.

[0242] (2) Next, lubricating oil A and the amine compound are added to solvent A to obtain a mixed solution A (S21).

[0243] This step can be carried out in the same manner as step S11 of the first embodiment.

[0244] (3) Separately from the step (2) above, the diisocyanate compound is added to solvent B to obtain a mixed solution B' (S22).

[0245] At this time, the amount of the diisocyanate compound can be set to about 5% to about 60% by mass relative to 100% by mass of solvent B.

[0246] (4) Next, the mixed solution A and the mixed solution B' are mixed to react the amine compound with the diisocyanate compound to synthesize a biurea compound (S23).

[0247] Here, for the mixing of the mixed solution A and the mixed solution B', except that the mixed solution B' is used instead of the mixed solution B, it can be carried out in the same manner as step S13 of the first embodiment.

[0248] In the steps (2) to (4) above, the mixing of the amine compound, the diisocyanate compound, and the lubricating oil in the solvent, and the mixing of the mixed solution A and the mixed solution B' can be carried out using a stirrer in the same manner as in the first embodiment, and it is preferably carried out using a mechanical stirrer.

[0249] By going through the steps (1) to (4) like this, a mixture containing a biurea compound (thickener), lubricating oil A, and solvents A and B, that is, a raw material for the grease of the present invention, can be obtained.

[0250] (5) Then, in the same manner as in the first embodiment, solvents A and B are removed (S24), the mixture after removing solvents A and B is washed (S25), and the washed mixture is recovered to obtain a raw material for the grease containing the biurea compound and lubricating oil A (S26).

[0251] In this embodiment, as in the first embodiment, the order of the step S24 of removing solvents A and B and the step S25 of washing the remaining mixture can be reversed.

[0252] In this embodiment, the obtained raw material for the grease can also be subjected to a pulverization treatment as needed.

[0253] The raw materials of the grease manufactured through the above-mentioned steps (1) to (4) and the raw materials of the grease manufactured through the above-mentioned step (5) can be used in the grease manufacturing method described below.

[0254] (Third Embodiment)

[0255] Figure 9 It is a process diagram for explaining the manufacturing method of the raw materials of the grease in the third embodiment.

[0256] In the manufacturing method of the raw materials of the grease in the third embodiment, the mixed liquid containing the amine compound is different from that in the first embodiment.

[0257] (1) In this embodiment, first, a predetermined amount of amine compound, diisocyanate compound, lubricating oil B, solvent A, and solvent B are respectively prepared.

[0258] As these respective components, for example, the same substances as those in the first embodiment can be used.

[0259] (2) Next, the amine compound is added to solvent A to obtain a mixed liquid A' (S31).

[0260] At this time, the amount of the amine compound can be set to be about 5% to about 60% with respect to 100% by mass of solvent A.

[0261] (3) Next, separately from the step (2) above, the lubricating oil B and the isocyanate compound are added to solvent B to obtain a mixed liquid B (S32).

[0262] This step can be carried out in the same manner as step S12 in the first embodiment.

[0263] (4) Next, the mixed liquid A' and the mixed liquid B are mixed to react the amine compound with the diisocyanate compound to synthesize a biurea compound (S33).

[0264] Here, regarding the mixing of the mixed liquid A' and the mixed liquid B, except for using the mixed liquid A' instead of the mixed liquid A, it can be carried out in the same manner as step S13 in the first embodiment.

[0265] In the above steps (2) to (4), the mixing of the amine compound, the diisocyanate compound, and the lubricating oil in the solvent respectively, and the mixing of the mixed liquid A' and the mixed liquid B can be carried out in the same manner as in the first embodiment using a stirrer, and it is preferably carried out using a mechanical stirrer.

[0266] By going through the above steps (1) to (4), a mixture containing a biurea compound (thickener), lubricating oil B, and solvents A and B, that is, the raw materials of the grease of the present invention, can be obtained.

[0267] (5) Then, in the same manner as in the first embodiment, the solvents A and B are removed (S34), the mixture after the removal of the solvents A and B is washed (S35), and the washed mixture is recovered to obtain a raw material for grease containing the biurea compound and the lubricating oil B (S36).

[0268] In this embodiment, similar to the first embodiment, the order of the step S34 of removing the solvents A and B and the step S35 of washing the remaining mixture may be reversed.

[0269] In this embodiment, the obtained raw material for grease may be subjected to a pulverization treatment as needed.

[0270] The raw material for grease produced through the steps (1) to (4) above, and the raw material for grease produced through the step (5) above can be used in the method for manufacturing grease described later.

[0271] (Fourth Embodiment)

[0272] Figure 10 It is a process chart for explaining the method for manufacturing a raw material for grease of the fourth embodiment.

[0273] In the method for manufacturing a raw material for grease of the fourth embodiment, the timing of adding the lubricating oil A is different from that in the first to third embodiments.

[0274] (1) In this embodiment, first, a predetermined amount of an amine compound, a diisocyanate compound, a lubricating oil A, a solvent A, and a solvent B are prepared separately.

[0275] As these respective components, for example, the same substances as those in the first embodiment can be used.

[0276] (2) Next, the amine compound is added to the solvent A to obtain a mixed liquid A' (S101).

[0277] This step may be carried out in the same manner as the step S31 of the third embodiment.

[0278] (3) Separately from the step (2) above, the diisocyanate compound is added to the solvent B to obtain a mixed liquid B' (S102).

[0279] This step may be carried out in the same manner as the step S22 of the second embodiment.

[0280] '(4) Next, the mixed liquid A', the mixed liquid B', and the previously prepared lubricating oil A (S100) are mixed, and the amine compound and the diisocyanate compound are reacted to synthesize a biurea compound (S103).

[0281] Here, the mixture A', the mixture B' and the lubricating oil A are simultaneously mixed.

[0282] The method of simultaneously mixing the mixture A', the mixture B' and the lubricating oil A is not particularly limited.

[0283] (a) The mixture B' and the lubricating oil A can be put into the container containing the mixture A'.

