WO2012053575A1

WO2012053575A1 - Grease composition

Info

Publication number: WO2012053575A1
Application number: PCT/JP2011/074109
Authority: WO
Inventors: 今井　裕; 亮相田
Original assignee: 協同油脂株式会社
Priority date: 2010-10-20
Filing date: 2011-10-20
Publication date: 2012-04-26
Also published as: JP2012087221A; KR20130073977A; CN103210070A; EP2631284A4; EP2631284A1; JP5766425B2; EP2631284B1; CN103210070B

Abstract

The invention provides a grease composition containing: (A) a base oil that is a blend oil of a synthetic hydrocarbon oil and a highly purified mineral oil with a pour point of -35°C or less, wherein the mass ratio is 100:0-30:70; (B) a thickening agent represented by formula (1) R¹-NHCONH-R²-NHCONH-R³ (1) (In the formula, R² represents a C_6-15 divalent aromatic hydrocarbon group. R¹ and R³ are the same or different groups and represent cyclohexyl groups or C_8-18 straight or branched alkyl groups, and [{(no. of moles of the alkyl groups)/(no. of moles of the alkyl groups + no. of moles of cyclohexyl groups)}x100] = 30-100%); and (C) an alkenyl succinic anhydride and/or an organic zinc sulfonate. This grease composition has excellent low torque properties and anti-rust properties.

Description

Grease composition

The present invention relates to a grease composition used for automobile electrical equipment or rolling bearings for auxiliary equipment.

As grease used for automobile electrical equipment or rolling bearings for auxiliary machinery, diurea grease is often used mainly from the viewpoint of heat resistance. Among diurea greases, aromatic diurea is often used for high temperature durability.
However, aromatic diurea needs to be blended in a large amount in order to obtain grease having the same hardness as compared with diurea compounds other than aromatic diurea. As a result, the agitation resistance of the grease becomes high and the low torque property cannot be satisfied.
As an example using a thickener other than aromatic diurea, in Patent Document 1, a base oil containing an ether-based synthetic oil in an amount exceeding 50% by mass is represented by the following general formula:
R ² —NHCONH—R ¹ —NHCONH—R ³
(In the formula, R ¹ represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, R ² and R ³ are the same or different groups, and are a cyclohexyl group or a cyclohexyl derivative group having 7 to 12 carbon atoms. Or an alkyl group having 8 to 20 carbon atoms.)
And the content of cyclohexyl group or its derivative group [{(number of cyclohexyl group or its derivative group) / (number of cyclohexyl group or its derivative group + number of alkyl groups)] } × 100] has been proposed that contains a gelling agent having a content of 50 to 100%.
However, the pour point of phenyl ether oil, which is a base oil, is about −30 ° C., and the low temperature property is never satisfied, and therefore the torque at low temperature is high.
As another example using a thickener other than aromatic diurea, in Patent Document 2, a basic oil containing an ester-based synthetic oil is represented by the following general formula:
R ¹ —NHCONH—R ² —NHCONH—R ³
(In the formula, R ² represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms. R ¹ and R ³ are the same or different groups, and are a cyclohexyl group or a group having 8 to 22 carbon atoms. Represents an alkyl group, and the content of cyclohexyl group [{(number of cyclohexyl groups) / (number of cyclohexyl groups + number of alkyl groups)} × 100] is 60 to 95%) There has been proposed a grease composition characterized by containing a thickening agent represented.
However, ester-based synthetic oils are not preferable in that they are hydrolyzed when moisture is mixed in from the outside, and there is concern about the formation of rust by the generated acid component.

JP-A-6-17079 JP 2008-239706 A

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

As described above, in order to ensure low torque, it is necessary to reduce the amount of thickener, which is the main factor of grease stirring resistance, as much as possible, but if it is reduced too much, the desired hardness can be obtained. In addition, there is a problem that leakage changes from the bearing to the outside because the grease has a large change in consistency when it is subjected to shearing.
In the present invention, low torque at low temperatures is secured by including 30% by mass or more of the synthetic hydrocarbon oil having a low pour point in the base oil. When other base oils other than synthetic hydrocarbon oils were used in combination, highly refined mineral oil having a low pour point was used.
As the thickener, by using aliphatic diurea alone or in combination with aliphatic diurea and alicyclic diurea, a grease composition having an appropriate hardness even if the amount of the thickener is small. did.
Thus, the present inventors solved the said subject by selecting and combining a specific base oil, a thickener, and a rust inhibitor. That is, according to the present invention, the following grease composition is provided.

