JPWO2019087351A1 - Lubricating oil base oil and a lubricating oil composition containing the lubricating oil base oil - Google Patents

Abstract

The lubricating oil base oil of the present invention is a lubricating oil base oil containing a condensed ester of an alcohol (A) and a carboxylic acid (B), wherein the alcohol (A) contains trimethylol propane and the carboxylic acid. (B) contains a linear or branched saturated fatty acid (b1) having 7 carbon atoms, a linear or branched saturated fatty acid (b2) having 8 carbon atoms, and a linear or branched saturated fatty acid (b3) having 12 carbon atoms. .. The lubricating oil base oil of the present invention is excellent in heat resistance, lubricity, and hydrolysis resistance.

Description

The present invention relates to a lubricating oil base oil and a lubricating oil composition containing the lubricating oil base oil. The present invention also relates to the use of a lubricating oil composition and a lubricating method using the lubricating oil composition.

Lubricants are used in various fields that require friction reduction. In the olden days, natural fats and oils and refined petroleum products were used, but in recent years, synthetic lubricating oils have been synthesized and used according to the purpose. In particular, synthetic esters are excellent in thermal stability, and specific examples thereof include organic acid esters, phosphoric acid esters, and silicic acid esters.

Among the organic acid esters, 1) low pour point, high viscosity index and wide operating temperature range, 2) high ignition point, small amount of evaporation, 3) excellent thermal and oxidation stability, 4) lubrication Polyester esters (condensation esters of polyhydric alcohols and carboxylic acids) are used from the viewpoints of good properties, 5) clean dispersal action, and 6) biodegradability, and are particularly excellent in thermal and oxidative stability. Hindered esters are used in many fields.

However, in recent years, with the development of industrial technology, high productivity and operational stability have always been required, and more durable and highly heat-resistant lubricating oils have been required.

In addition, although synthetic esters have excellent performance as lubricating oil, they have the disadvantage that ester bonds are broken in the presence of moisture, so-called hydrolysis occurs, and they can withstand use in an environment exposed to moisture. There is a demand for synthetic esters with high hydrolysis resistance.

For example, Patent Document 1 states that the viscosity at −40 ° C. is 9000 mPa · s or less, the pour point is −40 ° C. or lower, and the volatilization amount when heated at 180 ° C. for 500 hours is 35% by weight or less. As a grease base oil having a viscosity index of 130 or more, an ester obtained from a trihydric alcohol and a linear fatty acid and a branched fatty acid is disclosed.

Patent Document 2 states that the maximum non-seizure load of the high-speed four-ball test of ASTM D2596, which is characterized in that the synthetic oil is an ester or polyoxyalkylene glycol, is 314 N or less, and the pour point is −35 ° C. or less. A grease composition for a one-way clutch is disclosed, which comprises a synthetic oil and a thickener.

Patent Document 3 has a general formula, R (OH) _n (in the formula, R is an aliphatic group or an alicyclic group having about 2 to 20 carbon atoms, and n is at least 2). a branched or linear alcohol, about 30 to 80 mol%, from about _{C 5} to and linear acids having carbon number in the range of _{C 12,} 20 to 70 mol%, the range of from about _{C 5} to _{C 13} A biodegradable synthetic ester-based stock containing a reaction product with a mixed acid of at least one branched chain acid having at least one carbon number of carbons, as measured by a modified stam test, at least 60% biodegradation in 28 days. Disclosed are biodegradable synthetic ester base stocks that exhibit a flow point below -25 ° C and a viscosity below 7500 cps at -25 ° C.

Patent Document 4 describes (a) neopentyl-type branched fatty acid residues 5 to 90%, (b) linear fatty acid residues having 4 to 20 carbon atoms, and / or (c) branched fatty acid residues 95-10. Lubricating oil based on neopentyl polyol ester consisting of% is disclosed.

Patent Document 5 describes trimethylolpropane and / or pentaerythritol, linear fatty acids having 7 to 18 carbon atoms, and 3,5,5-trimethylhexanoic acid in a molar ratio of 76:24 to 90:10, or carbon atoms. The main component is an ester consisting of 7 to 18 linear fatty acids, 3,5,5-trimethylhexanoic acid and 2-ethylhexanoic acid in a molar ratio of 60:23:17 to 85:10: 5, and the operation at 40 ° C. A biodegradable lubricant having a viscosity of 10 to 80 mm ² / s, a biodegradability of 60% or more, a flash point of 250 ° C. or higher, and a flow point of −15 ° C. or lower is disclosed.

