Alkyl-substituted phenoxathiins and lubricants

Abstract

To provide a lubricant having excellent wear resistance, corrosion resistance and heat resistance.SOLUTION: An alkylated phenoxathiin according to an embodiment of the present invention is represented by the formula (1) where R independently represent a C6-24 linear or branched alkyl group, and n and m each denote a real number satisfying 0<n+m<4.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to alkyl-substituted phenoxathiins and lubricants. [Background technology]

[0002] In recent years, lubricants such as lubricating oils and lubricating greases have come to be used under increasingly severe conditions, such as high temperatures, high speeds, and heavy loads, which has led to a demand for lubricants with better heat resistance and lubrication properties.

[0003] For example, Patent Document 1 describes a high-temperature lubricating oil containing alkyl diphenyl ether (ADE, alkyl diphenyl oxide). Patent Document 2 describes a synthetic lubricating oil containing alkyl-substituted diphenyl thioether (alkyl diphenyl sulfide, ADS). Patent Document 3 describes tests using an oil containing phenoxathiin-S-oxide (phenoxathiin 10,10-dioxide). Patent Document 4 describes an adduct that can be produced by catalytically reacting a compound i) containing a hydrocarbyl substituent or the like with a polynuclear aromatic compound ii). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 069670 [Patent Document 2] Japanese Patent Application Publication No. 58-208392 [Patent Document 3] Japanese Patent Publication No. 53-141306 [Patent Document 4] Special Publication No. 6-504289 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the prior art as described above still has room for further improvement from the perspective of realizing a lubricant with excellent lubricity, corrosion resistance, and heat resistance.

[0006] Therefore, one aspect of the present invention aims to realize a lubricant with excellent lubricity, corrosion resistance, and heat resistance.

Means for Solving the Problems

[0007] As a result of intensive research to solve the above problems, the inventors of the present invention have found that an alkyl-substituted phenoxathiin having a specific structure is excellent in lubricity, corrosion resistance, and heat resistance, and have completed the present invention. The present invention includes the following configurations. <1> An alkyl-substituted phenoxathiin represented by the following formula (1):

[0008]

Chemical formula

[0009] In formula (1), each R is independently a linear or branched alkyl group having 6 to 24 carbon atoms, and n and m are real numbers satisfying 0 < n + m < 4. <2> The alkyl-substituted phenoxathiin according to <1>, wherein the number of carbon atoms of R in formula (1) is 6 to 16. <3> The alkyl-substituted phenoxathiin according to <1> or <2>, wherein n + m in formula (1) is 1.0 to 2.6. <4> A lubricant containing the alkyl-substituted phenoxathiin according to any one of <1> to <3>.

Effects of the Invention

[0010] According to one aspect of the present invention, a lubricant with excellent lubricity, corrosion resistance, and heat resistance can be provided.

Brief Description of the Drawings

[0011] [Figure 1] It is a diagram showing the 1H-NMR spectrum of the model compound.

Mode for Carrying Out the Invention

[0012] An embodiment of the present invention will be described below, but the present invention is not limited thereto. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more and B or less".

[0013] 〔1. Alkyl-Substituted Phenoxathiin〕 The alkyl-substituted phenoxathiin according to an embodiment of the present invention is represented by the following formula (1).

[0014]

Chemical formula

[0015] In formula (1), each R is independently a linear or branched alkyl group having 6 to 24 carbon atoms, and n and m are real numbers satisfying 0 < n + m < 4. n + m indicates the number of alkyl substitutions. Since the above alkyl-substituted phenoxathiin has a phenoxathiin structure and the number of carbon atoms of the alkyl group and the number of alkyl substitutions are controlled within a specific range, it exhibits excellent lubricity, corrosion resistance, and heat resistance.

[0016] In this specification, the alkyl-substituted phenoxathiin may be a mixture of a plurality of compounds included in the range represented by formula (1).

[0017] In this specification, lubricity can be evaluated by a wear resistance test. Specifically, lubricity can be evaluated by the average wear scar diameter of steel balls measured by the method described in the examples.

[0018] In this specification, corrosion resistance can be evaluated by the degree of color change of a copper plate measured by the method described in the examples. Corrosion resistance can also be said to represent the influence of sulfur on metals.

