Alkyl-substituted diphenyl ether mixtures, lubricating oils, and methods of making alkyl-substituted diphenyl ethers

Abstract

An alkyl-substituted diphenyl ether mixture which is a mixture of diphenyl ethers substituted with 2 to 10 straight-chain or branched-chain alkyl groups having a carbon number of 8 to 24, wherein the mixture substantially does not contain a diphenyl ether substituted only with a branched-chain alkyl group.

Description

Technical Field

[0001] This invention relates to mixtures of alkyl-substituted diphenyl ethers, lubricating oils, and methods for manufacturing alkyl-substituted diphenyl ethers. This application claims priority to Japanese Patent Application No. 2023-206192, filed December 6, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0002] As a base oil for lubricating oils, base oils with alkyl-substituted diphenyl ethers as the main component are known. For example, Patent Document 1 (Japanese Patent Publication No. 58-22515) discloses alkyl-substituted diphenyl ethers having three or more alkyl groups having 10 to 20 carbon atoms. In the embodiments of Patent Document 1, it is described that an α-olefin having 12 to 16 carbon atoms is added to the diphenyl ether, and the average molar number of the olefin added is 3.5 to 5.2 moles.

[0003] Patent Document 2 (International Publication No. 2005 / 040081) discloses a grease composition containing a mixture of alkyl-substituted diphenyl ethers having 10 to 20 carbon atoms as substituents, having 2 or more substituents, and having an addition rate of 5% or more at the 1-position of the substituent. Patent Document 2 also discloses that the alkyl-substituted diphenyl ethers disclosed in Patent Document 2 possess both excellent high-temperature and excellent low-temperature properties.

[0004] Patent Document 3 (International Publication No. 2022 / 172935) discloses a dinaphthyl ether compound, which is used as a lubricant with excellent heat resistance. The dinaphthyl ether compound of Patent Document 3 is characterized by having substituents as straight-chain or branched hydrocarbon groups having 6 to 32 carbon atoms, with a substitution number of 1.0 or more and 3.0 or less.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 58-22515.

[0008] Patent Document 2: International Publication No. 2005 / 040081.

[0009] Patent document 3: International Publication No. 2022 / 172935. Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] As shown in Patent Documents 1-3, lubricating oils are required to have heat resistance. Lubricating oils with a mixture of diphenyl ether compounds as the base oil are known to have high heat resistance. On the other hand, lubricating oils with high heat resistance tend to have high viscosity, and high-viscosity lubricating oils can sometimes increase the torque during the operation of the lubricated component. In other words, heat resistance and viscosity are a trade-off. Therefore, one object of the present invention is to provide a lubricating oil that combines high heat resistance and low viscosity, a diphenyl ether mixture serving as its base oil, and a method for manufacturing the same.

[0012] Methods for solving problems

[0013] The alkyl-substituted diphenyl ether mixtures according to this disclosure are mixtures of diphenyl ethers substituted with 2 to 10 straight-chain or branched alkyl groups having 8 to 24 carbon atoms. Here, an alkyl-substituted diphenyl ether mixture refers to a mixture consisting solely of straight-chain or branched alkyl-substituted diphenyl ethers. In the case of compositions containing unreacted substances such as phenol or additives such as antioxidants, the portion consisting solely of alkyl-substituted diphenyl ethers is equivalent to an alkyl-substituted diphenyl ether mixture. The aforementioned mixture substantially does not contain diphenyl ethers substituted only with branched alkyl groups. In other words, when the composition is a composition containing various compounds other than alkyl-substituted diphenyl ethers, the alkyl-substituted diphenyl ether mixture contained in that composition substantially does not contain diphenyl ethers substituted only with branched alkyl groups. That is, most of the alkyl-substituted diphenyl ether molecules constituting the alkyl-substituted diphenyl ether mixture are substantially not diphenyl ethers substituted only with branched alkyl groups.

[0014] The alkyl-substituted diphenyl ether mixtures according to this disclosure are mixtures of diphenyl ethers substituted with 2 to 10 alkyl groups having 8 to 24 carbon atoms. The aforementioned mixtures are substantially composed only of diphenyl ethers having at least one straight-chain alkyl group. In other words, when the composition is a composition containing various compounds other than alkyl-substituted diphenyl ethers, the alkyl-substituted diphenyl ethers contained in the composition substantially have at least one straight-chain alkyl group. That is, the majority of the alkyl-substituted diphenyl ether molecules constituting the alkyl-substituted diphenyl ether mixture are substantially all diphenyl ethers having at least one straight-chain alkyl group.

[0015] The alkyl-substituted diphenyl ether mixtures according to this disclosure are mixtures of diphenyl ethers substituted with 2 to 10 alkyl groups having 8 to 24 carbon atoms. In the aforementioned diphenyl ether mixtures, the percentage of alkyl groups in which the carbon at the benzyl position is a secondary carbon is 25% or more.

[0016] The method for manufacturing alkyl-substituted diphenyl ethers according to this disclosure includes a diphenyl etherification step and an alkyl addition step. The aforementioned diphenyl etherification step involves reacting an alkyl-substituted phenol having a straight-chain alkyl group with an alkyl-substituted or unsubstituted halobenzene, or reacting an alkyl-substituted or unsubstituted phenol with a straight-chain alkyl group to obtain a diphenyl ether having a straight-chain alkyl group. The aforementioned alkyl addition step is an alkyl addition step involving the addition of an alkyl group to the diphenyl ether obtained in the aforementioned diphenyl etherification step. These steps are performed sequentially. The alkyl group added in the aforementioned alkyl addition step has 8 to 24 carbon atoms.

[0017] Invention Effects

[0018] Based on the above-mentioned alkyl-substituted diphenyl ether mixture, it is possible to provide a lubricating oil that combines high heat resistance and low viscosity, as well as a diphenyl ether mixture that serves as its base oil.

[0019] According to the above method for manufacturing alkyl-substituted diphenyl ether mixtures, it is possible to provide a lubricating oil that combines high heat resistance and low viscosity, as well as a diphenyl ether mixture that serves as its base oil. Attached Figure Description

[0020] Figure 1 It is Example 1 (mixture 3) 1 H-NMR spectrum.

[0021] Figure 2 It is Example 1 (mixture 3) 13 C-NMR spectrum.

[0022] Figure 3 It is Example 5 (mixture 5) 13 C-NMR spectrum.

[0023] Figure 4 This is a DEPT-135 diagram of Example 4 (Mixture 5). Detailed Implementation

[0024] [Summary of Implementation Methods]

[0025] First, embodiments of the alkyl-substituted diphenyl ether mixtures and methods for manufacturing the alkyl-substituted diphenyl ethers disclosed herein will be described. It should be noted that, unless otherwise specified, in this specification, "A to B" indicating a numerical range means "A or more and B or less".

[0026] The alkyl-substituted diphenyl ether mixtures according to this disclosure are mixtures of diphenyl ethers substituted with 2 to 10 straight-chain or branched alkyl groups having 8 to 24 carbon atoms. The aforementioned mixtures do not substantially contain diphenyl ethers substituted only with branched alkyl groups.