1. (A) a base oil having a blend ratio of a synthetic hydrocarbon oil and a highly refined mineral oil having a pour point of −35 ° C. or less and 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 the formula, R ² represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.
R ¹ and R ³ are the same or different groups and represent a cyclohexyl group or a linear or branched alkyl group having 8 to 18 carbon atoms,
[{(Number of moles of the alkyl group) / (number of moles of the alkyl group + number of moles of cyclohexyl group)} × 100] = 30 to 100%)
(C) an alkenyl succinic anhydride and / or an organic zinc sulfonate,
A grease composition comprising:
2. ^2. The grease composition as described in 1 above, wherein the base oil has a kinematic viscosity at 40 ° C. of 80 to 150 mm ² / s.
3. 3. The grease composition according to 1 or 2 above, 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). 4. The grease composition as described in any one of 1 to 3 above, wherein the content of the thickener in the grease composition is 10 to 20% by mass.
5. 5. The grease composition according to any one of the above 1 to 4, which is used for a rolling bearing.
6). 6. The grease composition as described in 5 above, wherein the rolling bearing is a rolling bearing for automobile electrical equipment or auxiliary equipment.

Since the grease composition of the present invention is excellent in low torque property in a wide temperature range, it can contribute to CO ₂ reduction by improving fuel efficiency. The grease composition of the present invention is also excellent in rust prevention. 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 highly refined mineral oil having a pour point of -35 ° C or lower. The mass ratio of the synthetic hydrocarbon oil to the highly refined mineral oil having a pour point of −35 ° C. or lower is 100: 0 to 30:70. When the ratio of the synthetic hydrocarbon oil in the base oil is 30% by mass or more, low torque at low temperatures can be satisfied.
Examples of the synthetic hydrocarbon oil include poly-α-olefin, polybutene, and ethylene-α-olefin oligomer. Of these, poly-α-olefins are preferred.
The highly refined mineral oil used in the present invention reduces the precipitation of wax components at a low temperature by dewaxing treatment, whereby the pour point is higher than the pour point (−5 ° C. to −20 ° C.) of the unrefined mineral oil. Mineral oil with low By including a highly refined mineral oil having a pour point of −35 ° C. or lower, it can be used without adversely affecting low torque at low temperatures. Also, the evaporation resistance can be used without any problem.
The kinematic viscosity of the base oil at 40 ° C. is preferably 80 to 150 mm ² / s. More preferably, it is 85 to 140 mm ² / s, and still more preferably 90 to 130 mm ² / s. When the kinematic viscosity of the base oil at 40 ° C. is higher than 150 mm ² / s, the viscosity of the grease increases and the low torque property cannot be satisfied. On the other hand, if the kinematic viscosity of the base oil at 40 ° C. is lower than 80 mm ² / s, the low torque property is satisfied, but the evaporation resistance is inferior.

The synthetic hydrocarbon oil preferably contains a kinematic viscosity at 40 ° C. of 300 mm ² / s or more. As a result, the base oil kinematic viscosity can be set within a predetermined range without sacrificing evaporation resistance while satisfying low torque characteristics at low temperatures.
The highly refined mineral oil preferably contains a kinematic viscosity at 40 ° C. of 80 to 130 mm ² / s, more preferably 80 to 110. Thereby, low torque characteristics can be satisfied. Evaporation resistance is also improved.
The pour point of the synthetic hydrocarbon oil is preferably −35 ° C. or lower. As a result, low torque characteristics at low temperatures can be satisfied.
Other base oils that can be used in combination with synthetic hydrocarbon oils include diester oils, ester-based synthetic oils typified by polyol esters, ether-based synthetic oils typified by alkyl diphenyl ether, and polyglycol-based synthetic oils typified by polypropylene glycol. , Silicone-based synthetic oil, and fluorine-based synthetic oil. However, as described above, the ester-based synthetic oil is not preferable in terms of concern about hydrolysis when moisture is mixed from the outside. Ether-based synthetic oils have a high pour point of about −30 ° C. and a high torque at low temperatures. Polyglycol-based synthetic oil, silicone-based synthetic oil, and fluorine-based synthetic oil are poor in lubricity and expensive.