Japanese Unexamined Patent Publication No. 2005-213377 WO2006 / 109541 Special Table No. 10-511711 Japanese Unexamined Patent Publication No. 5-17787 Japanese Unexamined Patent Publication No. 2004-31553

As described above, in the prior art, various condensed esters have been used as lubricating oils, but in order to improve productivity and operational stability, they further have high heat resistance, lubricity, and hydrolysis resistance. Lubricating oil base oil is required.

Therefore, an object of the present invention is to provide a lubricating oil base oil containing a condensed ester having excellent heat resistance, lubricity, and hydrolysis resistance, and a lubricating oil composition containing the lubricating oil base oil. ..

That is, the present invention is a lubricating oil base oil containing a condensed ester of an alcohol (A) and a carboxylic acid (B), wherein the alcohol (A) contains a trimethylol propane and the carboxylic acid (B). Is characterized by containing a linear or branched saturated fatty acid having 7 carbon atoms (b1), a linear or branched saturated fatty acid having 8 carbon atoms (b2), and a linear or branched saturated fatty acid having 12 carbon atoms (b3). Lubricating oil base oil.

The present invention also relates to a lubricating oil composition containing the lubricating oil base oil.

The details of the action mechanism of the effect in the lubricating oil base oil according to the present invention are unknown, but it is presumed as follows. However, the present invention does not have to be construed as being limited to this mechanism of action.

The present invention comprises an alcohol (A) containing trimethylol propane, a linear or branched saturated fatty acid having 7 carbon atoms (b1), a linear or branched saturated fatty acid having 8 carbon atoms (b2), and a direct fatty acid having 12 carbon atoms. A lubricating oil base oil containing a condensed ester of a carboxylic acid (B) containing a chain or branched saturated fatty acid (b3). In general, a lubricating oil base oil having good lubricity contains a compound having a polar group and a hydrophobic group, so that the polar group is adsorbed (bonded) to the surface of a metal or the like to which lubricity should be imparted, and the hydrophobic group has lubricity. Is considered to be expressed. Therefore, in order to impart excellent lubricity to the lubricating oil base oil, it is preferable to design a good balance between the polar group and the hydrophobic group in the molecule of the condensed ester. Since the condensed ester of the present invention has a polar group for three ester bonds and a hydrophobic group for carbon chains of different lengths, it is presumed to have excellent lubricity.

On the other hand, the longer the carbon chain of the condensed ester, the higher the thermal decomposition temperature, so that the heat resistance is improved, and the hydrophobicity is increased, so that the hydrolysis resistance is improved. However, the longer the carbon chain of the condensed ester, the higher the melting point, and therefore the higher the pour point. In particular, when all the carbon chains of the condensed ester are single, the structure of the ester group on the carbon chain is directional, so that the intermolecular packing property is improved, so that the fluidity is lowered and lubrication is performed. Sexuality also declines. Since the condensed ester of the present invention uses carboxylic acids having carbon chains of different lengths as a raw material, it is presumed that the pour point can be lowered and the lubricity and hydrolyzability can be improved because the packing property is low. Will be done.

From the above, it is presumed that the lubricating oil base oil containing the condensed ester of the present invention is excellent in heat resistance, lubricity, and hydrolysis resistance because the above mechanism works sufficiently.

The lubricating oil base oil of the present invention is a lubricating oil base oil containing a condensed ester of an alcohol (A) and a carboxylic acid (B), wherein the alcohol (A) contains trimethylol propane and the carboxylic acid. (B) contains a linear or branched saturated fatty acid (b1) having 7 carbon atoms, a linear or branched saturated fatty acid (b2) having 8 carbon atoms, and a linear or branched saturated fatty acid (b3) having 12 carbon atoms. .. The lubricating oil base oil of the present invention is the main component of the lubricating oil composition, and the viscosity of the lubricating oil composition can be obtained by blending with various lubricating oil additives that impart various functions to the lubricating oil composition. It refers to a compound that controls physical properties such as.

