JP2017088778A - Lubricant composition and lubrication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition having high flash point of 250°C or more as well as excellent life capable of maintaining excellent oxidation stability even when long term use under high temperature environment and a lubrication method using the lubricant composition.SOLUTION: There is provided a lubricant composition containing purified paraffinic mineral oil (A) and alkylbenzene with flash point of 160°C or more and having flash point of 250°C or more.SELECTED DRAWING: None

Description

  The present invention relates to a lubricating oil composition and a lubricating method using the lubricating oil composition.

Lubricating oil compositions used for turbines such as steam turbines and gas turbines, rotary gas compressors, hydraulic equipment and the like are circulated and used for a long time in a system in a high temperature environment.
Lubricating oil compositions that have been used for a long time in a high-temperature environment are likely to cause problems such as performance degradation due to oxidation and sludge precipitation due to oxidation. The deposited sludge generates heat by adhering to the bearing of the rotating body and may cause damage to the bearing, clogging of the filter provided in the circulation line, accumulation of sludge on the control valve, It may cause problems such as malfunctions.
Therefore, lubricating oil compositions used for turbines, rotary gas compressors, hydraulic equipment, and the like are required to have excellent oxidation stability that can withstand long-term use in a high-temperature environment.

For example, Patent Document 1 discloses a lubricating oil containing two kinds of naphthylamine antioxidants having a specific structure in a predetermined ratio using a refined mineral oil or a synthetic hydrocarbon oil such as poly-α-olefin as a base oil. A composition is disclosed.
Patent Document 2 discloses that the aromatic content (% C _A ) is 2 or less, the ratio of paraffin content (% C _P ) to naphthene content (% C _N ) is 6 or more, and the iodine value is 2.5 or less. A lubricating oil composition containing a certain lubricating oil base oil, an ashless antioxidant containing no sulfur atom, and further containing an alkyl group-substituted aromatic hydrocarbon compound such as alkylnaphthalene is disclosed.
Patent Documents 1 and 2 both aim to provide a lubricating oil composition with improved oxidation stability and sludge suppression.

Japanese Patent Laid-Open No. 7-252489 JP 2008-13687 A

By the way, according to the provisions of the Fire Service Act enforced in Japan in 2002, “a substance that shows liquid at 20 ° C. at one atmospheric pressure and has a flash point of 200 ° C. or higher and lower than 250 ° C.” is the fourth of “Fourth Oil”. Classified as a dangerous goods. For “Dangerous Goods”, the Fire Service Act imposes restrictions on storage methods and transportation methods, and restrictions such that only qualified persons can handle those that exceed the specified capacity.
Many of the lubricating oil compositions used in conventional turbines and hydraulic equipment have a flash point of less than 250 ° C. Is imposed.
On the other hand, “substances that show liquid at 20 ° C. at one atmospheric pressure and have a flash point of 250 ° C. or higher (excluding gear oil and cylinder oil)” are classified as “flammable liquids” and firefighting started in 2002. Excluded from the designation of dangerous goods as required by law. Liquids classified as “flammable liquids” are less regulated in terms of storage, transportation, handling, etc. than liquids classified as dangerous goods.
Therefore, as a lubricating oil composition used for turbines, hydraulic equipment, etc., there is a background that there is a demand for a lubricating oil composition having a flash point of 250 ° C. or higher, which is classified as “flammable liquids” in the Fire Service Act. .

Further, such a high flash point lubricating oil composition has been conventionally demanded from the viewpoints of safety and handling during storage and transportation.
However, in general, a high flash point lubricating oil composition often has a high viscosity, and when used in a high temperature environment for a long period of time, performance deterioration due to oxidation and sludge precipitation are likely to occur, and oxidation stability is improved. There's a problem.

In Patent Documents 1 and 2, there is no description or examination about the flash point of the lubricating oil composition, and there are concerns in terms of safety and handling.
Furthermore, in the examples of Patent Document 2, a lubricating oil composition containing alkylnaphthalene is disclosed. However, when alkylnaphthalene is used for a long period of time exceeding 1000 hours in a high temperature environment, the naphthalene ring gradually Cleavage and sludge solubility decreases. Therefore, it can be said that the lubricating oil composition causes a decrease in oxidation stability when used for a long time.

  The present invention provides a lubricating oil composition having a high flash point of 250 ° C. or higher and an excellent life that can maintain excellent oxidation stability even for long-term use in a high-temperature environment, and An object of the present invention is to provide a lubricating method using the lubricating oil composition.

The present inventors have found that a lubricating oil composition containing an alkylbenzene having a flash point in a specific range together with a refined paraffinic mineral oil can solve the above-mentioned problems, and has completed the present invention.
That is, the present invention provides the following [1] and [2].
[1] A lubricating oil composition comprising a refined paraffinic mineral oil (A) and an alkylbenzene (B) having a flash point of 160 ° C. or higher and a flash point of 250 ° C. or higher.
[2] A lubricating method using a lubricating oil composition containing a refined paraffinic mineral oil (A) and an alkylbenzene (B) having a flash point of 160 ° C. or higher and having a flash point of 250 ° C. or higher.

  The lubricating oil composition of the present invention has a high flash point of 250 ° C. or higher, and has an excellent life that can maintain excellent oxidation stability even for long-term use in a high temperature environment.

