JP2960561B2 - Grease composition for resin speed reducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease composition for a reduction gear made of a resin, which reduces wear of a resin member in contact with a metal output shaft in the reduction gear and has excellent rubber resistance. is there.

[0002]

2. Description of the Related Art A typical example of a reduction gear in which a rubber case and a reduction gear made of natural rubber or synthetic rubber are accommodated in a gear case is a power window motor. In this power window motor, corrosion of a metal member caused by rainwater or the like that has conventionally penetrated into the device, or deterioration or swelling of a rubber member caused by a lubricant such as grease used in the device. Problem was raised. To meet these requirements, a grease that has excellent rust prevention properties and has little effect on rubber is disclosed in
No. 9591 and JP-A-64-29496.

[0003]

The load applied to the output shaft of the power window motor mainly depends on the weight of the window glass, the contact resistance when the glass is up and down, and the like. The gear case serves as a bearing for this output shaft, and its material is becoming more and more resinous due to the reduction in size and weight of automobile parts. Therefore, the grease used not only lubricates between the worm gear and the worm wheel gear, but also lubricates the output shaft and the bearing of the gear case. Recently, the load on the output shaft has increased with the increase in size of the window glass, and there has been a problem that the wear of the resin gear case, which has been directly received by the conventional grease, has increased. If the wear is large, there is a backlash between the output shaft and the gear case, and there is also a problem that abnormal noise is generated during operation. Further, in such a power window motor, rubber materials such as natural rubber and synthetic rubber such as EPDM are conventionally used as damper materials, but these have a property of being easily swelled by a lubricant.

[0004] Therefore, the problem to be solved by the invention is to prevent corrosion of metal members as well as to suppress abrasion of the resin case without swelling rubber materials such as natural rubber and synthetic rubber such as EPDM. To provide grease. Needless to say, this grease is a grease on the premise that it can be used stably for a long period of time.

[0005]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies to solve the above-mentioned problems. That is, the present invention uses a rubber part made of natural rubber or synthetic rubber such as EPDM in a gear case, and A resin reduction gear grease composition for use in a reduction gear having at least a bearing portion made of resin, wherein a kinematic viscosity at a temperature of 40 ° C. is 10 to 1500 cSt, and 100 parts by weight of a polyoxyalkylene and / or an ether derivative thereof. (1) 2 to 35 parts by weight of a fatty acid metal salt, (2) 1 to 35 parts by weight of an organic molybdenum compound and / or polytetrafluoroethylene, (3)

Component (1) in grease composition of the present invention
Is for the base oil. In the present invention, a polyoxyalkylene or an ether derivative thereof having little adverse effect on rubber is used as a base oil. These are the following general formula 1

Embedded image Indicated by

A polyoxyalkylene or an ether derivative thereof means that R ₁ and R ₃ in the formula are H or carbon such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, etc. It is an alkyl group of Formulas 1 to 6, and n represents an integer. Among them, polyoxyalkylene is a diol obtained by ring-opening polymerization of an alkylene oxide such as ethylene oxide or propylene oxide. In addition, the ether derivatives thereof is a diether either of R _1, R ₃ is a mono ether, R _1, R ₃ both alkyl groups of 1 or more carbon atoms is a alkyl group having 1 or more carbon atoms. R ₂ represents hydrogen or an alkyl group.

Specific examples of the polyoxyalkylene diol include polyoxyethylene, polyoxypropylene,
Poly (oxypropyleneoxyethylene), poly (oxybutyleneoxyethylene), poly (oxybutyleneoxypropylene), poly (oxypentyleneoxyethylene), poly (oxypentyleneoxypropylene), etc., and polyoxyalkylene ethers. Derivatives include polyoxypropylene monopropyl ether, polyoxypropylene monobutyl ether, polyoxybutylene monobutyl ether, polyoxyethyleneoxypropylene monopropyl ether, polyoxyethyleneoxypropylene monobutyl ether, polyoxyethyleneoxypropylene monopentyl ether, and the like. . Incidentally, among these, polyoxyethylene, poly (oxypropyleneoxyethylene) and its ether derivatives are water-soluble, and therefore, greases based on them are inferior in water resistance. For this reason, those suitable for the present invention are polyoxyalkylenes having an alkyl group in which R ₂ is a methyl group or more and ether derivatives thereof, and particularly preferably polyoxypropylene monobutyl ether.