[0284] (b) The mixture A' and the lubricating oil A can also be put into the container containing the mixture B'.

[0285] (c) The mixture A' and the mixture B' can also be put into the container containing the lubricating oil A.

[0286] (d) The mixture A', the mixture B' and the lubricating oil A can also be put into an empty container.

[0287] In the processes of (2) to (4) above, the mixing of the amine compound and the diisocyanate compound in the solvent respectively, and the mixing of the mixture A', the mixture B' and the lubricating oil A can be carried out using a stirrer in the same manner as in the first embodiment, and preferably using a mechanical stirrer.

[0288] By going through the processes of (1) to (4) like this, a mixture containing a biurea compound (thickener), the lubricating oil A, and the solvents A and B, that is, the raw material of the grease of the present invention, can be obtained.

[0289] (5) Then, in the same manner as in the first embodiment, the solvents A and B are removed (S104), the mixture after the removal of the solvents A and B is washed (S105), and the washed mixture is recovered to obtain the raw material of the grease containing the biurea compound and the lubricating oil A (S106).

[0290] In the present embodiment, as in the first embodiment, the order of the process S104 of removing the solvents A and B and the process S105 of washing the remaining mixture can be reversed.

[0291] In the present embodiment, the obtained raw material of the grease can also be subjected to a pulverization treatment as needed.

[0292] The raw material of the grease manufactured through the processes of (1) to (4) above, and the raw material of the grease manufactured through the process of (5) above can be used in the method for manufacturing the grease described later.

[0293] (Fifth Embodiment)

[0294] Figure 11 It is a process chart for explaining the method for manufacturing the raw material of the grease of the fifth embodiment.

[0295] In the method for manufacturing the raw material of the grease according to the fifth embodiment, the timing of coexisting the biurea compound and the lubricating oil is different from that of the first to third embodiments.

[0296] (1) In the present embodiment, first, a predetermined amount of a biurea compound, a lubricating oil C, and a solvent C are prepared separately.

[0297] The above biurea compound is a biurea compound known as a thickener for urea-based grease. As the above biurea compound, for example, a substance synthesized by reacting an amine compound with a diisocyanate compound in a solvent can be used.

[0298] As the above amine compound and the above diisocyanate compound, for example, the same substances as those in the first embodiment can be used respectively.

[0299] The above biurea compound may also be a commercially available product.

[0300] As the above lubricating oil C, for example, the same substance as the lubricating oil A in the first embodiment can be used.

[0301] As the above solvent C, as long as the boiling point is lower than the prepared lubricating oil C and the solvent C dissolves the lubricating oil C but does not dissolve the biurea compound, for example, the same substance as the solvent A in the first embodiment can be exemplified.

[0302] The viscosity of the above solvent C is preferably lower than that of the above lubricating oil C.

[0303] (2) Next, lubricating oil C is added to solvent C to obtain solution C (S41).

[0304] Here, for example, while stirring solvent C with a stirrer or the like, lubricating oil C can be dropped into solvent C.

[0305] At this time, the amount of lubricating oil C can be set to about 0.3 mass% to about 30 mass% relative to 100 mass% of solvent C.

[0306] (3) The above biurea compound is impregnated into the solution C obtained in the step (2) (S42).

[0307] Here, for example, solution C can be placed in a container and the above biurea compound can be added little by little to solution C while stirring with a stirrer or the like. Additionally, for example, the above biurea compound can be placed in a container and solution C can be added little by little to the biurea compound while stirring with a stirrer or the like.

[0308] At this time, the amount of the above biurea compound can be set to about 5 mass% to about 60 mass% relative to 100 mass% of solvent C.

[0309] By performing the steps of (2) and (3) as described above, a mixture containing a biurea compound (thickener), lubricating oil C, and solvent C, i.e., the raw material of the grease of the present invention, can be obtained.

[0310] (4) Remove solvent C (S43) from the mixture obtained in the step (3) above.

[0311] The method for removing solvent C is not particularly limited, and can be carried out by the same method as the method for removing solvent A exemplified in the first embodiment, taking into account the boiling point of solvent C, etc.

[0312] (5) Recover the mixture after removing solvent C to obtain the raw material of the grease containing the biurea compound and lubricating oil C (S44).

[0313] The obtained raw material of the grease may be subjected to a pulverization treatment as needed.

[0314] In the case of performing the above pulverization treatment, the pulverization treatment can be carried out, for example, by the same method as in the first embodiment.

[0315] The raw material of the grease manufactured through the steps (1) to (3) above, and the raw material of the grease manufactured through the steps (4) to (5) above can be used in the method for manufacturing the grease described later.

[0316] (Sixth Embodiment)

[0317] Figure 12 It is a process chart for explaining the method for manufacturing the raw material of the grease of the sixth embodiment.

[0318] In the method for manufacturing the raw material of the grease of the sixth embodiment, the timing of coexisting the biurea compound and the solvent is different from that of the fifth embodiment.

[0319] (1) In the present embodiment, first, a predetermined amount of a biurea compound, lubricating oil D, and solvent D are respectively prepared.

[0320] As the above biurea compound, for example, the same substance as in the fifth embodiment can be used.

[0321] In addition, the above biurea compound may also be a commercially available product.

[0322] As the above lubricating oil D, for example, the same substance as lubricating oil A in the first embodiment can be used.

[0323] As the above solvent D, as long as its boiling point is lower than that of the prepared lubricating oil D and it dissolves the lubricating oil D but does not dissolve the biurea compound, for example, the same substance as solvent A in the first embodiment can be exemplified.

[0324] Preferably, the viscosity of the above-mentioned solvent D is lower than that of the above-mentioned lubricating oil D.

[0325] (2) Next, the above-mentioned biurea compound is added to the solvent D to obtain a mixture D (S51).

[0326] Here, for example, the above-mentioned biurea compound can be dropped into the solvent D while stirring the solvent D with a stirrer or the like.