<Alcohol (A)>
The alcohol (A) contains trimethylolpropane.

In the alcohol (A), various monohydric alcohols or polyhydric alcohols can be appropriately used as alcohol components other than trimethylolpropane. The monohydric alcohol usually has 1 to 24 carbon atoms, and the carbon chain may be either linear or branched. As the polyhydric alcohol, those having 2 to 10 valences are usually used. The monohydric alcohol and the polyhydric alcohol may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, and 1, 4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,2-pentane Diol compounds such as diols, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol; trimethylolethane, 1,2,4-butanetriol, 1,3,5-pentanetriol, 1 , Triol compounds such as 2,6-hexanetriol; Tetraol compounds such as pentaerythritol; Multimers of trimethylolalkanes such as dipentaerythritol, tripentaerythritol; Polyglycerin such as glycerin, diglycerin, triglycerin, tetraglycerin Sugars such as sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol, xylose, arabinose, ribose, ramnorth, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, etc. Can be mentioned.

<Carboxylic acid (B)>
The carboxylic acid (B) is a linear or branched saturated fatty acid (b1) having 7 carbon atoms, a linear or branched saturated fatty acid (b2) having 8 carbon atoms, and a linear or branched saturated fatty acid (b3) having 12 carbon atoms. Contains.

Examples of the linear or branched saturated fatty acid (b1) having 7 carbon atoms include n-heptane (enanthic acid), 4,4-dimethylpentanoic acid, 2-methylhexanoic acid, 5-methylhexanoic acid and the like. Be done. The linear or branched saturated fatty acid (b1) having 7 carbon atoms is preferably n-heptanoic acid (enanthic acid) from the viewpoint of improving the heat resistance of the condensed ester. The linear or branched saturated fatty acid (b1) having 7 carbon atoms may be used alone or in combination of two or more.

Examples of the linear or branched saturated fatty acid (b2) having 8 carbon atoms include n-octanoic acid, 2,2-dimethylhexanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid and the like. The linear or branched saturated fatty acid (b2) having 8 carbon atoms is preferably 2-ethylhexanoic acid from the viewpoint of improving the heat resistance of the condensed ester. The linear or branched saturated fatty acid (b2) having 8 carbon atoms may be used alone or in combination of two or more.

Examples of the linear or branched saturated fatty acid (b3) having 12 carbon atoms include n-dodecanoic acid (lauric acid), 2-ethyldecanoic acid, 2-butyloctanoic acid and the like. The linear or branched saturated fatty acid (b3) having 12 carbon atoms is preferably n-dodecanoic acid (lauric acid) from the viewpoint of improving the heat resistance of the condensed ester. The linear or branched saturated fatty acid (b3) having 12 carbon atoms may be used alone or in combination of two or more.

In the carboxylic acid (B), the linear or branched saturated fatty acid (b1) having 7 carbon atoms, the linear or branched saturated fatty acid (b2) having 8 carbon atoms, and the linear or branched saturated fatty acid having 12 carbon atoms. As the carboxylic acid component other than (b3), various carboxylic acids (hereinafter, also referred to as other carboxylic acid compounds) can be appropriately used. Other carboxylic acid compounds include, for example, cycloalkanecarboxylic acids such as cyclohexanecarboxylic acid, cycloheptanecarboxylic acid and methylcyclohexanecarboxylic acid; aromatic carboxylic acids such as benzoic acid and naphthoic acid; capric acid, myristic acid and palmitic acid. , Stealic acid and the like.

Hereinafter, the blending amount of each component of the present invention will be described.

The ratio of trimethylolpropane in the alcohol (A) is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, from the viewpoint of improving the heat resistance and lubricity of the condensed ester. 98 mol% or more is even more preferable, and 100 mol% is even more preferable.

Among the carboxylic acids (B), the linear or branched saturated fatty acid (b1) having 7 carbon atoms, the linear or branched saturated fatty acid (b2) having 8 carbon atoms, and the linear or branched saturated fatty acid having 12 carbon atoms. The total ratio of (b3) is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, and 98 mol% or more from the viewpoint of improving the heat resistance and lubricity of the condensed ester. Even more preferred, 100 mol% is even more preferred.