(B) Thickeners Thickeners generally used in grease compositions include metal soaps including Li and Na, benton, silica gel, diurea compounds, fluorine-based thickeners typified by polytetrafluoroethylene, etc. Non-soaps. However, metal soaps do not satisfy the heat resistance, that is, the bearing lubrication life under high temperature, Benton and silica gel are inferior in water resistance, and fluorinated thickeners satisfy the heat resistance but are very expensive. And lacks versatility.
Accordingly, the grease composition of the present invention uses a thickener represented by the above formula (1).
The content of the alkyl group in the formula (1), that is, {(number of moles of alkyl group) / (number of moles of alkyl group + number of moles of cyclohexyl group)} × 100 is 30 to 100%, If the content is less than 30%, the amount of the thickener increases and the low torque property is inferior.
The amount of the thickener (B) in the grease composition of the present invention is preferably 10 to 20% by mass, more preferably 12 to 17% by mass, from the viewpoint of low torque.

(C) Rust inhibitor The grease composition of the present invention contains zinc organic sulfonate and / or alkenyl succinic anhydride as a rust inhibitor. These rust inhibitors have the 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 sulfonic acids include aromatic hydrocarbon components in lubricating oil fractions, petroleum sulfonic acids obtained by sulfonation of petroleum high-boiling fractions, synthetic sulfonic acids such as dinonylnaphthalene sulfonic acid and heavy alkylbenzene sulfonic acid, and the like. is there.
An organic zinc sulfonate represented by the following general formula (2) is preferred.
[R ⁴ —SO ₃ ] ² Zn (2)
(In the formula, R ⁴ represents an alkyl group, an alkenyl group, an alkyl naphthyl group, a dialkyl naphthyl group, an alkylphenyl group, and a petroleum high-boiling fraction residue. The alkyl or alkenyl is linear or branched and has a carbon number. Is 2-22.)
Specific examples include zinc dioctyl naphthalene sulfonate, zinc dinonyl naphthalene sulfonate, zinc didecyl naphthalene sulfonate, zinc petroleum sulfonate, and high basic zinc alkylbenzene sulfonate. Of these, zinc dinonylnaphthalenesulfonate is most preferred.
As the alkenyl succinic anhydride, an alkenyl succinic anhydride having an alkenyl group having 6 to 18 carbon atoms can be suitably used. In particular, an alkenyl succinic anhydride having an alkenyl group having 10 to 15 carbon atoms is preferred.
The amount of the (C) rust inhibitor in the grease composition of the present invention is preferably 0.1 to 3% by mass, more preferably 0.5 to 2% from the viewpoint of securing rust preventive properties in an environment where salt water can be mixed. % By mass.

The grease composition of the present invention may contain additives that are usually used in grease compositions as necessary. Examples include antioxidants typified by amines and phenols, inorganic passivating agents such as sodium nitrite, rust inhibitors typified by amines and carboxylates, and metal corrosion inhibitors typified by benzotriazoles. , Fatty agents represented by fatty acids, fatty acid esters and phosphate esters, antiwear agents and extreme pressure agents represented by phosphorus, sulfur and organometallics, solid lubricants represented by metal oxide salts and molybdenum disulfide Agents and the like.
The grease composition of the present invention can be used as a rolling bearing, particularly as a rolling bearing for automobile electrical equipment or auxiliary equipment. Examples of rolling bearings for automobile electrical equipment or auxiliary equipment include bearings used in electromagnetic clutches for car air conditioners, intermediate pulleys, idler pulleys, tension pulleys, alternators, water pumps, and the like. In particular, when used at high temperatures, the grease composition is subject to oxidative degradation. Therefore, it is desirable to use an antioxidant in combination rather than using an amine or phenolic alone.