[0027] Conventionally, to provide diphenyl ether compositions with excellent heat resistance for use as base oils in lubricants, schemes have been proposed that specify the number and distribution of alkyl groups added to the diphenyl ether skeleton within a specific range. Additionally, schemes have been proposed that specify the addition mode of the alkyl substituents added to the diphenyl ether skeleton (e.g., the addition rate of the alkyl group at the 1-position) within a specific range. However, the demand for heat resistance continues, further requiring lubricants that balance high heat resistance and low viscosity. Under these circumstances, the inventors, through repeated research, discovered that a mixture of diphenyl ethers that does not contain diphenyl ethers substituted only with branched alkyl groups and must have straight-chain alkyl groups possesses both low viscosity and high heat resistance. In the manufacture of alkyl-substituted diphenyl ethers, unlike existing methods that add alkyl groups to diphenyl ethers as raw materials, this is achieved by preparing a diphenyl ether skeleton compound pre-added with straight-chain alkyl groups and then further adding alkyl groups to that skeleton compound.

[0028] The mixture disclosed herein is characterized by having alkyl substitution numbers and carbon numbers within specific ranges, and substantially not containing diphenyl ethers substituted only with branched alkyl groups. The alkyl-substituted diphenyl ether mixture, in its manufacturing process, is not composed of identical compounds, but rather is obtained as a mixture of alkyl-substituted diphenyl ether compounds with different alkyl addition numbers and addition forms. Existing alkyl-substituted diphenyl ether compositions specify the alkyl addition number (i.e., the average alkyl addition number) and alkyl addition form relative to the overall composition, without specifying the specific form of each compound constituting the alkyl-substituted diphenyl ether composition. In contrast, the diphenyl ether mixture of this invention is characterized by substantially not containing diphenyl ethers substituted only with branched alkyl groups; in other words, the compounds constituting the diphenyl ether mixture are not diphenyl ether compounds substituted only with branched alkyl groups. Here, "substantially not containing" means not only the absence of diphenyl ether compounds substituted only with branched alkyl groups, but also the presence of diphenyl ethers substituted only with branched alkyl groups in small, undetectable amounts when analyzed by commonly used analytical methods (e.g., NMR). Furthermore, this also includes cases where the diphenyl ether mixture contains a small amount of "diphenyl ether compounds substituted only with branched alkyl groups" to a degree that does not affect its performance as a lubricating oil base. Specifically, the diphenyl ether compounds substituted only with branched alkyl groups contained in the alkyl-substituted diphenyl ether mixture are less than 2% of the total amount of the alkyl-substituted diphenyl ether mixture.

[0029] Although not bound by a specific theory, it is believed that the mixture disclosed contains a higher proportion of straight-chain alkyl chains that exhibit high heat resistance compared to branched alkyl chains, thus achieving high heat resistance even with a small alkyl addition number. Therefore, it is considered to achieve a balance between low viscosity and high heat resistance.

[0030] Furthermore, the alkyl-substituted diphenyl ether mixture disclosed herein is a mixture of diphenyl ethers substituted with an average of 2 to 10 alkyl groups having a carbon number of 8 to 24. The aforementioned mixture is substantially composed only of diphenyl ethers having at least one straight-chain alkyl group. Here, "composed only of" means that the total amount of diphenyl ethers having at least one straight-chain alkyl group relative to the alkyl-substituted diphenyl ether mixture is 98% or more. More preferably, the total amount of diphenyl ethers having at least one straight-chain alkyl group relative to the alkyl-substituted diphenyl ether mixture is 99% or more. As described above, such a diphenyl ether mixture has been found to achieve both low viscosity and high heat resistance.

[0031] The aforementioned alkyl-substituted diphenyl ether mixture can be a mixture of diphenyl ethers substituted with an average of 2 to 5 alkyl groups. When the number of alkyl substitutions is within this range, alkyl-substituted diphenyl ether mixtures can be obtained by combining known raw materials and manufacturing methods, while reliably achieving the effects of the present invention.

[0032] When the aforementioned alkyl-substituted diphenyl ether mixture is composed of a compound having at least one straight-chain alkyl group, at least one of the aforementioned straight-chain alkyl groups can be bonded to the ortho or meta position of a carbon atom in the benzene ring that is bonded to an oxygen atom. Alkyl-substituted diphenyl ether mixtures composed of such compounds exhibit increased heat resistance.

[0033] In the aforementioned alkyl-substituted diphenyl ether mixture, the average total number of carbon atoms in the alkyl groups of the aforementioned diphenyl ether mixture may be 25 or more and 100 or less.

[0034] The alkyl-substituted diphenyl ether mixture disclosed herein is a mixture of diphenyl ethers substituted with 2 to 10 alkyl groups having 8 to 24 carbon atoms. In the aforementioned diphenyl ether mixture, the ratio of alkyl groups in which the carbon at the benzyl position is a secondary carbon is 25% or more. The method for determining and calculating the ratio of "alkyl groups in which the carbon at the benzyl position is a secondary carbon" in the diphenyl ether mixture is described in detail in the examples.

[0035] The alkyl-substituted diphenyl ether mixture disclosed herein is produced by a different manufacturing method than existing alkyl-substituted diphenyl ether mixtures, resulting in a high ratio of alkyl groups where the carbon at the benzylic position is a secondary carbon, exceeding 25%. Existing alkyl-substituted diphenyl ethers are produced by adding alkyl groups to diphenyl ethers using the Friedel-Crafts reaction. In the alkyl addition based on the Friedel-Crafts reaction, the olefin compound that becomes the alkyl group during the addition reaction may rearrange probabilistically. Therefore, even when an α-olefin is used as the alkyl group, the ratio of alkyl groups where the carbon at the benzylic position is a secondary carbon does not reach a limit. Furthermore, diphenyl ethers in which all substituted alkyl groups are branched are generated. In contrast, the mixture disclosed herein can be obtained by preparing a diphenyl ether skeleton compound pre-added with a straight-chain alkyl group and further adding alkyl groups to that skeleton compound. Therefore, it is possible to obtain an alkyl-substituted diphenyl ether mixture with a high ratio of alkyl groups where the carbon at the benzylic position is a secondary carbon, exceeding 25%. Furthermore, the generated alkyl-substituted diphenyl ether compound has at least one straight-chain alkyl group. That is, the diphenyl ethers contained in the aforementioned alkyl-substituted diphenyl ether mixture can substantially consist only of diphenyl ethers having at least one straight-chain alkyl group. The diphenyl ether mixture according to this disclosure achieves a balance between low viscosity and high heat resistance.

[0036] The aforementioned alkyl-substituted diphenyl ether mixture is a mixture of diphenyl ethers substituted with 2 to 5 alkyl groups, and at least one of the aforementioned straight-chain alkyl groups may be a meta-linear alkyl group bonded to a carbon atom with an oxygen atom bonded to a benzene ring.

[0037] The lubricating oil disclosed herein is a lubricating oil containing the above-mentioned diphenyl ether mixture.

