Base oil for metalworking oil and water-insoluble metalworking oil composition

Abstract

To provide a base oil for a metal processing oil to be blended in a water-insoluble metal processing oil composition, and the water-insoluble metal processing oil composition containing the base oil for the metal processing oil, wherein the base oil for the metal processing oil has both a high flash point and a low viscosity near a room temperature and has fluidity at low temperatures.SOLUTION: The base oil for the metal processing oil of the present invention comprises an ester of a fatty acid and neopentyl glycol, wherein the fatty acid contains decanoic acid and dodecanoic acid, and a molar ratio of the decanoic acid to the dodecanoic acid (decanoic acid / dodecanoic acid) is 30 / 70 or more to 70 / 30 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a base oil for metalworking oil and a water-insoluble metalworking oil composition. [Background technology]

[0002] In cutting and grinding processes, metalworking oils are used to extend the life of cutting tools by providing cooling properties, and to increase processing efficiency by providing lubrication. Metalworking oil compositions are broadly divided into two types: water-soluble metalworking oils, which have lubricating components dispersed / dissolved in water and are excellent at extending tool life, and water-insoluble metalworking oils, which are based on oily components such as mineral oils and synthetic oils and are excellent at increasing processing efficiency.

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

[0004] For example, Patent Document 1 discloses a metalworking oil composition that has high processing performance, excellent wear resistance, and can suppress the generation of oily smoke, and is made by blending (A) an ester of a polyhydric alcohol and a fatty acid, and (B) elemental sulfur, and has a kinematic viscosity of 5 mm at 40°C. 2 / s or more 70mm 2 / s or less and a flash point of 200°C or more.

[0005] Furthermore, Patent Document 2 discloses a synthetic ester-based lubricating base oil that is suitable for use in cutting processes, has a high flash point, and exhibits a good balance of improved lubricity (seizure resistance and wear resistance), low-temperature fluidity, and oxidation stability, all of which are required for bearing oils. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2015 / 107828 publication [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-102235 Summary of the Invention [Problem to be solved by the invention]

[0007] However, increasing the flash point of the ester to solve the problem of flammability tends to increase the viscosity, while low viscosity at around room temperature (up to 40°C) is desirable to improve processability during use.

[0008] An object of the present invention is to provide a base oil for metal working oil to be blended into a water-insoluble metal working oil composition, which has both a high flash point and a low viscosity around room temperature and also has fluidity at low temperatures, and a water-insoluble metal working oil composition containing the base oil for metal working oil. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by using the following base oil for metal working oil.

[0010] That is, the present invention relates to a base oil for metal working oil, which contains an ester of a fatty acid and neopentyl glycol, wherein the fatty acid contains decanoic acid and dodecanoic acid, and the molar ratio of the decanoic acid to the dodecanoic acid (decanoic acid / dodecanoic acid) is 30 / 70 or more and 70 / 30 or less. [Effects of the Invention]

[0011] The base oil for metalworking oils of the present invention contains an ester of a specific fatty acid and neopentyl glycol, and therefore can achieve both a high flash point and a low viscosity at around room temperature, and further has excellent fluidity at low temperatures. Because the base oil for metalworking oils of the present invention has these properties, it is suitable for use as a base oil to be blended into water-insoluble metalworking oil compositions. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below.

[0013] <Base oil for metal working oil> The base oil for metal working oil of the present invention contains an ester of a fatty acid and neopentyl glycol, the fatty acid contains decanoic acid and dodecanoic acid, and the molar ratio of the decanoic acid to the dodecanoic acid (decanoic acid / dodecanoic acid) is 30 / 70 or more and 70 / 30 or less.

[0014] The molar ratio of the decanoic acid to the dodecanoic acid (decanoic acid / dodecanoic acid) is preferably 35 / 65 or more, more preferably 37 / 63 or more, from the viewpoint of improving the flash point, and is preferably 65 / 35 or less, more preferably 63 / 37 or less, from the viewpoint of reducing the viscosity and pour point.

[0015] The content of decanoic acid in the fatty acid is not particularly limited, but from the viewpoint of increasing the flash point, decreasing the viscosity around room temperature, and improving the fluidity at low temperatures, it is preferably 30 mol% or more, more preferably 35 mol% or more, even more preferably 40 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 60 mol% or less.

[0016] The content of dodecanoic acid in the fatty acid is not particularly limited, but from the viewpoint of increasing the flash point, decreasing the viscosity around room temperature, and improving the fluidity at low temperatures, it is preferably 30 mol% or more, more preferably 35 mol% or more, even more preferably 40 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 60 mol% or less.

[0017] The total content of the decanoic acid and the dodecanoic acid in the fatty acid is not particularly limited, but from the viewpoint of increasing the flash point, decreasing the viscosity around room temperature, and improving the fluidity at low temperatures, it is preferably 90 mol % or more, more preferably 95 mol % or more, and even more preferably 100 mol %.

