JP7104576B2 - Lubricating oil composition - Google Patents

Description

The present invention relates to a lubricating oil composition.

A door closer is a device that is generally attached to the top of a door and works to automatically close an opened door. At that time, the door closer also has a function of slowing the closing operation so that the door does not close suddenly. The door closer also works to prevent the door from opening due to wind or the like. When closing the door, the door closer allows you to set the speed in several steps, such as the speed at which the door moves when it is wide open and the speed at which it moves just before the door closes. Specifically, the door closer performs a quick closing operation with a fast movement while the door is closing, and slowly closes from a position where there is a danger of pinching a finger just before the door is completely closed, which is safe. And close it quietly.

In the door closer, lubricating oil (oil for the door closer) is sealed inside the door closer in order to smoothly open and close the door. Various additives are added to the base oil (base oil) for the lubricating oil (oil for door closer).
For example, a hydraulic fluid for a door closer in which a viscosity index improver is blended with a base oil is disclosed (see Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2007-091768 JP-A-2007-106878

In order for the door closer to open and close the door smoothly, the lubricating oil must (1) have an appropriate viscosity, (2) be exposed to the outside air, so there is little change in viscosity due to differences in temperature, and (3). ) It is required to have good low-temperature fluidity even in extremely cold regions, etc., and (4) good defoaming property because abnormal noise will be generated when opening and closing the door if bubbles are mixed. ..
However, conventional lubricating oils as described in Patent Documents 1 and 2 are insufficient for such requirements, and there is still a problem in terms of defoaming property.

The present invention has been made in view of the above circumstances, and is a lubricating oil having an appropriate viscosity, little change in viscosity due to a difference in temperature, good low-temperature fluidity, and improved defoaming performance. An object of the present invention is to provide a composition.

Aspect of the present invention is a lubricating oil composition containing a base oil and a defoaming agent (AF), wherein the defoaming agent (AF) is a dimethyl silicone defoaming agent (af1) and a weight average molecular weight ( A lubricating oil having Mw) of 25,000 or more selected from the group consisting of 25,000 or more defoaming agents (af2) (excluding those corresponding to the dimethyl silicone defoaming agent (af1)). It is a composition.

In the lubricating oil composition according to the aspect of the present invention, the defoaming agent (AF) preferably contains the dimethyl silicone defoaming agent (af1).
The content of the dimethyl silicone defoaming agent (af1) is preferably 0.0001 to 0.1% by mass.

In the lubricating oil composition according to the aspect of the present invention, the defoaming agent (AF) preferably contains the dimethyl silicone defoaming agent (af1) and the defoaming agent (af2).
The content of the defoaming agent (af2) is preferably 0.0001 to 0.1% by mass.

The lubricating oil composition according to the aspect of the present invention preferably further contains polymethacrylate as a viscosity index improver.
The lubricating oil composition according to the aspect of the present invention is suitable as an oil for a door closer.

According to the present invention, it is possible to provide a lubricating oil composition having an appropriate viscosity, little change in viscosity due to a difference in temperature, good low temperature fluidity, and improved defoaming performance.

(Lubricating oil composition)
The lubricating oil composition of the present embodiment contains at least a base oil and a defoaming agent, and may contain other components if necessary. The lubricating oil composition is characterized by an antifoaming agent, and various known lubricating oil compositions can be applied to other configurations.

<Base oil>
Examples of the base oil in the present embodiment include mineral oils, synthetic oils, and oils containing a mixture thereof. Among the base oils, mineral oil is preferable.
As mineral oil, the distillate obtained by atmospheric distillation or vacuum distillation of crude oil is subjected to solvent desorption, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, acid cleaning, and white clay. Examples thereof include paraffin-based mineral oils and naphthen-based mineral oils obtained by appropriately combining one or more types of refining means such as treatment, and among these, paraffin-based mineral oils are more preferable.

As the base oil in this embodiment, any of groups I to IV in the classification of base oils by the American Petroleum Institute (API) can be used, and two or more of these may be appropriately mixed and used. May be good.

The kinematic viscosity of the base oil in the present embodiment is preferably 3 to 30 mm ² / s and particularly preferably 6 to 15 mm ² / s at 40 ° C.
If the kinematic viscosity of the base oil is less than the lower limit of the above-mentioned preferable range, the time for the hydraulic oil to pass through the orifice is likely to be shortened, and the door may be closed rapidly, for example, in a door closer application. On the other hand, when it is not more than the upper limit value of the above-mentioned preferable range, the fluidity of the lubricating oil composition is properly ensured, and the door can be easily opened and closed.