Component (2) is a grease thickener component, and any known fatty acid metal salt can be used as a grease thickener. Examples of fatty acid metal salts include lauric acid having 12 carbon atoms, myristic acid having 14 carbon atoms, and 16 carbon atoms.
Fatty acids such as palmitic acid, stearic acid having 18 carbon atoms, 12 hydroxystearic acid, oleic acid and monovalent metal salts such as Na and Li, divalent metal salts such as Ba and Ca, and trivalent metal such as Al Metal salts. It is also possible to use two or more kinds of fatty acids including dibasic acids and metal salts such as Al, Ca and Li, that is, complex soaps. Among them, in the present invention, lithium 12-hydroxystearic acid is most preferred in view of its water resistance, heat resistance and mechanical stability. In addition, the amount of the fatty acid metal salt is 2 to 35 parts per 100 parts by weight of the base oil.
If the amount is less than 2 parts by weight, the obtained grease is too fluid and soft, and if it exceeds 35 parts by weight, any grease is too hard to use as a lubricating grease for this application.

The component (3) is a load-bearing additive. In the present invention, an organic molybdenum compound and / or polytetrafluoroethylene is used. Among them, the organic molybdenum compound is a generic name of the organometallic load-bearing additives in which the metal group is molybdenum.

Embedded image It is shown by.

In the present invention, all of the above organic molybdenum compounds can be used. Further, Sakura Lube marketed by Asahi Denka Co., Ltd. as an amine complex organic molybdenum which is not included in the above general formula but does not contain S and P.
700 is also valid.

[0012] Polytetrafluoroethylene is a molding powder for molding, a fine powder obtained by emulsion polymerization or suspension polymerization, etc., and is mainly a white powder having a melting point of about 320 ° C. It is a chemically stable substance. In general, the following formula 3

Embedded image Represented by

When the amount of these additives is from 1 to 35 parts by weight, less than 1 part by weight has no effect on the abrasion resistance of the resin. On the other hand, if it is a solid, on the contrary, it becomes too hard and cannot be used as grease.

Further, the grease composition according to the present invention includes:
In addition to the base oils and thickeners shown in components (1) and (2), other types of base oils and thickeners can be used in combination. Base oils that can be used in combination include mineral oils, synthetic hydrocarbon oils, alkyl diphenyl ether oils, silicone oils, and the like, and thickeners include organic bentonite. Further, in addition to the components (1), (2), and (3), the grease composition of the present invention may contain an antioxidant, a rust inhibitor, a metal deactivator and an organic molybdenum, and a load-bearing additive other than polytetrafluoroethylene. Various additives such as agents can be used together in an amount of usually 5% by weight or less of the composition. Antioxidants that can be used in combination include 2,6-di-
Examples include a phenolic antioxidant represented by t-butyl cresol, an amine antioxidant represented by phenyl-α-naphthylamine, and a quinoline antioxidant represented by trimethyldihydroquinoline oligomer. Examples of the rust inhibitor include sulfonic acid metal salt rust inhibitors represented by petroleum sulfonic acid and alkylnaphthalene sulfonic acid, succinic acid rust inhibitors represented by alkenyl succinic anhydride, and fatty acid amine salt rust inhibitors. . The metal deactivator is benzotriazole or the like, and the load-bearing additive is an S-based extreme pressure agent, a Cl-based extreme pressure agent,
I-type extreme pressure agents, phosphorus-based antiwear agents, organometallic salt-based antiwear agents, and solid lubricants such as molybdenum disulfide and graphite.

[0015]

As described above, the grease of the present invention has abrasion resistance to a base oil containing the polyoxyalkylene of component (1) or an ether derivative thereof as the base oil and the fatty acid metal salt of the component (2) as the thickener. The organic molybdenum compound and / or polytetrafluoroethylene as the component (3) is added to provide the rubber member, and the wear amount of the resin member is greatly reduced without affecting the rubber member. This effect is presumed as follows.

In the case where the organic molybdenum compound is added, the organic molybdenum compound itself exhibits a friction relaxing effect as a solid lubricant, and reduces wear. In addition, the organic molybdenum compound is said to react with the metal material to form a substance having a structure corresponding to molybdenum disulfide, which is easily sheared on the friction surface. As a result, it is considered that the friction between the metal and the resin is reduced, and the wear is reduced. In the case of polytetrafluoroethylene, the particles are spread on both surfaces of the metal material and the resin material in the form of fine flakes due to shear stress. Since polytetrafluoroethylene itself is a material having the lowest friction coefficient, it is considered that friction between metal and resin is reduced and wear is reduced.

[0017]

Examples and Comparative Examples The present invention will be specifically described with reference to Examples and Comparative Examples. The greases shown in Examples and Comparative Examples were obtained as follows. In addition, the consistency of grease was unified to No. 2 grade.

Examples 1 to 5 and Comparative Examples 1 to 7 Base greases were prepared by the following methods, and
And the additives shown in Table 2 were added and mixed well using a three-roll mill to obtain greases of Examples 1 to 5 and Comparative Examples 1 to 7.