[0327] At this time, the amount of the above-mentioned biurea compound can be set to about 5% by mass to about 60% by mass relative to 100% by mass of the solvent D.

[0328] (3) Lubricating oil D is added to the mixture D obtained in the step (2) above (S52).

[0329] Here, for example, the mixture D can be placed in a container and lubricating oil D can be dropped into the mixture D while stirring with a stirrer or the like. Conversely, lubricating oil D can be placed in a container and the mixture D can be dropped into the lubricating oil D while stirring with a stirrer or the like.

[0330] At this time, the amount of the above-mentioned lubricating oil D can be set to about 0.3% by mass to about 30% by mass relative to 100% by mass of the solvent D.

[0331] By going through the steps (2) and (3) as described above, a mixture containing a biurea compound (thickener), lubricating oil D, and solvent D, that is, a raw material for the grease of the present invention, can be obtained.

[0332] (4) Solvent D is removed from the mixture obtained in the step (3) above (S53).

[0333] The method for removing solvent D is not particularly limited, and it can be carried out by the same method as the method for removing solvent A exemplified in the first embodiment, considering the boiling point of solvent D and the like.

[0334] (5) The mixture after removing solvent D is recovered to obtain a raw material for the grease containing a biurea compound and lubricating oil D (S54).

[0335] The obtained raw material for the grease can also be subjected to a pulverization treatment as needed.

[0336] In the case of performing the above-mentioned pulverization treatment, the pulverization treatment can be carried out, for example, by the same method as in the first embodiment.

[0337] The raw material for the grease manufactured through the steps (1) to (3) above, and the raw material for the grease manufactured through the steps (4) to (5) above can be used in the method for manufacturing the grease described later.

[0338] According to the first to sixth embodiments described above, raw materials for manufacturing the grease of the present invention can be produced.

[0339] Next, a method for manufacturing grease using the above-mentioned raw materials for grease will be described.

[0340] (Seventh Embodiment)

[0341] Figure 13 It is a process diagram for explaining the method for manufacturing grease according to the seventh embodiment.

[0342] (1) In the method for manufacturing grease according to the present embodiment, first, a base oil is added to the raw materials for grease (S13 in the first embodiment, S23 in the second embodiment, S33 in the third embodiment, S103 in the fourth embodiment) manufactured in the first to fourth embodiments, which contain a biurea compound (thickener), lubricating oil A and / or lubricating oil B, and solvent A and solvent B, and the two are mixed (S61).

[0343] As the above-mentioned base oil, conventionally known lubricating oils used as base oils for grease can be used. As specific examples, for example, ether oils such as alkyl diphenyl ether (ADE), ester oils, poly-α-olefins (PAO), polyalkylene glycols, fluorinated oils, silicone oils, mineral oils, etc. can be cited. The above-mentioned base oil can be used alone or in combination of two or more.

[0344] The base oil used in this process may be the same as or different from the lubricating oil contained in the above-mentioned raw materials for grease.

[0345] As the above-mentioned base oil, poly-α-olefin (PAO) or trimellitate as a kind of ester oil is preferred. From the viewpoint of ensuring oil retention while ensuring good abrasion resistance, trimellitate is more preferred as the above-mentioned base oil.

[0346] As the above-mentioned poly-α-olefin (PAO), PAO6 and PAO8 are preferred.

[0347] As the above-mentioned trimellitate, trimellitate triester is preferred.

[0348] As the above-mentioned trimellitate triester, for example, reaction products of trimellitic acid and monohydric alcohols having 6 to 18 carbon atoms can be cited. Among them, reaction products of trimellitic acid and monohydric alcohols having 8 and / or 10 carbon atoms are preferred.

[0349] As specific examples of the above-mentioned trimellitate triester, for example, tris(2-ethylhexyl) trimellitate, trinorbornanyl trimellitate (C8, C10), triisodecyl trimellitate, tri-n-octyl trimellitate, etc. can be cited.

[0350] The above trimellitate preferably has a kinematic viscosity of the base oil at 40 °C of 37 to 57 mm 2 / s.

[0351] The above kinematic viscosity of the base oil is based on the value of JIS K 2283:2000.

[0352] Here, the raw materials of the above grease can be added dropwise to the above base oil while stirring the base oil to mix the two, or the base oil can be added dropwise to the raw materials of the above grease while stirring the raw materials of the above grease to mix the two.

[0353] The mixing of the raw materials of the above grease and the above base oil is preferably carried out under heating. At this time, the heating temperature can be set to about 130 °C to about 180 °C.

[0354] The mixing time of the raw materials of the above grease and the above base oil is not particularly limited. For example, it can be set to about 0.5 hours to about 2 hours.

[0355] The method of mixing the raw materials of the above grease and the above base oil is not particularly limited as long as the two can be uniformly mixed. For example, methods such as using a mechanical stirrer and a magnetic stirrer can be cited. Among them, from the viewpoint of easily mixing the two uniformly, the method using a mechanical stirrer is preferred.

[0356] (2) Remove solvent A and solvent B (S62) from the mixture obtained in the process of (1) above.

[0357] The method of removing solvent A and solvent B is not particularly limited. Solvent A and solvent B can be vaporized at room temperature or while appropriately heating, reducing pressure, stirring, etc. as needed. The specific method can be appropriately selected according to the types of solvent A and solvent B, and the following methods can be cited, etc.

[0358] For example, a method of placing the above mixture at room temperature and atmospheric pressure to vaporize solvent A and solvent B can be cited.

[0359] In addition, for example, a method of heating the above mixture at a temperature lower than the boiling points of solvent A and solvent B under atmospheric pressure to vaporize solvent A and solvent B can be cited. In this case, as the heating conditions, it can be exemplified that the mixture is heated in a constant temperature bath at 40 °C under atmospheric pressure for 5 to 10 hours.

[0360] These methods can be combined.

[0361] By passing through the processes of (1) and (2) like this, a grease containing a biurea compound (thickener) and a base oil can be manufactured.

