Metalworking fluid base oil

Abstract

To provide a base oil for a metal processing oil to be blended in a water-insoluble metal processing oil composition, which combines a high flash point with low viscosity near room temperature, and further has flowability at low temperatures.SOLUTION: A base oil for a metal processing oil comprises an ester of a fatty acid and glycerin. The fatty acids include caprylic acid and dodecanoic acid, the molar ratio (caprylic acid / dodecanoic acid) of the caprylic acid to the dodecanoic acid is 70 / 30 or more and 90 / 10 or less, and the total content of the caprylic acid and the dodecanoic acid in the fatty acids is 80 mol% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a base oil for metal working oil. [Background technology]

[0002] In cutting and grinding processes, the cooling properties of cutting tools extend their lifespan and the lubrication properties improve processing efficiency. Metalworking oils are used for the purpose of increasing the lubricating properties of metals. It is a mixture of water-soluble metalworking oil, which is excellent for extending the service life, and oily components such as mineral oil and synthetic oil. They are broadly divided into two types: water-insoluble metalworking oils that are excellent at increasing processing efficiency and water-insoluble metalworking oils that are based on water.

[0003] Water-insoluble metalworking oils have the problem of flammability because they are based on oily components.

[0004] The following Patent Documents 1 and 2 disclose a metalworking oil having a higher flash point than a water-insoluble metalworking oil based on an oily component. A synthetic ester-based metalworking oil composition having the formula: [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-147787 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-73079 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional synthetic ester metalworking oil compositions have a high flash point and a low viscosity. There was room for improvement in this respect.

[0007] The present invention achieves both a high flash point and low viscosity around room temperature, and also has fluidity at low temperatures. The present invention aims to provide a base oil for metalworking oil to be blended into a water-insoluble metalworking oil composition. . [Means for solving the problem]

[0008] The present invention provides A base oil for metal working oil, comprising an ester of a fatty acid and glycerin, The fatty acids include caprylic acid and dodecanoic acid, and the monoesters of the caprylic acid and the dodecanoic acid are The caprylic acid / dodecanoic acid ratio is 70 / 30 or more and 90 / 10 or less, The total content of the caprylic acid and the dodecanoic acid in the fatty acid is 80 mol % or more. It is a base oil for metalworking oils. [Effects of the Invention]

[0009] According to the present invention, a high flash point and low viscosity at around room temperature are both achieved, and further, fluidity at low temperatures is improved. It is possible to provide a base oil for metal working oil to be blended into a water-insoluble metal working oil composition, do. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Base oil for metal working oil> The base oil for metal working oil of this embodiment is A base oil for metal working oil, comprising an ester of a fatty acid and glycerin, The fatty acids include caprylic acid and dodecanoic acid, and the monoesters of the caprylic acid and the dodecanoic acid are The caprylic acid / dodecanoic acid ratio is 70 / 30 or more and 90 / 10 or less, The total content of the caprylic acid and the dodecanoic acid in the fatty acid is 80 mol % or more. do. The base oil for metalworking oil of this embodiment has both a high flash point and a low viscosity around room temperature, and further It has fluidity at low temperatures.

[0011] The molar ratio of the caprylic acid to the dodecanoic acid (caprylic acid / dodecanoic acid) is Comb, in order to improve lubricity and fluidity at low temperatures, 70 / 30 or more, Preferably, it is 72.5 / 27.5 or more, more preferably 75 / 25 or more, and 9 0 / 10 or less, preferably 88.5 / 11.5 or less, more preferably 87 / 13 or less. do.

[0012] The content of caprylic acid in the fatty acid is not particularly limited, but it is preferable to use caprylic acid to increase the flash point and improve lubrication. From the viewpoint of improving the viscosity and improving the fluidity at low temperatures, it is preferably 70 mol % or more, More preferably, it is 72.5 mol % or more, and even more preferably, it is 75 mol % or more. Preferably 90 mol % or less, more preferably 88.5 mol % or less, and even more preferably 87 mol % or less.

