KR20130073977A - Grease composition - Google Patents

Abstract

The present invention is a blend oil of (A) synthetic hydrocarbon oil and mineral oil having a pour point of -35 ° C or less, a base oil having a mass ratio of 100: 0 to 30:70,
(B) Thickener represented by following formula (1), and
R ¹ -NHCONH-R ² -NHCONH-R ³ (1)
(In formula, R <^2> represents a C6-C15 bivalent aromatic hydrocarbon group. R <^1> and R <^3> is the same or different group, and represents a cyclohexyl group or a C8-C18 linear or branched alkyl group, [ {(Moles of said alkyl group) / (moles of said alkyl group + moles of cyclohexyl group)} × 100] = 30-100%)
(C) alkenylsuccinic anhydride and / or organic zinc sulfonate
It provides a grease composition comprising a. The grease composition of the present invention is excellent in low torque and anti-rust properties.

Description

Grease composition {GREASE COMPOSITION}

The present invention relates to a grease composition for use in rolling bearings for automotive electrical or automotive accessories.

As greases used for rolling bearings for electric vehicles or for automobiles, diurea greases are often used from the viewpoint of heat resistance. Among the diurea greases, in particular, aromatic diureas are often used for high temperature durability.

However, compared with diurea compounds other than aromatic diurea, aromatic diurea needs to be mix | blended in a large amount in order to obtain grease of the same hardness. As a result, the stirring resistance of grease becomes high and low torque cannot be satisfied.

As an example of using a thickener other than aromatic diurea, Patent Document 1 discloses a base oil containing an ether-based synthetic oil in an amount exceeding 50% by mass as an essential component.

R ² -NHCONH-R ¹ -NHCONH-R ³

(In formula, R <^1> represents a C6-C15 bivalent aromatic hydrocarbon group, R <^2> and R <^3> is the same or different group and is a cyclohexyl group, a C7-C12 cyclohexyl derivative group, or a C8-C20 group. It consists of at least 1 sort (s) of the diurea compound represented by the alkyl group, and also contains content of a cyclohexyl group or its derivative group [{(number of cyclohexyl group or its derivative group) / (cyclohexyl group or its derivative group) A grease characterized by containing a gelling agent having from 50 to 100% of the number of the number + of the alkyl groups)} × 100] is proposed.

However, since the pour point of phenyl ether oil which is a base oil is about -30 degreeC and it does not satisfy low temperature at all, the torque at low temperature is high.

As another example using a thickener other than an aromatic diurea, Patent Document 2 discloses the following general formula as an essential component in a base oil containing an ester-based synthetic oil:

R ¹ -NHCONH-R ² -NHCONH-R ³

(In formula, R <^2> represents a C6-C15 bivalent aromatic hydrocarbon group. R <^1> and R <^3> is the same or different group, shows a cyclohexyl group, or a C8-C22 alkyl group, and is a cyclohexyl group of A grease composition comprising a thickener represented by a content rate [{(number of cyclohexyl groups) / (number of cyclohexyl groups + number of alkyl groups)} × 100] is 60 to 95%) is proposed. have.

However, ester-based synthetic oils are not preferable in that they are hydrolyzed when moisture is mixed from the outside, and rust is generated by the generated acid component.

Japanese Patent Application Publication No. 6-17079 Japanese Patent Application Publication No. 2008-239706

The problem to be solved by the present invention is to provide a grease composition excellent in low torque and anti-rust properties.

As described above, in order to ensure low torque, it is necessary to reduce the amount of thickener which is the main factor of the stirring resistance of the grease as much as possible, but if it is excessively reduced, the target hardness cannot be obtained, and the shear is further reduced. Since the grease is softened due to a large change in consistency when received, there is a problem of leaking from the bearing to the outside.

In the present invention, by containing 30% by mass or more of synthetic hydrocarbon oil having a low pour point in the base oil, low torque at low temperature is ensured. When using other types of base oils other than synthetic hydrocarbon oil together, a fixative mineral oil having a low pour point was used.

As a thickener, aliphatic diurea was used individually, or aliphatic diurea and alicyclic diurea were used together, and even if a small amount of thickener was made into the grease composition of suitable hardness.

Thus, the present inventors solved the said subject by selecting and combining specific base oil, thickener, and rust inhibitor. That is, according to this invention, the following grease compositions are provided.