[0362] In this embodiment, in the above step (2), after removing Solvent A and Solvent B, homogenization treatment using a roll mill or the like may be performed as needed.

[0363] In addition, in the case of manufacturing a grease containing an additive, for example, necessary additives may be mixed after removing Solvent A and Solvent B.

[0364] (Eighth Embodiment)

[0365] Figure 14 It is a process diagram for explaining the manufacturing method of the grease of the eighth embodiment.

[0366] (1) In the manufacturing method of the grease of this embodiment, a base oil is added to the raw material of the grease (S16 of the first embodiment, S26 of the second embodiment, S36 of the third embodiment, S106 of the fourth embodiment, S44 of the fifth embodiment, S54 of the sixth embodiment) manufactured in the first to sixth embodiments, which contains a biurea compound (thickener), lubricating oil A and / or lubricating oil B, and lubricating oil C or lubricating oil D, and the two are mixed (S71).

[0367] As the above base oil, for example, the same substances as those exemplified for the base oil in the seventh embodiment can be cited.

[0368] The base oil used in this step may be the same as or different from the lubricating oil contained in the raw material of the above grease.

[0369] Here, the raw material of the grease can be added dropwise to the base oil while stirring the base oil to mix the two, or the base oil can be added dropwise to the raw material of the grease while stirring the raw material of the grease to mix the two.

[0370] The mixing of the raw material of the grease and the base oil is preferably carried out under heating. At this time, the heating temperature can be set to about 130°C to about 180°C.

[0371] The mixing time of the raw material of the grease and the base oil is not particularly limited, and can be set to about 0.5 hours to about 2 hours, for example.

[0372] The method of mixing the raw material of the grease and the base oil is not particularly limited as long as the two can be uniformly mixed. For example, methods using a mechanical stirrer, a magnetic stirrer, etc. can be cited. Among them, from the viewpoint of easily mixing the two uniformly, the method using a mechanical stirrer is preferred.

[0373] In this embodiment, since the raw material of the grease after removing the solvent is mixed with the above base oil, through the above step (1), a grease containing a biurea compound (thickener) and a base oil can be manufactured.

[0374] In this embodiment, after mixing the raw materials of the grease with the base oil, homogenization treatment using a roll mill or the like can also be performed as needed.

[0375] In addition, in the case of manufacturing a grease containing an additive, for example, necessary additives can be mixed after mixing the raw materials of the above grease with the above base oil.

[0376] (Ninth Embodiment)

[0377] Figure 15 It is a process chart for explaining the manufacturing method of the grease of the ninth embodiment.

[0378] (1) In the manufacturing method of the grease of this embodiment, base oil is added to the raw materials of the grease (S42 in the fifth embodiment, S52 in the sixth embodiment) manufactured in the fifth embodiment to the sixth embodiment, which contains a biurea compound (thickener), lubricating oil C and solvent C or lubricating oil D and solvent D, and the two are mixed (S81).

[0379] As the above base oil, for example, the same substances as those exemplified for the base oil in the seventh embodiment can be cited.

[0380] The base oil used in this process may be the same as or different from the lubricating oil contained in the above raw materials of the grease.

[0381] Here, the above raw materials of the grease can be added dropwise to the base oil while stirring the base oil to mix the two, or the base oil can be added dropwise to the raw materials of the grease while stirring the raw materials of the grease to mix the two.

[0382] The mixing of the above raw materials of the grease and the above base oil is preferably carried out under heating. At this time, the heating temperature can be set to about 130°C to about 180°C.

[0383] The mixing time of the above raw materials of the grease and the base oil is not particularly limited, and can be set to about 0.5 hours to about 2 hours, for example.

[0384] The method of mixing the above raw materials of the grease and the base oil is not particularly limited as long as the two can be uniformly mixed. For example, methods using a mechanical stirrer or a magnetic stirrer can be cited. Among them, from the viewpoint of easily mixing the two uniformly, the method using a mechanical stirrer is preferred.

[0385] (2) Solvent C or solvent D is removed from the mixture obtained in the step (1) above (S82).

[0386] Here, the method for removing solvent C or solvent D is not particularly limited. For example, the same method as the method for removing solvents A and B in the seventh embodiment can be used. The specific method can be appropriately selected according to the types of solvents C and D to be removed, and the following methods can be cited, etc.

[0387] For example, a method of allowing solvent C (or solvent D) to vaporize by leaving the above mixture at room temperature and atmospheric pressure can be cited.

[0388] In addition, for example, a method of heating the above mixture at a temperature lower than the boiling point of solvent C (or solvent D) under atmospheric pressure to vaporize solvent C (or solvent D) can be cited. In this case, as the heating conditions, heating in a constant temperature bath at 40°C for 5 to 10 hours under atmospheric pressure can be exemplified, etc.

[0389] These methods can be combined.

[0390] By going through the processes of (1) and (2) like this, a grease containing a biurea compound (thickener) and a base oil can be manufactured.

[0391] In the present embodiment, in the above process (2), after removing solvent C or solvent D, homogenization treatment using a roll mill or the like can also be performed as needed.

[0392] In addition, in the case of manufacturing a grease containing an additive, for example, necessary additives can be mixed after removing solvent C or solvent D.

[0393] According to the method for manufacturing a grease of the seventh to ninth embodiments, a grease capable of ensuring oil retention can be provided.

[0394] In the above method for manufacturing a grease, a grease raw material containing a lubricating oil in a thickener is mixed with a base oil to manufacture a grease. Therefore, it is considered that the affinity between the thickener (grease raw material) and the base oil is good, and the oil retention of the obtained grease can be ensured.

[0395] In addition, in the above method for manufacturing a grease, when the grease raw material is mixed with the base oil, it is considered that the lubricating oil contained in the thickener attracts the base oil and the thickener powder is pulverized, so that the thickener is refined. This is also considered to be one of the reasons for the good oil retention of the manufactured grease. In addition, it is considered that due to the refinement of the thickener, seizure resistance and wear resistance are easily ensured.