[0013] The content of dodecanoic acid in the fatty acid is not particularly limited, but it is effective in increasing the flash point and lubricating the fatty acid. From the viewpoint of improving the viscosity and improving the fluidity at low temperatures, it is preferably 10 mol % or more, More preferably, it is 11.5 mol % or more, and even more preferably, it is 13 mol % or more. Preferably, it is 30 mol % or less, more preferably 27.5 mol % or less, and even more preferably 25 mol % or less.

[0014] The total content of the caprylic acid and the dodecanoic acid in the fatty acid is 80 mol % or more, preferably 90 mol % or more, and more preferably 100 mol % or more, from the viewpoint of increasing the flash point, improving lubricity, and improving fluidity at low temperatures. %in be.

[0015] The fatty acid may be caprylic acid or dodecanoic acid within a range that does not impair the effects of the present invention. The fatty acid other than caprylic acid and dodecanoic acid may be Examples of methyl valeric acid include valeric acid, 2-methyl valeric acid, 4-methyl valeric acid, n-hexanoic acid, 2-methyl Hexanoic acid, 5-methylhexanoic acid, 4,4-dimethylpentanoic acid, n-heptanoic acid, 2-Methylheptanoic acid, 2-ethylhexanoic acid, 2,2-dimethylhexanoic acid, 3,5, 5-trimethylhexanoic acid, n-nonanoic acid, n-decanoic acid, etc. Fatty acids: tridecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, oleic acid Fat with 13 to 26 carbon atoms, such as linoleic acid, eicosanoic acid, behenic acid, and cerotic acid Fatty acids: 13-methyltetradecanoic acid, 12-methyltetradecanoic acid, 15-methylhexanoic acid Decanoic acid, 14-methylhexadecanoic acid, 10-methylhexadecanoic acid, 2-hexyldecanoic acid Carbonates such as citric acid, isopalmitic acid, isostearic acid, isoarachidic acid, and phytanic acid Fatty acids with 15 to 20 branched chains; cyclopropanecarboxylic acid, cyclobutanecarboxylic acid , cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cycloheptanecarboxylic acid, Cycloalkane monocarboxylic acids with 4 to 8 carbon atoms, such as methylcyclohexanecarboxylic acid Examples include phosphate.

[0016] The ester mainly contains a glycerin triester, but it is not necessary to impair the effects of the present invention. The glycerin triester may contain a glycerin partial ester within the range. Triester of caprylic acid and glycerin, Triester of dodecanoic acid and glycerin and triesters of mixed fatty acids of caprylic acid and dodecanoic acid and glycerin. can be done.

[0017] The molar ratio of the fatty acid to the glycerin increases the flash point and improves lubricity, From the viewpoint of improving fluidity at low temperatures, the viscosity is preferably 2.6 or more, and more preferably 2. 8 or more, more preferably 2.9 or more, and preferably 3.4 or less, more preferably It is preferably 3.2 or less, and more preferably 3.1 or less.

[0018] The esters increase the flash point, improve lubricity, and improve flow at low temperatures. From the viewpoint of the above, a triester of a mixed fatty acid of caprylic acid and dodecanoic acid and glycerin is included. It is preferable.

[0019] The content of the glycerin triester in the ester is not particularly limited, but the flash point From the viewpoint of increasing the viscosity, improving lubricity, and improving fluidity at low temperatures, it is preferably 8 0 mol% or more, more preferably 90 mol% or more, and even more preferably substantially 100 mol%; It is even more preferably 100 mol %. "%" refers to a state in which trace amounts of impurities are unavoidably contained.

[0020] The base oil for metal working oil may contain a base oil other than the ester. Other base oils include, for example, mineral oils and synthetic oils. Mineral oils include, for example, para Atmospheric distillation of Finnish, intermediate or naphthenic crude oils or residues of atmospheric distillation Distillate oil obtained by vacuum distillation of oil, or by refining it according to conventional methods Refined oils obtained by the above methods (for example, solvent refined oils, hydrogenated refined oils, dewaxed oils, clay-treated oils, etc.) Examples of synthetic oils include esters other than the esters of the present invention. , poly-α-olefin, olefin copolymer alkylbenzene, alkylnaphthalene , polyoxyalkylene glycol, polyphenyl ether, etc.

