JP3988898B2 - Grease composition for constant velocity joints - Google Patents

Description

また、市販二硫化モリブデンに硫黄−リン系極圧剤とナフテン酸の鉛塩を含有するリチウムグリースを比較例３のグリースとした。
【００１４】
これらのグリースにつき以下に示す試験方法で物性の評価を行い、得られた結果を表１に併記する。
＜ちょう度＞ ＩＳＯ ２１３７ による
＜滴 点＞ ＩＳＯ ２１７６ による

【００１５】
＜実ジョイント台上耐久試験＞
下記条件にて、実ジョイントでの台上耐久試験を行い、フレーキング等の発生の有無を評価した。

【００１６】
【表１】

【００１７】
1) モノアミンとして、シクロヘキシルアミンとアニリンを混合使用したジウレア化合物を用いたジウレアグリース
2) モノアミンとして、オクチルアミンを使用したジウレア化合物を用いたジウレアグリース
3) 二硫化モリブデン（商品名：Molysulfide CLIMAX MOLYBDENUM COMPANY 製平均粒径0.45μｍ）
4) 二硫化モリブデン（商品名：Molysulfide CLIMAX MOLYBDENUM COMPANY 製平均粒径0.7 μｍ）
5) モリブデンジチオカーバメート（商品名：Molyvan A R.T.Vanderbilt 社製)
6) モリブデンジチオカーバメート（商品名：Molyvan 822 R.T.Vanderbilt社製)
7) 硫黄含有有機錫化合物〔ジメチル錫ビス（イソオクチルメルカプトアセテート）とモノメチル錫トリス（イソオクチルメルカプトアセテート）の、７５／２５（重量比）混合物〕
8) 硫黄含有有機錫化合物〔ジ（ｎ−オクチル）錫ビス（イソオクチルメルカプトアセテート）〕
9) 平均摩擦係数
10) 台上耐久試験：バーフィールドジョイント
11) 台上耐久試験：クロスグルーブジョイント
（フレーキング発生 有：×、無：○）
* 比較例３：市販二硫化モリブデン、硫黄−リン系極圧剤、ナフテン酸鉛入りグリース[0001]
[Technical field to which the invention belongs]
The present invention relates to a grease composition for a constant velocity joint, and particularly to a grease composition for a plunging type constant velocity ball joint or a fixed type constant velocity ball joint. The lubrication condition of the constant velocity joint is an extremely high surface pressure, and as a result, the peeling phenomenon, that is, the flaking of the joint due to the occurrence of abnormal wear and metal fatigue is likely to occur. The present invention relates to a grease composition for a constant velocity joint that can lubricate such a constant velocity joint, effectively reduce wear of the joint, and effectively prevent flaking of the lubricated portion. is there.
[0002]
[Prior art]
Conventional lubricating greases used in such constant velocity joints include lithium-based extreme pressure grease containing molybdenum disulfide, molybdenum disulfide and sulfur-phosphorus extreme pressure agents, and lead salts of naphthenic acid. And lithium-based extreme pressure grease. However, these constant velocity joint greases are not always satisfactory under the severe working conditions that occur in recent high performance automobiles.
There are 6 double offset type constant velocity joints and cross groove type constant velocity joints used as plunging type constant velocity ball joints, and 6 Barfield joints used as fixed type constant velocity ball joints. It has a structure that transmits torque with a ball. In these constant velocity joints, the reciprocating motion of a complex rolling slide under high surface pressure during rotation applies a repeated stress to the ball and the metal surface in contact with the ball, and a flaking phenomenon due to metal fatigue tends to occur. With the recent increase in engine output and the reduction in weight of automobiles to improve fuel efficiency, the joint size is also reduced, resulting in a relatively high surface pressure, and conventional grease can sufficiently prevent flaking. Can not. In addition, it has become necessary to improve the heat resistance of grease.
[0003]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a novel grease composition for a constant velocity joint excellent in anti-flaking performance and heat resistance performance.
[0004]
[Means for Solving the Problems]
The present inventors conducted various studies to optimize the constant velocity joint wear, to prevent joint flaking due to abnormal wear and metal fatigue, and to develop a grease composition having excellent heat resistance. Vibration friction wear known as SRV (Schwingung Reibung und Verschleiss) testing machine, focusing on the sliding performance, focusing on the performance of the grease used in the lubrication conditions involving the complex rolling and sliding reciprocating motion under high surface pressure as described above This was carried out using a testing machine, and the lubrication characteristics (friction coefficient) by various extreme pressure additives, solid lubricants, or combinations of each additive were examined. As a result, the present inventors have found that a grease composition containing a base oil, a urea-based thickener, molybdenum disulfide, molybdenum dithiocarbamate, and a sulfur-containing organotin compound exhibits desirable lubricating properties with a low coefficient of friction. In addition, in a durability performance test using an actual constant velocity joint, it was confirmed that unlike the conventional constant velocity joint grease, occurrence of flaking phenomenon could be prevented, and the present invention was completed. It was.
[0005]
The above object of the present invention can be effectively achieved by a grease composition for a constant velocity joint including the following components.
(a) base oil,
(b) a urea-based thickener;
(c) molybdenum disulfide,
(d) molybdenum dithiocarbamate, and
(e) A grease composition for a constant velocity joint containing a sulfur-containing organotin compound.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the base oil of component (a) used in the present invention include commonly used lubricating oils such as mineral oils, ester-based synthetic oils, ether-based synthetic oils, hydrocarbon-based synthetic oils, or mixed oils thereof. However, it is not limited to these.
Examples of the urea thickener used in the present invention include, but are not limited to, diurea compounds and polyurea compounds.
A diurea compound is obtained by reaction of a diisocyanate and a monoamine, for example. Examples of the diisocyanate include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, occadecane diisocyanate, decane diisocyanate, hexane diisocyanate, and monoamines include octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, Aniline, p-toluidine, cyclohexylamine and the like can be mentioned.
The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those used for the production of diurea compounds. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, and the like. Is mentioned.