[0396] The grease manufactured in the embodiment of the present invention can be used, for example, as a grease filled in gears such as gears for electric power steering of automobiles, rolling bearings, etc.

[0397] (Tenth Embodiment)

[0398] The grease according to an embodiment of the present invention contains a thickener, a base oil, and an additive. The thickener is a biurea compound, the base oil is a poly-α-olefin and a trimellitate, and in the grease, the amount of the thickener is 20.0 to 40.0% by mass, the amount of the poly-α-olefin is 0.1 to 5.0% by mass, and the amount of the trimellitate is 59.9 to 75% by mass, based on the total amount of the thickener and the base oil.

[0399] The grease of the present embodiment has good oil retention property and excellent abrasion resistance when used for rolling bearings, gears, etc.

[0400] There are no particular limitations on the above-mentioned biurea compound, the above-mentioned poly-α-olefin, and the above-mentioned trimellitate, and they are the same as the substances used in the first to ninth embodiments.

[0401] There are no particular limitations on the above-mentioned additive, and it may be a conventionally known additive contained in the grease.

[0402] Examples of the above-mentioned additive include a rust inhibitor, an antioxidant, an extreme pressure agent, an oiliness agent, an antiwear agent, a dye, a hue stabilizer, a thickening agent, a structure stabilizer, a metal deactivator, a viscosity index improver, etc.

[0403] In the above-mentioned grease, the amount of the thickener is 20.0 to 40.0% by mass, the amount of the poly-α-olefin is 0.1 to 5.0% by mass, and the amount of the trimellitate is 59.9 to 75% by mass, based on the total amount of the thickener and the base oil, and thus the above-mentioned effects are exhibited.

[0404] The total content of the above-mentioned additives is, for example, about 1% by mass to about 20% by mass based on the total amount of the thickener and the base oil.

[0405] The above-mentioned grease can be appropriately manufactured by the method for manufacturing the grease according to the seventh to ninth embodiments.

[0406] (Other embodiments)

[0407] In the first to tenth embodiments, the thickener is a biurea compound, but in the embodiments of the present invention, the thickener is not limited to a biurea compound, and may also be a monourea compound, or a polyurea compound such as a triurea compound or a tetraurea compound.

[0408] Thus, in the case where the thickener is a urea thickener other than a biurea compound, the present invention can be implemented as long as an amine compound is selected as one of the first thickener raw material and the second thickener raw material and a diisocyanate compound is selected as the other.

[0409] In an embodiment of the present invention, the thickener is not limited to urea thickeners, and other thickeners may also be used.

[0410] As other thickeners, for example, soap thickeners such as lithium soap, calcium soap, and lithium complex soap can be cited.

[0411] When the thickener is lithium soap, for example, a fatty acid can be selected as one of the first thickener raw material and the second thickener raw material, and lithium hydroxide can be selected as the other.

[0412] When the thickener is calcium soap, for example, a fatty acid can be selected as one of the first thickener raw material and the second thickener raw material, and calcium hydroxide can be selected as the other.

[0413] When the thickener is lithium complex soap, for example, a fatty acid and an organic acid different from the fatty acid can be selected as one of the first thickener raw material and the second thickener raw material, and lithium hydroxide can be selected as the other.

[0414] Examples

[0415] Next, the invention of the present disclosure will be described in more detail based on examples, but the invention of the present disclosure is not limited to the examples.

[0416] In the examples / comparative examples, the following raw materials were used.

[0417] · Diisocyanate compound: 4,4'-diphenylmethane diisocyanate (MDI)

[0418] · Amine compound: octylamine

[0419] · Base oil (lubricating oil): poly-α-olefin: PAO6 (kinematic viscosity of the base oil at 40°C is 30.5 mm 2 / s)

[0420] · Base oil (lubricating oil): poly-α-olefin: PAO8 (kinematic viscosity of the base oil at 40°C is 46 mm 2 / s)

[0421] · Base oil (lubricating oil): trimellitate: TRIMEX N-08 (manufactured by Kao Corporation)

[0422] · Solvent: toluene

[0423] (Example 1)

[0424] (1) With respect to 100% by mass of toluene, 9% by mass of PAO8 was dissolved as the lubricating oil coexisting during synthesis. A predetermined amount of octylamine was further mixed into the obtained solution to obtain a mixed solution A1.

[0425] (2) Separately from the process of (1) above, a specified amount of MDI was mixed into a solution in which 1% by mass of PAO8 was dissolved in 100% by mass of toluene as a lubricating oil coexisting during synthesis, to obtain a mixed solution B1.

[0426] In the processes of (1) and (2) above, the amounts of the above-mentioned octylamine and the above-mentioned MDI were set as follows: the mixing ratio of the two (octylamine: MDI) was 2:1 in terms of molar ratio, and the amount of the resulting biurea compound was 30.0% by mass relative to 100% by mass of toluene.

[0427] The preparation of the mixed solution A1 was carried out by adding PAO8 and octylamine while stirring toluene with a mechanical stirrer.

[0428] In addition, the preparation of the mixed solution B1 was carried out by adding PAO8 and MDI while stirring toluene with a mechanical stirrer.

[0429] (3) While stirring the mixed solution B1 with a mechanical stirrer, the mixed solution A1 was added dropwise to the mixed solution B1 to mix the two.

[0430] After the dropwise addition of the mixed solution A1 was completed, while continuously stirring for 0.5 hours, octylamine and MDI were allowed to react at room temperature to form a biurea compound.

[0431] (4) Then, the mixture containing the biurea compound, PAO8, and toluene was left at room temperature for 24 hours to evaporate and remove toluene. Further, it was pulverized using a Labo Milser manufactured by OSAKA CHEMICAL to produce a raw material for grease.

[0432] (5) The raw material for grease at room temperature was put into PAO8 at room temperature as a base oil, and while stirring with a mechanical stirrer, it was heated to 150°C. While maintaining the base oil mixed with the raw material for grease at 150°C, it was continuously stirred with a mechanical stirrer for 1 hour. Then, while continuously stirring with a mechanical stirrer, it was naturally cooled to room temperature and the stirring was stopped.