<Test grease>
Using the (A) base oil shown in Table 1, the (B) thickener shown in Table 2, and the (C) rust inhibitor shown in Table 3, the amounts of Examples and Comparative Examples shown in Table 4 were used. A grease composition was prepared. Specifically, diphenylmethane diisocyanate and a predetermined amine are reacted in the base oil, diluted with the base oil so that the penetration (test method JIS K2220 7.) is 240 to 280, and the additive is added thereto. The grease compositions of Examples and Comparative Examples were prepared by adding The kinematic viscosity of the base oil at 40 ° C. is JIS K2220 23. Measured according to

<Test method>
1. Low torque property JIS K2220 18. The test was conducted in accordance with the low temperature torque test specified in 1.
Bearing type: 6204
Test temperature: 25 ° C and -30 ° C
Rotation speed: 1rpm
Measurement item: Rotational torque (average torque in the last 15 seconds of 10 minutes of rotation)

Evaluation criteria Rotational torque (25 ° C) Less than 40 mNm: Pass (○)
40 mNm or more: Fail (×)
Rotational torque (-30 ℃) Less than 200mNm: Pass (○)
200 mNm or more: Fail (×)

2. Rust prevention The rust prevention was performed in accordance with a bearing rust prevention test specified in ASTM D1743-73.
Bearing type: HR32304J
Test conditions: 52 ° C, 48h, 0.1% salt water Measurement item: Confirmation of rust occurrence # 1 ... No rust # 2 ... Within 3 points of rust # 3 ... Worse than # 2

Evaluation criteria Bearing rust prevention # 1: Pass (○)
# 2 and # 3: Fail (×)

3. Comprehensive evaluation / Rotation torque (25 ° C), Rotation torque (-30 ° C), Bearing anticorrosion pass: Pass (○)
・ Even one of rotational torque (25 ° C), rotational torque (-30 ° C), and bearing rust is rejected: Fail (×)

In each of Examples 1 to 6, the low torque property and the rust prevention property were within the acceptance standards.
On the other hand, Comparative Example 1 in which the synthetic hydrocarbon oil was 30% by mass or less failed in the low torque property. Further, Comparative Examples 2 and 3 containing mineral oil which is not highly refined mineral oil also failed in low torque property. In Comparative Examples 4 and 5 in which the alkyl group content was 30% or less, the low torque property was unacceptable.
As a rust inhibitor, Comparative Example 6 in which sorbitan trioleate was added instead of alkenyl succinic anhydride or organic zinc sulfonate, and Comparative Example 7 in which sorbitan trioleate was not added failed in rust preventive properties.
From the above results, it can be seen that the grease composition of the present invention is excellent in both low torque property and rust prevention property.

Claims

(A) a base oil having a blend ratio of a synthetic hydrocarbon oil and a highly refined mineral oil having a pour point of −35 ° C. or less and 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 the formula, R 2 represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.
R 1 and R 3 are the same or different groups and represent a cyclohexyl group or a linear or branched alkyl group having 8 to 18 carbon atoms,
[{(Number of moles of the alkyl group) / (number of moles of the alkyl group + number of moles of cyclohexyl group)} × 100] = 30 to 100%)
(C) an alkenyl succinic anhydride and / or an organic zinc sulfonate,
A grease composition comprising:
The grease composition according to claim 1, wherein the base oil has a kinematic viscosity at 40 ° C of 80 to 150 mm 2 / s.
The grease composition according to claim 1 or 2, wherein the synthetic hydrocarbon oil comprises a synthetic hydrocarbon oil having a kinematic viscosity at 40 ° C of 300 mm 2 / s or more.
The grease composition according to any one of claims 1 to 3, wherein the content of the thickener in the grease composition is 10 to 20% by mass.
The grease composition according to any one of claims 1 to 4, which is used for a rolling bearing.
The grease composition according to claim 5, wherein the rolling bearing is a rolling bearing for automobile electrical equipment or auxiliary equipment.