A particularly preferred urea-based thickener is a diurea compound obtained by reacting an aromatic amine such as aniline or p-toluidine, cyclohexylamine, or a mixture thereof with a diisocyanate compound, and an aryl group in the diurea compound. Having 6 or 7 carbon atoms, and the ratio of the aryl group to the cyclohexyl group in the diurea compound is preferably 100 to 0%.
[0007]
Next, molybdenum disulfide, which is the component (c) used in the present invention, is generally widely used as an extreme pressure additive. As the lubrication mechanism, it is known that it has a layered lattice structure, easily shears into a thin layer by a sliding motion, and reduces the friction coefficient. It is also effective in preventing joint burn-in.
[0008]
Preferable examples of the molybdenum dithiocarbamate which is the component (d) used in the present invention include those represented by the following formula (1).
^{[(R 1 R 2 N-C} (= S) -S- ] ₂ -Mo ₂ -O _m S _n
(Wherein R ¹ and R ² each independently represents an alkyl group having 1 to 24 carbon atoms, preferably 3 to 18 carbon atoms, m is 0 to 3, n is 4 to 1, and m + n = 4. .)
The preferred sulfur-containing organotin compound (e) used in the present invention is selected from those represented by the following formula (2).
(R ³ ) _m Sn (X) _4-m (2)
In the formula, R ³ represents an alkyl group, X represents —S— (CH ₂ ) n—CO—OR ⁴ or —S— (CH ₂ ) n—O—CO—R ⁴ , and R ⁴ represents an alkyl group. A group or an alkenyl group, n represents an integer of 1 to 18, m represents an integer of 0 to ³ , and when two or more of R3 and X are present, they may be the same or different.
Preferable alkyl groups represented by R ³ are those having 1 to 18 carbon atoms, such as methyl, butyl, octyl, octadecyl and the like. Preferable alkyl groups and alkenyl groups represented by R ⁴ are those having 1 to 18 carbon atoms, such as methyl, octyl, dodecyl, octadecyl, oleyl and the like.
[0009]
More specific examples include the following compounds.
Compound A Dimethyltin bis (isooctyl mercaptoacetate )
_{(CH 3) 2 -Sn- (S} -CH 2 CO-O-isoC 8 H 17) 2
Compound B Monomethyltin tris (isooctyl mercaptoacetate )
_{CH 3 -Sn- (S-CH 2} CO-O-isoC 8 H 17) 3
Compound C Di (n-octyl) tin bis (isooctyl mercaptoacetate)
_{(N-C 8 H 17)} 2 -Sn- (S-CH 2 CO-O-isoC 8 H 17) 2
Compound D Monomethyltin tris (2-mercaptoethyl oleate)
_{CH 3 -Sn- (S- (CH 2} ) 2 O-CO-C 18 H 35) 3
Compound E Dimethyltin bis (2-mercaptoethyl oleate)
_{(CH 3) 2 -Sn- (S-} (CH 2) 2 O-CO-C 18 H 35) 2
In addition to the above components, the grease composition for constant velocity joints of the present invention can contain an antioxidant, a rust inhibitor, an anticorrosive, and the like.
[0010]
The grease composition for constant velocity joints of the present invention is preferably a base oil of component (a): 60.0 to 98.7% by weight, and a urea system of component (b), based on the total weight of the grease composition. Thickener: 1 to 25% by weight, (c) component disulfide molybdenum: 0.1 to 5% by weight, (d) component molybdenum dithiocarbamate: 0.1 to 5% by weight, (e) component sulfur It contains 0.1 to 5% by weight of the organic tin compound.
The grease composition for constant velocity joints of the present invention is more preferably the base oil of component (a): 71.0 to 93.5% by weight, and the urea of component (b), based on the total weight of the grease composition. System thickener: 5 to 20% by weight, component (c) molybdenum disulfide: 0.5 to 3% by weight, component (d) molybdenum dithiocarbamate: 0.5 to 3% by weight, component (e) It contains 0.5 to 3% by weight of a sulfur-containing organotin compound.
If the content of the component (b) is less than 1% by weight, the thickening effect is reduced and it becomes difficult to form a grease, and if it is more than 25% by weight, the resulting composition becomes too hard and the desired effect is obtained. It becomes difficult. (C) When the component content is less than 0.1% by weight, (d) the component content is less than 0.1% by weight, and (e) the component content is less than 0.1% by weight, the desired effect On the other hand, the content of component (c) is more than 5% by weight, the content of component (d) is more than 5% by weight, and the content of component (e) is 5% by weight. When the amount is larger, the effect is not increased and the anti-flaking effect is not obtained.
[0011]
【Example】
Next, the present invention will be described with reference to examples and comparative examples.
[Examples 1 to 5, Comparative Examples 1 and 2]
A container was charged with 4100 g of base oil and 1012 g of diphenylmethane-4,4′-diisocyanate, and the mixture was heated to 70-80 ° C. In a separate container, 4100 g of base oil, 563 g of cyclohexylamine and 225 g of aniline were taken, heated to 70-80 ° C., and added to the previous container. The mixture was allowed to react for 30 minutes with good stirring, then heated to 160 ° C. with stirring and allowed to cool to obtain a base urea grease. Additives were added to this base grease in the formulation shown in Table 1, base oil was added as appropriate, and the resulting mixture was adjusted to a consistency No. 1 grade with a three-stage roll mill.
[0012]
Example 6
A container was charged with 440 g of base oil and 58.9 g of diphenylmethane-4,4′-diisocyanate, and the mixture was heated to 70-80 ° C. In a separate container, 440 g of base oil and 61.1 g of octylamine were taken, heated to 70-80 ° C., added to the previous container, and allowed to react for 30 minutes with good stirring. Thereafter, the temperature was raised to 160 ° C. with stirring, and after cooling, a base aliphatic amine urea grease was obtained. Additives were added to this base grease in the formulation shown in Table 1, base oil was added as appropriate, and the resulting mixture was adjusted to a consistency No. 1 grade with a three-stage roll mill.
[0013]
In the above Examples and Comparative Examples, the following grease base oils were used.