[0433] At this time, the amount of the raw material for grease was set to 24.7% by mass relative to the total amount of the base oil and the raw material for grease.

[0434] Then, homogenization treatment using a roll mill was carried out to produce grease.

[0435] (Comparative Example 1)

[0436] (1) A specified amount of octylamine was mixed into toluene to obtain a mixed solution A2'.

[0437] (2) Separately from the process of (1) above, a specified amount of MDI was mixed into toluene to obtain a mixed solution B2'.

[0438] In the processes (1) and (2), the amounts of the above-mentioned octylamine and the above-mentioned MDI are set as follows: the mixing ratio of the two (octylamine: MDI) is 2:1 in terms of molar ratio, and the amount of the generated biurea compound is 30.0% by mass relative to 100% by mass of toluene.

[0439] The preparation of the mixed liquid A2’ is carried out by adding octylamine while stirring toluene with a mechanical stirrer.

[0440] The preparation of the mixed liquid B2’ is carried out by adding MDI while stirring toluene with a mechanical stirrer.

[0441] (3) While stirring the mixed liquid B2’ with a mechanical stirrer, the mixed liquid A2’ is dropped into the mixed liquid B2’ to mix the two.

[0442] After the dropping of the mixed liquid A2’ is completed, while continuously stirring for 0.5 hours, octylamine and MDI are reacted at room temperature to generate a biurea compound.

[0443] (4) Then, the mixture containing the biurea compound and toluene is left at room temperature for 24 hours to evaporate and remove toluene. Further, it is pulverized using a Labo Milser manufactured by OSAKA CHEMICAL to produce a raw material for grease.

[0444] (5) The raw material for grease at room temperature is put into PAO8 as a base oil at room temperature, and while stirring with a mechanical stirrer, it is heated to 150°C. While maintaining the base oil mixed with the raw material for grease at 150°C, it is continuously stirred with a mechanical stirrer for 1 hour. Then, while continuously stirring with a mechanical stirrer, it is naturally cooled to room temperature and the stirring is stopped.

[0445] At this time, the amount of the raw material for grease is set to 34.5% by mass relative to the total amount of the base oil and the raw material for grease.

[0446] Then, homogenization treatment using a roll mill is carried out to produce grease.

[0447] For Example 1 and Comparative Example 1, the following evaluations are carried out.

[0448] 1. Measurement of average particle size

[0449] For the raw material for grease manufactured in Example 1 and the raw material for grease manufactured in Comparative Example 1, the average particle size of the thickener (biurea compound) is measured. The results are shown in Table 2.

[0450] The above-mentioned average particle size is measured using a confocal laser microscope TCS SP8 manufactured by Leica Microsystems.

[0451] 2. Blended Consistency (60W)

[0452] For the grease produced in Example 1 and the grease produced in Comparative Example 1, the blended consistency (60W) was measured by the method according to JIS K 2220:2013. The results are shown in Table 2.

[0453] 3. Sintering Load Limit

[0454] For the grease produced in Example 1 and the grease produced in Comparative Example 1, the sintering load limit was measured by the following method. The results are shown in Table 2.

[0455] The measurement of the above sintering load limit was carried out by a reciprocating sliding test using an SRVII testing machine manufactured by PARKER Heat Treatment Industries. The details of the measurement conditions are shown in Table 1.

[0456] [Table 1]

[0457] Item Condition Specimen Material SUJ2 Frequency 50Hz Amplitude 1.5mm Test Temperature 25℃、100℃ Specimen Shape Steel Ball: 10mm Testing Machine SRVII

[0458] 4. Oil Separation Rate

[0459] For the grease produced in Example 1 and the grease produced in Comparative Example 1, the oil separation rate was measured by the method according to JIS K 2220:2013. The results are shown in Table 2 and Figure 16 in

[0460] At this time, the test temperature was set at 100 °C, and the oil separation rate after 24 hours, 36 hours, and 60 hours was measured.

[0461] [Table 2]

[0462]

[0463] As can be seen from the results shown in Table 2, according to the invention of the present disclosure, a grease with good oil retention and sintering resistance can be produced.

[0464] (Example 2)

[0465] (1) With respect to 100% by mass of toluene, 1% by mass of PAO8 was dissolved as a lubricating oil coexisting during synthesis. A predetermined amount of octylamine was further mixed into the obtained solution to obtain a mixed solution A3.

[0466] (2) Separately from the step (1) above, a predetermined amount of MDI was mixed with respect to 100% by mass of toluene to obtain a mixed solution B3'.

[0467] In the processes (1) and (2), the amounts of the above-mentioned octylamine and the above-mentioned MDI are set as follows: the mixing ratio of the two (octylamine: MDI) is 2:1 in terms of molar ratio, and the amount of the generated biurea compound is 30.0% by mass relative to 100% by mass of toluene.

[0468] The preparation of the mixed liquid A3 is carried out by adding PAO8 and octylamine while stirring toluene with a mechanical stirrer.

[0469] In addition, the preparation of the mixed liquid B3' is carried out by adding MDI while stirring toluene with a mechanical stirrer.

[0470] (3) While stirring the mixed liquid B3' with a mechanical stirrer, the mixed liquid A3 is added dropwise to the mixed liquid B3' to mix the two.

[0471] After the dropping of the mixed liquid A3 is completed, while continuously stirring for 0.5 hours, octylamine and MDI are reacted at room temperature to generate a biurea compound.

[0472] (4) Then, the mixture containing the biurea compound, PAO8 and toluene is left at room temperature for 24 hours to evaporate and remove toluene. Further, it is pulverized using a Labo Milser manufactured by OSAKA CHEMICAL to produce a raw material for grease.