[0019] In this specification, heat resistance can be evaluated by the amount of evaporation of a sample measured by the method described in the examples. It can also be said that heat resistance represents evaporation resistance.

[0020] In this specification, the term "phenoxathiin structure" refers to a structure in which two aromatic rings are bonded via a thioether bond (-S-) and an ether bond (-O-). The alkyl-substituted phenoxathiin has a phenoxathiin structure, and therefore can improve lubricity and heat resistance compared to alkyldiphenyloxide and alkyldiphenylsulfide. In addition, the alkyl-substituted phenoxathiin also has better corrosion resistance compared to alkyldiphenylsulfide.

[0021] The phenoxathiin 10,10-dioxide described in Patent Document 3 is prone to generating sludge due to the dioxide, whereas the alkyl-substituted phenoxathiins described above do not have a dioxide structure and therefore are less likely to generate sludge.

[0022] R may be bonded to any position on the aromatic ring. If the carbon number of R is 6 or more, evaporation is difficult, which is preferable from the viewpoint of heat resistance. Furthermore, if the carbon number of R is 6 or more, the influence of sulfur can be suppressed, which is preferable from the viewpoint of corrosion resistance. If the carbon number of R is 24 or less, dilution of the effect attributable to the phenoxathiin structure can be suppressed, and this effect can be fully exhibited. Furthermore, if the carbon number of R is 24 or less, viscosity can be suppressed. The number of carbon atoms in R is more preferably 6 to 16, even more preferably 6 or more but less than 16, and particularly preferably more than 6 but less than 16.

[0023] If 0 < n + m, it is difficult to evaporate and the influence of sulfur can be suppressed, which is preferable from the viewpoints of heat resistance and corrosion resistance. If n + m < 4, it is possible to suppress the dilution of the effects resulting from the above phenoxazine structure, and the effects can be fully exerted. Also, if n + m < 4, it is preferable from the viewpoint of oxidation resistance. It is more preferable that n and m satisfy 0 < n + m ≤ 3.6, still more preferable that 0 < n + m ≤ 3.0, particularly preferable that 0 < n + m ≤ 2.6, and most preferable that 0 < n + m < 1.5. Preferably, in the above alkyl-substituted phenoxazine, the carbon number of R exceeds 6 and is less than 16, and n and m satisfy 0 < n + m < 1.5.

[0024] Note that the degree of alkylation of the alkylated phenoxazine described in Patent Document 4 is not specified. In one embodiment of the present invention, as described later, for example, by performing simple distillation or molecular distillation, an alkyl-substituted phenoxazine in which the degree of alkyl substitution is within a specific range can be obtained.

[0025] The above degree of alkyl substitution can be determined by analyzing the 1H-NMR spectrum. Detailed measurement conditions will be described in the examples. Also, using the 1H-NMR spectrum of the model compound shown in FIG. 1, the method for calculating the degree of alkyl substitution will be described. In FIG. 1, a (chemical shift 6.5 to 7.3) indicates the peak of the hydrogen of the aromatic ring. b1 (chemical shift 2.8 to 3.3) and b2 (chemical shift 2.2 to 2.7) indicate the peaks of the hydrogen at the benzylic position. c (chemical shift 0.5 to 1.9) indicates the peak of the hydrogen of the alkyl group. Based on the integral values (ratios) of these peaks a, b1, bx, and c, the degree of alkyl substitution can be calculated from the following formula: Degree of alkyl substitution (m + n) = (number of hydrogens of aromatic ring)(b1 + b2 + c) / [(average number of hydrogens of alkyl group)a + b1 + b2 + c] In the above formula, a, b1, b2, and c represent the integral values of the peaks a, b1, b2, and c, respectively.

[0026] The mass average molecular weight of the alkyl-substituted phenoxathiin is preferably 200 to 1200 g / mol, more preferably 250 to 1000 g / mol, even more preferably 250 to 800 g / mol, and particularly preferably 250 to 700 g / mol. A mass average molecular weight within the above range is preferable from the viewpoint of lubricity. The mass average molecular weight can be measured using 1H-NMR.

[0027] The kinematic viscosity of the alkyl-substituted phenoxathiin at 40°C is 20 to 600 mm 2 / s is preferable, and 25 to 300 mm 2 / s, more preferably 30 to 100. A kinematic viscosity within the above range is preferable from the viewpoint of lubricity. The kinematic viscosity can be measured by the method described in the examples.