The ratio of the linear or branched saturated fatty acid (b1) having 7 carbon atoms to the carboxylic acid (B) is from the viewpoint of maintaining the high lubricity of the condensed ester, lowering the pour point, and improving the hydrolysis resistance. It is preferably 1 mol% or more and 50 mol% or less. The ratio of the linear or branched saturated fatty acid (b1) having 7 carbon atoms in the carboxylic acid (B) is more preferably 5 mol% or more, further preferably 10 mol% or more from the viewpoint of lowering the flow point of the condensed ester. From the viewpoint of improving the hydrolysis resistance of the condensed ester, 45 mol% or less is more preferable, and 40 mol% or less is further preferable.

The ratio of the linear or branched saturated fatty acid (b2) having 8 carbon atoms in the carboxylic acid (B) is from the viewpoint of maintaining the high lubricity of the condensed ester, lowering the pour point, and improving the hydrolysis resistance. , 30 mol% or more and 90 mol% or less is preferable. The ratio of the linear or branched saturated fatty acid (b2) having 8 carbon atoms in the carboxylic acid (B) is more preferably 35 mol% or more, further preferably 40 mol% or more from the viewpoint of lowering the flow point of the condensed ester. From the viewpoint of improving the hydrolysis resistance of the condensed ester, 85 mol% or less is more preferable, and 80 mol% or less is further preferable.

The ratio of the linear or branched saturated fatty acid (b3) having 12 carbon atoms in the carboxylic acid (B) is 1 mol% or more and 30 mol from the viewpoint of improving the lubricity, hydrolysis resistance and heat resistance of the condensed ester. % Or less is preferable. The ratio of the linear or branched saturated fatty acid (b3) having 12 carbon atoms in the carboxylic acid (B) is more preferably 5 mol% or more from the viewpoint of improving the lubricity, hydrolysis resistance and heat resistance of the condensed ester. , 8 mol% or more is more preferable, and 28 mol% or less is more preferable, and 25 mol% or less is further preferable from the viewpoint of lowering the flow point of the condensed ester.

The total ratio of the linear or branched saturated fatty acid (b1) having 7 carbon atoms and the linear or branched saturated fatty acid (b2) having 8 carbon atoms in the carboxylic acid (B) provides high lubricity of the condensed ester. From the viewpoint of retaining, lowering the flow point, and improving heat resistance, it is preferably 60 mol% or more and 95 mol% or less. The total ratio of the linear or branched saturated fatty acid (b1) having 7 carbon atoms and the linear or branched saturated fatty acid (b2) having 8 carbon atoms in the carboxylic acid (B) is a viewpoint of lowering the flow point of the condensed ester. Therefore, 65 mol% or more is more preferable, 70 mol% or more is further preferable, and from the viewpoint of improving the heat resistance of the condensed ester, 93 mol% or less is more preferable, and 91 mol% or less is further preferable.

The ratio of the condensed ester in the lubricating oil base oil is preferably 50% by mass or more and 100% by mass or less, and more preferably 60% by mass or more, from the viewpoint of improving the heat resistance and lubricity of the condensed ester. , 70% by mass or more is further preferable, 80% by mass or more is further preferable, 90% by mass or more is further preferable, and 100% by mass is further preferable.

<Preparation method of condensed ester>
The condensed ester includes an alcohol (A) containing trimethylol propane, the linear or branched saturated fatty acid (b1) having 7 carbon atoms, the linear or branched saturated fatty acid (b2) having 8 carbon atoms, and the carbon. The carboxylic acid (B) containing the linear or branched saturated fatty acid (b3) of No. 12 can be prepared by carrying out an esterification reaction according to a known method. Further, in the condensed ester of the present invention, the linear or branched saturated fatty acid (b1) having 7 carbon atoms and the linear or branched saturated fatty acid (b2) having 8 carbon atoms are added to three hydroxyl groups in the molecule of trimetylolpropane. ), And at least a compound in which each carboxy group of the linear or branched saturated fatty acid (b3) having 12 carbon atoms is ester-bonded. Further, the linear or branched saturated fatty acid (b1) having 7 carbon atoms is enanthic acid, and the linear or branched saturated fatty acid (b2) having 8 carbon atoms is 2-ethylhexanoic acid, which has 12 carbon atoms. It is preferred that the linear or branched saturated fatty acid (b3) is lauric acid.