[0473] (5) The raw material for grease at room temperature is put into trimellitate at room temperature as a base oil, and while stirring with a mechanical stirrer, it is heated to 150 °C. While maintaining the base oil mixed with the raw material for grease at 150 °C, it is continuously stirred with a mechanical stirrer for 1 hour. Then, while continuously stirring with a mechanical stirrer, it is naturally cooled to room temperature and the stirring is stopped.

[0474] At this time, the amount of the raw material for grease is set to 34.6% by mass relative to the total amount of the base oil and the raw material for grease.

[0475] Then, homogenization treatment using a roll mill is carried out to produce grease.

[0476] (Example 3)

[0477] In (1) of Example 2, PAO6 is used instead of PAO8 as the lubricating oil coexisting during synthesis, and the amount of the raw material for grease put into in (5) of Example 2 is set to 33.8% by mass relative to the total amount of the base oil and the raw material for grease. Except for this, grease is produced in the same manner as in Example 2.

[0478] (Comparative Example 2)

[0479] Grease containing trimellitate as a base oil and biurea as a thickener is prepared through the following processes.

[0480] (1) Use trimellitate as the base oil and preheat the base oil to 100 °C in advance.

[0481] (2) Measure the base oil, octylamine, and 4,4'-diphenylmethane diisocyanate (MDI).

[0482] (3) Put half of the amount of the base oil (100 °C) and MDI into container A and stir at 100 °C for 30 minutes.

[0483] (4) Put the remaining half of the amount of the base oil (100 °C) and octylamine into container B and stir at 100 °C for 30 minutes.

[0484] (5) Slowly drop the amine solution in container B into the isocyanate solution in container A.

[0485] (6) After confirming that the entire amount of the amine solution in container B has been put into container A, raise the temperature to 170 °C.

[0486] (7) Stir while heating and keep the temperature at 170 °C for 30 minutes.

[0487] (8) Stop heating and cool naturally while stirring until the temperature reaches 100 °C.

[0488] (9) After confirming that the temperature has dropped below 100 °C, stop stirring and cool naturally to room temperature in this state.

[0489] (10) Perform homogenization treatment with a roll mill.

[0490] Through the above steps (1) to (10), a grease is prepared.

[0491] The amount of the thickener in this grease is 32.0% by mass based on the total amount of the base oil and the thickener.

[0492] (Example 4)

[0493] (1) Prepare the raw materials for the grease in the same manner as in steps (1) to (4) of Example 2.

[0494] (2) Put the raw materials for the grease at room temperature into PAO6 as the base oil at room temperature and heat to 150 °C while stirring with a mechanical stirrer. While maintaining the base oil mixed with the raw materials for the grease at 150 °C, continuously stir with a mechanical stirrer for 1 hour. Then, cool naturally to room temperature while continuously stirring with a mechanical stirrer and stop stirring.

[0495] At this time, the amount of the raw materials for the grease is set to 33.2% by mass based on the total amount of the base oil and the raw materials for the grease.

[0496] Then, homogenization treatment using a roll mill is carried out to produce grease.

[0497] (Example 5)

[0498] (1) In (1) of Example 2, 1% by mass of trimellitate is used instead of 1% by mass of PAO8 as the lubricating oil coexisting during synthesis, and the raw materials for grease are manufactured in the same manner as in (1) to (4) of Example 2.

[0499] (2) The raw materials for grease at room temperature are put into PAO8 as the base oil at room temperature, and while stirring with a mechanical stirrer, it is heated to 150 °C. While maintaining the base oil mixed with the raw materials for grease at 150 °C, continuous stirring is carried out with a mechanical stirrer for 1 hour. Then, while continuously stirring with a mechanical stirrer, it is naturally cooled to room temperature and the stirring is stopped.

[0500] At this time, the amount of the raw materials for grease is set to 30.8% by mass based on the total amount of the base oil and the raw materials for grease.

[0501] Then, homogenization treatment using a roll mill is carried out to produce grease.

[0502] (Comparative Example 3)

[0503] PAO8 is used as the base oil instead of trimellitate, and grease is manufactured in the same manner as in Comparative Example 2.

[0504] The amount of the thickener of this grease is set to 33.5% by mass based on the total amount of the base oil and the thickener.

[0505] The following evaluations are carried out for Examples 2 to 5 and Comparative Examples 2 to 3.

[0506] 1. Measurement of average particle size <>

[0507] For the raw materials for grease manufactured in Examples 2 to 5, the average particle size of the thickener (biurea compound) is measured by the same method as used in Example 1 above. The results are shown in Table 4.

[0508] 2. Mixing consistency (60W)

[0509] For the grease manufactured in Examples 2 to 5 and the grease manufactured in Comparative Examples 2 to 3, the mixing consistency (60W) is measured by the method according to JIS K2220:2013. The results are shown in Table 4.

[0510] 4. Oil separation

[0511] For the greases produced in Examples 2 to 5, the oil separation degree was measured by the method according to JIS K 2220:2013. The results are shown in Table 4.

[0512] At this time, the test temperature was set at 100 °C, and the oil separation degree after 24 hours was measured.

[0513] 5. Friction and Wear Test

[0514] For the greases produced in Examples 2 to 5 and the greases produced in Comparative Examples 2 to 3, a ball-on-disk friction and wear test was performed using a friction and wear testing machine (manufactured by RHESCA, Friction Player FPR2100), and the wear amount (steel ball wear scar area) was evaluated.

[0515] Here, the grease was applied to the side surface of a raceway disk (shaft raceway disk or housing raceway disk) made of SUJ2, a load was applied thereto so that the contact surface pressure was 2.4 GPa, and a SUJ2 steel ball was brought into contact.

[0516] In such a state, the raceway disk was rotated for 1800 seconds, and then, the wear scar area (mm 2 ) of the steel ball was measured as the wear amount. The details of the test conditions are shown in Table 3.

[0517] The results are shown in Table 4 and Figure 17 , 18 . Figure 17 The results of the grease using trimellitate as the base oil are shown in Figure 18 The results of the grease using PAO (poly-α-olefin) as the base oil are shown in

[0518] [Table 3]

[0519]

[0520] [Table 4]

[0521]

[0522] As can be seen from the results shown in Table 4, according to the invention of the present disclosure, a grease having good oil retention property and ensuring good wear resistance can be produced.