[0028] 2. Method for producing alkyl-substituted phenoxathiins An alkyl-substituted phenoxathiin according to one embodiment of the present invention can be obtained, for example, by the Friedel-Crafts reaction of phenoxathiin with a linear or branched olefin or alkyl halide having 6 to 24 carbon atoms.

[0029] An example of the production method is described below. First, a catalyst is added to phenoxathiin and heated, typically to 80-110°C, to uniformly dissolve the catalyst in the phenoxathiin. Then, while maintaining the reaction temperature at 80-110°C, an olefin or alkyl halide is added dropwise. After the dropwise addition is complete, stirring is continued at 80-110°C, followed by the addition of an alkaline neutralizer and stirring for approximately 30 minutes. Activated clay is then added and the mixture is stirred at 80-90°C for 0.5-3 hours. The catalyst and other acidic by-products are then removed by vacuum filtration. The resulting filtrate is distilled under reduced pressure to remove unreacted raw materials, etc. Further, by appropriately repeating vacuum distillation under specific pressure and temperature conditions, alkyl-substituted phenoxathiin with the desired alkyl substitution number can be obtained as a fraction (distillate) and / or distillation bottoms.

[0030] Examples of olefins include 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, and 2-decyl-1-tetradecene. One of these may be used alone, or two or more may be used in combination. The number of carbon atoms in the olefin is preferably 6 to 16, more preferably 6 or more but less than 16, and particularly preferably more than 6 but less than 16.

[0031] Examples of alkyl halides include 1-chlorohexane, 1-chloroheptane, 1-chlorooctane, 1-chlorononane, 1-chlorodecane, 1-chloroundecane, 1-chlorododecane, 1-chlorotridecane, 1-chlorotetradecane, 1-chloropentadecane, 1-chlorohexadecane, 1-chloro-2-decyl-1-tetradecane, 1-bromohexane, 1-bromoheptane, 1-bromooctane, 1-bromononane, 1-bromodecane, 1-bromoundecane, 1-bromododecane, 1-bromotridecane, 1-bromotetradecane, 1-bromopentadecane, 1-bromohexadecane, 1-bromo-2-decyl-1-tetradecane, etc. One of these may be used alone, or two or more may be used in combination. The alkyl halide more preferably has 6 to 16 carbon atoms, even more preferably 6 or more but less than 16, and particularly preferably more than 6 but less than 16 carbon atoms.

[0032] Examples of the catalyst include aluminum chloride, sulfated zirconia, and zinc chloride.

[0033] [3. Lubricants] One embodiment of the present invention also includes a lubricant base oil containing the alkyl-substituted phenoxathiin according to one embodiment of the present invention, and a lubricant containing the lubricant base oil. In other words, the lubricant according to one embodiment of the present invention contains the alkyl-substituted phenoxathiin according to one embodiment of the present invention as a base oil. The lubricant can be used as a bearing oil, fluid bearing oil, oil-impregnated bearing oil, grease base oil, oil-impregnated plastic oil, gear oil, jet engine oil, heat-insulating engine oil, gas turbine oil, automatic transmission oil, vacuum pump oil, hydraulic fluid, etc. used under high-temperature conditions.

[0034] The lubricant may be the alkyl-substituted phenoxathiin according to one embodiment of the present invention itself, but may also be mixed with synthetic oils such as mineral oil, α-olefin oligomer, polyol ester, diester, polyalkylene glycol, silicone oil, modified silicone oil, etc. Furthermore, the lubricant may contain additives such as antiwear agents, extreme pressure agents, antioxidants, viscosity index improvers, pour point depressants, rust and corrosion inhibitors, and conductivity imparting agents, as needed.

[0035] Whether or not a lubricant according to one embodiment of the present invention contains an alkyl-substituted phenoxathiin as a base oil can be determined based on the sulfur content in the lubricant, which is represented by the following formula. Sulfur content [%] = (100 × atomic weight of sulfur atom / molecular weight of alkyl-substituted phenoxathiin) × (amount of alkyl-substituted phenoxathiin added in lubricant [wt%] / 100) The atomic weight of the sulfur atom in the above formula is intended to mean the atomic weight of the sulfur atom contained in one molecule of the alkyl-substituted phenoxathiin.