1. (A) A blend oil of a synthetic hydrocarbon oil and a fixed mineral oil having a pour point of -35 ° C or less, a base oil having a mass ratio of 100: 0 to 30:70,

(B) a thickener represented by the following formula (1), and

R ¹ -NHCONH-R ² -NHCONH-R ³ (1)

(In formula, R <^2> represents a C6-C15 bivalent aromatic hydrocarbon group.

R <^1> and R <^3> is the same or different group, and represents a cyclohexyl group or a C8-18 linear or branched alkyl group, and [{(mole number of the said alkyl group) / (mole number of the said alkyl group + mole number of the cyclohexyl group) )} × 100] = 30-100%)

(C) alkenylsuccinic anhydride and / or organic zinc sulfonate

A grease composition comprising a.

2. The grease composition according to the above 1, wherein the kinematic viscosity at 40 ° C of the base oil is 80 to 150 mm ² / s.

3. The grease composition according to the above 1 or 2, wherein the synthetic hydrocarbon oil contains a synthetic hydrocarbon oil having a kinematic viscosity at 40 ° C of 300 mm ² / s or more.

4. The grease composition according to any one of the above 1 to 3, wherein the content of the thickener in the grease composition is 10 to 20% by mass.

5. The grease composition according to any one of the above 1 to 4 for rolling bearings.

6. The grease composition according to the above 5, wherein the rolling bearing is a rolling bearing for an electric vehicle or an automobile.

The grease composition of the present invention, so that torque is excellent in a wide temperature range, it is possible to contribute to the CO ² reduced by the improved fuel economy. Moreover, the grease composition of this invention is excellent in rust prevention property. The grease composition of the present invention is also excellent in evaporation resistance.

(A) base oil

The base oil used in the present invention is a blend oil of a synthetic hydrocarbon oil and a fixed mineral oil having a pour point of -35 ° C or lower. The mass ratio of the synthetic hydrocarbon oil and the fixed mineral oil having a pour point of -35 ° C or lower is 100: 0 to 30:70. When the proportion of the synthetic hydrocarbon oil in the base oil is 30% by mass or more, low torque at low temperature can be satisfied.

Examples of the synthetic hydrocarbon oil include poly-α-olefins, polybutenes, ethylene-α-olefin oligomers, and the like. Among them, poly-α-olefins are preferable.

The fixative mineral oil used in the present invention reduces the precipitation of wax components at low temperatures by dewaxing, thereby lowering the pour point than the pour point (about -5 ° C to -20 ° C) of the unrefined mineral oil. Say mineral oil. By containing the fixative mineral oil whose pour point is -35 degrees C or less, it can be used without adversely affecting the low torque property at the time of low temperature. In addition, evaporation resistance can also be used without problems.

It is preferable that the kinematic viscosity of base oil in 40 degreeC is 80-150 mm <^2> / s. More preferably 85~140 mm ² / s, more preferably 90~130 mm ² / s. When the kinematic viscosity of base oil at 40 degreeC is higher than 150 mm <^2> / s, grease viscosity will become high and low torque will not be satisfied. On the other hand, when the kinematic viscosity of the base oil at 40 degreeC is lower than 80 mm <^2> / s, low torque is satisfied, but it is inferior to evaporation resistance and is unpreferable.

It is preferable that synthetic hydrocarbon oil contains the thing whose kinematic viscosity in 40 degreeC is 300 mm <^2> / s or more. Accordingly, the base oil kinematic viscosity can be set within a predetermined range without sacrificing evaporation resistance while satisfying low torque at low temperature.

It is preferable that the fixative mineral oil contains the thing whose kinematic viscosity in 40 degreeC is 80-130 mm <^2> / s, More preferably, it is 80-110. Accordingly, low torque can be satisfied. Evaporation resistance is also improved.

It is preferable that the pour point of synthetic hydrocarbon oil is -35 degreeC or less. Thereby, the low torque property at low temperature can be satisfied.

Other base oils that can be used in combination with synthetic hydrocarbon oils include diester oils, ester synthetic oils represented by polyol esters, ether synthetic oils represented by alkyldiphenyl ethers, polyglycol synthetic oils represented by polypropylene glycol, silicone synthetic oils, Fluorine-based synthetic oils are exemplified. However, as mentioned above, ester type synthetic oil is not preferable at the point which concerns about hydrolysis when water mixes from the exterior. In addition, the ether-based synthetic oil has a high pour point of about -30 ° C and high torque at low temperatures. Polyglycol synthetic oil, silicone synthetic oil, and fluorine synthetic oil are poor in lubricity and expensive.