[0038] The method for manufacturing alkyl-substituted diphenyl ethers disclosed herein includes a diphenyl etherification step and an alkyl addition step. The diphenyl etherification step involves reacting an alkyl-substituted phenol having a straight-chain alkyl group with an alkyl-substituted or unsubstituted halobenzene, or reacting an alkyl-substituted or unsubstituted phenol with an alkyl-substituted or unsubstituted phenol, to obtain a diphenyl ether having a straight-chain alkyl group. The alkyl addition step involves adding an alkyl group to the diphenyl ether obtained in the diphenyl etherification step. These steps are performed sequentially. The alkyl group added in the alkyl addition step has 8 to 24 carbon atoms. The alkyl-substituted diphenyl ether mixture obtained by this manufacturing method combines high heat resistance and low viscosity, making it suitable as a base oil for lubricating oils.

[0039] In the aforementioned method for manufacturing alkyl-substituted diphenyl ethers, the aforementioned alkyl-substituted phenol having a straight-chain alkyl group can be an alkyl-substituted phenol having a straight-chain alkyl group bonded to a meta-position of a carbon atom in the benzene ring bonded with an oxygen atom. Based on this configuration, by combining commonly used raw materials and manufacturing methods, a mixture of alkyl-substituted diphenyl ethers that balances high heat resistance and low viscosity can be obtained at a practically reasonable cost.

[0040] [Specific examples of implementation methods]

[0041] The alkyl-substituted diphenyl ether mixtures of this disclosure will be described in more detail.

[0042] [Compounds constituting a mixture of alkyl-substituted diphenyl ethers]

[0043] The alkyl-substituted diphenyl ether mixture disclosed herein is a mixture of alkyl-substituted diphenyl ether compounds, wherein the alkyl-substituted diphenyl ether compounds constituting the alkyl-substituted diphenyl ether mixture substantially do not contain diphenyl ethers that are substituted only by branched alkyl groups. Here, "substantially do not contain" means, specifically, that the total amount of diphenyl ethers substituted only by branched alkyl groups relative to the alkyl-substituted diphenyl ether mixture is 2% or less. More preferably, the total amount of diphenyl ethers substituted only by branched alkyl groups relative to the alkyl-substituted diphenyl ether mixture is 1% or less.

[0044] The alkyl-substituted diphenyl ether mixture disclosed herein is substantially composed only of diphenyl ether compounds having at least one straight-chain alkyl group. This means that the total amount of diphenyl ether compounds having at least one straight-chain alkyl group relative to the alkyl-substituted diphenyl ether mixture is 98% or more. More preferably, the proportion of diphenyl ether compounds having at least one straight-chain alkyl group relative to the total amount of the alkyl-substituted diphenyl ether mixture is 99% or more. The compounds constituting the alkyl-substituted diphenyl ether mixture are compounds represented by the following general formula (1). In general formula (1), R can substitute for a hydrogen atom of any one of the two benzene rings.

[0045]

[0046] (In formula (1), R is a straight-chain or branched alkyl group with 8 to 24 carbon atoms that are the same or different from each other, at least one of R is a straight-chain alkyl group, 1≤a≤10, and a is an integer.)

[0047] The alkyl-substituted diphenyl ether mixture is substantially composed only of compounds represented by general formula (1). Here, "substantially composed only of compounds represented by general formula (1)" includes not only cases where 100% of the compounds contained in the alkyl-substituted diphenyl ether mixture are represented by general formula (1), but also cases where, when the alkyl-substituted diphenyl ether mixture is analyzed by commonly used analytical methods (e.g., NMR), compounds other than the diphenyl ether compounds represented by general formula (1) are present in small quantities to a degree that is difficult to detect. Furthermore, it also includes cases where compounds other than the diphenyl ether compounds represented by general formula (1) are present in small quantities to a degree that does not affect the performance of the diphenyl ether mixture as a lubricating oil base. Specifically, 98% or more of the diphenyl ether compounds contained in the alkyl-substituted diphenyl ether mixture are represented by general formula (1). More preferably, 99% or more of the diphenyl ether compounds contained in the alkyl-substituted diphenyl ether mixture are represented by general formula (1).

[0048] In general formula (1), R is an alkyl group with 8 to 24 carbon atoms that are the same or different from each other, and 1 ≤ a ≤ 10. The alkyl group represented by R can be a straight-chain alkyl group or a branched alkyl group, but at least one of R is a straight-chain alkyl group.

[0049] Specifically, as R, examples of straight-chain alkyl groups include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, octadecyl, eicosyl, dodecyl, and tetradecyl. Examples of branched alkyl groups include 1-methylundecyl, 1-ethyldecyl, 1-methyltridecyl, 1-ethyldodecyl, 1-methylpentadecanyl, 1-ethyltetradecyl, 1-ethyltetra(dodecyl), 1-methylheptadecyl, 1-ethyloctadecyl, 1-methylnonadecanyl, 1-ethyloctadecyl, 2-ethylhexyl, 2-octyldodecyl, 2-decyltetradecyl, 2-dodecylhexadecyl, 1-butyl-1-methylpentyl, 1-butyl-1-methylheptyl, 1-methyl-1-pentyloctyl, 1-hexyl-1-methylnonyl, 1-heptyl-1-methyldecyl, 1-methyl-1-octylundecyl, and 1-decyl-1-methyltridecyl.

[0050] Heat resistance can be obtained by using alkyl groups with 8 or more carbon atoms. In addition, by using alkyl groups with 24 or fewer carbon atoms, the viscosity will not be too high, and alkyl-substituted diphenyl ether mixtures that balance low viscosity and heat resistance can be obtained.

[0051] The linear alkyl group in R is not limited to any alkyl group having 8 to 24 carbon atoms, but is preferably an alkyl group having 12 to 18 carbon atoms, specifically dodecyl, tridecyl, tetradecyl, pentadecyl, or hexadecyl. The compound represented by general formula (1) may have one or more linear alkyl groups. In addition, R is preferably a linear alkyl group in the ortho or meta position of a carbon atom bonded to an oxygen atom in the benzene ring, and more preferably a linear alkyl group bonded to the meta position.

[0052] 'a' represents the number of alkyl groups substituted in the diphenyl ether skeleton, and is 1 ≤ a ≤ 10, preferably 2 ≤ a ≤ 5. The 'a' alkyl substituents R can be all straight-chain alkyl groups, or a mixture of straight-chain and branched alkyl groups. The 'a' alkyl substituents R can be substituted on the same benzene ring in two benzene rings, or on different benzene rings.

[0053] [Mixture of alkyl-substituted diphenyl ethers]

[0054] The alkyl-substituted diphenyl ether mixture is a mixture of compounds represented by the above general formula (1), and is represented by the following general formula (2).

[0055]

[0056] (In formula (2), R is a straight-chain or branched alkyl group with 8 to 24 carbon atoms that are the same or different from each other, at least one of R is a straight-chain alkyl group, 2≤x≤10, and x is a real number.)

[0057] Where x is the average number of alkyl groups (average alkyl substitution number) of the diphenyl ether compounds constituting the alkyl-substituted diphenyl ether mixture. An alkyl-substituted diphenyl ether mixture may also contain monoalkyl-substituted diphenyl ether compounds as long as the average alkyl substitution number is 2 or more.

