Compounding agent for lubricating oil, method for manufacturing the same, and lubricating oil

Abstract

The present invention provides a compound for lubricating oils that exhibits excellent fluidity while minimizing the degradation of rubber and resins in the operating environment, as well as a method for producing the same and a lubricating oil. [Solution] The lubricating oil compound of the present invention contains an ester complex whose constituent components are (A) dimer acid, (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms, and (C) a monohydric fatty acid or monohydric alcohol, with a weight-average molecular weight Mw of 2750 to 15000. The lubricating oil compound of the present invention also contains an ester complex whose constituent components are (A) dimer acid, (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms, and (C) a monohydric fatty acid or monohydric alcohol, with a molar ratio of (A) dimer acid to (B) dihydric alcohol of 0.5 to 1.5:1.

Description

[Technical Field]

[0001] This invention relates to a compound for lubricating oils, a method for producing the same, and lubricating oils. [Background technology]

[0002] Traditionally, ester-based synthetic lubricants have been used as lubricants with good lubrication properties due to their excellent thermal and oxidative stability, high flash point, and low pour point, resulting in a wide operating temperature range.

[0003] Among these, ester complexes obtained from the reaction of polyhydric alcohols, polybasic acids, and aliphatic monohydric alcohols (and / or aliphatic monocarboxylic acids) have been undergoing development in recent years because they can improve upon the shortcomings of conventional synthetic lubricants, such as their susceptibility to hydrolysis, heat resistance, and viscosity index.

[0004] Various ester complex synthetic lubricants have been investigated to date, addressing issues such as excellent thermal and oxidative stability, high flash point, and low pour point. For example, Patent Document 1 describes an aliphatic polyester for lubricating oil base oils with a kinematic viscosity of 3 to 50 cSt at 100°C, obtained by condensing an ester polymer obtained by condensing a saturated aliphatic dicarboxylic acid or its derivative having 4 to 10 carbon atoms in the main chain with at least two diols selected from saturated aliphatic diols having 4 to 8 carbon atoms in the main chain, and then terminally modifying the polymer with an alcohol having 6 to 10 carbon atoms in the main chain. Patent Document 2 describes an alcohol component containing 90% or more by weight of trimethylolpropane, a monovalent fatty acid having 8 to 12 carbon atoms and adipic acid, and a total of 90% by weight of caprylic acid and / or capric acid. A lubricating oil base oil comprising a synthetic ester obtained by reacting a monovalent fatty acid having 8 to 12 carbon atoms, containing % or more of adipic acid, with a carboxylic acid component containing 90% or more by weight in total adipic acid, wherein the molar ratio of adipic acid to trimethylolpropane (adipic acid / trimethylolpropane) is 0.65 to 0.74, the acid value of the synthetic ester is 1 mg KOH / g or less, and the hydroxyl value is 10 to 70 mg KOH / g. Patent Document 3 proposes a complex ester obtained by esterifying (A) pentaerythritol, (B) aliphatic dicarboxylic acid having 6 to 10 carbon atoms, (C) oleic acid, and (D) linear or branched aliphatic monocarboxylic acid having 6 to 10 carbon atoms in a specific molar ratio. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-80332 [Patent Document 2] Japanese Patent Publication No. 2012-102235 [Patent Document 3] Japanese Patent Publication No. 2020-66645 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in some environments where lubricants are used, the components that come into contact with the lubricant may contain rubber or resin, and the lubricant can accelerate the swelling and deterioration of these materials, which is a problem.

[0007] This invention has been made in view of the above circumstances, and aims to provide a lubricating compound, a method for producing the same, and a lubricating oil that has excellent fluidity and causes little deterioration of rubber and resin in the usage environment. [Means for solving the problem]

[0008] To solve the above problems, the inventors conducted diligent research and found that by using a lubricating compound containing an ester complex whose constituent components are (A) dimer acid, (B) aliphatic dihydric alcohol having 2 to 8 carbon atoms, and (C) monohydric fatty acid or monohydric alcohol, with a weight-average molecular weight Mw within a specific range, and an ester complex using (A) dimer acid and (B) aliphatic dihydric alcohol having 2 to 8 carbon atoms in a specific molar ratio, it is possible to obtain a lubricating oil that has excellent fluidity and causes less deterioration of rubber and resin in the operating environment, thus completing the present invention.