(B) thickener

As a thickener generally used for grease compositions, non- soaps, such as metal soap containing Li, Na, etc., benton, a silica gel, a diurea compound, the fluorine thickener represented by polytetrafluoroethylene, are mentioned. However, metal soaps are not capable of satisfying heat resistance, that is, bearing lubrication life under high temperature. Benton and silica gel are inferior in water resistance, and fluorine-based thickeners are satisfactory in heat resistance but are very expensive, and thus lack generality.

Therefore, the grease composition of this invention uses the thickener represented by said formula (1).

Thickener when content rate of the alkyl group in Formula (1), ie, {(mole number of alkyl group) / (mole number of alkyl group + mole number of cyclohexyl group)} x 100, is 30-100% and the content rate of an alkyl group is less than 30%. Since the amount is large and the low torque property is inferior, it is not preferable.

The amount of the thickener (B) in the grease composition of the present invention is preferably from 10 to 20% by mass, more preferably from 12 to 17% by mass, from the viewpoint of low torque.

(C) rust preventive

The grease composition of the present invention contains organic sulfonic acid zinc and / or alkenylsuccinic anhydride as rust inhibitor. These rust preventive agents have an effect of dispersing moisture even when moisture is mixed from the outside.

Organic zinc sulfonate is a zinc salt of sulfonic acid having an organic group which is a lipophilic group. Examples of the sulfonic acid include petroleum sulfonic acid obtained by sulfonation of an aromatic hydrocarbon component in lubricating oil fraction and petroleum high boiling point fraction, synthetic sulfonic acids such as dinonylnaphthalene sulfonic acid and heavy alkylbenzene sulfonic acid. Organic zinc sulfonate represented by the following general formula (2) is preferable.

[R ⁴ -SO ₃ ] ² Zn (2)

(In formula, R <^4> represents an alkyl group, an alkenyl group, an alkyl naphthyl group, a dialkyl naphthyl group, an alkylphenyl group, and petroleum high boiling oil fraction residue. The said alkyl or alkenyl is linear or branched, and is C2-C22. .)

Specifically, zinc dioctyl naphthalene sulfonate, zinc dinonyl naphthalene sulfonate, zinc didecyl naphthalene sulfonate, zinc petroleum sulfonate, high basic alkylbenzene sulfonate, etc. are mentioned. Among these, zinc dinonyl naphthalene sulfonate is most preferable.

As alkenyl succinic anhydride, the alkenyl succinic anhydride which has a C6-C18 alkenyl group can be used preferably. In particular, the alkenyl succinic anhydride which has a C10-C15 alkenyl group is preferable.

The amount of the (C) rust preventive agent in the grease composition of the present invention is preferably 0.1 to 3% by mass, more preferably 0.5 to 2% by mass, from the viewpoint of ensuring rust prevention under an environment where salt water may be mixed.

The grease composition of this invention can contain the additive normally used for a grease composition as needed. Examples include inorganic passivating agents such as antioxidants represented by amines and phenols, sodium nitrite, rust inhibitors represented by amines and carboxylates, metal corrosion inhibitors represented by benzotriazoles, fatty acids, fatty acid esters and phosphate esters. Abrasion-resistant agents represented by an oily agent, phosphorus type | system | group, sulfur type | system | group, and an organometallic system, a solid lubricant represented by extreme pressure agent, a metal oxide, molybdenum sulfide, etc. are mentioned.

The grease composition of the present invention can be used as a rolling bearing, in particular as a rolling bearing for automotive electric or bogie. Examples of rolling bearings for automotive electric or bogies include bearings used for electronic clutches for automobile air conditioners, intermediate pulleys, idler pulleys, tension pulleys, alternators, water pumps, and the like. When using especially under high temperature, since grease composition degrades oxidation, it is preferable to use antioxidant together rather than using amine type and a phenol type independently.

[Example]

<Test Grease>

Using the base oil (A) shown in Table 1, the (B) thickener shown in Table 2, and the (C) rust inhibitor shown in Table 3, the grease compositions of Examples and Comparative Examples having a compounding amount shown in Table 4 were prepared. Specifically, diphenylmethane diisocyanate is reacted with a predetermined amine in base oil, and diluted with base oil so as to have a working penetration (test method JIS K2220 7.) of 240 to 280, and an additive is added thereto. Thus, the grease compositions of Examples and Comparative Examples were prepared. And the kinematic viscosity of base oil in 40 degreeC was measured based on JISK2220 23 ..