In this specification, “flash point” is a value measured by the COC method in accordance with JIS K2265, and “kinematic viscosity” and “viscosity index” are values measured in accordance with JIS K2283. .
Further, in the present specification, the definition of “lubricating oil composition substantially free of component X” is “the lubricating oil composition intentionally blended with component X with a specific motive”. The lubricating oil composition may contain a trace amount of the component X that can be contained as an impurity.

[Lubricating oil composition]
The lubricating oil composition of the present invention contains refined paraffinic mineral oil (A) and alkylbenzene (B) having a flash point of 160 ° C. or higher, and has a flash point of 250 ° C. or higher.
The lubricating oil composition of the present invention contains the component (A) and the component (B) at a ratio such that the flash point is 250 ° C. or higher, and is defined by the Fire Service Law that came into effect in 2002 in Japan. It is classified as a “flammable liquid”. Therefore, the lubricating oil composition is excellent in safety and handleability.

Also, in general, a high flash point lubricating oil composition is prone to performance deterioration and sludge precipitation due to oxidation when used under a high temperature environment for a long period of time, resulting in poor oxidation stability and low life. Is a problem.
However, the lubricating oil composition of the present invention contains the refined paraffinic mineral oil (A) together with the alkylbenzene (B) having a flash point in the above range, so that the flash oil has a flash point of 250 ° C. or higher. Oxidative deterioration of the product can be suppressed, sludge generated with use can be dissolved, and precipitation of sludge can be suppressed, contributing to improvement in oxidation stability.
Furthermore, since the component (B) alkylbenzene has high durability against long-term use in a high-temperature environment, it contributes to extending the life of the lubricating oil composition.

In addition, from the viewpoint of improving antifoaming properties and air release properties, the lubricating oil composition of one embodiment of the present invention preferably further contains an antifoaming agent (C) containing a polyacrylate antifoaming agent (C1). .
Moreover, from the viewpoint of further improving the antioxidant performance, the lubricating oil composition of one embodiment of the present invention preferably further contains an antioxidant (D) containing an amine-based antioxidant (D1).
Furthermore, the lubricating oil composition of one embodiment of the present invention may contain base oils and additives for lubricating oil other than the components (A) to (D) as long as the effects of the present invention are not impaired.

  In the lubricating oil composition of one embodiment of the present invention, the total content of the component (A) and the component (B) is preferably 60.1% by mass or more based on the total amount (100% by mass) of the lubricating oil composition. More preferably 70% by mass or more, still more preferably 75% by mass or more, still more preferably 80% by mass or more, particularly preferably 85% by mass or more, and usually 100% by mass or less, preferably 95% by mass or less. It is.

  In the lubricating oil composition of one embodiment of the present invention, the total content of the component (A), the component (B), and the component (C) is preferably based on the total amount (100% by mass) of the lubricating oil composition. 62% by mass or more, more preferably 70% by mass or more, further preferably 75% by mass or more, still more preferably 80% by mass or more, particularly preferably 85% by mass or more, and usually 100% by mass or less, preferably It is 95 mass% or less.

  In the lubricating oil composition of one embodiment of the present invention, the total content of the component (A), the component (B), and the component (D) is preferably based on the total amount (100% by mass) of the lubricating oil composition. 62% by mass or more, more preferably 70% by mass or more, further preferably 75% by mass or more, still more preferably 80% by mass or more, particularly preferably 85% by mass or more, and usually 100% by mass or less, preferably It is 95 mass% or less.

  In the lubricating oil composition of one embodiment of the present invention, the total content of the component (A), the component (B), the component (C), and the component (D) is the total amount (100% by mass) of the lubricating oil composition. Preferably, it is 65% by mass or more, more preferably 70% by mass or more, further preferably 75% by mass or more, still more preferably 80% by mass or more, particularly preferably 85% by mass or more, and usually 100% by mass. % Or less, preferably 95% by mass or less.

  In this specification, antifoaming agents, viscosity index improvers, etc. are dissolved in diluent oil such as mineral oil, synthetic oil, light oil, etc. in consideration of handling properties and solubility in components (A) and (B). In some cases, it may be blended with other ingredients in the form of a solution. In such a case, in this specification, content, such as an antifoamer and a viscosity index improver, means content in the active ingredient conversion (resin component conversion) excluding diluent oil.

  Hereinafter, each component constituting the lubricating oil composition of one embodiment of the present invention will be described.

<Purified paraffinic mineral oil (A)>
As the refined paraffinic mineral oil (A) used in the present invention, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrogenation. Mineral oil obtained through one or more refining processes selected from refining, sulfuric acid washing, and clay treatment; mineral oil produced by a method of isomerizing wax isomerized mineral oil or GTL WAX (Gas Liquid Liquid or Fischer-Tropsch Wax) Etc.
In addition, the refined paraffinic mineral oil (A) used in the present invention may be used alone or in combination of two or more.

The paraffin content (% C _P ) of the purified paraffinic mineral oil (A) is preferably 65 or more, more preferably 70 or more, still more preferably 72 or more, and even more preferably 75 or more.

The naphthene content (% C _N ) of the refined paraffinic mineral oil (A) is preferably 35 or less, more preferably 30 or less, still more preferably 28 or less, and even more preferably 25 or less.

The aromatic content (% C _A ) of the refined paraffinic mineral oil (A) is preferably less than 2.0, more preferably less than 1.5, still more preferably less than 1.0, and even more preferably less than 0.1. It is.

In the present specification, the values of% C _P ,% C _N and% C _A of component (A) were measured by a method (ndM ring analysis) based on ASTM D 3238-85. It is a value, and means “ratio of carbon number of paraffin”, “ratio of carbon number of naphthene”, and “ratio of aromatic carbon number” with respect to the total carbon number (100%) of component (A), respectively.