[0018] The fatty acid may contain a fatty acid other than decanoic acid and dodecanoic acid, provided that the effects of the present invention are not impaired. Examples of the fatty acid other than decanoic acid and dodecanoic acid include fatty acids having 5 to 9 carbon atoms, such as valeric acid, 2-methylvaleric acid, 4-methylvaleric acid, n-hexanoic acid, 2-methylhexanoic acid, 5-methylhexanoic acid, 4,4-dimethylpentanoic acid, n-heptanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 2,2-dimethylhexanoic acid, n-octanoic acid, 3,5,5-trimethylhexanoic acid, and n-nonanoic acid; and fatty acids having 13 or more carbon atoms, such as tridecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, oleic acid, linoleic acid, eicosanoic acid, behenic acid, and cerotic acid. fatty acids having 26 or less carbon atoms; branched fatty acids having 15 to 20 carbon atoms, such as 13-methyltetradecanoic acid, 12-methyltetradecanoic acid, 15-methylhexadecanoic acid, 14-methylhexadecanoic acid, 10-methylhexadecanoic acid, 2-hexyldecanoic acid, isopalmitic acid, isostearic acid, isoarachic acid, and phytanic acid; and cycloalkane monocarboxylic acids having 4 to 8 carbon atoms, such as cyclopropanecarboxylic acid, cyclobutanecarboxylic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cycloheptanecarboxylic acid, and methylcyclohexanecarboxylic acid.

[0019] The ester mainly contains neopentyl glycol diester, but may contain neopentyl glycol monoester as long as the effects of the present invention are not impaired. Examples of the neopentyl glycol diester include a diester of decanoic acid and neopentyl glycol, a diester of dodecanoic acid and neopentyl glycol, and a diester of neopentyl glycol and a mixed fatty acid of decanoic acid and dodecanoic acid (i.e., a diester of decanoic acid, dodecanoic acid, and neopentyl glycol).

[0020] The molar ratio of the fatty acid to the neopentyl glycol is preferably 1.6 or more, more preferably 1.8 or more, even more preferably 1.9 or more, from the viewpoints of increasing the flash point, decreasing the viscosity around room temperature, and improving the fluidity at low temperatures, and is preferably 2.4 or less, more preferably 2.2 or less, even more preferably 2.1 or less.

[0021] From the viewpoints of increasing the flash point, decreasing the viscosity at around room temperature, and improving the fluidity at low temperatures, the ester preferably contains a diester of a mixed fatty acid of decanoic acid and dodecanoic acid with neopentyl glycol (i.e., a diester of decanoic acid, dodecanoic acid, and neopentyl glycol).

[0022] The content of the neopentyl glycol diester in the ester is not particularly limited, but from the viewpoints of increasing the flash point, decreasing the viscosity around room temperature, and improving the fluidity at low temperatures, it is preferably 90 mol % or more, more preferably 95 mol % or more, and even more preferably 100 mol %.

[0023] The base oil for metalworking oil may contain a base oil other than the ester. Examples of base oils other than the ester include mineral oils and synthetic oils. Examples of mineral oils include distillate oils obtained by atmospheric distillation of paraffinic crude oil, intermediate crude oil, or naphthenic crude oil, or by vacuum distillation of the residual oil from atmospheric distillation, and refined oils obtained by refining these according to conventional methods (e.g., solvent-refined oil, hydrogenated refined oil, dewaxed oil, clay-treated oil, etc.). Examples of synthetic oils include esters other than the esters of the present invention, poly-α-olefins, olefin copolymer alkylbenzenes, alkylnaphthalenes, polyoxyalkylene glycols, polyphenyl ethers, etc.

[0024] The content of the ester in the base oil for metal working oil is not particularly limited, but from the viewpoints of increasing the flash point, decreasing the viscosity around room temperature, and improving the fluidity at low temperatures, it is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass.

[0025] The kinematic viscosity at 40°C of the base oil for metal working oil is preferably 14mm from the viewpoint of reducing the viscosity at around room temperature. 2 / s or less, preferably 13 mm 2 / s or less, and from the viewpoint of improving lubrication during metal processing, it is preferably 10 mm 2 / s or more, preferably 11 mm 2 / s or more, more preferably 12 mm 2 / s or more.

[0026] The viscosity index of the base oil for metal working oil is preferably 100 or more, more preferably 120 or more, from the viewpoint of minimizing viscosity changes due to temperature.

[0027] The pour point of the base oil for metal working oil is preferably −10° C. or lower, more preferably −15° C. or lower, from the viewpoint of improving fluidity at low temperatures.