In the reaction of the alcohol (A) and the carboxylic acid (B), the equivalent ratio of the two is usually the carboxylic acid with respect to 1 equivalent of the hydroxyl group of the alcohol component of the alcohol (A) from the viewpoint of promoting the esterification reaction. The carboxy group of the carboxylic acid component (B) is adjusted to preferably 1.05 to 1.5 equivalents, more preferably 1.1 to 1.3 equivalents. When the ratio of the carboxy group of the carboxylic acid component of the carboxylic acid (B) is increased, the reactivity between the alcohol component and the carboxylic acid component becomes good, but after the reaction is completed, excess carboxylic acid (B) is added. Needs to be removed. Examples of the removing method include vacuum distillation, steaming, adsorption using an adsorbent, and removal.

From the viewpoint of ensuring lubricity at low temperatures, the condensed ester of the present invention preferably has a kinematic viscosity at 40 ° C., which will be described later, of 5 mm ² / s or more, and more preferably 10 mm ² / s or more. The thickness is preferably 50 mm ² / s or less, and more preferably 40 mm ² / s or less. Further, the condensed ester of the present invention preferably has a kinematic viscosity at 100 ° C., which will be described later, of 1 mm ² / s or more, and more preferably 3 mm ² / s or more, from the viewpoint of ensuring lubricity at high temperatures. Then, it is preferably 20 mm ² / s or less, and more preferably 10 mm ² / s or less.

Further, the condensed ester of the present invention preferably has a pour point, which will be described later, of −50 ° C. or lower from the viewpoint of ensuring lubricity at low temperatures.

<Lubricating oil composition>
The lubricating oil composition of the present invention contains the lubricating oil base oil.

If necessary, other additives can be added to the lubricating oil composition as long as the effects of the present invention are not impaired. Other additives include, for example, cleaning agents, dispersants, antioxidants, oiliness improvers, anti-wear agents, extreme pressure agents, rust inhibitors, corrosion inhibitors, metal defoamers, viscosity index improvers, etc. Examples include pour point depressants, defoamers, emulsifiers, anti-emulsifiers, antifungal agents, and solid lubricants.

The total amount of the other additives to be blended is usually 10 parts by mass or less, preferably 5 parts by mass or less, based on 100 parts by mass of the lubricating oil composition.

The lubricating oil composition of the present invention is a combustion system lubricating oil such as gasoline engine oil, diesel engine oil, marine engine oil; gear oil, automatic transmission oil, hydraulic oil, flame retardant hydraulic fluid, refrigerating machine oil, compressor oil, vacuum. It can be used as a non-combustible lubricating oil such as pump oil, bearing oil, insulating oil, turbine oil, sliding surface oil, rock drill oil, metal processing oil, plastic processing oil, heat treatment oil, and grease. Further, the lubricating oil composition of the present invention can be used for sliding portions such as rotary sliding such as sliding bearings, surface sliding such as thrust bearings, and sliding sliding such as splines, and clutch discs. It can be used for the lubrication method of the spline part of the transmission, the shaft and gear inner diameter bearing part of the transmission, the spline part of the hub sleeve, the part supported by metal of each part, the spline part of the change operation system, and the like.

Regarding the above-described embodiment, the present specification further discloses the following lubricating oil base oil and a lubricating oil composition containing the lubricating oil base oil.
<1> A lubricating oil base oil containing a condensed ester of an alcohol (A) and a carboxylic acid (B), wherein the alcohol (A) contains trimethylol propane and the carboxylic acid (B) is carbon. Lubricating oil base oil containing a linear or branched saturated fatty acid (b1) having the number 7, a linear or branched saturated fatty acid having 8 carbon atoms (b2), and a linear or branched saturated fatty acid (b3) having 12 carbon atoms.