The flash point of the refined paraffinic mineral oil (A) is preferably 250 ° C. or higher, more preferably 253 ° C. or higher, still more preferably 255 ° C. or higher, and preferably 280 ° C. or lower.
If the flash point of component (A) is 250 ° C. or higher, a lubricating oil composition having a flash point of 250 ° C. or higher can be prepared. In addition, excellent oxidation stability can be maintained for a long period of time, which contributes to extending the life of the lubricating oil composition.
In addition, refined paraffin mineral oil (A) with a high flash point can be obtained by sufficiently refining a lubricating oil fraction obtained by atmospheric distillation of a crude oil by combining a plurality of the above-described refining steps. That is, the more the refinement is performed, the higher the flash point of the obtained paraffinic mineral oil.

The kinematic viscosity at 40 ° C. of the refined paraffinic mineral oil (A) is preferably 20 to 300 mm ² / s, more preferably 23 to ²⁰⁰ mm ² / s, still more preferably 25 to 100 mm ² / s.

  The viscosity index of the refined paraffinic mineral oil (A) is preferably 100 or more, more preferably 110 or more, still more preferably 120 or more, and still more preferably 130 or more.

The acid value of the refined paraffinic mineral oil (A) is preferably 0.05 mgKOH / g or less, more preferably 0.03 mgKOH / g or less, and still more preferably 0.01 mgKOH / g or less.
In addition, in this specification, an acid value means the value measured based on the indicator method of JISK2501.

The density of the refined paraffinic mineral oil (A) at 15 ° C. is preferably 0.800 to 0.930 g / cm ³ , more preferably 0.810 to 0.900 g / cm ³ , and still more preferably 0.820 to 0. .880 g / cm ³ .
In this specification, the density at 15 ° C. means a value measured according to JIS K2249-1.

The pour point of the refined paraffinic mineral oil (A) is preferably 0 ° C. or lower, more preferably −5 ° C. or lower, still more preferably −10 ° C. or lower, and still more preferably −15 ° C. or lower.
In addition, in this specification, a pour point means the value measured based on JISK2269.

In the lubricating oil composition of one embodiment of the present invention, the content of the component (A) is preferably 60 to 99.9% by mass, more preferably 70, based on the total amount (100% by mass) of the lubricating oil composition. To 99.5% by mass, more preferably 80 to 99.0% by mass, and still more preferably 85 to 99.0% by mass.
If content of a component (A) is 60 mass% or more, it can be set as the lubricating oil composition whose flash point is 250 degreeC or more. In addition, excellent oxidation stability can be maintained for a long period of time, which contributes to extending the life of the lubricating oil composition.
On the other hand, if the content of the component (A) is 99.9% by mass or less, the content of the alkylbenzene (B) can be ensured, and oxidative deterioration of the lubricating oil composition and sludge precipitation are suppressed, Excellent oxidation stability can be maintained for a long time.

<Other base oils>
In the lubricating oil composition of one embodiment of the present invention, other base oils other than the component (A) may be contained. Other base oils may be mineral oils or synthetic oils.

  Examples of the mineral oil include atmospheric residual oil obtained by atmospheric distillation of crude oil such as intermediate-based mineral oil and naphthene-based mineral oil; distillate obtained by vacuum distillation of the atmospheric residual oil; Mineral oils and waxes that have been subjected to one or more purification treatments such as solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, and the like; Mineral oils classified into Group 2 and Group 3 of the oil category are preferred, and mineral oils classified into Group 3 are more preferred.

Examples of the synthetic oil include polybutene and α-olefin homopolymers or copolymers (for example, α-olefin homopolymers or copolymers having 8 to 14 carbon atoms such as ethylene-α-olefin copolymers). ) And the like; and the like.
In the present invention, “alkylbenzene” does not belong to the category of “synthetic oil” but belongs to component (B) described later.

  In the lubricating oil composition of one embodiment of the present invention, the content of the other base oil is preferably 0 to 30 parts by mass, more preferably 0 to 20 parts by mass with respect to 100 parts by mass of the total amount of the component (A). More preferably, it is 0-10 mass parts, More preferably, it is 0-5 mass parts.

<Alkylbenzene (B)>
The alkylbenzene (B) used in the present invention may be a compound in which at least one hydrogen atom of one benzene ring is substituted with an alkyl group.
Alkylbenzene (B) may be used alone or in combination of two or more.

Examples of the alkyl group that the alkylbenzene (B) has include, for example, a methyl group, an ethyl group, various propyl groups, various butyl groups, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, and various decyl groups. Group, various undecyl groups, various dodecyl groups, various tridecyl groups, various tetradecyl groups, various pentadecyl groups, various hexadecyl groups, various heptadecyl groups, various octadecyl groups, various nonadecyl groups, various icosyl groups, various heicosyl groups, various docosyl groups, Various tricosyl groups, various tetracosyl groups, various pentacosyl groups, various hexacosyl groups, various heptacosyl groups, various octacosyl groups, various nonacosyl groups, various triacontyl groups, various hentriacontyl groups, various dotriacontyl groups, various tritriacontyl groups, various Ratoria Con butyl group, various types of penta triacontyl groups, various hexa triacontyl groups, various hepta triacontyl groups, various octa triacontyl groups, various nonadecyl triacontyl groups, various tetracontyl group.
The term “various” is a term used to indicate all isomers of the target alkyl group.