[0009] In other words, the lubricating oil compound of the present invention is characterized by containing an ester complex whose constituent components are (A) a dimer acid, (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms, and (C) a monohydric fatty acid or monohydric alcohol, with a weight-average molecular weight Mw of 2750 to 15000. The lubricating oil compound of the present invention is characterized by containing an ester complex in which the constituent components are (A) a dimer acid, (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms, and (C) a monohydric fatty acid or monohydric alcohol, and the molar ratio of (A) dimer acid to (B) dihydric alcohol is 0.5 to 1.5:1. The lubricating oil of the present invention contains the above-mentioned compounding agent for lubricating oil. The present invention provides a method for producing a lubricating compound, comprising the steps of (A) reacting a dimer acid with (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms to obtain an intermediate, and The present invention is characterized by a step of reacting the aforementioned intermediate with an excess amount of (C) monohydric fatty acid or monohydric alcohol, recovering the unreacted (C) monohydric fatty acid or monohydric alcohol, and obtaining an ester complex having a weight-average molecular weight Mw of 2750 to 15000. The present invention provides a method for producing a lubricating compound, comprising the steps of: reacting (A) a dimer acid with (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms in a molar ratio of 0.5 to 1.5:1 to obtain an intermediate; The present invention is characterized by comprising the step of reacting the aforementioned intermediate with an excess amount of (C) monohydric fatty acid or monohydric alcohol, recovering the unreacted (C) monohydric fatty acid or monohydric alcohol, and obtaining an ester complex. [Effects of the Invention]

[0010] According to the present invention, the lubricating oil compound and the lubricating oil using it have excellent fluidity while causing less deterioration of rubber and resin in the operating environment. [Modes for carrying out the invention]

[0011] Specific embodiments of the present invention will be described below. (Formulating agent for lubricating oils) The lubricating oil compound of the present invention comprises an ester complex whose constituent components are (A) a dimer acid, (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms, and (C) a monohydric fatty acid or monohydric alcohol.

[0012] In the lubricating oil compound of the present invention, the term ester complex (complex ester) is recognized in the field of lubricants and is obtained by reacting components (A), (B), and (C). In particular, it is obtained by a step of reacting (A) a dimer acid with (B) an aliphatic dihydric alcohol to obtain an intermediate, and a step of reacting this intermediate with an excess amount of (C) a monohydric fatty acid or monohydric alcohol. Conceptually, it is a polyester formed by sealing the ends of a polyester of (A) a dimer acid, which is mainly a dibasic acid, and (B) a dihydric alcohol, which is a diol, with component (C). However, regarding the molecular structure of the final product, the ester complex, it is difficult to accurately determine the composition if the molar ratio of components (A) and (B) is different, and it is difficult to accurately determine the composition because (A) a dimer acid may contain acids other than dibasic acids, and the sealing of the ends by component (C) may not be complete and it has an acid value and a hydroxyl value, so it is difficult to express it with a general formula (structure) or to directly identify it by its properties. Even if molecular weight and other properties can be determined to some extent, it is impossible or impractical to directly identify the substance based on its precise structure or properties. Furthermore, there is no other terminology that clearly identifies the above-mentioned characteristics structurally or property-wise. Identifying the structure or properties of such ester complexes through measurement-based analysis is also impossible, given the analytical technology available at the time of filing this application, as appropriate measurement and analysis methods did not exist. Even if the structure or properties of the ester complex could be measured, it would require numerous difficult operations and measurements, and a great deal of trial and error to find indicators that identify the above-mentioned characteristics, making it highly impractical.

[0013] In the compounding agent for lubricating oil of the present invention, the (A) dimer acid constituting the ester complex is a dimer of a fatty acid having an unsaturated bond. Preferably, it is a fatty acid containing a dibasic acid (dicarboxylic acid) produced by dimerization of an unsaturated fatty acid using vegetable oil and fat as a raw material as a main component and containing a monobasic acid and / or a tribasic acid. The (A) dimer acid may be either a chain aliphatic compound or an alicyclic compound. Here, the alicyclic compound contains one or more saturated or unsaturated carbocyclic rings having no aromaticity and may have a chain aliphatic branch. In the present invention, examples of the fatty acid having an unsaturated bond that is a raw material for the (A) dimer acid include unsaturated fatty acids having 18 to 22 carbon atoms, such as oleic acid (C18:1), linoleic acid (C18:2), eicosenoic acid (C20:1), erucic acid (C22:1), and the like. The dibasic acid having 36 carbon atoms, which is a chain aliphatic compound or an alicyclic compound produced by dimerization of an unsaturated fatty acid having 18 carbon atoms, is preferable from the viewpoint of being easily compatible with suppression of deterioration of rubber and resin and fluidity in the use environment. The (A) dimer acid may be used alone or in combination of two or more.

[0014] In the compounding agent for lubricating oil of the present invention, the (B) aliphatic dihydric alcohol constituting the ester complex is not particularly limited, but the number of carbon atoms is 2 to 8, and 2 to 5 is preferable. The (B) aliphatic dihydric alcohol may be linear, branched, or cyclic, that is, it may be either a chain aliphatic alcohol or an alicyclic alcohol. Specific examples of the (B) aliphatic dihydric alcohol include ethylene glycol, propylene glycol, trimethylene glycol, butanediol, heptanediol, cyclopentanediol, neopentyl glycol, hexanediol, cyclohexanediol, heptanediol, octanediol, cyclohexanedimethanol, and the like. Among them, neopentyl glycol is preferable. The (B) aliphatic dihydric alcohol may be used alone or in combination of two or more.