[0036] If the sulfur content in the lubricant is 2.5% or more (preferably 3.0% or more), it is understood that an alkyl-substituted phenoxathiin is contained as a base oil.

[0037] The upper limit of the sulfur content of the lubricant according to one embodiment of the present invention is not particularly limited, but may be, for example, 11.5% or less, preferably 11.3% or less. The sulfur content can be measured by the method described in the Examples.

[0038] The lubricant or lubricant base oil preferably has an acid value of 0.25 mg KOH / g or less, more preferably 0.2 mg KOH / g or less. A smaller acid value is preferable from the viewpoint of oxidation resistance. The lower limit of the acid value may be 0 mg KOH / g. The acid value can be measured by the method described in the Examples.

[0039] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Example]

[0040] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0041] [Evaluation method] <Mass average molecular weight and alkyl substitution number> The 1H-NMR spectrum of each compound was measured using a nuclear magnetic resonance spectrometer JNM-ECX400 manufactured by JEOL Ltd. The measurement conditions were a temperature of 80°C and no solvent or standard substance was used.

[0042] In addition, 1H-NMR measurements were performed on the same compound using deuterated chloroform as the solvent and TMS as the standard. The chemical shifts were determined by comparing the results of these measurements with those obtained without the solvent or standard. This is because when deuterated chloroform is used, the peaks of deuterated chloroform and the benzene ring overlap, making it impossible to obtain accurate integral values.

[0043] Using 1H-NMR under the above conditions, the obtained compounds of Examples 1 to 9 and Comparative Examples 1, 2, 4, and 5 were analyzed to determine the mass average molecular weight of each compound.

[0044] The alkyl substitution number of each compound was determined by analyzing its 1H-NMR spectrum. As with the model compound described in [1. Alkyl-substituted phenoxathiins], the alkyl substitution number was calculated using the following formula based on the integrals of peak a representing hydrogen on the aromatic ring, peaks b1 and b2 representing hydrogen at the benzyl position, and peak c representing hydrogen on the alkyl group. Number of alkyl substitutions (m+n) = (number of hydrogen atoms in aromatic ring) (b1+b2+c) / [(average number of hydrogen atoms in alkyl group) a+b1+b2+c] In the above formula, a, b1, b2, and c represent the integral values ​​of peaks a, b1, b2, and c, respectively.

[0045] <Lubricity> To evaluate lubricity, a wear resistance test (high-speed four-ball test) was conducted as follows in accordance with ASTM D4172. The test was conducted under conditions of a load of 392 N, a temperature of 75°C, and a rotation speed of 1200 rpm. Also, 1 / 2-inch SUJ-2 steel balls were used. The average wear scar diameter of the steel balls after the test was calculated. In this test, an average wear scar diameter of 700 μm or less was evaluated as ◎, 701 to 770 μm as ◯, 771 to 840 μm as △, and 841 μm or more as ×. The smaller the average wear scar diameter, the better the lubricity.

[0046] <Corrosion resistance> Corrosion resistance was evaluated as follows. Corrosion resistance was evaluated with reference to JIS K 2513, by comparing the discoloration of a copper plate after leaving it at 100°C for 7 days with a standard plate. In this test, if the degree of discoloration of the copper plate was 1a, it was evaluated as ◎, if it was 1b, it was evaluated as 〇, if it was 2a to 2e, it was evaluated as △, and if it was 3a or higher (3b, 4a, etc.), it was evaluated as ×. The degree of discoloration of the copper plate increases in the order 1a<1b<2a to 2e<3a<3b<4a. It can also be said that the smaller the degree of discoloration, the better the corrosion resistance.

[0047] <Heat resistance> Heat resistance was evaluated as follows: 20 g of sample was placed in a 30 mL beaker and left to stand at 150°C for 20 days, and the amount of evaporation was calculated from the weight before and after standing. In this test, if the amount of evaporation was 10% or less, it was marked as ◎, if it was 11-20%, it was marked as ○, if it was 21-30%, it was marked as △, and if it was 31% or more, it was marked as ×. The smaller the amount of evaporation, the better the heat resistance.

[0048] <Viscosity characteristics> The viscosity characteristics were evaluated as follows: 40°C kinematic viscosity (mm 2 / s) was measured and calculated in accordance with JIS K 2283 (2000).