In the alkylbenzene (B), the number of alkyl groups substituted on one benzene ring is 1 or more, preferably 1 to 4, more preferably 1 to 2.
In the present invention, when the alkylbenzene (B) has a plurality of alkyl groups, the plurality of alkyl groups may be the same or different from each other.

  As carbon number of each alkyl group which alkylbenzene (B) has, Preferably it is 1-40, More preferably, it is 4-35, More preferably, it is 8-30.

The flash point of the alkylbenzene (B) used in the present invention is 160 ° C. or higher, preferably 170 ° C. or higher, more preferably 175 ° C. or higher, still more preferably 180 ° C. or higher, and still more preferably 185 ° C. or higher.
When the flash point of the component (B) is less than 160 ° C, it becomes difficult to prepare a lubricating oil composition having a flash point of 250 ° C or higher. Although it is possible to increase the flash point of the resulting lubricating oil composition by reducing the content of the component (B), since the content of the component (B) is small, the lubricating oil composition The effect of suppressing harmful effects such as oxidative deterioration of materials and sludge precipitation tends to be insufficient.

  The flash point of alkylbenzene (B) is preferably 250 ° C. or lower, more preferably 230 ° C. or lower, still more preferably 220 ° C. or lower, and still more preferably 210 ° C. or lower.

The kinematic viscosity at 40 ° C. of the alkylbenzene (B) is preferably 45 to 80 mm ² from the viewpoint of a long-life lubricating oil composition capable of maintaining excellent oxidation stability even for long-term use. / s, more preferably 47~75mm ² / s, more preferably 50 to 70 mm ² / s, even more preferably from 52~65mm ² / s.

The kinematic viscosity at 100 ° C. of the alkylbenzene (B) is preferably 1 to 40 mm ² from the viewpoint of a long-life lubricating oil composition capable of maintaining excellent oxidation stability even for long-term use. / s, more preferably 2 to 30 mm ² / s, more preferably 3 to 20 mm ² / s, even more preferably from 4 to 10 mm ² / s.

The density of the alkylbenzene (B) at 15 ° C. is preferably 0.820 to 0.940 g / cm ³ , more preferably 0.835 to 0.920 g / cm ³ , and still more preferably 0.850 to 0.900 g / cm ³ . cm ³ .

  The pour point of the alkylbenzene (B) is preferably −10 ° C. or lower, more preferably −15 ° C. or lower, still more preferably −20 ° C. or lower, and still more preferably −30 ° C. or lower.

In the lubricating oil composition of one embodiment of the present invention, the content of the component (B) is preferably 0.1 to 10% by mass, more preferably 0, based on the total amount (100% by mass) of the lubricating oil composition. 15 to 9% by mass, more preferably 0.2 to 7.5% by mass, still more preferably 0.3 to 6% by mass, and particularly preferably 0.4 to 5.5% by mass.
When the content of the component (B) is 0.1% by mass or more, a lubricating oil composition capable of suppressing oxidative degradation and sludge precipitation and maintaining excellent oxidation stability for a long period can be obtained.
On the other hand, if content of a component (B) is 10 mass% or less, it can be set as the lubricating oil composition whose flash point is 250 degreeC or more. In addition, excellent oxidation stability can be maintained for a long period of time, which contributes to extending the life of the lubricating oil composition.

In the lubricating oil composition of one embodiment of the present invention, it is preferable that substantially no alkylnaphthalene is contained.
When alkylnaphthalene is used for a long period of time in a high temperature environment, the naphthalene ring is gradually cleaved, resulting in a decrease in sludge solubility. As a result, a lubricating oil composition containing an alkylnaphthalene tends to have a reduced oxidative stability with long-term use and tends to have a short life.
Therefore, in the lubricating oil composition of one embodiment of the present invention, the alkyl naphthalene content is preferably as small as possible.
In the lubricating oil composition of one embodiment of the present invention, the alkylnaphthalene content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably with respect to 100 parts by mass of the total amount of the component (B). 1 part by mass or less, more preferably 0.1 part by mass or less.

<Antifoaming agent (C)>
In the lubricating oil composition of one embodiment of the present invention, it is preferable that an antifoaming agent (C) including a polyacrylate antifoaming agent (C1) is further contained from the viewpoint of improving the antifoaming property and the air releasing property.
Examples of the polyacrylate antifoaming agent (C1) include polymethacrylate (PMA) and modified products thereof, and polymethacrylate is preferable.
The polyacrylate antifoaming agent (C1) may be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the polyacrylate antifoaming agent (C1) is preferably 10,000 to 200,000, more preferably 15,000 to 150,000, and still more preferably 20,000 to 100,000.
In the present specification, the weight average molecular weight (Mw) is a value measured in terms of standard polystyrene by the GPC (gel permeation chromatography) method, specifically by the method described in the examples. It is a measured value.

In one embodiment of the present invention, an antifoaming agent other than the component (C1) may be contained as the antifoaming agent (C).
Examples of the antifoaming agent other than the component (C1) include fatty acid derivatives such as alkenyl succinic acid derivatives, alcohols such as o-hydroxybenzyl alcohol and derivatives thereof, esters of polyhydroxy aliphatic alcohols and long chain fatty acids, and the like. .
Antifoaming agents other than these components (C1) may be used alone or in combination of two or more.

