JP2005213330A - Grease composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition which has excellent lubricity, silencing effect, operability at low temperature, and load resistant performance. <P>SOLUTION: This grease composition comprising a thickening agent and a base oil is characterized by containing (a) a hydrocarbon-based polymer, (b) an organic molybdenum compound, and (c) zinc dithiophosphate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a grease composition.

In the mechanical parts of automobiles and various mechanical parts such as optical equipment, precision equipment, etc., the lubricant, especially base oil, is used for the purpose of reducing the sliding resistance of the sliding part and reducing the operating noise. Grease made by adding a thickener to a semi-solid is used (for example, Patent Documents 1 and 2).
Conventionally, the lubricant is properly used depending on the application site. For example, greases having different characteristics have been used in a sliding part where the surface pressure is high and a part (such as a spring) that generates an operating noise.
As a result, grease that has been used properly mixes when used, resulting in performance degradation, a malfunction that occurs when another grease is accidentally applied during manufacturing, and the use of different greases complicates manufacturing equipment and increases costs. There was a problem.
In recent years, with the miniaturization of products, it has become increasingly difficult to properly use two or more types of grease, and the characteristics required of lubricants have become increasingly stringent, such as lower noise of parts and reduced operating torque at low temperatures. It has become to.

JP-A-7-173383 JP2003-3186

  An object of the present invention is to provide a grease composition, and in particular, to provide a grease composition having excellent lubricity, noise reduction effect, low temperature operability, and load bearing performance.

The present invention provides the following grease composition.
1. In a grease composition containing a thickener and a base oil,
(A) a hydrocarbon polymer;
A grease composition containing (b) an organic molybdenum compound, and (c) zinc dithiophosphate.
2. ^2. The grease composition according to claim 1, wherein the mixture of the base oil and (a) the hydrocarbon polymer has a kinematic viscosity at 40 ° C. of 200 mm ² / s or more.
3. The grease composition according to claim 1 or 2, wherein the thickener is lithium soap.
4). The grease composition according to any one of claims 1 to 3, comprising at least one compound selected from the group consisting of a fatty acid containing a hydroxyl group and a fatty acid ester containing a hydroxyl group.
5). In the whole composition, the content of the thickener is 3 to 15% by mass, the content of the polyisobutylene compound is 5 to 25% by mass, the content of the organic molybdenum compound is 1 to 10% by mass, the content of zinc dialkyldithiophosphate The door lock grease according to claim 1, wherein the content of at least one compound selected from the group consisting of 1 to 10 mass%, a fatty acid containing a hydroxyl group and a fatty acid ester containing a hydroxyl group is 1 to 10 mass%. Composition.

  The grease composition of the present invention is excellent in lubricity, noise reduction effect, low temperature operability, and load bearing performance. Therefore, galvanized steel plate sliding parts for household electrical products such as VTR, CD, DVD, digital camera, etc., galvanized steel plate sliding parts for car electrical components such as car navigation systems, seat slides, window regulators, door hinges and door locks. It is preferably used for reducing the friction at the sliding portion and exerting a silencing effect.

Base oils used in the grease composition of the present invention include ester synthetic oils such as carbonate compounds and polyol ester oils, ether synthetic oils such as alkyldiphenyl ethers, synthetic hydrocarbon oils such as polyalpha-olefins, and paraffinic oils. Although mineral oils, such as mineral oil, are mentioned, a synthetic hydrocarbon oil is preferable.
Synthetic hydrocarbon oils have a molecular structure consisting of carbon and hydrogen. Examples thereof include polyolefins such as PAO (poly α-olefin), polybutene, and polyethylene, and copolymers of α-olefin and ethylene. By using a synthetic hydrocarbon oil as the base oil, stress cracking does not occur even when the grease composition is applied to resin parts. The base oil used in the present invention preferably has a kinematic viscosity at 40 ° C. of 17 to 48 mm ² / s.