<2> The linear or branched saturated fatty acid (b1) having 7 carbon atoms is preferably n-heptanoic acid (enanthic acid), 4,4-dimethylpentanoic acid, 2-methylhexanoic acid, or 5-methylhexanoic acid. The lubricating oil base oil according to <1>, wherein n-heptanic acid (enanthic acid) is more preferable.
<3> The linear or branched saturated fatty acid (b2) having 8 carbon atoms is preferably n-octanoic acid, 2,2-dimethylhexanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, and 2-ethylhexanoic acid. The lubricating oil base oil according to <1> or <2>, wherein an acid is more preferable.
<4> The linear or branched saturated fatty acid (b3) having 12 carbon atoms is preferably n-dodecanoic acid (lauric acid), 2-ethyldecanoic acid, or 2-butyloctanoic acid, and n-dodecanoic acid (lauric acid) is preferable. The lubricating oil base oil according to any one of <1> to <3>, which is more preferable.
<5> The ratio of trimethylolpropane in the alcohol (A) is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, further preferably 98 mol% or more, 100. The lubricating oil base oil according to any one of <1> to <4>, wherein mol% is even more preferable.
<6> In the carboxylic acid (B), the linear or branched saturated fatty acid (b1) having 7 carbon atoms, the linear or branched saturated fatty acid (b2) having 8 carbon atoms, and the linear or branched fatty acid having 12 carbon atoms. The total ratio of branched saturated fatty acids (b3) is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, further preferably 98 mol% or more, still more preferably 100 mol%. The lubricating base oil according to any one of <1> to <5>, which is preferable.
<7> The proportion of the linear or branched saturated fatty acid (b1) having 7 carbon atoms in the carboxylic acid (B) is preferably 1 mol% or more and 50 mol% or less, and 5 mol% or more. The lubricating oil base oil according to any one of <1> to <6>, wherein 10 mol% or more is more preferable, 45 mol% or less is more preferable, and 40 mol% or less is further preferable.
<8> The proportion of the linear or branched saturated fatty acid (b2) having 8 carbon atoms in the carboxylic acid (B) is preferably 30 mol% or more and 90 mol% or less, and 35 mol% or more. The lubricating oil base oil according to any one of <1> to <7>, wherein 40 mol% or more is more preferable, 85 mol% or less is more preferable, and 80 mol% or less is further preferable.
<9> The ratio of the linear or branched saturated fatty acid (b3) having 12 carbon atoms in the carboxylic acid (B) is preferably 1 mol% or more and 30 mol% or less, and 5 mol% or more. The lubricating oil base oil according to any one of <1> to <8>, more preferably 8 mol% or more, still more preferably 28 mol% or less, still more preferably 25 mol% or less.
<10> The total ratio of the linear or branched saturated fatty acid (b1) having 7 carbon atoms and the linear or branched saturated fatty acid (b2) having 8 carbon atoms to the carboxylic acid (B) is 60 mol% or more. It is preferably 95 mol% or less, more preferably 65 mol% or more, further preferably 70 mol% or more, still more preferably 93 mol% or less, still more preferably 91 mol% or less. The lubricating base oil described in any of>.
<11> The condensed ester has three hydroxyl groups in the molecule of trimetylolpropane, the linear or branched saturated fatty acid having 7 carbon atoms (b1), and the linear or branched saturated fatty acid having 8 carbon atoms (b2). The lubricating oil base oil according to <1>, which is a compound in which each carboxy group of the linear or branched saturated fatty acid (b3) having 12 carbon atoms is ester-bonded.
<12> The linear or branched saturated fatty acid (b1) having 7 carbon atoms is enanthic acid, the linear or branched saturated fatty acid (b2) having 8 carbon atoms is 2-ethylhexanoic acid, and the 12 carbon atoms. The lubricating oil base oil according to <11> above, wherein the linear or branched saturated fatty acid (b3) is lauric acid.
<13> The proportion of the condensed ester in the lubricating oil base oil is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more, further preferably 70% by mass or more, and 80% by mass or more. The lubricating oil base oil according to any one of <1> to <12>, wherein the mass% or more is more preferable, 90% by mass or more is further preferable, and 100% by mass is further preferable.
<14> A lubricating oil composition containing the lubricating oil base oil according to any one of <1> to <13>.
<15> Use of the lubricating oil composition according to <14> above for sliding parts.
<16> A lubrication method using the lubricating oil composition according to <14>.

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples.