  However, the content ratio of the component (C1) in the component (C) is based on the total amount (100% by mass) of the component (C) from the viewpoint of a lubricating oil composition with improved defoaming and releasing properties. Preferably, it is 70-100 mass%, More preferably, it is 80-100 mass%, More preferably, it is 90-100 mass%, More preferably, it is 95-100 mass%.

In the lubricating oil composition of one embodiment of the present invention, it is preferable that component (C) does not substantially contain a silicone-based antifoaming agent.
A lubricating oil composition containing a silicone-based antifoaming agent has a problem in air release because the generated foam is difficult to disappear. In addition, the lubricating oil composition is inferior in air release, so it is difficult to remove air, and oxidation of the lubricating oil composition proceeds due to the presence of air, and the life is likely to be shortened.
Therefore, in the lubricating oil composition of one embodiment of the present invention, the content of the silicone antifoaming agent is preferably as small as possible.
In the lubricating oil composition of one embodiment of the present invention, the content of the silicone-based antifoaming agent is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of component (C) (100% by mass). More preferably, it is 1% by mass or less, and still more preferably 0.1% by mass or less.

In the lubricating oil composition of one embodiment of the present invention, the content of the component (C) is preferably 0.0001 to 5% by mass, more preferably 0, based on the total amount (100% by mass) of the lubricating oil composition. .0002-3 mass%, More preferably, it is 0.0003-1 mass%, More preferably, it is 0.0004-0.1 mass%.
In addition, although component (C) may be blended in the form of a solution dissolved in diluent oil, the content of the above-mentioned component (C) is defined as an active ingredient conversion (resin component equivalent) excluding diluent oil. ) Means the content.

<Antioxidant (D)>
The lubricating oil composition of one embodiment of the present invention preferably contains an antioxidant (D) containing an amine-based antioxidant (D1) from the viewpoint of further improving the antioxidant performance.
The amine antioxidant (D1) may be used alone or in combination of two or more.

The amine antioxidant (D1) may be any antioxidant having at least one amino group, but a monoamine compound having only one amino group is preferred, and the following general formula (d-1) The compound represented by these is more preferable.
R ^A —NH—R ^B (d-1)

In the general formula (d-1), R ^A and R ^B are each independently an aryl group having 6 to 18 ring carbon atoms which may be substituted with an alkyl group having 1 to 20 carbon atoms.
Examples of the aryl group include a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, an anthryl group, and a fluorenyl group, and a phenyl group or a naphthyl group is preferable.
Examples of the alkyl group that may be substituted with the aryl group include the same alkyl groups as those having 1 to 20 carbon atoms among the alkyl groups that the alkylbenzene (B) may have.
As carbon number of the said alkyl group, Preferably it is 4-18, More preferably, it is 6-16, More preferably, it is 8-14.

In one embodiment of the present invention, from the viewpoint of further improving the antioxidant performance, the amine-based antioxidant (D1) includes a diphenylamine-based compound (D11) and a phenyl-naphthylamine-based compound (D12). preferable.
The total content of the component (D11) and the component (D12) in the component (D1) is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, based on the total amount (100% by mass) of the component (D1). %, More preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass.

As a diphenylamine type compound (D11), the compound represented by the following general formula (d-11) is preferable.
Moreover, as a phenyl- naphthylamine type compound (D12), the compound represented by the following general formula (d-121) or the compound represented by the following general formula (d-122) is preferable.

In the general formulas (d-11), (d-121), and (d-122), R ^{1 to} R ⁸ each independently represent 1 to 20 carbon atoms (preferably 4 to 18 carbon atoms, more preferably 6 to 6 carbon atoms). 16, more preferably 8-14) alkyl groups. As the said alkyl group, the same thing as a C1-C20 alkyl group is mentioned among the alkyl groups which the above-mentioned alkylbenzene (B) may have.
n1, n2, n3, and n6 are each independently an integer of 0 to 5, preferably an integer of 0 to 3, more preferably an integer of 0 to 1, and still more preferably 1.
m4 and m7 are each independently an integer of 0 to 3, preferably an integer of 0 to 1, and more preferably 0.
p5 and p8 are each independently an integer of 0 to 4, preferably an integer of 0 to 2, more preferably an integer of 0 to 1, and still more preferably 0.

  The content ratio [D11 / D12] of the component (D11) and the component (D12) is preferably a mass ratio, preferably 0.1 / 1 to 1/1, more preferably, from the viewpoint of further improving the antioxidant performance. It is 0.15 / 1 to 0.85 / 1, more preferably 0.2 / 1 to 0.7 / 1, and still more preferably 0.25 / 1 to 0.6 / 1.

In the lubricating oil composition of one embodiment of the present invention, it is preferable that the amine-based antioxidant (D1) does not substantially contain a phenylenediamine-based compound.
Lubricating oil compositions containing phenylenediamine compounds tend to generate sludge when used for a long period of time at high temperatures, and the sludge suppression effect due to containing alkylbenzene (B) tends to be less likely to be fully expressed. .
Therefore, in the lubricating oil composition of one embodiment of the present invention, the content of the phenylenediamine compound is preferably as small as possible.
In the present invention, the “phenylenediamine compound” refers to a compound having one benzene ring and at least two hydrogen atoms of the benzene ring substituted with amino groups, and the benzene ring is other than an amino group. Also included are compounds having a substituent such as an alkyl group.

  In the lubricating oil composition of one embodiment of the present invention, the content of the phenylenediamine compound in the component (D1) is preferably based on the total amount (100% by mass) of the amine antioxidant (D1). Is 10% by mass or less, more preferably 5% by mass or less, still more preferably 1% by mass or less, and still more preferably 0.1% by mass or less.