In the present invention, "kinematic viscosity" can be measured by a method according to JIS K 2283 (2000).

The viscosity index of the base oil in this embodiment is preferably 95 to 150, more preferably 100 to 140.
When the viscosity index of the base oil is at least the lower limit of the above-mentioned preferable range, the change in viscosity due to temperature is easily suppressed, while when it is at least the upper limit of the above-mentioned preferable range, the fluidity at a low temperature is maintained. It will be easier to secure.

In the present invention, the "viscosity index" can be measured by a method according to JIS K 2283 (2000).

The pour point of the base oil in the present embodiment is preferably 0 ° C. or lower, more preferably −10 ° C. or lower.
When the pour point of the base oil is equal to or less than the upper limit of the above-mentioned preferable range, the fluidity at a low temperature can be easily ensured.

In the present invention, the "pour point" can be measured by a method according to JIS K 2269 (1987).

The content of the base oil in the lubricating oil composition is preferably 70% by mass or more, more preferably 70 to 90% by mass, based on the total amount (100% by mass) of the lubricating oil composition.

<Defoamer (AF)>
The defoaming agent (AF) in the present embodiment includes a dimethyl silicone defoaming agent (af1) and a defoaming agent (af2) having a weight average molecular weight (Mw) of 25,000 or more (however, the dimethyl silicone defoaming agent (af1). ), Which includes two or more selected from the group consisting of).

≪Defoamer (af1) ≫
The dimethyl silicone defoaming agent (af1) (hereinafter, also simply referred to as "defoaming agent (af1)") refers to a defoaming agent made of dimethyl silicone.
As the defoaming agent (af1), dimethylpolysiloxane (dimethicone) represented by the following chemical formula (af1-1) is used. In the formula, n indicates the number of repetitions of the structural unit [-(CH ₃ ) ₂ SiO-].

The weight average molecular weight (Mw) of the defoaming agent (af1) is preferably 30,000 to 50,000, more preferably 35,000 to 45,000.
When the Mw of the defoaming agent (af1) is at least the lower limit of the above-mentioned preferable range, a sufficient defoaming effect is likely to be exhibited. On the other hand, when it is not more than the upper limit value of the above preferable range, the solubility is improved.

In the present invention, "weight average molecular weight (Mw)" can be measured by gel permeation chromatography (GPC) in terms of polystyrene.

In the lubricating oil composition of the present embodiment, only one type of defoaming agent (af1) may be used, or two or more types may be used in combination.
The content of the defoaming agent (af1) in the lubricating oil composition is preferably 0.0001 to 0.1% by mass with respect to the total amount (100% by mass) of the lubricating oil composition. More preferably, it is 001 to 0.01% by mass.

≪Defoamer (af2) ≫
The defoaming agent (af2) is a defoaming agent having a weight average molecular weight (Mw) of 25,000 or more.
The weight average molecular weight (Mw) of the defoaming agent (af2) is 25,000 or more, preferably 25,000 to 35,000.
When the Mw of the defoaming agent (af2) is at least the lower limit of the above range, the defoaming effect is more likely to be enhanced.

As the defoaming agent (af2), those exhibiting a defoaming effect having an Mw of 25,000 or more, excluding those corresponding to the defoaming agent (af1), can be used.
In the lubricating oil composition of the present embodiment, the silicone compound is preferable among the defoaming agents (af2) because the interaction with the defoaming agent (af1) is high. Among these, a silicone compound containing a fluorine atom (that is, fluorosilicone) is more preferable because the defoaming effect on the high temperature side is likely to be enhanced.

Preferred antifoaming agents (af2) include, for example, fluorosilicone represented by the following chemical formula (af2-1). In the formula, m ₁ indicates the number of repetitions of the structural unit [-(CH ₃ ) ₂ SiO-]. m ₂ indicates the number of repetitions of the structural unit [-(CH ₃ ) (Rf) SiO-]. The Rf represents an alkyl fluorinated group, preferably an alkyl fluorinated group having 1 to 5 carbon atoms.

Fluorosilicone suitable as an antifoaming agent (af2) can be blended with, for example, the product names "Shin-Etsu Silicone FA-600" and "Shin-Etsu Silicone FA-630" manufactured by Shin-Etsu Chemical Co., Ltd.