[0049] <Sulfur content> The sulfur content was calculated using the following formula. Sulfur content [%] = (100 × atomic weight of sulfur atom / molecular weight of alkyl-substituted phenoxathiin) × (amount of alkyl-substituted phenoxathiin added in lubricant [wt%] / 100) For comparative examples using compounds other than alkyl-substituted phenoxathiin, the sulfur content was calculated using the molecular weight and amount of the compound. The compounds in Examples 1 to 9 and Comparative Examples 1 and 5 contain one sulfur atom per molecule. The atomic weight of the sulfur atom is 32.07. The mass-average molecular weight determined by 1H-NMR described above was used as the molecular weight of each compound. In the following examples and comparative examples, each compound was used as a base oil, and the amount of each compound added to the lubricant was 100% by weight.

[0050] <Acid value> The acid value was measured in accordance with JIS K 2501.

[0051] [Examples 1 and 5] A 1 L four-neck flask equipped with a stirrer, dropping funnel, and thermometer was charged with 400 g (2.0 mol) of phenoxathiin (Tokyo Chemical Industry Co., Ltd.) and 32.0 g (0.24 mol) of anhydrous aluminum chloride, and heated to 90°C to dissolve the anhydrous aluminum chloride. Subsequently, while maintaining the temperature of the reaction system at 100°C, 84.2 g (1.0 mol) of 1-hexene was added dropwise to the four-neck flask over 2 hours to carry out a substitution reaction. After the dropwise addition, stirring was continued for 5 hours at 100°C, and then Kyoward (registered trademark) 1000s (alkaline neutralizer, Kyowa Chemical Industry Co., Ltd., Mg 4.5 Al2(OH) 13 A 5.5-fold amount of anhydrous aluminum chloride (CO3·3.5H2O) was added and stirred for 30 minutes. Subsequently, activated clay was added in an amount 3.65 times the amount of anhydrous aluminum chloride, and the mixture was stirred at 90°C for 30 minutes. After that, anhydrous aluminum chloride and other by-product acidic substances were removed by vacuum filtration. The filtrate obtained here was distilled under reduced pressure at 40 Pa and 140°C to remove unreacted raw materials. Subsequently, vacuum distillation was performed under conditions of 40 Pa and 200°C to obtain an alkyl-substituted phenoxathiin (Example 1) composed primarily of monoalkyl (C6)-phenoxathiin as a fraction (distillate). Here, "C6" refers to the number of carbon atoms per alkyl group, and the same applies hereinafter. Furthermore, the distillation bottom residue from this vacuum distillation at 200°C was obtained as an alkyl-substituted phenoxathiin composed primarily of di- and trialkyl (C6)-phenoxathiin (Example 5). That is, the alkyl-substituted phenoxathiin of Example 5 is mainly composed of a mixture of dialkyl(C6)-phenoxathiin and trialkyl(C6)-phenoxathiin.

[0052] [Examples 2, 6, and 9] A 2L four-neck flask equipped with a stirrer, dropping funnel, and thermometer was charged with 565g (2.82 mol) of phenoxathiin (Tokyo Chemical Industry Co., Ltd.) and 32.0g (0.24 mol) of anhydrous aluminum chloride. The mixture was heated to 90°C to dissolve the anhydrous aluminum chloride. Subsequently, while maintaining the reaction temperature at 100°C, 190.0g (1.13 mol) of a mixture of 1-dodecene and 1-tetradecene (45:55 mixture) was added dropwise to the four-neck flask over 2 hours to carry out a substitution reaction. After the addition, stirring was continued at 100°C for 5 hours, after which Kyoward® 1000s was added in an amount 5.5 times the amount of anhydrous aluminum chloride and stirred for 30 minutes. Subsequently, activated clay was added in an amount 3.65 times the amount of anhydrous aluminum chloride and stirred at 90°C for 30 minutes. The anhydrous aluminum chloride and other by-product acidic substances were removed by vacuum filtration. The filtrate obtained here was distilled under reduced pressure at 40 Pa and 140°C to remove unreacted raw materials, etc. Subsequently, distillation was carried out under reduced pressure at 40 Pa and 220°C to obtain an alkyl-substituted phenoxathiin (Example 2) containing monoalkyl (C12 & C14)-phenoxathiin as the main component as a fraction. That is, the alkyl-substituted phenoxathiin of Example 2 is mainly composed of a mixture of monoalkyl (C12)-phenoxathiin and monoalkyl (C14)-phenoxathiin.

