Base oil for refrigerator oil, refrigerator oil, and working fluid composition

Abstract

A base oil for refrigerator oil, which contains an olefin represented by formula (1). In the formula, R1 represents an alkyl group, one of R2 and R3 represents an alkyl group, and the other of R2 and R3 represents a hydrogen atom or an alkyl group. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a base oil for refrigeration oil, refrigeration oil, and a working fluid composition. Background Art

[0002] In refrigerators, there is an increasing demand to replace refrigerants having a high global warming potential (GWP) with, for example, low-GWP refrigerants having a GWP of less than 150. Examples of low-GWP refrigerants include carbon dioxide (R744) refrigerants and hydrocarbon refrigerants.

[0003] In addition, for refrigerators, energy saving is also required. Generally, the lower the viscosity of the refrigeration oil, the more the stirring resistance can be reduced. Therefore, the reduction of the viscosity of the refrigeration oil is related to the energy saving of the refrigerator. For example, refrigeration oil having a viscosity of VG3 or more and VG8 or less is disclosed in Patent Document 1. In addition, for example, refrigeration oil containing a mixed base oil composed of a low-viscosity base oil and a high-viscosity base oil is disclosed in Patent Document 2. On the other hand, if the viscosity of the refrigeration oil becomes low, it becomes difficult to maintain an oil film in the sliding portion, and for example, the friction coefficient may increase. Therefore, a refrigeration oil having a low viscosity is not simply preferred.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: WO 2006 / 062245

[0007] Patent Document 2: WO 2007 / 105452 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] An object of one aspect of the present invention is to provide a refrigeration oil capable of reducing a friction coefficient and a base oil for refrigeration oil used for the refrigeration oil.

[0010] Means for Solving the Problems

[0011] As a result of research by the present inventors, it has been found that by using a base oil containing a specific olefin, the friction coefficient can be reduced as compared with a base oil containing only other olefins (α-olefins) and a base oil containing only hydrocarbon oils other than olefins.

[0012] The present invention includes the following aspects.

[0013] [1] A base oil for refrigeration oil, which contains an olefin represented by the following formula (1).

[0014]

[0015] In the formula, R1 represents an alkyl group, R 2 and R 3 in which one of them represents an alkyl group, R 2 and R 3 and the other represents a hydrogen atom or an alkyl group.

[0016] [2] The base oil according to [1], wherein the average carbon number of the aforementioned base oil is 8 or more and 30 or less.

[0017] [3] The base oil according to [1] or [2], wherein the biomass content of the aforementioned base oil is 10% or more.

[0018] [4] The base oil according to any one of [1] to [3], which further contains a hydrocarbon oil other than the aforementioned olefin.

[0019] [5] A refrigeration oil containing the base oil according to any one of [1] to [4] and an additive.

[0020] [6] The refrigeration oil according to [5], which is used together with a refrigerant containing a hydrocarbon.

[0021] [7] A working fluid composition containing the refrigeration oil according to [5] or [6] and a refrigerant.

[0022] [8] The working fluid composition according to [7], wherein the refrigerant contains a hydrocarbon.

[0023] Effects of the Invention

[0024] According to one aspect of the present invention, a refrigeration oil capable of reducing the friction coefficient and a base oil for refrigeration oil used for the refrigeration oil can be provided. In one aspect of the present invention, the effect of reducing the friction coefficient can also be obtained when the base oil for refrigeration oil and the refrigeration oil have a low viscosity. Detailed Description of the Embodiments

[0025] Hereinafter, the embodiments of the present invention will be described in detail. One embodiment of the present invention is a base oil for refrigeration oil (hereinafter also referred to as "base oil for refrigeration oil (A)") containing an olefin represented by the following formula (1).

[0026]

[0027] In the formula, R 1 represents an alkyl group, R 2 and R 3 in which one of them represents an alkyl group, R 2 and R 3 and the other represents a hydrogen atom or an alkyl group.

[0028] The olefin represented by formula (1) has a carbon-carbon double bond further inward at the α-position and is therefore also called an internal olefin.

[0029] R 1 The alkyl group shown may be linear or branched. 1 The carbon number of the alkyl group may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more, and may be 27 or less, 21 or less, 17 or less, 15 or less, 12 or less, 11 or less, 10 or less, 9 or less, or 8 or less.

[0030] R 2 or R 3 The alkyl group shown may be linear or branched. 2 or R 3 The carbon number of the alkyl group may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more, and may be 12 or less, 11 or less, 10 or less, 9 or less, or 8 or less.

[0031] R 1 、R 2 and R 3 The total number of carbon atoms in the alkyl group or the average of the total number of carbon atoms may be 6 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, or 13 or more, and may be 28 or less, 23 or less, 18 or less, 17 or less, 16 or less, or 15 or less.