[0021] The content of the ester in the base oil for metalworking oil is not particularly limited. From the viewpoint of improving lubricity and improving fluidity at low temperatures, it is preferable that the amount of the hydroxybenzoate is 90 mass % or more. % or more, more preferably 95% by mass or more, even more preferably substantially 100% by mass, and even more preferably The most preferred is 100% by mass.

[0022] The kinematic viscosity at 40°C of the base oil for metal working oil is preferably 1 6mm 2 / s or less, preferably 15 mm 2 / s or less, and is intended to improve wear resistance. From the point, preferably 14 mm 2 / s or more.

[0023] The viscosity index of the base oil for metal working oil is preferably 0.1 to 1.0% from the viewpoint of reducing the viscosity change due to temperature. It is preferably 100 or more, and more preferably 120 or more.

[0024] The pour point of the base oil for metal working oil is preferably It is -10°C or lower, more preferably -15°C or lower.

[0025] The flash point of the base oil for metalworking oil is preferably 250°C from the viewpoint of reducing flammability. That's all.

[0026] [Method for producing ester] The ester is prepared by esterifying the fatty acid and glycerin according to a known method. For example, it can be prepared by esterifying caprylic acid with glycerin. The triester obtained by the reaction is esterified with dodecanoic acid and glycerin to give A method of obtaining a specific ratio of caprylic acid and dodecyl triester by mixing the resulting triester in a specific ratio. One method is to obtain it by esterification of mixed fatty acids of carboxylic acid with glycerin, which can be done at low temperature. In order to improve the fluidity of the product, a specific ratio of caprylic acid and dodecanoic acid mixed fatty acid and glycerin The preferred method is to obtain the ester of fatty acid with glycerin by esterification with serine. The molar ratio of caprylic acid to dodecanoic acid in It can be calculated from the number of moles of each of carboxylic acids.

[0027] In the production of the ester, from the viewpoint of accelerating the esterification reaction, The esterification reaction is carried out using an excess of 1 equivalent of the carboxyl group of the fatty acid relative to 1 equivalent of the group. and a step of removing excess fatty acids after the esterification reaction. The equivalent of the carboxyl group of the fatty acid is 1.1 relative to 1 equivalent of the hydroxyl group of the glycerin. An equivalent amount or more is preferable, and from the viewpoint of reducing the load in the step of removing fatty acids, 1. The hydroxyl value of the resulting ester is preferably 5 equivalents or less, more preferably 1.3 equivalents or less. Preferably, the KOH content is 3.0 mgKOH / g or less, more preferably 1.5 mgKOH / g or less. It is preferable to carry out the esterification reaction until the excess fatty acid is removed after the esterification reaction. Examples of methods for this include vacuum distillation, steaming, and adsorption removal using an adsorbent. The acid value of the resulting ester is preferably 0.3 mg KOH / g or less, more preferably 0.5 mg KOH / g or less. It is preferable to remove fatty acids until the concentration is 0.1 mgKOH / g or less.

[0028] Specifically, the method for producing the base oil for metal working oil includes the following steps 1 and 2. A method for producing a base oil for metalworking oil, comprising the following steps 1 and 2: Step 1: A step of carrying out an esterification reaction between glycerin and a fatty acid, the equivalent of the carboxyl group of the fatty acid is 1.1 or more equivalents relative to 1 equivalent of the hydroxyl group of the fatty acid; The fatty acid is a mixed fatty acid of caprylic acid and dodecanoic acid, and the caprylic acid and The total content of the dodecanoic acid is 90 mol % or more, and the caprylic / capric triglycerides in the mixed fatty acid are The molar ratio of caprylic acid to dodecanoic acid (caprylic acid / dodecanoic acid) is 70 / 30 or more and 90 / 1 Processes that are 0 or less Step 2: Removing excess fatty acid after esterification reaction