<Synthesis example 1>
<Preparation of condensed ester>
81.3 g of heptanoic acid (n-heptanoic acid) and 372.0 g of 2-ethylhexanoic acid as carboxylic acid (B) in a 1-liter four-necked flask equipped with a stirrer, a thermometer, a nitrogen blowing tube and a cooling tube. , 191.7 g of lauric acid (n-dodecanoic acid) was added, and 155.1 g of trimethylol propane was added as alcohol (A). The amount of the carboxylic acid (B) added was such that the total carboxy group of the carboxylic acid (B) was 1.2 equivalents with respect to 1 equivalent of the hydroxyl group of the alcohol (A).

Next, nitrogen gas was blown into the flask, the temperature was raised to 250 ° C. with stirring, the temperature was maintained at 250 ° C. for 18 hours, and the distilled water was removed from the flask using a cooling tube. After completion of the reaction, excess carboxylic acid component was distilled off under a reduced pressure of 0.13 kPa, steaming was performed for 1 hour under a reduced pressure of 0.13 kPa, and an adsorbent (trade name: Kyoward 500SH, Kyowa Chemical Industry Co., Ltd.) After adsorbing the carboxylic acid component remaining on the product), filtration was performed to obtain a condensed ester 1.

<Synthesis Examples 2-14>
Condensation esters 2 to 14 were prepared in the same manner as in Synthesis Example 1 except that the types of each raw material and the blending amount thereof were changed as shown in Table 1.

<Examples 1 to 7, Comparative Examples 1 to 11>
The condensed esters 1 to 14 obtained above are used, and if necessary, two or more kinds of condensed esters are mixed in the blending amounts shown in Table 2, and as shown in Table 2, Examples 1 to 7 and Lubricating oil base oils of Comparative Examples 1 to 11 were prepared. The following evaluation was performed on the obtained lubricating oil base oil. The evaluation results are shown in Table 2.

<Evaluation of lubricity>
For the evaluation of lubricity, a friction and wear test conforming to ASTM D6425 was performed, a load of up to 1500 N was applied, and seizure was confirmed. In Table 2, the case where the product does not seize at a load of 1500 N is indicated as A, and the case where the product is seized up to a load of 1500 N is indicated as B.

<Evaluation of kinematic viscosity>
For evaluation of kinematic viscosity, 40 ° C kinematic viscosity and 100 ° C kinematic viscosity (mm ² / s) are measured with a Stavinger kinematic viscometer (trade name: SVM3000, manufactured by Antonio Par) that meets the accuracy required by ASTM D7042. did.

<Evaluation of pour point>
For the evaluation of the pour point, the pour point (° C.) was measured by a measuring method based on JIS K2269. In Table 2, when the pour point is −50 ° C. or lower, it is indicated as A, and when it is solid at 25 ° C., it is indicated as B.

<Evaluation of hydrolysis resistance>
To evaluate the hydrolysis resistance, add 10 mL of a 2 mass% sodium hydroxide aqueous solution and 10 mL of the lubricating oil base oil obtained above to a 25 mL screw cap test tube. After premixing the aqueous phase and the oil phase by tightening the screw caps and reversing the top and bottom three times, the mixture was shaken up and down 30 times within 1 minute with a swing width of about 30 cm. After shaking, the test tube was allowed to stand, and the inside of the test tube was observed 5 minutes and 10 minutes later, and evaluated according to the following criteria. This test shows the superiority or inferiority of hydrolysis resistance by the following mechanism. The fact that the interface between the aqueous phase and the oil phase is emulsified and the boundary becomes unclear means that the soap is produced by hydrolysis in a short time, or it is easily hydrolyzed by being easily mixed with water. .. Therefore, Evaluation A, which separates immediately after shaking, is excellent in hydrolysis resistance.
A: The boundary between the aqueous phase and the oil phase is clear within 5 minutes, and each phase separates into 10 mL. B: The boundary between the aqueous phase and the oil phase becomes clear within 5 to 10 minutes, and each phase is 10 mL each. C: The boundary between the aqueous phase and the oil phase is not clear even after 10 minutes or more.