[0053] The distillation residue obtained during the reduced pressure distillation at 220°C was alkyl-substituted phenoxathiin, mainly composed of a mixture of di-, tri-, and tetra-alkyl substitutions. -2 The distillation was carried out under reduced pressure at 1 Pa and 160°C to obtain alkyl-substituted phenoxathiins, mainly composed of dialkyl (C12 & C14)-phenoxathiins (Example 6). The distillation bottoms obtained from the reduced pressure distillation at 160°C yielded alkyl-substituted phenoxathiins, mainly composed of tri- and tetra-alkyl (C12 & C14)-phenoxathiins (Example 9).

[0054] That is, the alkyl-substituted phenoxathiins of Example 6 may include (i) dialkylphenoxathiins having only 12-carbon alkyl groups, (ii) dialkylphenoxathiins having only 14-carbon alkyl groups, and (iii) phenoxathiins having both 12-carbon alkyl groups and 14-carbon alkyl groups.

[0055] The alkyl-substituted phenoxathiin of Example 9 contains a mixture of trialkylphenoxathiin and tetraalkylphenoxathiin as a main component. The alkyl-substituted phenoxathiin of Example 9 may include (i) trialkylphenoxathiin having only a 12-carbon alkyl group, (ii) tetraalkylphenoxathiin having only a 12-carbon alkyl group, (iii) trialkylphenoxathiin having only a 14-carbon alkyl group, (iv) tetraalkylphenoxathiin having only a 14-carbon alkyl group, (v) trialkylphenoxathiin having both a 12-carbon alkyl group and a 14-carbon alkyl group, and (vi) tetraalkylphenoxathiin having both a 12-carbon alkyl group and a 14-carbon alkyl group.

[0056] [Examples 3 and 7] A 500 mL four-neck flask equipped with a stirrer, dropping funnel, and thermometer was charged with 240 g (1.2 mol) of phenoxathiin (Tokyo Chemical Industry Co., Ltd.) and 32.0 g (0.24 mol) of anhydrous aluminum chloride. The mixture was heated to 90°C to dissolve the anhydrous aluminum chloride. Subsequently, while maintaining the reaction temperature at 100°C, 108 g (0.48 mol) of 1-hexadecene was added dropwise to the four-neck flask over 2 hours to carry out a substitution reaction. After the addition, stirring was continued at 100°C for 5 hours, and then Kyoward® 1000s was added in an amount 5.5 times the amount of anhydrous aluminum chloride and stirred for 30 minutes. Subsequently, activated clay was added in an amount 3.65 times the amount of anhydrous aluminum chloride and stirred at 90°C for 30 minutes. The anhydrous aluminum chloride and other by-product acidic substances were then removed by vacuum filtration. The filtrate thus obtained was distilled under reduced pressure at 40 Pa and 140°C to remove unreacted raw materials, etc. Subsequently, the distillation bottom was diluted with 3.2 × 10 -2The mixture was distilled under reduced pressure at 1 Pa and 200°C to obtain an alkyl-substituted phenoxathiin (Example 3) composed primarily of monoalkyl(C16)-phenoxathiin. The distillation residue obtained from the distillation at 240°C under reduced pressure was alkyl-substituted phenoxathiin (Example 7) composed primarily of di- and trialkyl(C16)-phenoxathiin. The alkyl-substituted phenoxathiin of Example 7 is composed primarily of a mixture of dialkyl(C16)-phenoxathiin and trialkyl(C16)-phenoxathiin.