[0058] The alkyl-substituted diphenyl ether mixture represented by general formula (2) can also be represented by the following general formula (3). For ease of explanation, general formula (3) will be used as a reference. In general formula (3), m and n are respectively R among the alkyl groups of the diphenyl ether compounds constituting the alkyl-substituted diphenyl ether mixture. 1 R 2 The average number of alkyl groups (average alkyl substitution number). R 1 and R 2 It can be bonded to the same benzene ring in two benzene rings, or it can be bonded to different benzene rings.

[0059]

[0060] (In equation (3), R) 1 They are straight-chain alkyl groups with 8 to 24 carbon atoms, which may be the same as or different from each other.2 With R 1 Different alkyl groups are straight-chain or branched alkyl groups with 8 to 24 carbon atoms, which may be the same as or different from each other, where 1 ≤ m, 0 ≤ n, and 2 ≤ m + n ≤ 10, and m + n is a real number.

[0061] Alkyl-substituted diphenyl ether mixtures have one or more (1≤m) alkyl Rs consisting of straight-chain alkyl groups. 1 As R 1 Specifically, straight-chain alkyl groups selected as R can be cited, preferably alkyl groups having 12 to 18 carbon atoms, and more preferably one or more selected from the group consisting of dodecyl, tridecyl, tetradecyl, pentadecyl, and hexadecyl. m is preferably 1 or more and 5 or less.

[0062] R 2 With R 1 The difference lies in the presence or absence of carbon atoms; these are straight-chain or branched alkyl groups with 8 to 24 carbon atoms that are the same as or different from each other. Examples of alkyl groups listed as R are provided. 2 It is greater than or equal to 0 (0 ≤ n). That is to say, R 2 It may not exist. n is preferably 4 or less.

[0063] The number of substituents in the alkyl-substituted diphenyl ether mixture is preferably 2 ≤ m + n ≤ 5. That is, the average number of substituents in the mixture is preferably 2 to 5. Within this range, the alkyl-substituted diphenyl ether mixture becomes liquid at room temperature and can form a composition with suitable physical properties as a base oil for lubricating oil. The number of alkyl substitutions can be determined and calculated using the method shown in the examples described later.

[0064] In the alkyl-substituted diphenyl ether mixtures disclosed herein, the average carbon number of the alkyl groups (the average number of carbons in each alkyl group) is preferably 8 to 20. The average carbon number of the alkyl groups is a real number representing the average number of carbons in each alkyl group of the compounds included in the alkyl-substituted diphenyl ether mixture. The average carbon number of the alkyl groups can be determined by the method shown in the examples described later.

[0065] Furthermore, the lower limit of the average total carbon number of alkyl groups in the alkyl-substituted diphenyl ether mixture of the present invention (the sum of the carbon numbers of the alkyl groups in one molecule of alkyl-substituted diphenyl ether is called the total carbon number of alkyl groups. The average total carbon number of alkyl groups in the alkyl-substituted diphenyl ether mixture is called the average total carbon number of alkyl groups) is 16 or more, preferably 25 or more, more preferably 30 or more. The upper limit of the average total carbon number of alkyl groups in the mixture is 240 or less, preferably 100 or less, more preferably 70 or less, and even more preferably 60 or less. The average total carbon number of alkyl groups in the alkyl-substituted diphenyl ether mixture is a real number calculated from the average carbon number of alkyl groups and m+n.

[0066] The number-average molecular weight of the alkyl-substituted diphenyl ether mixture disclosed herein is preferably around 500 to 1000. A higher number-average molecular weight tends to result in excellent heat resistance, but also tends to lead to excessively high kinematic viscosity. Conversely, a lower number-average molecular weight results in lower kinematic viscosity, but also tends to lead to poor heat resistance. As long as the number-average molecular weight is within the aforementioned range, a low-viscosity alkyl-substituted diphenyl ether mixture with excellent heat resistance can be obtained.

[0067] It should be noted that the number-average molecular weight of the alkyl-substituted diphenyl ether mixture is as shown in the examples described later, utilizing... 1 The values ​​measured by ¹H-NMR. It should be noted that the number-average molecular weight is sometimes referred to as "average molecular weight" below.

[0068] In the alkyl-substituted diphenyl ether mixtures of this disclosure, the ratio of the carbon at the benzyl position of the alkyl group of the alkyl-substituted diphenyl ether to a secondary carbon (referred to as the secondary carbon ratio) is preferably 25% or more, more preferably 35% or more, and even more preferably 38% or more. When the alkyl-substituted diphenyl ether mixture of this disclosure is composed of a diphenyl ether compound having at least one straight-chain alkyl group, the carbon at the benzyl position of the straight-chain alkyl group added to the benzene ring must be a secondary carbon. Although not particularly theoretically constrained, when the secondary carbon ratio of the alkyl-substituted diphenyl ether mixture is high, oxidation reactions based on oxygen in the air are difficult to occur under high-temperature conditions, thus making evaporation difficult. Therefore, it is believed that even with a small number of alkyl additions, high heat resistance can be exhibited, which helps to balance low viscosity and high heat resistance. There is no particular upper limit to the secondary carbon ratio of the benzyl group, which can be 100% or less, 70% or less, or 55% or less.

[0069] [Manufacturing Method]

[0070] The method for manufacturing the above-mentioned alkyl-substituted diphenyl ether mixture is not particularly limited, but the following manufacturing method is preferred. In other words, the method for manufacturing the alkyl-substituted diphenyl ether disclosed herein includes a diphenyl etherification step and an alkyl addition step. The aforementioned diphenyl etherification step is a step of reacting an alkyl-substituted phenol having a straight-chain alkyl group with an alkyl-substituted or unsubstituted halobenzene, or reacting an alkyl-substituted or unsubstituted phenol with an alkyl-substituted or unsubstituted phenol, to obtain a diphenyl ether having a straight-chain alkyl group. From the viewpoint of obtaining materials, it is preferable to react an alkyl-substituted phenol with an alkyl-substituted or unsubstituted haloalkylbenzene to obtain a diphenyl ether having a straight-chain alkyl group.

[0071] The diphenyl etherification process is the process of synthesizing diphenyl ethers with an alkyl-addition skeleton. As the starting material in this diphenyl etherification process, alkyl-substituted phenols having a straight-chain alkyl group or halobenzenes having a straight-chain alkyl group are used. The straight-chain alkyl group is preserved independently of subsequent reaction processes, so the final alkyl-substituted diphenyl ether compound also has the straight-chain alkyl group present in the starting compound. Therefore, regardless of the form of the alkyl group added in the subsequent alkyl addition process, a diphenyl ether compound having at least one straight-chain alkyl group can be obtained. The straight-chain alkyl group from the starting compound corresponds to R in general formula (2). 1 There are no particular limitations on the raw materials used as alkyl-substituted phenols having a straight-chain alkyl group. For example, from the viewpoint of heat resistance, hydrogenated cashew phenol (an alkyl-substituted phenol having 15 carbon atoms in the meta position) is preferred.