[0015] In the lubricating oil compound of the present invention, the monohydric alcohol among the (C) monohydric fatty acid or monohydric alcohol constituting the ester complex is not particularly limited, but an aliphatic monohydric alcohol is preferred. The aliphatic monohydric alcohol may be linear, branched, or cyclic, that is, it may be either a chain-type aliphatic alcohol or an alicyclic alcohol, but linear or branched types are preferred. It may also be used alone or in combination of two or more types.

[0016] Examples of linear aliphatic monohydric alcohols include methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, allyl alcohol, hexenol, heptenol, octenol, nonenol, and others.

[0017] Examples of branched-chain aliphatic monohydric alcohols include 2-propanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 4-methyl-1-pentanol, 2-methyl-2-pentanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-3-pentanol, 2,2-dimethyl-1-butanol, 2,3-dimethyl-1-butanol, 3,3-dimethyl-1-butanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-heptanol, 3-heptanol, 4-heptanol, isooctyl alcohol, 2-ethylhexanol, isononanol, isodecanol, isoundecanol, isododecanol, isostearyl alcohol, and the like.

[0018] From the viewpoint of having a low boiling point and facilitating the removal of the excess alcohol component during the production of the ester complex, the number of carbon atoms of the aliphatic monohydric alcohol is preferably 10 or less, more preferably 8 or less. Also, from the viewpoint of reactivity during the production of the ester complex, the number of carbon atoms is preferably 2 or more, more preferably 4 or more. The aliphatic monohydric alcohol may be either linear or branched-chain, but is more preferably branched-chain from the viewpoint of the fluidity of the ester complex.

[0019] In the compounding agent for lubricating oil of the present invention, among the (C) monohydric fatty acids or monohydric alcohols constituting the ester complex, the monohydric fatty acids are not particularly limited and may be linear, branched-chain, or cyclic, that is, either chain aliphatic alcohols or alicyclic alcohols, but linear and branched-chain are preferred. Also, it may be used alone or in combination of two or more.

[0020] Examples of linear monounsaturated fatty acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentagonal acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, henicosyl acid, behenic acid, tricosylic acid, lignoceric acid, acrylic acid, crotonic acid, pentenoic acid, hexenoic acid, heptenic acid, octenic acid, nonenic acid, 10-hydroxy-2-decenoic acid, undecenoic acid, dodecenoic acid, myristoleic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, and nervonic acid.

[0021] Examples of branched-chain monounsaturated fatty acids include isobutyric acid, isovaleric acid, isocaproic acid, isocaprylic acid, 2-ethylhexanoic acid, isocapric acid, isolauric acid, isopalmitic acid, and isostearic acid.

[0022] From the viewpoint of having a low boiling point and facilitating the removal of excess fatty acid components during the production of the ester complex, the number of carbon atoms in the monounsaturated fatty acid is preferably 10 or less, and more preferably 8 or less. Furthermore, from the viewpoint of reactivity during the production of the ester complex, the number of carbon atoms is preferably 2 or more, and more preferably 4 or more. The monounsaturated fatty acid may be linear or branched, but from the viewpoint of the fluidity of the ester complex, it is more preferable to be branched.

[0023] In the lubricating oil compound of the present invention, the ester complex has a weight-average molecular weight Mw of 2750 to 15000. From the viewpoint of thermal and oxidative stability and the effect on rubber and resin, the weight-average molecular weight Mw is preferably 2750 or higher, and more preferably 3000 or higher. From the viewpoint of the handling properties of the lubricating oil compound, the weight-average molecular weight Mw is preferably 15000 or lower, and more preferably 10000 or lower. The weight-average molecular weight Mw of an ester complex can be determined, for example, by comparing it with a standard substance of known molecular weight using gel permeation chromatography (GPC), specifically under the following apparatus and conditions. [GPC measurement device] Column: SHODEX Corporation Detector: RI-930, manufactured by JASCO Corporation, a radioisotope detector for liquid chromatography. [Measurement conditions] Solvent: Chloroform (special grade) Measurement temperature: 50℃ Flow rate: 0.5ml / min Sample concentration: 15 mg / ml Injection volume: 2μl Calibration curve: Universal Calibration Analysis program: ChromNAV (Ver.1.19.02)

[0024] In addition, from another perspective, in the lubricating oil compound of the present invention, the ester complex has a molar ratio of (A) dimer acid to (B) aliphatic dihydric alcohol having 2 to 8 carbon atoms of 0.5 to 1.5:1. From the viewpoint of keeping the kinematic viscosity low and improving handling properties, the molar ratio is preferably 1.1 to 1.5:1, more preferably 1.15 to 1.5:1, and even more preferably 1.2 to 1.5:1. Furthermore, from the viewpoint of increasing thermal and oxidative stability and flash point, the molar ratio is preferably 0.6 to 1.4:1, more preferably 0.7 to 1.3:1, and even more preferably 0.75 to 1.25:1.