In the lubricating oil composition of one embodiment of the present invention, an antioxidant other than the amine-based antioxidant (D1) may be contained as the component (D).
However, the content ratio of the component (D1) in the component (D) is preferably 50 to 100% by mass, more preferably based on the total amount (100% by mass) of the component (D) contained in the lubricating oil composition. Is 60 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 80 to 100% by mass.

As an antioxidant other than the component (D1), a phenolic antioxidant (D2) is preferable.
Examples of the phenolic antioxidant (D2) include 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4,6-triphenol. -T-butylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, 2,6-di-t-butylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t -Butyl-4- (N, N-dimethylaminomethyl) phenol, 2,6-di-t-amyl-4-methylphenol, n-octadecyl-3- (3,5-di-t-butyl-4- Monocyclic phenolic compounds such as hydroxyphenyl) propionate, 4,4′-methylenebis (2,6-di-t-butylphenol), 4,4′-isopropylidenebis (2,6-di-t-butylphenol) ), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-bis (2,6-di-tert-butylphenol), 4,4′-bis (2-methyl-) 6-t-butylphenol), 2,2′-methylenebis (4-ethyl-6-t-butylphenol), 4,4′-butylidenebis (3-methyl-6-t-butylphenol) and the like. Can be mentioned.
These phenolic antioxidants (D2) may be used alone or in combination of two or more.

  When the amine antioxidant (D1) and the phenolic antioxidant (D12) are used in combination, the content of the phenolic antioxidant (D2) is 100 parts by mass of the total amount of the amine antioxidant (D1). On the other hand, it is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 60 parts by mass, still more preferably 1.0 to 40 parts by mass, and still more preferably 2.0 to 20 parts by mass.

  In the lubricating oil composition of one embodiment of the present invention, the content of the component (D) is preferably 0.01 to 15% by mass, more preferably 0, based on the total amount (100% by mass) of the lubricating oil composition. 0.05 to 10% by mass, more preferably 0.10 to 5% by mass, and still more preferably 0.20 to 3% by mass.

<Additive for lubricating oil>
The lubricating oil composition of one embodiment of the present invention is used for a lubricating oil used in a general lubricating oil composition that does not fall under the components (A) to (D) as long as the effects of the present invention are not impaired. An additive may be contained.
Examples of such lubricant additives include viscosity index improvers, detergents, dispersants, metal deactivators, pour point depressants, antiwear agents, friction modifiers, extreme pressure agents, and rust inhibitors. Etc.
Each of these additives may be used alone or in combination of two or more.

  In the lubricating oil composition of one embodiment of the present invention, the content of each additive for lubricating oil is preferably 0.001 to 10% by mass, based on the total amount (100% by mass) of the lubricating oil composition. Preferably it is 0.005-7 mass%, More preferably, it is 0.01-5 mass%, More preferably, it is 0.05-2 mass%.

[Method for producing lubricating oil composition]
The lubricating oil composition of the present invention can be produced by blending refined paraffinic mineral oil (A) and alkylbenzene (B) having a flash point of 160 to 220 ° C. At this time, if necessary, together with components (A) and (B), mineral oil not corresponding to components (A) and (B), the above-mentioned antifoaming agent (C), antioxidant (D), and You may mix | blend the above-mentioned additive for lubricating oil.
In addition, the compounding quantity of each component is as above-mentioned.
After blending each component, it is preferable to stir and disperse uniformly by a known method.
In addition, the lubricating oil composition obtained when a part of the components is modified after the respective components are blended or the two components react with each other to form another component also belongs to the technical scope of the present invention. It is.

[Various physical properties of lubricating oil composition]
The flash point of the lubricating oil composition of the present invention is 250 ° C. or higher, preferably 253 ° C. or higher, more preferably 255 ° C. or higher, and preferably 260 ° C. or lower.

The kinematic viscosity at 40 ° C. of the lubricating oil composition of one embodiment of the present invention is preferably 20 to 300 mm ² / s, more preferably 25 to ²⁰⁰ mm ² / s, still more preferably 30 to 100 mm ² / s.

  The viscosity index of the lubricating oil composition of one embodiment of the present invention is preferably 115 or higher, more preferably 125 or higher, and still more preferably 135 or higher.

The acid value of the lubricating oil composition of one embodiment of the present invention is preferably 1.00 mgKOH / g or less, more preferably 0.50 mgKOH / g or less, still more preferably 0.30 mgKOH / g or less, still more preferably 0.00. It is 12 mgKOH / g or less.
The base number of the lubricating oil composition of one embodiment of the present invention is preferably 1.00 mgKOH / g or less, more preferably 0.50 mgKOH / g or less, still more preferably 0.30 mgKOH / g or less, and still more preferably. It is 0.10 mgKOH / g or less.
In addition, in this specification, a base number means the value measured based on the hydrochloric acid method of JISK2501.

The density at 15 ° C. of the lubricating oil composition of one embodiment of the present invention is preferably 0.800 to 0.930 g / cm ³ , more preferably 0.810 to 0.900 g / cm ³ , and still more preferably 0.8. 820 to 0.880 g / cm ³ .

  The pour point of the lubricating oil composition of one embodiment of the present invention is preferably 0 ° C. or lower, more preferably −5 ° C. or lower, still more preferably −10 ° C. or lower, and still more preferably −15 ° C. or lower.