[0072] The diphenyl etherification process is not particularly limited, but for example, the following synthetic method using the Ullmann reaction can be employed. For example, in the presence of a base, hydrogenated cashew phenol is mixed with copper iodide and subjected to nitrogen substitution, followed by the dropwise addition of bromobenzene, thereby yielding a diphenyl ether having a straight-chain alkyl group. The molar ratio of hydrogenated cashew phenol to bromobenzene can be in the range of 10:1 to 1:10. The reaction temperature can be 100 to 200 °C. From the viewpoint of reactivity and reaction efficiency, a solvent can be used. Examples of solvents include dimethyl sulfoxide and N-methyl-2-pyrrolidone. As a base, basic compounds such as potassium carbonate, potassium phosphate, potassium hydroxide, sodium hydroxide, and sodium hydride can be used. The amount of base added relative to the hydroxyl group of phenol can be 1 to 10 equivalents. In the aforementioned example, copper iodide is used as a catalyst, but copper chloride, copper bromide, etc., can also be appropriately selected as catalysts. The amount of catalyst added, for example, relative to the hydroxyl group of phenol can be 0.1 to 1 equivalent.

[0073] The alkyl addition step following the diphenyl etherification step is an alkyl addition step in which an alkyl group is added to the diphenyl ether obtained in the diphenyl etherification step. The alkyl group added in the alkyl addition step has 8 to 24 carbon atoms. The alkyl addition step can be carried out using the Friedel-Crafts reaction, with known conditions and equipment. For example, using aluminum chloride as a catalyst, a mixture of alkyl-substituted diphenyl ethers can be obtained by reacting a diphenyl ether having a straight-chain alkyl group with a straight-chain or branched olefin. The amount of olefin added relative to the diphenyl ether can be set according to the number of alkyl groups to be added to the diphenyl ether. For example, when two olefins are to be added to the diphenyl ether, the amount of olefin added relative to the diphenyl ether (molar ratio) can be 1:1 to 3. The reaction temperature of the alkyl addition reaction can be 40 to 130°C. From the viewpoint of reactivity and reaction efficiency, a solvent can also be used. Examples of solvents include nitrobenzene and dichloromethane. When using a catalyst, ferric bromide and zirconium oxide sulfate can be appropriately selected as catalysts. The amount of catalyst added can be, for example, 0.0046 to 20% by mass relative to the olefin.

[0074] Following the alkyl addition step, the reaction mixture is typically distilled to remove unreacted compounds. This allows for the recovery of the alkyl-substituted diphenyl ether mixture that is the subject of this invention.

[0075] [Base oil used in lubricating oils]

[0076] The alkyl-substituted diphenyl ether mixtures disclosed herein can be used alone or in combination with other compounds and compositions as base oils for lubricating oils. Regarding lubricating oil compositions, in addition to the alkyl-substituted diphenyl ether mixtures disclosed herein, to further improve their performance or to impart further properties as needed, synthetic oils such as α-olefin oligomers, polyol esters, diesters, polyalkylene glycols, silicone oils, modified silicone oils, alkyl diphenyl ether oils, multiple alkylate cyclopentane oils, and silahydrocarbon oils can be mixed in addition to mineral oils, without impairing the effects of the invention. Furthermore, various additives such as antioxidants, extreme pressure agents, friction modifiers, metal passivators, defoamers, tackifiers, colorants, and thickeners can be formulated individually or in combination as needed.

[0077] As an additive, antioxidants commonly used in lubricating oils can be used without particular limitation. Examples of antioxidants include phenolic compounds, amine compounds, phosphorus compounds, and sulfur compounds.

[0078] Examples of extreme pressure agents include phosphorus compounds and sulfur compounds.

[0079] Examples of friction modifiers include molybdenum compounds such as molybdenum dithiocarbamate and fatty acid derivatives such as glyceryl monostearate.

[0080] Examples of metal passivating agents include benzotriazole, toluenetriazole, thiadiazole, and imidazole compounds.

[0081] Examples of defoamers include polyacrylates and styrene polymers.

[0082] Examples of thickeners include inorganic systems such as metal soaps (e.g., lithium soap), silica, graphite, and clay (e.g., lithium montmorillonite or bentonite), as well as organic systems such as polyurea, polyether ether ketone, and polyphenylene sulfide.

[0083] When the lubricating oil composition contains a mixture of alkyl-substituted diphenyl ethers disclosed herein, from the viewpoint of ensuring heat resistance, its content percentage relative to the total mass of the lubricating oil composition is preferably about 50 to 100% by mass. Furthermore, in this case, the content of additives, etc., in the lubricating oil composition is preferably about 50 to 0% by mass.

[0084] Furthermore, the alkyl-substituted diphenyl ether mixtures disclosed herein can also be used as additives in lubricating oil compositions. In this case, the content of the alkyl-substituted diphenyl ether mixture relative to the total mass of the lubricating oil composition is preferably about 1 to 49% by mass.

[0085] In addition, the alkyl-substituted diphenyl ether mixtures disclosed herein can be used as components of high-temperature lubricating oils and heat-resistant greases.

[0086] The lubricating oil compositions, high-temperature lubricating oils, and heat-resistant greases are suitable for use as bearing lubricants, bearing impregnation lubricants, grease-based oils, refrigeration oils, plasticizers, etc. In particular, they are suitable for use as various lubricating oils for high-temperature conditions, such as bearing oils, fluid bearing oils, oil-impregnated bearing oils, grease-based oils, oil-impregnated plastic oils, gear oils, jet engine oils, insulating engine oils, gas turbine oils, automatic transmission fluids, vacuum pump oils, hydraulic oils, etc. Furthermore, the alkyl-substituted diphenyl ether mixtures disclosed herein also exhibit excellent radiation resistance, and are therefore considered suitable for use as radiation-resistant lubricating oils or radiation-resistant greases.

[0087] [Example]

[0088] The present invention will be described in more detail below through examples, but the present invention is not limited to these examples.

[0089] [Determination Method]

[0090] 1. NMR

[0091] The compounds and mixtures synthesized in the examples and comparative examples were identified using NMR. The methods for calculating the number of alkyl substitutions and the carbon order at the benzylic positions of alkyl groups in the synthesized mixtures will be described later. NMR determinations were performed using the following apparatus and under the following conditions.

[0092] Device: JNM-ECX series FT NMR device manufactured by Nippon Electronics Co., Ltd., 400MHz.

[0093] Solvent: None.

[0094] Temperature: 70℃.

[0095] Measurement conditions: 1 H-NMR: 8 scans.

[0096] 13 C-NMR: 1024 scans.

[0097] DEPT-135: 512 scans, 135° angle.

[0098] 2. GC

[0099] The reaction was confirmed using gas chromatography. The reaction was considered to be proceeding if a new peak was formed on the side with a higher boiling point than the material.

[0100] Device: Shimadzu Corporation, GC-2010Plus.

[0101] Chromatographic column: Ultra ALLOY Capillary Column UA17-15W-0.25F (30m × 0.250mm 0.10μm (Micron)) manufactured by Frontier Laboratories Ltd.

[0102] Vaporization chamber temperature: 350℃.

[0103] Injection method: Total volume injection method.

[0104] Temperature conditions: 50℃~350℃, increase the temperature at 12.5℃ / min, and then maintain at 350℃ for 15 minutes.

[0105] Carrier gas: nitrogen (column flow rate: 1.48 mL / min).

[0106] 3. HPLC

[0107] Diphenyl ether compounds with different molecular weights were separated using HPLC. The proportions of diphenyl ether compounds with different molar numbers of alkyl substitution were calculated from the obtained peak areas.