In the lubricating oil composition of the present embodiment, only one type of defoaming agent (af2) may be used, or two or more types may be used in combination.
The content of the defoaming agent (af2) in the lubricating oil composition is preferably 0.0001 to 0.1% by mass with respect to the total amount (100% by mass) of the lubricating oil composition. More preferably, it is 0005 to 0.003% by mass.

In the lubricating oil composition of the present embodiment, the defoaming agent (AF) contains two or more kinds selected from the group consisting of the defoaming agent (af1) and the defoaming agent (af2). Since the defoaming performance is easily improved, it is more preferable to use the defoaming agent (af1) and the defoaming agent (af2) in combination. Among these, it is particularly preferable to have both dimethyl silicone and fluorosilicone as the defoaming agent (AF) because the defoaming performance is likely to be further enhanced.

When the defoamer (af1) and the defoamer (af2) are used in combination, the mass ratio of the defoamer (af1) and the defoamer (af2) is the defoamer (af1) / defoamer (af1). af2) = 1/5 to 5/1 is preferable, and 1/3 to 1/1 is more preferable.
If the mass ratio is within the above-mentioned preferable range, the defoaming effect is further improved, and in particular, the defoaming effect on the high temperature side is likely to be enhanced.

In the lubricating oil composition of the present embodiment, the defoaming agent (AF) includes a defoaming agent other than the defoaming agent (af1) and the defoaming agent (af2) (hereinafter, this is also referred to as "defoaming agent (af3)". ) May be used. However, since the defoaming performance is more likely to be improved, it is preferable to use a defoaming agent (AF) composed of only the defoaming agent (af1) and the defoaming agent (af2).
As the defoaming agent (af3), for example, a compound exhibiting a defoaming effect having an Mw of less than 25,000 (excluding those corresponding to the defoaming agent (af1)) can be used, specifically. Examples thereof include polymethacrylate-based polymers.

<Other ingredients>
Other components that may be contained in the lubricating oil composition of the present embodiment include, for example, a viscosity index improver, an antioxidant, an anticorrosive agent (rust preventive), an extreme pressure agent / anti-wear agent, and a metal-free material. Examples thereof include activators, friction modifiers, flow point lowering agents, metal-based cleaning agents, ashless dispersants, and corrosion inhibitors.

≪Viscosity index improver≫
In the lubricating oil composition of the present embodiment, it is preferable to further contain polymethacrylate as a viscosity index improver in addition to the base oil and the antifoaming agent (AF). By selecting polymethacrylate among the viscosity index improvers, the effect of lowering the pour point can be easily obtained.

Polymethacrylate as a viscosity index improver includes, for example, product names "Acluve 740" and "Sunlube E5070" manufactured by Sanyo Chemical Industries, Ltd .; product names "VISCOPLEX 3-201" manufactured by Ebonic Japan Co., Ltd., and manufactured by Chevron Japan Co., Ltd. Product name "PALATONE 8057" and the like are used.

The weight average molecular weight (Mw) of such polymethacrylate is preferably 200,000 to 600,000, more preferably 2400,000 to 550000, and even more preferably 250,000 to 500,000.
When the Mw of polymethacrylate is at least the lower limit of the above-mentioned preferable range, the change in viscosity due to temperature is likely to be suppressed, while when it is at least the upper limit of the above-mentioned preferable range, the fluidity or solubility is improved. ..

In the lubricating oil composition of the present embodiment, only one type of polymethacrylate as a viscosity index improver may be used, or two or more types may be used in combination. Above all, it is preferable to use two or more kinds of polymethacrylate in combination.
For example, a polymethacrylate having an Mw of 200,000 to 400,000 (hereinafter referred to as "PMA (1)") and a polymethacrylate having an Mw of 400,000 to 600,000 (hereinafter referred to as "PMA (2)") are used in combination. This contributes to high viscosity indexing.
In this case, the mass ratio of PMA (1) to PMA (2) is preferably PMA (1) / PMA (2) = 5/5 to 9/1, more preferably 7/3 to 9/1, and 8 / 2 to 9/1 is particularly preferable.

The content of polymethacrylate in the lubricating oil composition is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and 15 by mass, based on the total amount (100% by mass) of the lubricating oil composition. It is more preferably ~ 25% by mass.