[0025] In the lubricating oil compound of the present invention, the content of the ester complex is not particularly limited. The lubricating oil compound of the present invention can be used as a base oil and an additive for lubricating oil. For example, when used as a base oil for lubricating oil, the content may be increased, and the content of the ester complex may be 100% by mass. When used as an additive for lubricating oil, it may be used as a mixture with other additives (for example, those exemplified as other components in lubricating oil described later), and the lubricating oil compound of the present invention only needs to contain at least the ester complex. For example, the lubricating oil compound of the present invention may be used as one of the additives exemplified as other components in lubricating oil described later. From the viewpoint of lubricity, etc., the content of the ester complex in the lubricating oil compound of the present invention can be, for example, 0.01 to 99.99% by mass, preferably 0.1 to 99.99% by mass, more preferably 1 to 99.99% by mass, and even more preferably 10 to 99.99% by mass.

[0026] In the lubricating oil compound of the present invention, the acid value is not particularly limited, but from the viewpoint of stability over time, it is preferably 15 mg·KOH / g or less, more preferably 10 mg·KOH / g or less, even more preferably 5 mg·KOH / g or less, and particularly preferably 3 mg·KOH / g or less.

[0027] In the lubricating oil compound of the present invention, the hydroxyl value is not particularly limited, but from the viewpoint of compatibility with other additives such as lubricating oils, it is preferably 45 mg·KOH / g or less, more preferably 40 mg·KOH / g or less, and even more preferably 30 mg·KOH / g or less.

[0028] In the lubricating oil compound of the present invention, the kinematic viscosity at 40°C is not particularly limited, but from the viewpoint of achieving both thermal and oxidative stability and the handling properties of the lubricating oil compound, it is 250 to 10000 mm. 2 / s is preferred, and 400~5000mm 2 / s is preferable.

[0029] In the lubricating oil compound of the present invention, the kinematic viscosity at 100°C is not particularly limited, but from the viewpoint of achieving both thermal and oxidative stability and the handling properties of the lubricating oil compound, it is 20 to 500 mm. 2 / s is preferred, 40-300mm 2 / s is preferable.

[0030] In the lubricating oil compound of the present invention, the viscosity index is not particularly limited, but from the viewpoint of lubrication performance when used at high temperatures, it is preferably 140 or higher, and more preferably 180 or higher.

[0031] In the lubricating oil compound of the present invention, the flash point is not particularly limited, but under the Fire Service Act, lubricating oils with a flash point of 250°C or higher are removed from the designation of Class 4 hazardous materials and become flammable liquids, which relaxes regulations on storage and handling. For example, they are exempt from installation permits and the appointment of hazardous materials safety supervisors, and standards for open space, fire extinguishing equipment, alarm equipment, etc., are relaxed. From the viewpoint of being able to raise the overall flash point of the composition when mixed with other lubricating oils or other additives, a flash point of 250°C or higher is preferred.

[0032] In the lubricating oil compound of the present invention, the pour point is not particularly limited, but from the viewpoint of handling properties, 0°C or lower is preferred.

[0033] In the lubricating oil compound of the present invention, the heat resistance temperature is not particularly limited, but it may be used in environments requiring extreme thermal conditions. In such environments, a rapid decrease in lubricity due to oil film breakdown and the resulting failure of the equipment used can occur, so a heat resistance temperature of 300°C or higher is preferred, and 350°C or higher is more preferred. Here, the heat resistance temperature refers to the 50% thermal decomposition temperature when the thermal decomposition curve is measured by thermogravimetric analysis (TGA) under conditions of room temperature to 500°C with a heating rate of 5°C / min.

[0034] In the lubricating oil compound of the present invention, the oxidation induction time (OIT) is not particularly limited, but from the viewpoint of use at high temperatures in the presence of oxygen and long-term stability, 40 minutes or more is preferred. Here, OIT refers to the time required for the oxygen partial pressure to decrease by 10% at an oxygen partial pressure of 700 kPa and 140°C.

[0035] In the lubricating oil compound of the present invention, the volume change rate (swelling rate, shrinking rate) when immersed in rubber or resin is not particularly limited, but from the viewpoint of preventing deterioration of rubber or resin (processing base material, packing, etc.) in the usage environment, a swelling rate of 10% or less and a shrinking rate of -5% or more are preferred. Here, the swelling rate and shrinking rate for rubber and resin are values ​​measured by the method described in the examples.