[0029] <Water-insoluble metal working oil composition> The water-insoluble metal working oil composition of this embodiment contains at least the base oil for metal working oil. The content of the base oil for metalworking oil in the water-insoluble metalworking oil composition is such that the flash point is high. From the viewpoint of improving lubricity and improving fluidity at low temperatures, it is preferable that the amount of the hydroxybenzoate is 90 mass % or more. % or more, more preferably substantially 100% by mass or more, and even more preferably 100% by mass In this specification, "substantially 100% by mass" means that a small amount of impurities is unavoidably present. It refers to a state that includes the following:

[0030] The water-insoluble metalworking oil composition contains, in addition to the base oil for metalworking oil, a general water-insoluble metal The metal processing oil composition may contain additives that are blended in the metal processing oil composition. Detergents, extreme pressure agents, surfactants, defoamers, rust inhibitors, preservatives, antioxidants, and metal deactivators These may be used alone or in combination of two or more.

[0031] The water-insoluble metal working oil composition contains the base oil for metal working oil, and therefore has a high flash point It has low viscosity at around room temperature and also has fluidity at low temperatures, making it suitable for cutting metals. - Ideal for use in grinding processes, etc. [Example]

[0032] The present invention will be specifically described below based on examples. However, the various measurement and evaluation methods are as follows:

[0033] <Preparation of condensed ester> Example 1 In a 1-liter four-neck flask equipped with a stirrer, thermometer, nitrogen inlet, and condenser , 387.81g of caprylic acid and 124.32g of dodecanoic acid were added as fatty acids to form a mixed fat. The fatty acid was prepared, and 127.00 g of glycerin was added. , so that the total carboxyl groups of fatty acids are 0.8 equivalents per equivalent of hydroxyl groups of glycerin. Next, nitrogen gas was blown into the flask, and the temperature was raised to 230°C while stirring. The temperature was maintained at 230°C for 1 hour, and the distilled water was removed from the flask using a cooling tube. After that, 238.65 g of caprylic acid was added, and the temperature was raised again to 230°C. The temperature was maintained at 0°C, and the distilled water was removed from the flask using a condenser. After the reaction was completed, the temperature was 0. Excess fatty acids were distilled off under reduced pressure of 13 kPa, and the resulting mixture was washed with an adsorbent (trade name: Kyoward 500SH). After absorbing the remaining fatty acids onto a filter (manufactured by Kyowa Chemical Industry Co., Ltd.), the filter was filtered and the condensation enzyme was removed. The resulting condensed ester had an acid value of less than 0.1 mg KOH / g and a hydroxyl value of Less than 1.0 mgKOH / g, partial esters of glycerin, unreacted fatty acids, unreacted It was confirmed that the obtained condensed ester was substantially free of any of the glycerin. The glycerin triester was essentially 100%. Triesters of caprylic acid, triesters of dodecanoic acid, and triesters of caprylic and dodecanoic acids The resulting condensed ester is a mixture containing caprylic acid and dodecane. It is a mixture of acids containing triesters of fatty acids and glycerin.

[0034] [Examples 2 and 3, Comparative Examples 1 and 2] The same method as in Example 1 was used except that the molar ratio of caprylic acid to dodecanoic acid was changed to that shown in Table 1. Condensed esters according to Examples 2 and 3 and Comparative Examples 1 and 2 were prepared.

[0035] <Evaluation method> [Evaluation of fatty acid binding ratio] The fatty acid bond ratio of the obtained condensed ester was determined by gas chromatography (hereinafter referred to as GC). Specifically, 10 mg of sample was dissolved in 1 mL of hexane solvent and analyzed by GC. Measurement was performed, and the results were calculated from the area ratio of the peaks of each compound. The analysis conditions were as follows: GC device: Product name 8890 GC System (Agilent Technolog Made by y) Column: Product name DB-1 30m x 250μm x 0.1μm (Agilent Tech (Made by Nology) Detector: Hydrogen flame ionization detector (FID) Injection temperature: 270℃ Detector temperature: 310℃ Oven: 60℃ (0 min.) → 10℃ / min. → 300℃ → 300℃ (36 min.) )

[0036] [Evaluation of lubricity (dynamic viscosity)] The kinematic viscosity was evaluated using the Stabinger kinematic viscosity tester, which met the accuracy required by ASTM D7042. The kinematic viscosity at 40°C was measured using a viscosity meter (product name: SVM3000, manufactured by Anton Paar). The lubricity was evaluated based on the results.