[Table 1]

Synthetic hydrocarbon oil A: poly-α-olefin having a kinematic viscosity of 40 ° C at 70.2 mm ² / s and a pour point of -55 ° C

Synthetic hydrocarbon oil B: Poly-α-olefin having a kinematic viscosity of 40 ° C. at 395 mm ² / s and a pour point of -35 ° C.

Mineral oil C: Fixed mineral oil having a kinematic viscosity of 40 ° C. at 91.0 mm ² / s and a pour point of -35 ° C.

Mineral oil C: Fixed mineral oil having a kinematic viscosity of 40 ° C. at 96.6 mm ² / s and a pour point of -15 ° C.

[Table 2]

[Table 3]

<Test method>

1. Low torque

Low torque performance was performed based on the low temperature torque test prescribed by JIS K2220 18.

Bearing Model ： 6204

Test temperature: 25 degrees Celsius and -30 degrees Celsius

Revolution number: 1 rpm

Measurement item: Rotational torque (average torque in the last 15 seconds of rotation ten minutes)

Evaluation standard

Rotary torque (25 degrees Celsius) less than 40mNm: Pass (○)

More than 40mNm: Fail (×)

Rotary torque (-30 degrees Celsius) less than 200mNm: Pass (○)

200 mNm or more: fail (×)

2. Antirust

The rust prevention property was performed based on the bearing rust prevention test prescribed | regulated to ASTMD1743-73.

Bearing type: HR32304J

Test conditions: 52 degrees Celsius, 48h, 0.1% brine

Measurement item: Check the rust occurrence status

＃ 1 ...

＃ 2 ... 3 shops or less

＃ 3 ... worse than ＃ 2

Evaluation criteria bearing antirust

＃ 1: Passed (○)

# 2 and # 3: Failed (×)

3. Comprehensive Evaluation

* Passes both rotation torque (25 ° C), rotation torque (-30 ° C) and bearing rust prevention: Passed (○)

Any of the rotational torque (25 ° C), rotational torque (-30 ° C) and bearing rust prevented: Failed (x)

[Table 4]

As for Examples 1-6, all had low torque property and antirust property within the acceptance criteria.

On the other hand, the comparative example 1 whose synthetic hydrocarbon oil is 30 mass% or less failed the low torque property. In addition, Comparative Examples 2 and 3 containing mineral oil other than a fixed mineral oil also failed the low torque property. In Comparative Examples 4 and 5 in which the content rate of the alkyl group was 30% or less, the low torque property was rejected.

The rust preventive property was unsuccessful in Comparative Example 6 in which sorbitan trioleate was added instead of alkenylsuccinic anhydride or organic zinc sulfonate as a rust preventive agent.

From the above result, it turns out that the grease composition of this invention is excellent in both low-torque property and antirust property.

Claims (6)

(A) a blend oil of a synthetic hydrocarbon oil and a fixed mineral oil having a pour point of -35 ° C or less, a base oil having a mass ratio of 100: 0 to 30:70,
(B) Thickener represented by following formula (1), and
R ¹ -NHCONH-R ² -NHCONH-R ³ (1)
(In said formula (1), R <^2> represents a C6-C15 bivalent aromatic hydrocarbon group,
R <^1> and R <^3> is the same or different group, and represents a cyclohexyl group or a C8-18 linear or branched alkyl group,
[{(Moles of alkyl group) / (moles of alkyl group + moles of cyclohexyl group)} × 100] = 30 to 100%)
(C) alkenylsuccinic anhydride and / or organic zinc sulfonate
A grease composition comprising a. The method of claim 1,
The grease composition whose kinematic viscosity in 40 degreeC of the said base oil is 80-150 mm <^2> / s. The method according to claim 1 or 2,
The grease composition in which the said synthetic hydrocarbon oil contains synthetic hydrocarbon oil whose kinematic viscosity in 40 degreeC is 300 mm <^2> / s or more. 4. The method according to any one of claims 1 to 3,
The grease composition whose content of the thickener in a grease composition is 10-20 mass%. 5. The method according to any one of claims 1 to 4,
Grease composition for rolling bearings. The method of claim 5,
A grease composition, wherein the rolling bearing is a rolling bearing for automotive electrical or automotive accessories.