[0036] (Method of manufacturing compounding agent for lubricating oil) The method for producing the lubricating oil compound of the present invention comprises the following steps 1 and 2: Step 1: A step in which a dimer acid and an aliphatic dihydric alcohol having 2 to 8 carbon atoms are reacted to obtain an intermediate. Step 2: The intermediate is reacted with an excess amount of (C) monohydric fatty acid or monohydric alcohol, and the unreacted (C) monohydric fatty acid or monohydric alcohol is recovered to obtain an ester complex.

[0037] In one embodiment of the present invention, in step 1, (A) a dimer acid and (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms are reacted in a molar ratio of 0.5 to 1.5:1 to obtain an intermediate. In another embodiment of the present invention, in step 2, the intermediate is reacted with an excess amount of (C) a monohydric fatty acid or monohydric alcohol, and then the unreacted (C) monohydric fatty acid or monohydric alcohol is recovered to obtain an ester complex having a weight-average molecular weight Mw of 2750 to 15000. Alternatively, any of these embodiments may be applied.

[0038] Step 1 can be carried out, for example, by charging (A) a dimer acid and (B) an aliphatic dihydric alcohol into a reaction vessel and reacting them under an inert gas atmosphere, preferably at 230-250°C, more preferably at 235-245°C, for preferably 3-10 hours, more preferably 4-7 hours. In Step 1, a (poly)ester of (A) the dimer acid and (B) the aliphatic dihydric alcohol is produced as an intermediate.

[0039] Step 2 involves adding an excess amount of (C) monohydric fatty acid or monohydric alcohol to the generated ester complex intermediate, and carrying out the reaction under heating and reflux in an inert gas atmosphere. If the molar ratio of (A) dimer acid to (B) aliphatic dihydric alcohol is large in Step 1, a monohydric alcohol is used as component (C), and the reaction is carried out by adding it in such an excess that its hydroxyl groups are in proportion to the carboxyl groups of the intermediate. If the molar ratio of (B) aliphatic dihydric alcohol to (A) dimer acid is large in Step 1, a monohydric fatty acid is used as component (C), and the reaction is carried out by adding it in such an excess that its carboxyl groups are in proportion to the hydroxyl groups of the intermediate. The reaction can be carried out preferably at 150 to 250°C, more preferably at 180 to 240°C, for preferably 5 to 10 hours, more preferably 6 to 9 hours. For example, the endpoint can be set using the acid value of the ester complex that changes during the reaction as an indicator. When recovering unreacted (C) monohydric fatty acids or monohydric alcohols, this can be done by distillation under reduced pressure, preferably at 120-250°C, more preferably at 150-240°C, for preferably 2-10 hours, more preferably 3-7 hours. For example, the endpoint can be set using the hydroxyl value of the ester complex that changes during the reaction as an indicator.

[0040] (lubricating oil) The lubricating oil of the present invention contains the lubricating oil compound described above. The lubricating oil of the present invention may be used as a lubricating oil with the lubricating oil compound alone, but may also contain other components as needed. Other components are not particularly limited, but examples include base oils for lubricating oils and components known as additives for lubricating oils. Specifically, examples of other components include other lubricating oils (base oils) other than the ester complex, solvents, and additives such as surfactants, antioxidants, rust inhibitors, corrosion inhibitors, extreme pressure agents, anti-wear agents, defoaming agents, anti-emulsifiers, oiliness agents, viscosity index improvers, pour point depressants, and detergent dispersants. These other components may be used individually or in combination of two or more. Each of these other components may also be used individually or in combination of two or more.

[0041] Other lubricants (base oils) besides the ester complex can be conventionally known lubricants, specifically hydrocarbon oils, mineral oils, synthetic esters, animal and vegetable oils, etc.

[0042] As the aforementioned solvent, for example, conventionally known solvents can be used, specifically, hydrocarbons such as hexane and heptane, alcohols such as methanol and ethanol, and water.

[0043] Examples of surfactants among the additives include anionic surfactants, amphoteric surfactants, nonionic surfactants, and cationic surfactants. Examples of anionic surfactants include alkyl sulfates, alkyl ether sulfates, alkyl phosphates, alkyl ether phosphates, and alkyl ether acetates. Examples of amphoteric surfactants include aminoacetic acid betaine, amidopropyl betaine, and imidazolinium betaine. Examples of nonionic surfactants include alkyl glucosides, fatty acid alkanolamides, alkylamine oxides, polyoxyalkylene fatty acid polyhydric alcohol esters, polyoxyalkylene hydrogenated castor oil, fatty acid polyhydric alcohol esters, and polyoxyalkylene alkyl ethers.

[0044] Examples of antioxidants include benzotriazole compounds, toltriazole compounds, thiadiazole compounds, and imidazole compounds.