[0037] [Evaluation of Pour Point] The pour point was evaluated by measuring the pour point (°C) according to the measurement method in accordance with JIS K2269. .

[0038] [Flash point evaluation] The flash point was evaluated using the measurement method (Cleveland open cup) according to JIS K2265. The flash point (°C) was measured by the flash point method. Specifically, the sample was placed exactly on the marked line of the metal cup. Put the Cleveland open-cup flash point and fire point tester (product name OptiFlash, PA Measurements were performed using a thermocouple manufactured by C.

[0039] The evaluation results are shown in Table 1.

[0040] [Table 1]

[0041] From Table 1, the molar ratio of caprylic acid to dodecanoic acid (decanoic acid / dodecanoic acid) is 70 / 30. or more and 90 / 10 or less, and the total content of the caprylic acid and the dodecanoic acid in the fatty acid is The condensed esters of Examples 1 to 3, in which the amount was 60 mol % or more, had a kinematic viscosity at 0°C of 16 (mm 2 / s) or less and a flash point of 250°C or more, and has both a high flash point and low viscosity around room temperature. It can be seen that the condensed esters of Examples 1 to 3 have a pour point of -10 ℃ or less, and has excellent fluidity at low temperatures. Comparative Example 1: The ratio of decanoic acid to dodecanoic acid does not satisfy the requirement of 70 / 30 or more and 90 / 10 or less The condensed ester of 2 has a kinematic viscosity of 16 (mm 2 / s) or the flash point The flash point is less than 250°C, and it is not possible to achieve both a high flash point and a low viscosity around room temperature. [Industrial Applicability]

[0042] The water-insoluble metalworking oil composition of the present invention is suitable for use in metal cutting and grinding processes. .

Claims

1. A base oil for metal working oil, comprising an ester of a fatty acid and glycerin, the fatty acid contains caprylic acid and dodecanoic acid, and the molar ratio of the caprylic acid to the dodecanoic acid (caprylic acid / dodecanoic acid) is 70 / 30 or more and 90 / 10 or less; the total content of the caprylic acid and the dodecanoic acid in the fatty acid is 80 mol% or more; The flash point of the base oil for metal working oil is 250°C or higher, The base oil for metal working oil has a kinematic viscosity at 40°C of 16 mm 2 / s or less.

2. 2. The base oil for metal working oils according to claim 1, wherein a molar ratio of the caprylic acid to the dodecanoic acid (caprylic acid / dodecanoic acid) is 70 / 30 or more and 87 / 13 or less.

3. 3. The base oil for metal working oils according to claim 1, wherein the total content of the caprylic acid and the dodecanoic acid in the fatty acids is 100 mol%.

4. The base oil for metal working oil according to any one of claims 1 to 3, wherein the flash point of the base oil for metal working oil is 254°C or higher.

5. The base oil for metal working oils according to any one of claims 1 to 4, wherein the ester comprises a triester of the mixed fatty acid of the caprylic acid and the dodecanoic acid and the glycerin.

6. A water-insoluble metal working oil composition comprising the base oil for metal working oil according to any one of claims 1 to 5.

7. 7. The water-insoluble metal working oil composition according to claim 6, wherein the content of the base oil for metal working oil is 90 mass% or more.

8. A method for producing a base oil for metal working oil according to any one of claims 1 to 7, A method for producing a base oil for metal working oil, comprising the following steps 1 and 2: Step 1: A step of carrying out an esterification reaction between glycerin and a fatty acid, wherein the equivalent of a carboxy group of the fatty acid relative to 1 equivalent of a hydroxyl group of the glycerin is 1.1 equivalents or more, the fatty acid is a mixed fatty acid of caprylic acid and dodecanoic acid, the total content of the caprylic acid and the dodecanoic acid in the fatty acid is 80 mol% or more, and the molar ratio of the caprylic acid to the dodecanoic acid in the mixed fatty acid (caprylic acid / dodecanoic acid) is 70 / 30 or more and 90 / 10 or less. Step 2: Removing excess fatty acid after esterification reaction

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