<Evaluation of heat resistance>
The heat resistance is evaluated using a differential thermogravimetric simultaneous measuring device (trade name: TG / DTA6200, manufactured by Seiko Instruments Co., Ltd.) under an atmosphere of 250 mL / min of nitrogen and air, and 550 ° C at 35 ° C to 10 ° C / min. The thermal response of the lubricating base oil was measured under the condition that the temperature was raised to 550 ° C. and the temperature was maintained for 10 minutes, and the residual ratio (mass%) was calculated by the following formula. The larger the residual rate value, the better the heat resistance.
Formula: Residual rate (mass%) = mass at 350 ° C / mass at 35 ° C x 100

In Table 1, each raw material is trimethylolpropane (manufactured by Tokyo Chemical Industry Co., Ltd.);
Pentaerythritol (manufactured by Tokyo Chemical Industry Co., Ltd.);
Heptanoic acid (n-heptane, manufactured by Tokyo Chemical Industry Co., Ltd.);
Caprylic acid (n-octanoic acid, manufactured by Tokyo Chemical Industry Co., Ltd.);
2-Ethylhexanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.);
3,5,5-trimethylhexanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.);
Lauric acid (manufactured by Nacalai Tesque, Inc.);
Stearic acid (manufactured by Nacalai Tesque, Inc.);

Claims (14)

A lubricating oil base oil containing a condensed ester of an alcohol (A) and a carboxylic acid (B).
The alcohol (A) contains trimethylolpropane and
The carboxylic acid (B) is a linear or branched saturated fatty acid (b1) having 7 carbon atoms, a linear or branched saturated fatty acid (b2) having 8 carbon atoms, and a linear or branched saturated fatty acid (b3) having 12 carbon atoms. Lubricating oil base oil characterized by containing. The lubricating oil base oil according to claim 1, wherein the linear or branched saturated fatty acid (b1) having 7 carbon atoms is enanthic acid. The lubricating oil base oil according to claim 1 or 2, wherein the linear or branched saturated fatty acid (b2) having 8 carbon atoms is 2-ethylhexanoic acid. The lubricating oil base oil according to any one of claims 1 to 3, wherein the linear or branched saturated fatty acid (b3) having 12 carbon atoms is lauric acid. One of claims 1 to 4, wherein the ratio of the linear or branched saturated fatty acid (b1) having 7 carbon atoms in the carboxylic acid (B) is 1 mol% or more and 50 mol% or less. The lubricating base oil described. One of claims 1 to 5, wherein the ratio of the linear or branched saturated fatty acid (b2) having 8 carbon atoms in the carboxylic acid (B) is 30 mol% or more and 90 mol% or less. The lubricating base oil described. One of claims 1 to 6, wherein the ratio of the linear or branched saturated fatty acid (b3) having 12 carbon atoms in the carboxylic acid (B) is 1 mol% or more and 30 mol% or less. The lubricating base oil described. The ratio of the linear or branched saturated fatty acid (b1) having 7 carbon atoms to the carboxylic acid (B) is 10 mol% or more and 40 mol% or less, and the linear or branched saturated fatty acid (b2) having 8 carbon atoms is used. ) Is 30 mol% or more and 80 mol% or less, and the ratio of the linear or branched saturated fatty acid (b3) having 12 carbon atoms is 5 mol% or more and 30 mol% or less. The lubricating base oil according to any one of claims 1 to 7. The lubricating oil base oil according to any one of claims 1 to 8, wherein the ratio of the condensed ester in the lubricating oil base oil is 50% by mass or more and 100% by mass or less. The condensed ester has three hydroxyl groups in the molecule of trimetylolpropane, the linear or branched saturated fatty acid (b1) having 7 carbon atoms, the linear or branched saturated fatty acid (b2) having 8 carbon atoms, and the carbon. The lubricating oil base oil according to claim 1, wherein each carboxy group of the linear or branched saturated fatty acid (b3) of No. 12 is an ester-bonded compound. The linear or branched saturated fatty acid (b1) having 7 carbon atoms is enanthic acid, the linear or branched saturated fatty acid (b2) having 8 carbon atoms is 2-ethylhexanoic acid, and the linear chain having 12 carbon atoms. The lubricating base oil according to claim 10, wherein the branched saturated fatty acid (b3) is lauric acid. A lubricating oil composition containing the lubricating oil base oil according to any one of claims 1 to 11. Use of the lubricating oil composition according to claim 12 for sliding portions. A lubrication method using the lubricating oil composition according to claim 12.