  When the lubricating oil composition of one embodiment of the present invention was tested at a test temperature of 150 ° C. and an initial pressure of 620 kPa in accordance with the rotational cylinder type oxidation stability test (RBOT) of JIS K 2514-3, the pressure was The time (RBOT value) until the pressure drops by 175 kPa from the maximum pressure is preferably 1800 minutes or more, more preferably 2000 minutes or more, still more preferably 2200 minutes or more, and even more preferably 2400 minutes or more.

When the lubricating oil composition of one embodiment of the present invention was tested according to ASTM D7873 oxidation stability test (Dry-TOST method), RPVOT (rotary cylinder oxidation stability test) according to ASTM D2272 ) The time when the value is 25% of the RPVOT value before the test is preferably 1400 hours or more, more preferably 1500 hours or more, still more preferably 1600 hours or more, and even more preferably 1800 hours or more.
In addition, the amount of sludge produced at the time is preferably 7.0 mg / 100 ml or less, more preferably 5.0 mg / 100 ml or less, more preferably when measured using a Millipore membrane filter having an average pore size of 1.0 μm. Is 4.07.0 mg / 100 ml or less.

  With respect to the lubricating oil composition of one embodiment of the present invention, when the test is performed at a measurement temperature of 50 ° C. according to ASTM D3427, the time until the foam disappears is preferably less than 3.5 minutes, more Preferably it is less than 3.0 minutes, More preferably, it is less than 2.5 minutes, More preferably, it is less than 2.0 minutes.

  Regarding the lubricating oil composition of one embodiment of the present invention, when a water separability test at a temperature of 54 ° C. was performed in accordance with JIS K2520, the time until the emulsified layer reached 3 mL (demulsification degree) Preferably it is less than 10 minutes, More preferably, it is less than 8 minutes, More preferably, it is less than 6 minutes.

[Use of lubricating oil composition, lubricating method]
The lubricating oil composition of one embodiment of the present invention is used for lubricating various turbines such as steam turbines, nuclear turbines, gas turbines, hydroelectric turbines, etc .; used for lubricating various turbomachines such as blowers and compressors. It can be used as bearing oil, gear oil, control system hydraulic oil; hydraulic oil, internal combustion engine lubricating oil, and the like.
That is, the lubricating oil composition of the present invention is preferably used for lubricating applications such as various turbines, various turbo machines, and hydraulic equipment.
Therefore, the present invention includes a lubricating method using the above-described lubricating oil composition, that is, “refined paraffinic mineral oil (A) and alkylbenzene (B) having a flash point of 160 to 220 ° C. A lubricating method using a lubricating oil composition having a temperature of 250 ° C. or higher can also be provided.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

[Measurement methods for various physical properties]
(1) Weight average molecular weight (Mw)
It was measured by standard polystyrene conversion by GPC (gel permeation chromatography) method. Specifically, the measurement was performed under the following apparatus and conditions.
-GPC equipment: Waters 1515 Isocratic HPLC Pump + Waters 2414 Refractive Index Detector (all manufactured by Waters)
-Column: Two "TSKgel SuperMultipore HZ-M" (manufactured by Tosoh Corporation) connected.-Column temperature: 40 ° C
-Eluent: Tetrahydrofuran-Flow rate: 0.35 mL / min
-Detector: Refractive index detector (2) Kinematic viscosity Kinematic viscosity at each temperature was measured according to JIS K2283.
(3) Viscosity index Measured according to JIS K2283.
(4) Acid value It measured based on the indicator method of JISK2501.
(5) Base number (hydrochloric acid method)
The measurement was performed according to the hydrochloric acid method of JIS K2501.
(6) Density (15 ° C)
The density at 15 ° C. was measured according to JIS K2249-1.
(7) Flash point (COC)
Based on JIS K 2265, it measured by the Cleveland open type (COC) method.
(8) Pour point Measured according to JIS K2269.
(9)% C _P ,% C _N ,% C _A
ASTM D method based on 3238-85 (n-d-M ring analysis) is the measured value by, and the percentage of paraffin carbon atoms with (percentage)% and _{C P,} the percentage of naphthenic carbon atoms and (percentage)% and C _N, and the percentage of aromatic carbon atoms (the percentages) and% _{C a.}

Table 1 shows various physical property values measured based on the above-described methods for the refined paraffinic mineral oils (1) to (3) and alkylbenzene used in Examples and Comparative Examples. In addition, the alkylbenzene shown in Table 1 is an alkylbenzene having an alkyl group having 12 to 22 carbon atoms.

Examples 1-3, Comparative Examples 1-2
Refined paraffinic mineral oils (1) to (3) having the properties shown in Table 1, alkylbenzene, and various additives shown below in the blending amounts shown in Table 2, are mixed thoroughly, Lubricating oil compositions (I) to (V) were respectively prepared.
Details of various additives used in the examples and comparative examples described in Table 2 are as follows.