[0108] Device: Agilent Technologies, 1220 InfinityLC.

[0109] Developing solvent: CHCl3:acetonitrile = 50:50.

[0110] Chromatographic column: TSKgel ODS-100V 5μm 4.6mm×15cm, manufactured by Tosoh Corporation.

[0111] Flow rate: 1.00 mL / min.

[0112] Detector: UV 254nm.

[0113] [Preparation of mixtures of alkyl-substituted diphenyl ethers]

[0114] [Skeleton Synthesis 1]

[0115] Synthesis of m-pentadecanyl diphenyl ether

[0116] Hydrogenated cashew nut shell powder (Cardolite, NC-510) (30 g, 0.18 mol), bromobenzene (23.0 g, 0.15 mol), potassium carbonate (27.6 g, 0.2 mol), copper iodide (I) (1.9 g, 0.10 mol), and N-methylpyrrolidone (160 mL) were added, and the mixture was heated and stirred at 170 °C for 7 hours. The reaction was confirmed by GC. Potassium carbonate was removed by filtration, and the filtrate was treated with activated clay and hydrotalcite for adsorption. Unreacted components, solvent, and byproducts were removed by distillation, yielding 18.1 g of a white solid containing the skeleton compound 1. The yield was 26%. 1 H-NMR identified the skeleton compound 1 as m-pentadecanyl diphenyl ether.

[0117] [Skeleton Synthesis 2]

[0118] Synthesis of o-hexadecyl diphenyl ether

[0119] (1) Grignard reaction

[0120] In a flask, add Mg (10 g, 1.68 equivalents relative to o-phenoxybenzaldehyde), iodine (1 grain, approximately 0.02 g), and THF (1 M relative to o-phenoxybenzaldehyde). In a dropping funnel, add pentadecane bromide (98.7 g, 1.4 equivalents relative to o-phenoxybenzaldehyde). While adding pentadecane bromide dropwise through the dropping funnel, heat to 70°C. After the addition is complete, stir at 70°C for 1 hour, then cool to room temperature to synthesize the Grignard reagent.

[0121] In another flask, o-phenoxybenzaldehyde (48 g, 1.0 equivalent) and THF (2 M) were added, and the aforementioned Grignard reagents were added dropwise while stirring at room temperature. After the addition was complete, the reaction was confirmed by TLC, quenched with 1 M HCl, and then extracted with ethyl acetate. The solvent was removed by distillation, yielding 107 g of a yellow, transparent crude product.

[0122] (2) Reduction reaction

[0123] The crude product obtained in (1), dichloromethane (0.5 M relative to o-phenoxybenzaldehyde), and triethylsilane (56.3 g, 2.0 equivalents relative to o-phenoxybenzaldehyde) were added and cooled with ice water. A trifluoroborane-ether complex (69 g, 2.0 equivalents relative to o-phenoxybenzaldehyde) was added dropwise, and the reaction was confirmed by TLC after the addition was complete. The reaction was quenched with an aqueous solution of NaHCO3, and the solvent was removed by distillation to obtain a yellow, transparent crude product. This was then purified by column chromatography (AcOEt / Hex 1:50–1:1) to obtain 16.9 g of a white solid skeleton compound 2. The yield was 18.2%. 1 H-NMR identified the skeleton compound 2 as o-hexadecyl diphenyl ether.

[0124] [Skeleton Synthesis 3]

[0125] Synthesis of m-hexadecyl diphenyl ether

[0126] The o-phenoxybenzaldehyde was replaced with m-phenoxybenzaldehyde (50 g), and the same reaction steps as in skeleton synthesis 2 were performed. This yielded 13.8 g of skeleton compound 3 as a white solid. The yield was 14.3%. 1 H-NMR identified the skeleton compound 3 as m-hexadecyl diphenyl ether.

[0127] Synthesis of a mixture of alkyl-substituted diphenyl ethers

[0128] Using skeleton compounds 1-3 or diphenyl ethers as materials, mixtures of alkyl-substituted diphenyl ethers 1-11 were obtained. Specifically, the amounts of skeleton compounds or diphenyl ethers and aluminum chloride (2.8% by mass relative to the olefin) listed in Tables 1-3 were added to a flask and stirred at 85°C. The olefins listed in Tables 1-3 were added dropwise, and after the addition was complete, the mixture was stirred at 85°C for 2 hours. After cooling to room temperature, the mixture was then subjected to adsorption treatment with activated clay and KYOWAAD (trademark). Unreacted skeleton compounds and other light boiling substances were removed by vacuum distillation to obtain liquid mixtures 1-11.

[0129] It should be noted that mixture 11 is a mixture obtained by further synthesizing compound 4 as described above after obtaining monosubstituted hexadecyl diphenyl ether (100% presence rate, solid, compound 4) as an intermediate of mixture 11.

[0130] Tables 1-3 show the types of skeleton compounds, the types of olefins added to the skeleton compounds, the amount of addition (equivalents), the amount added (g), the appearance, yield, and output of the resulting diphenyl ether mixtures for each mixture 1-11.

[0131] [Table 1]

[0132] [Table 2]

[0133] [Table 3]

[0134] The following substances were used as the olefins shown in Tables 1-3.

[0135] 1-octene: LINEALENE 8 manufactured by Idemitsu Kosan Co., Ltd.

[0136] 1-dodecene: LINEALENE 12 manufactured by Idemitsu Kosan Co., Ltd.

[0137] 1-hexadecene: LINEALENE 16 manufactured by Idemitsu Kosan Co., Ltd.

[0138] 2-Octyl-1-dodecene: HS dimer A-20 manufactured by Toyokuni Oil Co., Ltd.

[0139] 1-Chlorododecane: Manufactured by Tokyo Chemical Industry Co., Ltd.

[0140] Diphenyl ether: Manufactured by Fujifilm and Koh Geny Co., Ltd.

[0141] [Identification and Evaluation of the Mixture]

[0142] In addition to the mixtures 1 to 11 obtained above, the following compositions were prepared as comparative examples 3 to 5. These compositions are generally used as base oils for lubricating oils.

[0143] Comparative Example 3: The kinematic viscosity of ExxonMobil's Spectra Syn10 and Spectra Syn40 at 40°C was calculated to be 100 mm. 2 Mix using the / s method.

[0144] Comparative Example 4: Cargill Japan, Triterpenoid PRIO 1943.

[0145] Comparative Example 5: Polyol ester FG100 manufactured by ZSCHIMMER, Germany.

[0146] In addition, as a comparative example 2, a skeleton compound 1 (m-pentadecanyl diphenyl ether) was prepared.

[0147] For the alkyl-substituted diphenyl ether mixtures 1-11 shown in Tables 1-3 and the compositions of Comparative Examples 2-5, the type and number of alkyl substitutions, the presence ratio of disubstituted and trisubstituted alkyl diphenyl ether compounds (the presence ratio of disubstituted and trisubstituted alkyl diphenyl ethers relative to the total mixture), the average number of carbon atoms of the substituted alkyl groups, the molecular weight, and the ratio of secondary, tertiary, and quaternary carbon atoms at the benzyl position of the alkyl group were determined and calculated. The results are summarized in Tables 4-6. It should be noted that the details of the calculation methods for the number of alkyl additions and the carbon order at the benzyl position of the alkyl group will be described later.