[0045] Examples of rust inhibitors and corrosion inhibitors include sorbitan fatty acid esters, neutral alkali metal or alkaline earth metal sulfonates, neutral alkali metal or alkaline earth metal phenates, neutral alkali metal or alkaline earth metal salicylates, thiadiazoles, and benzotriazoles.

[0046] Examples of extreme pressure agents include sulfur compounds such as sulfurized oils, sulfurized esters, sulfurized olefins, dialkyl polysulfides, diarylalkyl polysulfides, and diaryl polysulfides, as well as phosphorus compounds such as phosphate esters, thiophosphate esters, phosphite esters, alkyl hydrogen phosphites, phosphate ester amine salts, and phosphite ester amine salts.

[0047] Examples of anti-wear agents include zinc dithiophosphate (ZnDTP), zinc dithiocarbamate (ZnDTC), molybdenum oxydithiophosphate (MoDTP), and molybdenum oxydithiocarbamate (MoDTC).

[0048] Examples of antifoaming agents include silicones, alkenyl succinic acid derivatives, esters of polyhydroxyaliphatic alcohols and long-chain fatty acids, methyl salicylate, o-hydroxybenzyl alcohol, aluminum stearate, potassium oleate, N-dialkyl-allylamine nitroamino alkanol, aromatic amine salts of isoamyloctyl phosphate, alkylalkylene diphosphates, metal derivatives of thioethers, metal derivatives of disulfides, fluorinated compounds of aliphatic hydrocarbons, triethylsilane, dichlorosilane, alkylphenyl polyethylene glycol ether sulfide, and fluoroalkyl ethers.

[0049] Examples of anti-emulsifiers include polyoxyalkylene glycol, polyoxyalkylene alkyl ether, polyoxyalkylene alkylamide, and polyoxyalkylene fatty acid ester.

[0050] Examples of oily agents include alcohols, fatty acids, and fatty acid esters.

[0051] Examples of viscosity index improvers include polymethacrylate, dispersed polymethacrylate, and olefin copolymers (e.g., ethylene-propylene copolymer).

[0052] Examples of pour point depressants include polyalkyl (meth)acrylate, polyalkylstyrene, polystyrene-(meth)acrylate, polyvinyl acetate, polyethylene-vinyl acetate, and the like.

[0053] Examples of cleaning and dispersing agents include metal sulfonates, metal salicylates, metal phenates, alkenyl succinimides, and alkenyl succinate esters.

[0054] The content of the lubricating oil compound of the present invention in the lubricating oil of the present invention is not particularly limited. The lubricating oil compound of the present invention can be used as a base oil and an additive in the lubricating oil of the present invention. For example, when used as a base oil of the lubricating oil, the content may be increased, and the content of the lubricating oil compound of the present invention may be 100% by mass. When used as a base oil or an additive, for example, it may be a mixture with the aforementioned base oil and additive, and the lubricating oil of the present invention only needs to contain at least the lubricating oil compound of the present invention. From the viewpoint of lubricity, etc., the content of the lubricating oil compound of the present invention in the lubricating oil of the present invention can be, for example, 0.01 to 99.99% by mass, preferably 0.1 to 99.99% by mass, more preferably 1 to 99.99% by mass, and even more preferably 10 to 99.99% by mass.

[0055] The lubricating oil of the present invention is not particularly limited in its applications and can be used as an industrial lubricant, metalworking oil, automotive lubricant, grease base oil, bearing oil, refrigeration oil, etc. In particular, it is suitable for use in environments where the components in contact with the lubricating oil contain rubber or resin, taking advantage of its excellent fluidity and its characteristic of causing little deterioration of rubber or resin in the operating environment.

[0056] Furthermore, while the lubricating oil compound (lubricating oil compound 1) of the present invention described above contains an ester complex, this specification also provides, as an invention from a different perspective, a lubricating oil compound (lubricating oil compound 2) consisting of an ester complex. Its composition is the same as that of the ester complex described above, and it goes without saying that it can be mixed with the other components mentioned above, such as base oil and additives, to form a lubricating oil. [Examples]

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. (Production of ester complexes) Example 1 A stirrer, thermometer, nitrogen gas inlet, and condenser were attached to a four-necked flask. Dimerized oleic acid and neopentyl glycol were charged in a molar ratio of 1.40 mol:1.0 mol, and the mixture was reacted under a nitrogen atmosphere at 220-240°C for more than 4 hours to obtain an ester complex intermediate. Next, a reflux tube was attached to a four-necked flask, and 2-ethylhexyl alcohol was added to the resulting ester complex intermediate in the above molar ratio of 1.0 mol. The reaction was carried out under a nitrogen atmosphere at 220-240°C for 10 hours until the acid value of the ester complex was 3.0 or less. Subsequently, to recover the excess alcohol, the reaction was carried out for 10 hours under reduced pressure conditions of 220-240°C and 5kPa or less, until the hydroxyl value was 40 or less and the kinematic viscosity at 40°C was 350-450 mmHg. 2 The endpoint was reached when the reaction rate was 2 / s, and the desired ester complex was obtained. The weight-average molecular weight of the obtained ester complex was 2950.