In the lubricating oil composition of the present embodiment described above, two or more specific antifoaming agents are added to the base oil. Such a specific defoaming agent is selected from the group consisting of a dimethyl silicone defoaming agent and a defoaming agent having a weight average molecular weight (Mw) of 25,000 or more, and is defoamed by the synergistic effect of a combination thereof. A lubricating oil composition with higher foam performance is prepared.

In the present embodiment, for example, a lubricating oil composition having a kinematic viscosity at 40 ° C. of 40 to 70 mm ² / s, preferably 45 to 60 mm ² / s is easily prepared.
In the present embodiment, for example, a lubricating oil composition having a kinematic viscosity at 100 ° C. of 10 to 30 mm ² / s, preferably 15 to 25 mm ² / s is easily prepared.
Further, in the present embodiment, for example, a lubricating oil composition having a viscosity index in the range of 300 to 450, preferably in the range of 325 to 425 is easily prepared.
Further, in the present embodiment, for example, a lubricating oil composition having a pour point of −45 ° C. or lower is easily prepared.

The lubricating oil composition of the present embodiment has an appropriate viscosity, has little change in viscosity due to a difference in temperature, has good low-temperature fluidity, and has further enhanced defoaming performance. The lubricating oil composition is useful as a hydraulic fluid.
In addition, according to the lubricating oil composition, the friction of the sliding portion is reduced, and the lubricating oil composition has compatibility with a sealing material such as an O-ring. Such a lubricating oil composition is particularly suitable for an oil for a door closer.

Hereinafter, the effects of the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.
In this example, the kinematic viscosity (40 ° C.), kinematic viscosity (100 ° C.), viscosity index, and pour point of the lubricating oil composition and the hydrocarbon base oil were measured by the methods shown below.
Further, the density (15 ° C.), color (ASTM), flash point, acid value, aniline point, and copper plate corrosion (100 ° C., 3h) of the hydrocarbon base oil were measured by the methods shown below.

[Kinematic viscosity (40 ° C), kinematic viscosity (100 ° C)]
The kinematic viscosities (mm ² / s) of the lubricating oil composition and the hydrocarbon base oil were measured under the respective temperature conditions of 40 ° C. and 100 ° C. using a method conforming to JIS K 2283 (2000).

[Viscosity index]
The viscosity index for the lubricating oil composition and the hydrocarbon base oil was measured according to JIS K 2283 (2000).

[Pour point]
The pour point (° C.) of the lubricating oil composition and the hydrocarbon base oil was measured according to JIS K 2269 (1987).

[Density (15 ° C)]
The density (15 ° C.) (g / cm ³ ) for the hydrocarbon base oil was measured according to JIS K 2249 (1995).

[Color (ASTM)]
The color (ASTM) for the hydrocarbon base oil was measured according to ASTM D1500.

[Flash point]
The flash point (° C.) for the hydrocarbon base oil was measured according to JIS K 2265 (2007).

[Acid value]
The acid value (mgKOH / g) of the hydrocarbon base oil was measured according to JIS K 2501 (2003).

[Aniline point]
The aniline point (° C.) for the hydrocarbon base oil was measured according to JIS K 2256 (2013).

[Copper plate corrosion (100 ° C, 3h)]
Copper plate corrosion (100 ° C., 3 hours) for hydrocarbon base oil was measured according to JIS K 2513 (2000).

The base oil, antifoaming agent and other components used in this example are as follows.

-Base oil A base oil (1) was prepared by mixing the hydrocarbon base oil B and the hydrocarbon base oil C shown in Table 1 with each other.
The base oil (2) was prepared by mixing the hydrocarbon base oil A, the hydrocarbon base oil B, and the hydrocarbon base oil C shown in Table 1 with each other.

Base oil (1): A mixed solution of a hydrocarbon base oil B / a hydrocarbon base oil C = 25/75 (mass ratio) of a hydrocarbon base oil B / a hydrocarbon base oil C. Kinematic viscosity of base oil (1) (40 ° C) 9.1 mm ² / s

Base oil (2): Hydrocarbon base oil A / hydrocarbon base oil B / hydrocarbon base oil C = 60/30/10 (mass ratio) hydrocarbon base oil A, hydrocarbon base oil B, and hydrocarbon base oil Mixed solution with C. Kinematic viscosity of base oil (2) (40 ° C) 3.2 mm ² / s

-Defoaming agent Defoaming agent (af1): Dimethylpolysiloxane (oil-like) having a weight average molecular weight (Mw) of 40,000, product name "KF-96-3" manufactured by Shin-Etsu Chemical Industry Co., Ltd.