[0148] In addition, kinematic viscosity and viscosity index (VI), and heat resistance test results (evaporation rate, viscosity increase, and acid value change) were performed on the compositions of alkyl-substituted diphenyl ether mixtures 1-11 shown in Tables 1-3 and Comparative Examples 2-5. The determination and evaluation methods are shown below. The results are summarized in Tables 4-6.

[0149] [Physical property determination and heat resistance testing of the composition]

[0150] 1. Kinematic viscosity and viscosity index

[0151] The kinematic viscosity and viscosity index (VI) of the obtained mixtures and compositions were determined according to JIS K 2283. The kinematic viscosity at 40°C and 100°C was 150 (mm).2 When the viscosity is below 115 / s, it is evaluated as sufficiently low. Additionally, when the viscosity is above 115, it is evaluated as having good viscosity characteristics.

[0152] 2. Heat resistance test

[0153] In 33 5.0 g of sample was added to a petri dish and placed in a constant temperature bath at 180°C for 500 hours to conduct a heat resistance test. The weight, viscosity, and acid value of the sample before and after the 500-hour heat resistance test were measured. Using the values ​​measured before the heat resistance test as a baseline, the evaporation rate, viscosity increase rate, and acid value change were calculated using the following formulas. Viscosity was measured at 40°C using a Brookfield DV2T digital viscometer. Acid value was measured according to JIS K2501.

[0154] Evaporation rate (%) = 100 × (mass before heating - mass after heating) / mass before heating

[0155] Viscosity increase rate = viscosity after heating (mm) 2 / s) / Viscosity before heating (mm) 2 / s)

[0156] A viscosity increase rate of less than 12% is considered good.

[0157] Change in acid value (mgKOH / g) = Acid value after heating - Acid value before heating

[0158] When the change in acid value is less than 11 (mgKOH / g), it is rated as good.

[0159] [Table 4]

[0160] Example 1 (mixture 3) shown in Table 4 is a mixture in which an alkyl group is added to the skeleton compound 1 (m-pentadecanyl diphenyl ether), and according to its manufacturing method, it is a diphenyl ether mixture composed of diphenyl ether compounds having at least one straight-chain alkyl group.

[0161] Comparative Example 1 (Mixture 10) is a mixture of diphenyl ethers with added 1-chlorododecane, where the alkyl addition number (m+n) is 2.6 and the secondary carbon ratio is 5%. In Comparative Example 1, the proportion of compounds in which all substituted alkyl groups are branched alkyl groups, i.e., all carbons at the benzylic position are tertiary carbons, is (0.95). 2.6 =88%, presumably the presence of diphenyl ether compounds substituted only by branched alkyl groups.

[0162] Comparative Example 2 is skeletal compound 1 (m-pentadecanyl diphenyl ether), with an alkyl addition number of 1.

[0163] Comparative Examples 3-5 were not mixtures of diphenyl ethers.

[0164] As shown in Table 4, Example 1 exhibited good kinematic viscosity and viscosity index (VI). It is believed that using Example 1 as a lubricant resulted in low torque suppression. The heat resistance evaluation results were also good. In contrast, Comparative Example 1 showed a larger increase in viscosity and a greater change in acid value in its heat resistance test, indicating poorer heat resistance than Example 1. Comparative Example 2 was a mixture of white solids, making it impossible to determine its kinematic viscosity. In Comparative Examples 3-5, the heat resistance test (180°C × 500 hours) showed that solidification occurred, indicating poorer heat resistance than Example 1.

[0165] [Table 5]

[0166] Regarding Examples 2 to 4 shown in Table 5, Example 2 (mixture 6) is a mixture in which alkyl groups of skeletal compound 2 (o-hexadecyl diphenyl ether) have been added, Example 3 (mixture 7) is a mixture in which alkyl groups of skeletal compound 3 (m-hexadecyl diphenyl ether) have been added, and Example 4 (mixture 4) is a mixture in which alkyl groups of skeletal compound 1 (m-pentadecanyl diphenyl ether) have been added. According to its manufacturing method, it is a diphenyl ether mixture composed of diphenyl ether compounds having at least one straight-chain alkyl group.

[0167] Comparative Example 6 (Mixture 11) is a mixture of 1-hexadecene and 1-dodecene added to diphenyl ether. The alkyl addition number (m+n) is 2.5 and the secondary carbon ratio is 0%, thus confirming that it is a compound in which all substituted alkyl groups are branched.

[0168] Comparative Example 7 (Mixture 8) is a mixture of 1-dodecene and 1-tetradecene added to diphenyl ether. The alkyl addition number (m+n) is 2.9 and the secondary carbon ratio is 0%, thus confirming that it is a compound in which all substituted alkyl groups are branched.

[0169] As shown in Table 5, Examples 2-4 exhibited good kinematic viscosity and viscosity index (VI). Their heat resistance was also good. In contrast, Comparative Example 6 showed a large increase in viscosity and a large change in acid value, indicating poor heat resistance. Comparative Example 7 had a viscosity index (VI) less than 115, also indicating poor heat resistance.

[0170] [Table 6]

[0171] Table 6 shows Examples 5-7, which are mixtures in which alkyl groups have been added to the backbone compound 1 (m-pentadecanyl diphenyl ether). According to their manufacturing method, these are mixtures of diphenyl ether compounds having at least one straight-chain alkyl group. Example 5 added a branched alkyl group to the backbone compound 1. Example 6 added an alkyl group with 8 carbon atoms to the backbone compound 1. Example 7 added an alkyl group with 8 carbon atoms to the backbone compound 1, with a greater addition amount than in Example 6. It should be noted that in Example 7, the ratio of trisubstituted and tetrasubstituted ADE compounds (the ratio of trisubstituted and tetrasubstituted ADEs relative to the total ADE mixture) is 66%.

[0172] Comparative Example 8 (Composition 9) is a mixture formed by the addition of 2-octyl-1-decene to diphenyl ether. Since only branched alkyl groups are added, it consists only of diphenyl ether compounds substituted with branched alkyl groups. In addition, the number of alkyl additions (m+n) is 2.1, and the secondary carbon ratio is 23%, so it is mainly composed of compounds in which the carbon at the benzyl position of the alkyl group is tertiary or higher.

[0173] As shown in Table 6, the kinematic viscosity and viscosity index (VI) of Examples 5-7 were all good. The heat resistance evaluation results were also good. The evaporation rates of Examples 6 and 7 were 25.0% and 14.8%, respectively. Although no comparative examples were synthesized using conventional manufacturing methods to produce alkyl-substituted diphenyl ethers with the same degree of carbon number of alkyl groups as Examples 6 and 7, based on the results of Examples 1-5 and Comparative Examples 1 and 6-8, it is believed that the secondary carbon ratio of the mixtures synthesized using conventional manufacturing methods is lower than that of Examples 6 and 7. Therefore, it is speculated that the evaporation rates of Examples 6 and 7 are superior to those of alkyl-substituted diphenyl ethers synthesized in the prior art.