[0058] Example 2 The molar ratio of dimer acid was 1.25 mol, and the ester complex was synthesized in the same manner as in Example 1, except that the end point was determined when the kinematic viscosity of the final ester complex at 40 °C was 400 to 600 mm 2 / s. The weight average molecular weight of the obtained ester complex was 3108.

[0059] Example 3 The molar ratio of dimer acid was 1.11 mol, and the ester complex was synthesized in the same manner as in Example 1, except that the end point was determined when the kinematic viscosity of the final ester complex at 40 °C was 2400 to 2600 mm 2 / s. The weight average molecular weight of the obtained ester complex was 5671.

[0060] Example 4 The molar ratio of dimer acid was 1.07 mol, and the ester complex was synthesized in the same manner as in Example 1, except that the end point was determined when the kinematic viscosity of the final ester complex at 40 °C was 4900 to 5100 mm 2 / s. The weight average molecular weight of the obtained ester complex was 8766.

[0061] Example 5 The ester complex was synthesized in the same manner as in Example 1, except that the end point was determined when the acid value of the final ester complex was 10 or more and 15 or less and the hydroxyl value was 40 or more. The weight average molecular weight of the obtained ester complex was 3486.

[0062] Example 6 The molar ratio of dimer acid was 0.95 mol, 2-ethylhexanoic acid was used in a molar ratio of 1.0 mol instead of 2-ethylhexyl alcohol, and the reaction was carried out until the hydroxyl value of the ester complex was 40 or less. The ester complex was synthesized in the same manner as in Example 1, except that the end point was determined when the kinematic viscosity of the final ester complex at 40 °C was 7500 to 8500 mm 2 / s. The weight average molecular weight of the obtained ester complex was 12830.

[0063] Comparative Example 1 With a molar ratio of dimer acid of 1.75 mol, the kinematic viscosity of the final ester complex at 40°C is 200-400 mmHg. 2 The ester complex was synthesized in the same manner as in Example 1, except that the endpoint was set at / s. The weight-average molecular weight of the obtained ester complex was 2695.

[0064] Comparative Example 2 With a dimer acid molar ratio of 0.25 mol, the kinematic viscosity of the final ester complex at 40°C is 200-400 mmHg. 2 The ester complex was synthesized in the same manner as in Example 5, except that the endpoint was set at / s. The weight-average molecular weight of the obtained ester complex was 2732.

[0065] Comparative Example 3 The kinematic viscosity at 40°C is 600 mmHg. 2 Polyalphaolefin (PAO) synthetic oil product of approximately / s (weight-average molecular weight 4503)

[0066] Comparative Example 4 kinematic viscosity at 40°C is 1000 mm² 2 Polyalphaolefin (PAO) synthetic oil product (weight-average molecular weight 5396) of approximately / s

[0067] Comparative Example 5 The kinematic viscosity at 40°C is 1700 mmHg. 2 Polyalphaolefin (PAO) synthetic oil product of approximately / s (weight-average molecular weight 6087)

[0068] Comparative Example 6 Fatty acid ester-based synthetic oil (VOA-100 manufactured by Miyoshi Oil & Fat Co., Ltd.)

[0069] Comparative Example 7 Hindered ester synthetic oil (Miyoshi Oil & Fat Co., Ltd. "FLV-243T")

[0070] The measurement and evaluation methods for each evaluation item shown in Tables 1A and 1B are as follows. (Acid value) The acid value of each sample was measured in accordance with JIS K0070 (1992).

[0071] (Hydroxyl value) The hydroxyl value of each sample was measured in accordance with JIS K0070 (1992).

[0072] (Kinematic viscosity at 40℃) The kinematic viscosity of each sample at 40°C was measured using a kinematic viscometer compliant with ASTM D7042 (Anton Paar automatic kinematic viscometer SVM3001).

[0073] (Kinematic viscosity at 100℃) The kinematic viscosity at 100°C for each sample was measured using the same method as for 40°C kinematic viscosity, except that the temperature was set to 100°C.

[0074] (viscosity index) The viscosity index of each sample was calculated in accordance with JIS K 2283.