[0057] [Examples 4 and 8] A 2L four-neck flask equipped with a stirrer, dropping funnel, and thermometer was charged with 800g (4.0 mol) of phenoxathiin (Tokyo Chemical Industry Co., Ltd.) and 32g (0.24 mol) of anhydrous aluminum chloride, and heated to 90°C to dissolve the anhydrous aluminum chloride. Subsequently, while maintaining the reaction temperature at 100°C, 940g (2.80 mol) of 2-decyl-1-tetradecene was added dropwise to the four-neck flask over 4 hours to carry out a substitution reaction. After the addition, stirring was continued at 100°C for 5 hours, and then Kyoward® 1000s was added in an amount 5.5 times the amount of anhydrous aluminum chloride and stirred for 30 minutes. Subsequently, activated clay was added in an amount 3.65 times the amount of anhydrous aluminum chloride and stirred at 90°C for 30 minutes. The anhydrous aluminum chloride and other by-product acidic substances were then removed by vacuum filtration. The filtrate obtained here was distilled under reduced pressure at 40 Pa and 140°C to remove unreacted raw materials. Subsequently, it was distilled under reduced pressure at 40 Pa and 260°C to obtain alkyl-substituted phenoxathiin as the distillation residue, mainly composed of a mixture of mono-, di-, and tri-alkyl substitutions. The distillation residue was further purified by a molecular still to obtain 3.2 x 10 -2The mixture was distilled under reduced pressure at 1 Pa and 210°C to obtain an alkyl-substituted phenoxathiin (Example 4) composed primarily of monoalkyl (C24)-phenoxathiin. The distillation residue obtained from the distillation at 210°C yielded an alkyl-substituted phenoxathiin (Example 8) composed primarily of di- and trialkyl (C24)-phenoxathiin. The alkyl-substituted phenoxathiin of Example 8 is composed primarily of a mixture of dialkyl (C24)-phenoxathiin and trialkyl (C24)-phenoxathiin.

[0058] Comparative Example 1 A 500 mL four-neck flask equipped with a stirrer, dropping funnel, and thermometer was charged with 200 g (1.07 mol) of diphenyl sulfide and 2.85 g (0.24 mol) of anhydrous aluminum chloride. The mixture was heated to 90°C to dissolve the anhydrous aluminum chloride. Subsequently, while maintaining the reaction temperature at 100°C, 72.3 g (0.32 mol) of a mixture of 1-dodecene and 1-tetradecene (45:55 mixture) was added dropwise to the four-neck flask over 2 hours to carry out a substitution reaction. After the addition, the mixture was stirred at 100°C for 5 hours, after which Kyoward® 1000s was added in an amount 5.5 times the amount of anhydrous aluminum chloride and stirred for 30 minutes. Subsequently, activated clay was added in an amount 3.65 times the amount of anhydrous aluminum chloride and stirred at 90°C for 30 minutes. The anhydrous aluminum chloride and other by-product acidic substances were then removed by vacuum filtration. The filtrate obtained here was distilled under reduced pressure at 180°C and 40 Pa to remove unreacted raw materials, etc. The distillation bottoms obtained during this reduced pressure distillation at 180°C were alkyl-substituted diphenyl sulfide (ADS) composed primarily of monoalkyl (C12-14)-diphenyl sulfide. That is, the ADS of Comparative Example 1 was composed primarily of a mixture of monoalkyl (C12)-diphenyl sulfide and monoalkyl (C14)-diphenyl sulfide.

[0059] [Comparative Examples 2 and 4] A 500 mL four-neck flask equipped with a stirrer, dropping funnel, and thermometer was charged with 200 g (1.18 mol) of diphenyl oxide and 32.0 g (0.24 mol) of anhydrous aluminum chloride. The mixture was heated to 90°C to dissolve the anhydrous aluminum chloride. Subsequently, while maintaining the reaction temperature at 100°C, 168.32 g (1.0 mol) of a mixture of 1-dodecene and 1-tetradecene (45:55 mixture) was added dropwise to the four-neck flask over 2 hours to carry out a substitution reaction. After the addition, stirring was continued at 100°C for 5 hours, and then Kyoward® 1000s was added in an amount 5.5 times the amount of anhydrous aluminum chloride and stirred for 30 minutes. Subsequently, activated clay was added in an amount 3.65 times the amount of anhydrous aluminum chloride and stirred at 90°C for 30 minutes. The anhydrous aluminum chloride and other by-product acidic substances were then removed by vacuum filtration. The filtrate obtained here was distilled under reduced pressure at 40 Pa and 140°C to remove unreacted raw materials, etc. Subsequently, distillation was carried out under reduced pressure at 40 Pa and 260°C to obtain an alkyl-substituted diphenyl oxide (Comparative Example 2) containing monoalkyl (C12&14)-diphenyl oxide as the main component as a fraction. Furthermore, an alkyl-substituted diphenyl oxide (Comparative Example 4) containing dialkyl (C12&14)-diphenyl oxide as the main component as a distillation bottom residue at 260°C was obtained.