<Preparation method of base grease> 86.9% by weight of polyoxypropylene monobutyl ether having a kinematic viscosity of 105 cSt at 40 ° C. and 10.0% by weight of lithium 12-hydroxystearate as a thickener were mixed and stirred. The temperature was raised to 210 ° C. while dissolving completely. After cooling this to room temperature, BHT (di-t
-Butyl paracresol), 2.0% of oleic acid salt of dicyclohexylamine as a rust inhibitor, and 0.1% of benzotriazole as a metal deactivator. The mixture was kneaded with a three-stage roll mill and adjusted. Base grease.

Comparative Example 8 Lithium 12-hydroxystearate was used as a thickener,
Commercial grease based on mineral oil with a kinematic viscosity of 76.1 cSt at 40 ° C. Lithium 12 hydroxystearate is 8.0
% By weight.

Comparative Example 9 Commercially available grease using lithium 12-hydroxystearate as a thickener and polyoxyalkylene monoalkyl ether as a base oil, and melamine cyanurate as a load-bearing additive. The kinematic viscosity at 40 ° C. of the polyoxyalkylene monoalkyl ether used was 98.5 cSt (analytical value).

The following tests were performed using the greases obtained in the above Examples 1 to 5 and Comparative Examples 1 to 7 and the commercially available greases of Comparative Examples 8 and 9 as samples. The results are shown in Tables 1 and 2.

[0023]

[Table 1]

[0024]

[Table 2]

Next, test methods used in Examples and Comparative Examples will be described.

Rubber Dipping Test According to JIS K 6301 (Vulcanized Rubber Testing Method), a test rubber piece was immersed in a sample grease at 80 ° C. for 100 hours, and a change in volume and a change in hardness were determined for each rubber piece. The rubber material used was natural rubber.

Actual Machine Load Test In the test of the present invention, 0.4 g of grease was applied to the rotating shaft of the worm gear of the reduction gear, and the load on the output shaft of the motor was set to 16.8 kgf · cm in an atmosphere at room temperature of 25 ° C. Seconds-
Stopping 4.5 seconds-Reversing 3 seconds-Stopping 4.5 seconds, and taking this as one cycle, the visual situation of the reduction gear after 54000 cycles and the play of the resin bearing in contact with the output shaft were measured. The initial play in the above tests was 0.2
mm.

As can be seen from Comparative Example 8, a grease using a general mineral oil as a base oil shows good performance in an actual machine load test, but changes in volume or hardness become large in a rubber immersion test and cannot be used in rubber resistance. . Therefore, it is shown that the polyoxyalkylene or its ether derivative used in the present invention is suitable for the base oil. In the actual load test results, no improvement in wear resistance was observed in the case where no anti-wear agent or the like shown in Comparative Example 1 was added. The observed ZnDTP-based antiwear agents do not show good wear resistance. This is because such an anti-wear agent exhibits an effect by forming a reaction film on the steel surface. It is thought that there is no. In addition, such additives are liquid and exhibit a rubber swelling property, which is not preferable. Similarly, oils and fats and waxes which act as oil agents in steel-to-steel lubrication, ie, Comparative Examples 6 and 7, have no effect. Also, in Comparative Examples 2, 3, 4 and 9 using a non-reactive solid lubricant, no effect was observed.
The effect was confirmed only in Examples 1 to 5 of the present invention.

[0029]

The grease composition for a resin reduction gear according to the present invention prevents corrosion of metal members when used in a reduction gear having a rubber case in a gear case and a bearing portion of the gear case made of resin. Of course, it was confirmed that the rubber material was not deteriorated or swelled, and that the wear of the resin bearing portion due to the rotation of the output shaft was significantly reduced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C10N 10:12 20:02 30:06 40:02 40:04 50:10 (72) Inventor Mayumi Iida Fujisawa-shi, Kanagawa Tsujido Shindai 2-4-244-402 (72) Inventor Masahiko Hisada 390 Umeda, Kosai-shi, Shizuoka Prefecture Asmo Co., Ltd. (72) Inventor Tadashi Adachi 390 Umeda, Kosai-shi, Shizuoka Prefecture Asmo Co., Ltd. (56) References JP-A-64-29496 (JP, A) JP-A-63-309591 (JP, A) JP-A-52-16503 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10M 107/34 C10M 117/00 C10M 117/04 C10M 139/00 C10M 147/02 C10N 10:12 C10N 20:02 C10N 30:06 C10N 40:02 C10N 40:04 C10N 50:10

Claims (1)

(57) [Claims] 1. A grease composition for a reduction gear made of resin for use in a reduction gear in which a rubber part and a reduction gear are accommodated in a gear case, and at least the reduction gear bearing portion of the gear case is made of resin. The composition comprises 100 parts by weight of a polyoxyalkylene and / or an ether derivative of a polyoxyalkylene having a kinematic viscosity at a temperature of 40 ° C. of 10 to 1500 cSt, 2 to 35 parts by weight of a fatty acid metal salt, an organic molybdenum compound and / or polytetrafluoroethylene. A grease composition for a resin speed reducer, comprising 1 to 35 parts by weight.