(Defoamer)
-Polyacrylate antifoaming agent (1): A solution having a resin concentration of 1% by mass obtained by diluting polymethacrylate having Mw of 48,000 with light oil.
-Polyacrylate type antifoaming agent (2): Polymethacrylate having Mw of 51,000.
Silicone-based antifoaming agent: A solution having a resin concentration of 1% by mass obtained by diluting polydimethylsilicone having a kinematic viscosity of 12500 mm ² / s at 25 ° C. with light oil.
(Antioxidant)
Amine antioxidant (1): Dioctyl diphenylamine (in the general formula (d-11), R ¹ and R ² = octyl group, n1 and n2 = 1), and diphenylamine compound (D11) .
Amine-based antioxidant (2): pt-octylphenyl-1-naphthylamine (in the general formula (d-122), R ⁶ = t-octyl group, n6 = 1, m7 and p8 = 0. Compound), a phenyl-naphthylamine compound (D12).
Phenolic antioxidant: diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate.
(Other additives)
Extreme pressure agent: tricresyl phosphate.
Antirust agent: alkenyl succinic polyhydric alcohol ester.
Metal deactivator: N-dialkylaminomethylbenzotriazole.

  For each of the lubricating oil compositions (I) to (V), various physical property values shown in Table 2 are measured based on the above-mentioned methods, and the following tests are performed to determine the oxidation stability, the air releasing property, and the lubricating oil composition. And water separability was evaluated. These results are shown in Table 2.

(1) Rotating cylinder oxidation stability test (RBOT)
The test was performed at a test temperature of 150 ° C. and an initial pressure of 620 kPa in accordance with JIS K 2514-3, a rotary cylinder type oxidation stability test (RBOT), and the time until the pressure decreased to 175 kPa from the maximum pressure (RBOT value) was measured. It can be said that the longer the time is, the better the lubricating oil composition is in oxidation stability.

(2) Oxidation stability test (Dry-TOST method)
According to ASTM D7873 oxidation stability test (Dry-TOST method), RPVOT value according to ASTM D2272 is 25% of RPVOT value before test (unit: time), and sludge generation at that time The amount was measured.
The amount of sludge produced was measured using a Millipore membrane filter having an average pore size of 1.0 μm in accordance with ASTM D7873.

(3) Air release test Based on ASTM D3427, time (unit: minute) until foam disappears was measured at a measurement temperature of 50 ° C. It can be said that the shorter the time, the better the lubricating oil composition.

(4) Water separation test In accordance with JIS K2520, a water separation test at a temperature of 54 ° C. was performed, and the time until the emulsified layer reached 3 mL (demulsification degree, unit: minute) was measured. It can be said that the shorter the time is, the better the lubricating oil composition is in water separation.

The lubricating oil compositions (I) to (III) prepared in Examples 1 to 3 have a high flash point of 250 ° C. or higher, and excellent oxidation stability for long-term use in a high temperature environment. It has an excellent lifetime that can be maintained. Moreover, lubricating oil composition (I)-(III) is excellent also in air release and water-separability.
On the other hand, the lubricating oil compositions (IV) and (V) prepared in Comparative Examples 1 and 2 have a low flash point of less than 250 ° C., and the oxidation stability of the lubricating oil compositions (I) to (III) ) Was inferior to.

The lubricating oil composition of the present invention has a high flash point of 250 ° C. or higher, and has an excellent life that can maintain excellent oxidation stability even when used for a long time in a high temperature environment.
Therefore, the lubricating oil composition of one embodiment of the present invention can be suitably used as, for example, turbine oil, compressor oil, hydraulic fluid, and the like.

Claims (15)

  A lubricating oil composition comprising a refined paraffinic mineral oil (A) and an alkylbenzene (B) having a flash point of 160 ° C or higher and a flash point of 250 ° C or higher.   Furthermore, the lubricating oil composition of Claim 1 containing the antifoamer (C) containing a polyacrylate type antifoamer (C1).   The lubricating oil composition according to claim 2, wherein the polyacrylate antifoaming agent (C1) has a weight average molecular weight of 10,000 to 200,000.   The lubricating oil composition according to claim 2 or 3, wherein the antifoaming agent (C) contains substantially no silicone-based antifoaming agent.   Furthermore, the lubricating oil composition as described in any one of Claims 1-4 containing antioxidant (D) containing an amine antioxidant (D1).   The lubricating oil composition according to claim 5, wherein the amine-based antioxidant (D1) comprises a diphenylamine-based compound (D11) and a phenyl-naphthylamine-based compound (D12).   The lubricating oil composition according to claim 6, wherein the content ratio [D11 / D12] of the component (D11) and the component (D12) is 0.1 / 1 to 1/1 by mass ratio.   The lubricating oil composition according to any one of claims 5 to 7, wherein the amine-based antioxidant (D1) does not substantially contain a phenylenediamine-based antioxidant.   The lubricating oil composition according to any one of claims 1 to 8, wherein the flash point of the refined paraffinic mineral oil (A) is 250 ° C or higher.   The lubricating oil composition according to any one of claims 1 to 9, wherein the content of the refined paraffinic mineral oil (A) is 60 to 99.9 mass% based on the total amount of the lubricating oil composition. The lubricating oil composition according to any one of claims 1 to 10, wherein the refined paraffinic mineral oil (A) has a kinematic viscosity at 40C of ²⁰ to 300 mm2 / s.   The lubricating oil composition according to any one of claims 1 to 11, wherein the content of the alkylbenzene (B) is 0.1 to 10% by mass based on the total amount of the lubricating oil composition. Kinematic viscosity at 40 ° C. of alkylbenzenes (B) is 45~80mm ² / s, the lubricating oil composition according to any one of claims 1 to 12.   The lubricating oil composition according to any one of claims 1 to 13, which contains substantially no alkylnaphthalene.   A lubrication method using a lubricating oil composition containing a refined paraffinic mineral oil (A) and an alkylbenzene (B) having a flash point of 160 ° C or higher and a flash point of 250 ° C or higher.