[0028] The flash point of the base oil for metal working oil is preferably 250° C. or higher from the viewpoint of reducing flammability.

[0029] <Method for preparing esters> The base oil for metal working oil of the present invention contains an ester of a fatty acid and neopentyl glycol. The ester can be prepared by esterifying the fatty acid with neopentyl glycol according to a known method. For example, a method can be used in which a diester obtained by esterifying decanoic acid with neopentyl glycol and a diester obtained by esterifying dodecanoic acid with neopentyl glycol are mixed in a specific ratio, or a method can be used in which a mixed fatty acid of decanoic acid and dodecanoic acid in a specific ratio is esterified with neopentyl glycol. From the viewpoint of improving fluidity at low temperatures, a method in which a mixed fatty acid of decanoic acid and dodecanoic acid in a specific ratio is esterified with neopentyl glycol is preferred. The molar ratio of decanoic acid to dodecanoic acid in the ester of a fatty acid with neopentyl glycol can be calculated from the respective moles of decanoic acid and dodecanoic acid used in preparing the ester.

[0030] The production of the ester preferably includes, from the viewpoint of accelerating the esterification reaction, a step of carrying out an esterification reaction using an excess of more than 1 equivalent of carboxy groups of the fatty acid relative to 1 equivalent of hydroxyl groups of the neopentyl glycol, and a step of removing the excess fatty acid after the esterification reaction. The equivalent of carboxy groups of the fatty acid is preferably 1.1 equivalents or more relative to 1 equivalent of hydroxyl groups of the neopentyl glycol, and from the viewpoint of reducing the load in the fatty acid removal step, it is preferably 1.5 equivalents or less, more preferably 1.3 equivalents or less. The esterification reaction is preferably carried out until the hydroxyl value of the resulting ester is preferably 3.0 mgKOH / g or less, more preferably 1.5 mgKOH / g or less. Methods for removing excess fatty acid after the esterification reaction include, for example, vacuum distillation, steaming, and adsorption removal using an adsorbent. The fatty acid is preferably removed until the acid value of the resulting ester is preferably 0.3 mgKOH / g or less, more preferably 0.1 mgKOH / g or less.

[0031] Specifically, the method for producing a base oil for metal working oil of the present invention includes the following steps 1 and 2. Step 1: A step of carrying out an esterification reaction between neopentyl glycol and a fatty acid, wherein the number of equivalents of carboxyl groups in the fatty acid relative to 1 equivalent of hydroxyl groups in the neopentyl glycol is 1.1 or more, the fatty acid is a mixed fatty acid of decanoic acid and dodecanoic acid, the total content of the decanoic acid and the dodecanoic acid in the fatty acid is 90 mol % or more, and the molar ratio of the decanoic acid to the dodecanoic acid in the mixed fatty acid (decanoic acid / dodecanoic acid) is 30 / 70 or more and 70 / 30 or less. Step 2: Removing excess fatty acid after esterification reaction

[0032] <Water-insoluble metal working oil composition> The water-insoluble metal working oil composition of the present invention contains at least the base oil for metal working oil. In addition to the base oil for metal working oil, the water-insoluble metal working oil composition of the present invention may contain additives that are typically incorporated into water-insoluble metal working oil compositions. Examples of such additives include oiliness agents, extreme pressure agents, surfactants, antifoaming agents, rust inhibitors, preservatives, antioxidants, and metal deactivators. These may be used alone or in combination of two or more.

[0033] The water-insoluble metal working oil composition of the present invention contains the above-mentioned base oil for metal working oils, and therefore has both a high flash point and low viscosity at around room temperature, and also has fluidity at low temperatures, making it suitable for use in processes such as metal cutting and grinding. [Example]

[0034] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. Various measurement and evaluation methods are as follows.

[0035] Example 1 A 1-liter four-neck flask equipped with a stirrer, thermometer, nitrogen inlet, and condenser was charged with 374.67 g (2.17 mol) of decanoic acid and 261.02 g (1.30 mol) of dodecanoic acid to prepare a mixed fatty acid, and then 150.80 g (1.45 mol) of neopentyl glycol was added. The amount of fatty acid added was such that the total carboxyl groups of the fatty acid was 1.2 equivalents per equivalent of hydroxyl groups of neopentyl glycol. Next, nitrogen gas was blown into the flask, and the temperature was raised to 250°C while stirring. This temperature was maintained for 18 hours, and the distilled water was removed from the flask using a cooling tube. After the reaction was completed, excess fatty acids were distilled off under a reduced pressure of 0.13 kPa. Steaming was performed under a reduced pressure of 0.13 kPa for 1 hour. The remaining fatty acids were adsorbed onto an adsorbent (trade name: Kyoward 500SH, manufactured by Kyowa Chemical Industry Co., Ltd.). The resulting condensed ester was then filtered. 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 mg KOH / g, and was confirmed to be substantially free of neopentyl glycol monoesters, unreacted fatty acids, and unreacted neopentyl glycol. The resulting condensed ester was essentially 100% neopentyl glycol diester. The obtained condensed ester is a mixture containing a diester of decanoic acid, a diester of dodecanoic acid, and a diester of decanoic acid and dodecanoic acid. That is, the obtained condensed ester is a mixture containing a diester of a mixed fatty acid of decanoic acid and dodecanoic acid and neopentyl glycol. Since the fatty acid composition of the mixed fatty acid used to prepare the condensed ester is reflected in the diester, the fatty acid composition constituting the obtained condensed ester has a molar ratio of decanoic acid to dodecanoic acid (decanoic acid / dodecanoic acid) of 62.5 / 37.5.