A lithium grease containing a commercially available molybdenum disulfide containing a sulfur-phosphorus extreme pressure agent and a lead salt of naphthenic acid was used as the grease of Comparative Example 3.
[0014]
The physical properties of these greases are evaluated by the test methods shown below, and the results obtained are also shown in Table 1.
<Consistency> According to ISO 2137 <Drip point> According to ISO 2176

[0015]
<Durability test on actual joint table>
Under the following conditions, a bench durability test was performed with an actual joint, and the presence or absence of flaking was evaluated.

[0016]
[Table 1]

[0017]
1) Diurea grease using diurea compound with cyclohexylamine and aniline mixed as monoamine
2) Diurea grease using diurea compound using octylamine as monoamine
3) Molybdenum disulfide (trade name: Molysulfide CLIMAX MOLYBDENUM COMPANY average particle size 0.45μm)
4) Molybdenum disulfide (Brand name: Molysulfide CLIMAX MOLYBDENUM COMPANY average particle size 0.7 μm)
5) Molybdenum dithiocarbamate (trade name: manufactured by Molyvan A RTVanderbilt)
6) Molybdenum dithiocarbamate (trade name: Molyvan 822 RTVanderbilt)
7) Sulfur-containing organotin compound [75/25 (weight ratio) mixture of dimethyltin bis (isooctyl mercaptoacetate ) and monomethyltin tris (isooctyl mercaptoacetate )]
8) Sulfur-containing organotin compound [di (n-octyl) tin bis (isooctyl mercaptoacetate)]
9) Average friction coefficient
10) Bench durability test: Barfield joint
11) Bench durability test: Cross groove joint (flaking occurs Yes: ×, No: ○)
* Comparative Example 3: Grease containing commercially available molybdenum disulfide, sulfur-phosphorus extreme pressure agent, lead naphthenate

Claims (4)

(a) base oil,
(b) a urea-based thickener;
(c) molybdenum disulfide,
(d) molybdenum dithiocarbamate, and
(e) A grease composition for a constant velocity joint containing a sulfur-containing organotin compound.   In the total composition, the content of urea thickener is 1 to 25% by weight, the content of molybdenum disulfide is 0.1 to 5% by weight, the content of molybdenum dithiocarbamate is 0.1 to 5% by weight, The grease composition for a constant velocity joint according to claim 1, wherein the content of the sulfur-containing organotin compound is 0.1 to 5% by weight. The grease composition for constant velocity joints according to claim 1 or 2, wherein the sulfur-containing organotin compound is selected from those represented by the following formula (2).
(R ³ ) _m Sn (X) _4-m (2)
In the formula, R ³ represents an alkyl group, X represents —S— (CH ₂ ) n—CO—OR ⁴ or —S— (CH ₂ ) n—O—CO—R ⁴ , and R ⁴ represents an alkyl group. A group or an alkenyl group, n represents an integer of 1 to 18, m represents an integer of 0 to ³ , and when two or more of R3 and X are present, they may be the same or different. Sulfur-containing organic tin compounds, dimethyltin bis (isooctyl mercaptoacetate), is at least one selected from the group consisting of monomethyl tin tris (isooctyl mercaptoacetate) and di (n- octyl) tin bis (isooctyl mercaptoacetate) The grease composition for constant velocity joints of any one of Claims 1-3.