[0060] That is, the alkyl-substituted diphenyl oxide of Comparative Example 2 is mainly composed of a mixture of monoalkyl (C12)-diphenyl oxide and monoalkyl (C14)-diphenyl oxide. The alkyl-substituted diphenyl oxide of Comparative Example 4 may include (i) a dialkyl diphenyl oxide having only a C12 alkyl group, (ii) a dialkyl diphenyl oxide having only a C14 alkyl group, or (iii) a dialkyl diphenyl oxide having both a C12 alkyl group and a C14 alkyl group.

[0061] Comparative Example 3 As the lubricant in Comparative Example 3, Neovac MR-100 (mineral oil, manufactured by MORESCO Corporation) was used.

[0062] Comparative Example 5 A 2-L four-neck flask equipped with a stirrer, dropping funnel, and thermometer was charged with 700 g (3.53 mol) of ditosyl oxide and 94.0 g (0.70 mol) of anhydrous aluminum chloride. The mixture was heated to 100°C to dissolve the anhydrous aluminum chloride. Subsequently, while maintaining the reaction temperature at 100°C, 70.1 g (2.19 mol) of powdered sulfur was added to the four-neck flask and stirred for 2 hours. After cooling to room temperature, the mixture was washed with hydrochloric acid and extracted with toluene. Kyoward® 1000s was added to the toluene extract in an amount 1.5 times the amount of anhydrous aluminum chloride and stirred for 30 minutes. Subsequently, activated clay was added in an amount 1.5 times the amount of anhydrous aluminum chloride and stirred at 60°C for 30 minutes. The anhydrous aluminum chloride and other by-product acidic substances were removed by vacuum filtration. The resulting filtrate was vacuum distilled at 140°C and 40 Pa to remove unreacted raw materials. Subsequently, vacuum distillation was carried out under conditions of 40 Pa and 170°C to obtain dimethylphenoxathiin (Comparative Example 5) as a fraction.

[0063] [Evaluation results] Tables 1 and 2 show the evaluation results of lubricity, corrosion resistance, etc. for Examples 1 to 9 and Comparative Examples 1 to 5. Table 3 shows the evaluation results of heat resistance for Examples 2, 3, and 6 and Comparative Examples 1 and 2.

[0064] [Table 1]

[0065] [Table 2]

[0066] [Table 3]

[0067] The results in Table 1 confirm that the alkyl-substituted phenoxathiins of Examples 1 to 9 are superior in lubricity and / or corrosion resistance compared to those of Comparative Examples 1 to 5. More specifically, Examples 1 to 9 are superior in lubricity and corrosion resistance compared to the ADS of Comparative Example 1. Furthermore, Examples 1 to 9 are superior in lubricity compared to the alkyl-substituted diphenyl oxides of Comparative Examples 2 and 4 and the lubricant of Comparative Example 3. Furthermore, Examples 1 to 9 are superior in corrosion resistance compared to the dimethylphenoxathiin of Comparative Example 5.

[0068] Furthermore, from the results in Table 2, it was confirmed that the alkyl-substituted phenoxathiins of Examples 2, 3 and 5 exhibited superior heat resistance compared to Comparative Examples 1 and 2. [Industrial Applicability]

[0069] One aspect of the present invention can be used in the field of lubricants and the like.

Claims

1. A lubricant base oil comprising an alkyl-substituted phenoxathiin represented by the following formula (1): 【Chemistry 1】 In formula (1), each R is independently a linear or branched alkyl group having 6 to 24 carbon atoms, and n and m are real numbers satisfying the relationship 0<n+m<4. The base oil for lubricants has an acid value of 0.25 mgKOH / g or less.

2. 2. The lubricant base oil according to claim 1, wherein in formula (1), R has 6 to 16 carbon atoms.

3. 3. The lubricant base oil according to claim 1, wherein in formula (1), n ​​and m are real numbers satisfying 0<n+m≦2.

6.

4. A lubricant comprising the lubricant base oil according to any one of claims 1 to 3.

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