The thickener used in the grease composition of the present invention has a thickening action to make the above base oil semi-solid or solid, for example, lithium soap such as lithium hydroxystearate and lithium stearate, Examples include calcium soap, sodium soap and barium soap. These can be used alone or in combination of two or more. In particular, it is preferable to use lithium soap such as lithium hydroxystearate or lithium stearate.
The content of the thickener is preferably 1 to 20 mass%, more preferably 3 to 10 mass%, based on the entire grease composition.

Examples of the hydrocarbon polymer used in the grease composition of the present invention include olefin copolymers such as polybutene, polypropylene, polyisobutylene, and ethylene-propylene copolymer. The average molecular weight of the hydrocarbon-based polymer is preferably from several hundred to 100,000, and more preferably from 10,000 to 100,000. This is because a polymer having a large molecular weight can increase the kinematic viscosity of the base oil with a small amount of addition.
The content of the hydrocarbon-based polymer is preferably 5 to 40% by mass and more preferably 10 to 25% by mass with respect to the entire grease composition.

Examples of the organic molybdenum compound used in the grease composition of the present invention include molybdenum dialkyldithiocarbamate molybdenum (MoDTC) and molybdenum dithiophosphate (MoDTP). These can use 1 type (s) or 2 or more types.
Zinc dithiophosphate (ZnDTP) is a compound represented by the following formula, wherein R is an alkyl group having 1 to 24 carbon atoms or an aryl group having 6 to 30 carbon atoms.
_{(RO) 2 PS-S-} Zn-S-PS (OR) 2
The content of the organomolybdenum compound is preferably 1 to 10% by mass, more preferably 5 to 10% by mass, based on the entire grease composition.

Examples of the fatty acid containing a hydroxyl group used in the grease composition of the present invention include those having at least one carboxyl group and at least one hydroxyl group in the molecule, for example, those represented by the following general formula.
(HO) nR (COOH) m
R in the formula is a saturated or unsaturated aliphatic hydrocarbon group having 1 to 17 carbon atoms, n is 1 or 2, and m is 1, 2 or 3. Specific examples include glycolic acid, lactic acid, hydroacrylic acid, α-oxyacid, glyceric acid, tartronic acid, malic acid, tartaric acid, citric acid, ricinoleic acid, and 12-hydroxystearic acid.
Preferable examples of the fatty acid ester containing a hydroxyl group include ester compounds of ricinoleic acid or 12-hydroxystearic acid and an alcohol (preferably a monovalent or polyvalent aliphatic alcohol having 1 to 20 carbon atoms). Specific examples include refined castor oil (ricinoleic acid triglyceride), methyl ricinolate, ethyl ricinolate, butyl ricinolate, ethylene glycol monoricinolate, propylene glycol monoricinolate, trimethylolpropane monoricinolate, pentaerythritol monoricino. Examples include rate, sorbitan monoricinoleate, glyceryl monoricinoleate, methyl 12-hydroxystearate, and butyl 12-hydroxystearate. Particularly preferred is refined castor oil.
The content of the fatty acid containing a hydroxyl group and / or the fatty acid ester containing a hydroxyl group is preferably 1 to 10% by mass, more preferably 3 to 8% by mass, based on the entire grease composition.
In addition to the above additives, additives such as an antioxidant and a rust inhibitor may be added to the grease composition of the present invention.

<Example>
A base grease using a synthetic hydrocarbon oil having a kinematic viscosity at 40 ° C. of 30 mm ² / s as a base oil and a lithium hydroxy stearate as a thickener was prepared, and a grease composition containing the following additives was prepared. The characteristics were evaluated by the following methods. The results are shown in Table 1.
Additive (a) Hydrocarbon polymer (polyisobutylene)
(B) Organic molybdenum compound (molybdenum dialkyldithiocarbamate)
(C) Zinc dialkyl dithiophosphate (d) Fatty acid containing hydroxyl group and fatty acid ester containing hydroxyl group (refined castor oil)