[0174] In contrast, the viscosity index (VI) of Comparative Example 8 is less than 115. Furthermore, this results in poor heat resistance. Specifically, both Comparative Example 5 and Comparative Example 8 contain branched alkyl groups, with an alkyl addition molar ratio of 2.1, but Example 5, composed of a compound with straight-chain alkyl groups, exhibits significantly higher viscosity characteristics and heat resistance.

[0175] [Calculation of alkyl addition number]

[0176] Example 1 (mixture 3) will be used as an example for illustration.

[0177] Figure 1 This refers to Example 1 (mixture 3). 1 Overall H-NMR spectrum. (From...) 1 The H-NMR spectrum calculations represent the peak integral ratios of the aromatic ring, the benzyl carbon of the alkyl group, and the hydrogens bonded to the alkyl group except for the benzyl position. Figure 1 The numbers a to c shown correspond as follows.

[0178] Hydrogens bonded to aromatic rings: The integral ratio of 6.5 to 7.5 ppm is set as a (based on a, a=1).

[0179] Hydrogen at the benzyl position of the alkyl group: The integral ratio of 2.2 to 3.4 ppm is set as b.

[0180] Hydrogens bonded to alkyl groups other than the benzyl group: the integral ratio of 0.7 to 1.7 ppm is set as c.

[0181] Furthermore, the number of protons in the added alkyl chain is set to d. For example, in the case of addition to 1-octene, the added alkyl chain becomes C8H. 17 Therefore, d=17.

[0182] The alkyl addition number is calculated using the following formula.

[0183] Alkyl addition number = 10 × (b + c) / (b + c + a × d)

[0184] The calculations are as follows when adding alkyl groups with different numbers of carbon atoms.

[0185] Let d' be the number of protons in the alkyl group added via the Friedel-Crafts reaction.

[0186] The number of protons in the straight-chain alkyl group pre-bonded to the diphenyl ether before the Friedel-Krawtz reaction is set as e.

[0187] Let f be the number of additions to the alkyl group pre-bonded to the diphenyl ether.

[0188] Alkyl addition number = f + ((10-f)×(b+c)-a×e) / (b+c+a×d')

[0189] [Calculation of the order of carbons at the alkyl benzyl position]

[0190] (1) The case of addition to straight-chain olefins

[0191] Depend on Figure 2 shown 13 C-NMR spectra were used to calculate the integral ratios of each peak representing the β carbon of the aromatic ring and alkyl group, and to calculate the order of the carbon at the alkyl benzyl position. Figure 2 The A1 and A2 shown below correspond to each other.

[0192] Aromatic ring: The integral ratio of 152-160 ppm is set as A1 (based on A1, A1=1).

[0193] β-carbon of alkyl groups: The integral ratio of 31.0 to 32.0 ppm is set as A2.

[0194] The ratio of secondary carbons = (A2 / A1) ÷ number of alkyl additions × 100

[0195] The ratio of tertiary carbon = 100 - the ratio of secondary carbon

[0196] (2) Cases involving the addition of branched olefins

[0197] exist Figure 3 and Figure 4 Example 5 (mixture 5) is shown in the figure. 13 Overall C-NMR and DEPT-135 images. Comparison 13 C-NMR and DEPT-135 spectra identified peaks for secondary, tertiary, and quaternary carbons at 32.0–36.0 and 38.0–50.0 ppm, respectively.

[0198] exist 13 In the C-NMR peaks of 35.0–40.2 ppm, the integral ratio of secondary carbons is set as B1, the integral ratio of tertiary carbons as B2, and the integral ratio of quaternary carbons as B3. The carbon order of the benzyl position of the alkyl group is determined by the following formula.

[0199] Secondary carbon ratio = (B1 / (B1+B2+B3)) × 100

[0200] The ratio of tertiary carbons = (B2 / (B1+B2+B3)) × 100

[0201] The ratio of quaternary carbons = (B3 / (B1+B2+B3)) × 100

[0202] It should be understood that the embodiments disclosed herein are exemplary in all respects and are not restrictive in any way. The scope of the invention is defined by the claims and is intended to include all modifications equivalent to or within the scope of the claims.

Claims

1. A mixture of alkyl-substituted diphenyl ethers, comprising a mixture of diphenyl ethers substituted with 2 to 10 straight-chain or branched alkyl groups having 8 to 24 carbon atoms, wherein, The mixture does not substantially contain diphenyl ethers that are substituted only with branched alkyl groups.

2. A mixture of alkyl-substituted diphenyl ethers, wherein the mixture is a mixture of diphenyl ethers substituted with 2 to 10 alkyl groups having 8 to 24 carbon atoms, wherein... The mixture consists essentially only of diphenyl ethers having at least one straight-chain alkyl group.

3. The alkyl-substituted diphenyl ether mixture according to claim 1 or 2, wherein, The diphenyl ether mixture is a mixture of diphenyl ethers substituted with 2 to 5 alkyl groups.

4. The alkyl-substituted diphenyl ether mixture according to claim 1 or 2, wherein, At least one of the straight-chain alkyl groups is located at the ortho or meta position of a carbon atom in the benzene ring that is bonded to an oxygen atom.

5. The alkyl-substituted diphenyl ether mixture according to claim 1 or 2, wherein, The average total carbon number of the alkyl groups in the diphenyl ether mixture is 25 or more and 100 or less.

6. A mixture of alkyl-substituted diphenyl ethers, wherein the mixture is a mixture of diphenyl ethers substituted with 2 to 10 alkyl groups having 8 to 24 carbon atoms, wherein, In the diphenyl ether mixture, the ratio of alkyl groups in which the carbon at the benzyl position is a secondary carbon is 25% or more.

7. The alkyl-substituted diphenyl ether mixture according to claim 6, wherein, The alkyl-substituted diphenyl ether mixture contains diphenyl ethers that are substantially composed only of diphenyl ethers having at least one straight-chain alkyl group.

8. The alkyl-substituted diphenyl ether mixture according to claim 7, wherein, The alkyl-substituted diphenyl ether mixture is a mixture of diphenyl ethers substituted with 2 to 5 alkyl groups. At least one of the straight-chain alkyl groups is a meta-linear alkyl group bonded to a carbon atom with an oxygen atom bonded to a benzene ring.

9. A lubricating oil, wherein, It comprises the alkyl-substituted diphenyl ether mixtures as described in claim 1, 2 or 6.

10. A method for manufacturing an alkyl-substituted diphenyl ether, wherein, The manufacturing process is performed sequentially: The diphenyl etherification process involves reacting an alkyl-substituted phenol having a straight-chain alkyl group with an alkyl-substituted or unsubstituted halobenzene, or reacting an alkyl-substituted or unsubstituted halobenzene having a straight-chain alkyl group with an alkyl-substituted or unsubstituted phenol, to obtain a diphenyl ether having a straight-chain alkyl group. The alkyl addition process involves adding an alkyl group to the diphenyl ether obtained in the diphenyl etherification process. The alkyl group added in the alkyl addition process has 8 to 24 carbon atoms.

11. The method for producing alkyl-substituted diphenyl ethers according to claim 10, wherein, The alkyl-substituted phenol having a straight-chain alkyl group is an alkyl-substituted phenol having a meta-linear alkyl group with a carbon atom bonded to an oxygen atom in the benzene ring.

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