[0523] In particular, it can be seen that when trimellitate is used as the base oil and PAO is used as the lubricating oil coexisting during synthesis, the wear resistance is excellent.

[0524] Symbol Explanation

[0525] 1: Dual-pinion type electric power steering device, 2: Steering shaft, 3: Steering gear device, 33: Housing

[0526] 31: Rack shaft, 310: First rack tooth part, 311: First rack tooth, 312: Cylindrical surface, 313: Cylindrical surface, 314: Second rack tooth part, 315: Second rack tooth,

[0527] 32: First pinion shaft, 320: First pinion tooth part, 321: First pinion tooth, 392: First sheet-like member

[0528] 54: Second pinion shaft, 540: Second pinion tooth part, 541: Second pinion tooth, 592: Second sheet-like member

[0529] 601: Tubular electric power steering device, 602: Steering shaft, 603: Steering gear device, 633: Housing

[0530] 631: Rack shaft, 710: Rack tooth part, 711: Rack tooth, 712: Cylindrical surface

[0531] 632: Pinion shaft, 720: Pinion tooth part, 721: Pinion tooth, 792: Sheet-like member

[0532] 801: Ball bearing, 802: Inner ring, 803: Outer ring, 804: Ball, 805: Retainer, 806: Seal

[0533] G grease

Claims

1. A method for manufacturing a raw material of a grease, wherein, prepare a first thickener raw material, a second thickener raw material, a first lubricating oil, a second lubricating oil, a first solvent having a boiling point lower than those of the first lubricating oil and the second lubricating oil and dissolving the first lubricating oil but not dissolving the formed thickener, and a second solvent having a boiling point lower than those of the first lubricating oil and the second lubricating oil and dissolving the second lubricating oil but not dissolving the formed thickener; one of the first thickener raw material and the second thickener raw material is an amine compound; the other of the first thickener raw material and the second thickener raw material is a diisocyanate compound; dissolve the first lubricating oil and dissolve or disperse the first thickener raw material in the first solvent to form a first mixed solution; dissolve the second lubricating oil and dissolve or disperse the second thickener raw material in the second solvent to form a second mixed solution; mix the first mixed solution with the second mixed solution to react the first thickener raw material with the second thickener raw material to form a urea thickener; then, remove the first solvent and the second solvent from the mixture of the first mixed solution and the second mixed solution; crush the mixture after removing the first solvent and the second solvent, whereby, obtain a thickener powder, which is a raw material of a grease and contains the first lubricating oil and the second lubricating oil in a biurea compound as a urea thickener.

2. The manufacturing method of the raw material of the grease according to claim 1, wherein, At least one of the first lubricating oil and the second lubricating oil is a poly-α-olefin.

3. A method for manufacturing a raw material of a grease, wherein, prepare a first thickener raw material, a second thickener raw material, a first lubricating oil, a first solvent having a boiling point lower than that of the first lubricating oil and dissolving the first lubricating oil but not dissolving the formed thickener, and a second solvent having a boiling point lower than that of the first lubricating oil and not dissolving the formed thickener; one of the first thickener raw material and the second thickener raw material is an amine compound; the other of the first thickener raw material and the second thickener raw material is a diisocyanate compound; dissolve the first lubricating oil and dissolve or disperse the first thickener raw material in the first solvent to form a first mixed solution; dissolve or disperse the second thickener raw material in the second solvent to form a second mixed solution; mix the first mixed solution with the second mixed solution to react the first thickener raw material with the second thickener raw material to form a urea thickener; then, remove the first solvent and the second solvent from the mixture of the first mixed solution and the second mixed solution; crush the mixture after removing the first solvent and the second solvent, whereby, obtain a thickener powder, which is a raw material of a grease and contains the first lubricating oil in a biurea compound as a urea thickener.

4. The manufacturing method of the raw material of the grease according to claim 3, wherein, The first lubricating oil is a poly-α-olefin.

5. A method for manufacturing a raw material of a grease, wherein, prepare a first thickener raw material, a second thickener raw material, a first lubricating oil, a first solvent having a boiling point lower than that of the first lubricating oil and not dissolving the formed thickener, and a second solvent having a boiling point lower than that of the first lubricating oil and not dissolving the formed thickener; One of the first thickener raw material and the second thickener raw material is an amine compound, The other of the first thickener raw material and the second thickener raw material is a diisocyanate compound, Dissolve or disperse the first thickener raw material in the first solvent to prepare a first mixture, Dissolve or disperse the second thickener raw material in the second solvent to prepare a second mixture, Mix the first mixture, the second mixture and the first lubricating oil, and react the first thickener raw material with the second thickener raw material to generate a urea thickener, Then, remove the first solvent and the second solvent from the mixture of the first mixture, the second mixture and the first lubricating oil, Crush the mixture after removing the first solvent and the second solvent, whereby, A thickener powder containing the first lubricating oil in a biurea compound as a urea thickener, i.e., a raw material of grease, is obtained.

6. The manufacturing method of the raw material of the grease according to claim 5, wherein, The first lubricating oil is poly-α-olefin.

7. A method for manufacturing a grease, wherein, Add a third lubricating oil to the raw material of grease manufactured by the manufacturing method according to claim 1, 3 or 5.

8. The method for manufacturing a grease according to claim 7, wherein, The third lubricating oil is at least one selected from ester oil, ether oil, poly-α-olefin and mineral oil.

9. A method for manufacturing grease, the grease contains a raw material of grease generated by the manufacturing method of the raw material of grease according to any one of claims 1 to 6, a base oil and an additive, In the method for manufacturing grease, Put the raw material of grease generated by using poly-α-olefin or trimellitate as the lubricating oil coexisting during the synthesis of the urea thickener into poly-α-olefin or trimellitate as the base oil, The urea thickener is a biurea compound.

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