[0075] (flash point) The flash point of each sample was measured in accordance with JIS K 2265 (Cleveland open type), and the results were evaluated according to the following criteria. Evaluation Criteria ◎: Above 300℃ ○: 250℃ or higher and less than 300℃ △: Below 250℃

[0076] (Pour point) The pour point of each sample was measured in accordance with JIS K 2269 (1987). Low-temperature fluidity was evaluated according to the following criteria, with 0°C as the reference temperature. Evaluation Criteria ○: Below 0℃ ×: Greater than 0℃

[0077] (thermal stability) Thermogravimetric analysis (TGA) was used to measure the thermal decomposition curve under conditions of room temperature to 500°C with a heating rate of 5°C / min. The 50% thermal decomposition temperature (heat resistance temperature) was determined, and the results were evaluated according to the following criteria. Evaluation Criteria ◎: Heat resistant temperature 350℃ or higher ○: Heat resistance temperature 300℃ or higher but less than 350℃ ×: Heat resistance temperature less than 300℃

[0078] (oxidation stability) Each 4g sample was pressurized and sealed in a sealed container to an oxygen partial pressure of 700kPa, and then heated to 140°C. The time required for the oxygen partial pressure to decrease by 10% was defined as the oxidation induction time (OIT), and was evaluated according to the following criteria. A longer OIT indicates higher oxidation stability. Evaluation Criteria 〇: OIT is 40 minutes or more ×: OIT less than 40 minutes

[0079] (Rubber swelling and shrinkage resistance) Based on JIS K6258 (2016), various rubbers or resins were immersed in each sample, and the resistance to rubber swelling and shrinkage was evaluated from the rate of volume change. Test rubber (resin) pieces measuring 40 mm in length, 20 mm in width, and 0.2 mm in thickness were used, consisting of test nitrile rubber (NBR), chloroprene rubber (CR), fluororubber (F), and urethane rubber (U). Each sample was placed in a 50 ml glass bottle, and the test rubber (resin) pieces were immersed at an immersion temperature of 25°C for 168 hours. The rate of volume change was measured using the following formula. Volume change rate (%) = ([Volume of test specimen after testing] - [Volume of test specimen before testing]) / [Volume of test specimen before testing] × 100 The rubber swelling and shrinkage resistance was evaluated based on the obtained volume change rate according to the following criteria. Evaluation Criteria ◎: Volume change rate is between -2.5% and +5%. ○: Volume change rate is -5% or more but less than -2.5%, or greater than +5% but less than or equal to +10%. ×: Volume change rate is outside the above range.

[0080] As a comprehensive evaluation of rubber resistance, the following criteria were used based on the results of the above rubber swelling and shrinkage resistance evaluation. ○: All evaluations for each rubber used in the test were ○ or higher. ×: At least one of the evaluations for each rubber used in the test was marked with an "×".

[0081] The results of the above evaluation are shown in Tables 1A and 1B. [Table 1A]

[0082] [Table 1B]

Claims

1. A compound for lubricating oils comprising an ester complex whose constituent components are (A) a dimer acid, (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms, and (C) a monohydric fatty acid or monohydric alcohol, with a weight-average molecular weight Mw of 2750 to 15000.

2. The compound for lubricating oil according to claim 1, wherein the acid value of the ester complex is 15 mg / g or less and the hydroxyl value is 45 mg / g or less.

3. The kinematic viscosity of the ester complex at 40°C is 250 to 10000 mm². 2 A compound for lubricating oil according to claim 1, wherein the ratio is / s.

4. (C) The compound for lubricating oil according to claim 1, wherein the monohydric fatty acid or monohydric alcohol has 4 to 8 carbon atoms.

5. A compound for lubricating oils comprising an ester complex whose constituent components are (A) a dimer acid, (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms, and (C) a monohydric fatty acid or monohydric alcohol, wherein the molar ratio of (A) dimer acid to (B) dihydric alcohol is 0.5 to 1.5:

1.

6. The compound for lubricating oil according to claim 5, wherein the acid value of the ester complex is 15 mg / g or less and the hydroxyl value is 45 mg / g or less.

7. The kinematic viscosity of the ester complex at 40°C is 250 to 10000 mm². 2 The compound for lubricating oil according to claim 5, wherein the ratio is / s.

8. (C) The compound for lubricating oil according to claim 5, wherein the monohydric fatty acid or monohydric alcohol has 4 to 8 carbon atoms.

9. A lubricating oil comprising the lubricating oil compound according to any one of claims 1 to 8.

10. (A) A step of reacting a dimer acid with (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms to obtain an intermediate, and A method for producing a compound for lubricating oil, comprising the steps of reacting the aforementioned intermediate with an excess amount of (C) monohydric fatty acid or monohydric alcohol, recovering the unreacted (C) monohydric fatty acid or monohydric alcohol, and obtaining an ester complex having a weight-average molecular weight Mw of 2750 to 15000.

11. (A) A step of reacting a dimer acid with (B) an aliphatic dihydric alcohol having 2 to 8 carbon atoms in a molar ratio of 0.5 to 1.5:1 to obtain an intermediate, and A method for producing a compound for lubricating oil, comprising the steps of reacting the aforementioned intermediate with an excess amount of (C) monohydric fatty acid or monohydric alcohol, recovering the unreacted (C) monohydric fatty acid or monohydric alcohol, and obtaining an ester complex.

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