1. Noise reduction The attenuation rate was measured as part of the noise reduction evaluation to confirm the effect.
Test method: Ball drop method Grease is applied to a steel plate 100 × 100 × 1 mm (100 × 50 × 0.5 mm), a steel ball (φ10 mm) is dropped from a height of 70 mm, and the vibration of the steel plate is picked up by a pick-up sensor. Utilize and measure. The attenuation rate (%) is obtained by the following formula.
Attenuation rate (%) = 100 × (A−B) / B
A = Sound pressure level at the time of grease application B = Sound pressure level of steel plate only The evaluation criteria for muffling are as follows.
○: Attenuation rate of 80% or more
Δ: Attenuation rate 30% to less than 80% ×: Attenuation rate 30%

2. Lubrication characteristics A friction and wear tester was used to evaluate the measured friction coefficient.
conditions:
Number of actuations: 10,000 times Vertical load: 1 kg
Sliding speed: 500mm / s
Sliding width: 10mm
The evaluation criteria for the lubrication characteristics are as follows.
○: Friction coefficient less than 0.15 △: Friction coefficient 0.15 to less than 0.20 ×: Friction coefficient 0.2 or more

3. Low temperature operability Test method: Measured according to JIS K 222018.
Test temperature: -40 ° C
Evaluation items: Evaluation criteria for starting torque low temperature operability are as follows.
○: Starting torque at -40 ° C less than 50 N · cm ×: Starting torque at -40 ° C 50 N · cm or more
-: Not evaluated 4. Kinematic viscosity Measuring method: Measured according to JIS K 222023.
5). Mixing penetration Measuring method: Measured according to JIS K 2220 7.

The grease composition of Examples 1 to 3, which contains component (a) a hydrocarbon polymer, (b) an organomolybdenum compound, and (c) zinc dithiophosphate, and component (d) a fatty acid containing a hydroxyl group and The grease composition of Example 4 containing at least one compound selected from the group consisting of a fatty acid ester containing a hydroxyl group is excellent in silencing properties, lubricating properties, and low-temperature operability.
In contrast, the grease composition of Comparative Example 1 that does not contain components (a), (b), (c), and (d), contains a small amount of component (a), but components (b), (c), and The grease composition of Comparative Example 2 that does not contain (d) and the grease composition of Comparative Example 3 that does not contain component (a) are excellent in low-temperature operability, but have poor sound deadening properties.
In addition, the grease composition of Comparative Example 4, which contains component (a) but does not contain components (b), (c), and (d), contains components (a), (c), and (d). The grease composition of Comparative Example 5 that does not contain (b) and the components (a), (b), and (d), but the grease composition of Comparative Example 6 that does not contain the component (c) is excellent in noise reduction. However, the lubrication characteristics and low temperature operability are inferior.

Claims (5)

In a grease composition containing a thickener and a base oil,
(A) a hydrocarbon polymer;
A grease composition containing (b) an organic molybdenum compound, and (c) zinc dithiophosphate. ^2. The grease composition according to claim 1, wherein the mixture of the base oil and (a) the hydrocarbon polymer has a kinematic viscosity at 40 ° C. of 200 mm ² / s or more.   The grease composition according to claim 1 or 2, wherein the thickener is lithium soap.   The grease composition according to any one of claims 1 to 3, comprising at least one compound selected from the group consisting of a fatty acid containing a hydroxyl group and a fatty acid ester containing a hydroxyl group.   In the whole composition, the content of the thickener is 3 to 15% by mass, the content of the polyisobutylene compound is 5 to 25% by mass, the content of the organic molybdenum compound is 1 to 10% by mass, and the content of zinc dialkyldithiophosphate The door lock grease according to claim 1, wherein the content of at least one compound selected from the group consisting of 1 to 10% by mass, a fatty acid containing a hydroxyl group and a fatty acid ester containing a hydroxyl group is 1 to 10% by mass. Composition.