Defoamer (af2): Mw27300 fluorosilicone (oil-like), fluorine atom ratio (F modification rate) 50%, product name "Shin-Etsu Silicone FA-600" manufactured by Shin-Etsu Chemical Co., Ltd.

Defoamer (af3-1): Polymethacrylate-based polymer (oil-like) of Mw20900, product name "PX3841" manufactured by Dorf Ketal Chemicals.
Defoamer (af3-2): Fluorosilicone (oil-like) of Mw2650, product name "FS1265" manufactured by Toray Dow Corning Co., Ltd.

-Other ingredients Viscosity index improver A: Polymethacrylate, Mw230,000, Sanyo Chemical Industries, Ltd. product name "Acluve 740"
Viscosity index improver B: Polymethacrylate, Mw500,000, product name "VISCOPLEX 3-201" manufactured by Evonik Japan Co., Ltd.
Viscosity index improver C: Polymethacrylate, Mw250,000, product name "Sunlube E5070" manufactured by Sanyo Chemical Industries, Ltd.
Viscosity index improver D: Polymethacrylate, Mw160000, product name "PALATONE 8057" manufactured by Chevron Japan Ltd.

Rust inhibitor: Alkenyl succinic acid half ester, product name "OLOLA5653" manufactured by Chevron Japan Ltd.
Abrasion inhibitor (1): Zinc dialkyldithiophosphate, product name "OLOLA269RJ" manufactured by Chevron Japan Ltd.
Abrasion inhibitor (2): Zinc dialkyldithiophosphate, product name "HiTEC680" manufactured by Afton Chemical Japan Co., Ltd.
Cleaning agent: Magnesium sulfonate, product name "HiTEC 7637" manufactured by Afton Chemical Japan Co., Ltd.

<Manufacturing of lubricating oil composition>
(Example 1, Comparative Examples 1 to 5)
As shown in Table 2 (composition, blending ratio), the lubricating oil compositions of each example were produced by adding and mixing other components to the base oil and then adding a defoaming agent and mixing.

<Evaluation>
The viscosity characteristics and defoaming performance of the produced lubricating oil compositions of each example were evaluated.

[Viscosity characteristics]
The kinematic viscosity (40 ° C.), kinematic viscosity (100 ° C.), viscosity index, and pour point of each of the lubricating oil compositions of each example were measured by the above-mentioned methods, and the viscosity characteristics were evaluated. The results of these measurements are shown in Table 2.

[Defoaming performance]
The lubricating oil composition of each example was whipped for 5 minutes under the temperature conditions shown below by a method according to JIS K 2518 (2003), and then allowed to stand.
Temperature conditions Sequence I: 24 ° C,
Sequence II: 93.5 ° C,
Sequence III: Change from 93.5 ° C. to 24 ° C. Immediately after such standing, the amount of foam (mL) after 5 minutes and the amount of foam (mL) after 10 minutes were measured, respectively. The measurement results are shown in Table 2 as "5 minutes / 10 minutes".

From the results in Table 2, the lubricating oil composition of Example 1 to which the present invention is applied has an appropriate viscosity (from kinematic viscosity), little change in viscosity due to a difference in temperature (from viscosity index), and (pour point). It can be confirmed that the foam has good low temperature fluidity and the defoaming performance is further enhanced.

The lubricating oil compositions of Comparative Examples 1, 3 and 4, which are outside the scope of the present invention, had an insufficient defoaming effect on the high temperature side. Further, the lubricating oil compositions of Comparative Examples 2 and 5 outside the scope of the present invention had a low defoaming effect on the low temperature side, and further had a poor defoaming effect when the temperature was changed from high temperature to low temperature.

Claims (4)

A lubricating oil composition containing a base oil and an antifoaming agent (AF).
The defoaming agent (AF) contains a dimethyl silicone defoaming agent (af1) and a fluorosilicone defoaming agent having a weight average molecular weight (Mw) of 25,000 or more .
Lubricating oil composition which is an oil for a door closer . The lubricating oil composition according to claim 1 , wherein the content of the dimethyl silicone defoaming agent (af1) is 0.0001 to 0.1% by mass. The lubricating oil composition according to claim 1 or 2 , wherein the content of the fluorosilicone defoaming agent is 0.0001 to 0.1% by mass. The lubricating oil composition according to any one of claims 1 to 3 , further comprising polymethacrylate as a viscosity index improver.