[0036] Examples 2 and 3, Comparative Examples 1 to 4 Other condensed esters were prepared in the same manner as in Example 1, except that the molar ratio of decanoic acid to dodecanoic acid was changed as shown in Table 1.

[0037] Example 4 The condensation ester of Comparative Example 1 and the condensation ester of Comparative Example 4 were mixed in an equimolar ratio to prepare a mixture of a diester of decanoic acid and a diester of dodecanoic acid (a molar ratio of decanoic acid to dodecanoic acid (decanoic acid / dodecanoic acid) of 50 / 50). In other words, the prepared mixture of diesters is a mixture that is substantially free of a diester of a mixed fatty acid of decanoic acid and dodecanoic acid with neopentyl glycol.

[0038] The resulting condensed ester was subjected to the following evaluations. <Evaluation of dynamic viscosity> The kinematic viscosity was evaluated using a Stabinger kinematic viscometer (product name: SVM3000, manufactured by Anton Paar) that meets the accuracy requirements of ASTM D7042, measuring the kinematic viscosity at 40°C and 100°C (mm 2 / s) and viscosity index were measured.

[0039] <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.

[0040] <Flash point evaluation> The flash point was evaluated by measuring the flash point (°C) according to the measurement method (Cleveland open cup method) in accordance with JIS K2265.

[0041] [Table 1]

[0042] From Table 1, it can be seen that the condensed esters of Examples 1 to 4, in which the molar ratio of decanoic acid to dodecanoic acid (decanoic acid / dodecanoic acid) is 30 / 70 or more and 70 / 30 or less, have a kinematic viscosity at 40°C of 14 (mm 2 / s) or less and a flash point of 250°C or more, which shows that the condensed esters of Examples 1 to 4 have a pour point of -10°C or less and are excellent in fluidity at low temperatures. On the other hand, the condensed esters of Comparative Examples 1 to 4, in which the molar ratio of decanoic acid to dodecanoic acid (decanoic acid / dodecanoic acid) does not satisfy the requirement of 30 / 70 or more and 70 / 30 or less, have a kinematic viscosity at 40°C of 14 (mm 2 / s) or 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]

[0043] 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 metalworking oil to be blended into a water-insoluble metalworking oil composition, comprising: The base oil for metal working oil contains an ester of a fatty acid and neopentyl glycol, the fatty acid contains decanoic acid and dodecanoic acid, and the molar ratio of the decanoic acid to the dodecanoic acid (decanoic acid / dodecanoic acid) is 30 / 70 or more and 70 / 30 or less; the total content of the decanoic acid and the dodecanoic acid in the fatty acid is 100 mol %, 40℃ kinematic viscosity 10mm ２ / s or more 14mm ２ / s or less, and the viscosity index is 120 or more, The content of neopentyl glycol diester in the ester is 90 mol% or more, A base oil for metal working oil, wherein the content of the ester in the base oil for metal working oil is 90 mass% or more.

2. 2. The base oil for metal working oils according to claim 1, wherein the ester comprises a diester of a mixed fatty acid of the decanoic acid and the dodecanoic acid with the neopentyl glycol.

3. A water-insoluble metal working oil composition comprising the base oil for metal working oil according to claim 1 or 2.

4. A method for producing a base oil for metal working oil according to claim 1 or 2, 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 neopentyl glycol and a fatty acid, wherein the amount of carboxyl groups in the fatty acid relative to 1 equivalent of hydroxyl groups in the neopentyl glycol is 1.1 equivalents or more, the fatty acid is a mixed fatty acid of decanoic acid and dodecanoic acid, the total content of the decanoic acid and the dodecanoic acid in the fatty acid is 90 mol% or more, and the molar ratio of the decanoic acid to the dodecanoic acid (decanoic acid / dodecanoic acid) in the mixed fatty acid is 30 / 70 or more and 70 / 30 or less. Step 2: Removing excess fatty acid after esterification reaction

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