[0032] The carbon number of the olefin represented by formula (1) or the average carbon number of the olefin may be 8 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, or 15 or more, and may be 30 or less, 25 or less, 20 or less, 19 or less, 18 or less, or 17 or less.

[0033] About R 2 and R 3 , R 2 and R 3 One of them may be an alkyl group and the other may be a hydrogen atom. In this case, the olefin represented by formula (1) may be R 2 is an alkyl group, R 3 The cis-isomer olefins are hydrogen atoms, and R 2 is a hydrogen atom, R 3 An alkene which is the trans isomer of an alkyl group.

[0034] About R 2 and R 3 , R 2 and R 3 Both can be alkyl. In this case, R 2 The number of carbon atoms in the alkyl group shown is the same as that in R 3 The carbon number of the alkyl groups shown may be the same or different.2 When the number of carbon atoms of the alkyl group shown is different from that of R 3 When the number of carbon atoms of the alkyl group shown is different from that of R, the olefin represented by the formula (1) can be a cis-form olefin in which the number of carbon atoms of the alkyl group shown is greater than that of R 2 When the number of carbon atoms of the alkyl group shown is different from that of R, the olefin represented by the formula (1) can be a cis-form olefin in which the number of carbon atoms of the alkyl group shown is greater than that of R 3 When the number of carbon atoms of the alkyl group shown is different from that of R, the olefin represented by the formula (1) can be a cis-form olefin in which the number of carbon atoms of the alkyl group shown is greater than that of R, or can also be a trans-form olefin in which the number of carbon atoms of the alkyl group shown is more than that of R 3 When the number of carbon atoms of the alkyl group shown is different from that of R, the olefin represented by the formula (1) can be a cis-form olefin in which the number of carbon atoms of the alkyl group shown is greater than that of R, or can also be a trans-form olefin in which the number of carbon atoms of the alkyl group shown is more than that of R 2 When the number of carbon atoms of the alkyl group shown is different from that of R, the olefin represented by the formula (1) can be a trans-form olefin in which the number of carbon atoms of the alkyl group shown is more than that of R

[0035] The olefin represented by the formula (1) can be obtained, for example, by isomerizing an α-olefin having 8 to 30 carbon atoms obtained by a known method. As a specific method, for example, the following can be mentioned: a method of using an α-olefin obtained by polymerizing ethylene or the like and bringing it into contact with an α-olefin having a reduced water content in the presence of a zeolite and / or montmorillonite catalyst (Japanese Patent Application Laid-Open No. 2005-239651); a method obtained in the presence of water and using a crystalline metal silicate as a catalyst (Japanese Patent Application Laid-Open No. 10-167989); or a method of obtaining an olefin by decarbonylating a carboxylic acid having a β-hydrogen or its derivative (Japanese Patent Application Laid-Open No. 2011-168528); a method of isomerizing an α-olefin obtained by dehydrating an aliphatic primary alcohol in the presence of a solid catalyst (International Publication No. 2014 / 112522), etc.

[0036] The olefin represented by the formula (1) can be produced from conventional petroleum-based raw materials or from renewable raw materials. From the viewpoint of aiming for a sustainable society, renewable raw materials are preferably used as raw materials. Specifically, plant-derived raw materials such as vegetable oils, sugars, starches, animal fats, or microalgae and other biomass resources are preferably used. Furthermore, from the viewpoint of being able to produce a refrigerant oil corresponding to carbon neutrality, biomass raw materials such as plant-derived raw materials that absorb CO2 during growth are preferably used, and fatty acids obtained by hydrolyzing these biomass raw materials, aliphatic alcohols obtained by hydrogenating them, or α-olefins obtained by polymerizing ethylene obtained by decomposing these biomass raw materials are preferably used as raw materials.

[0037] Examples of biomass raw materials include animal fats such as beef tallow, lard, and bird oil, vegetable oils such as soybean oil, rapeseed oil, palm oil, corn oil, cottonseed oil, sunflower oil, olive oil, and safflower oil, non-edible oils, their waste oils, fatty acids obtained by hydrolyzing them, etc.

[0038] Whether the olefin represented by the formula (1), the base oil or the refrigerant oil containing the olefin represented by the formula (1) is derived from petroleum-based raw materials, biomass raw materials, or a mixture thereof can be confirmed by measuring the biomass degree described below.

[0039] The base oil (A) for refrigeration oil may contain only the olefin represented by the formula (1). From the viewpoint of rationality such as manufacturing / refining costs, it may further contain sub-components. Examples of the sub-components include by-products that can be generated in the manufacturing process of the olefin represented by the formula (1), unreacted components, or components that can be incidentally mixed in the manufacturing process of the olefin represented by the formula (1). Specific examples of these sub-components include hydrocarbon oils other than the olefin represented by the formula (1) such as α-olefins, paraffins, and aromatic compounds. The carbon number distribution of the sub-components may be at the same level as that of the olefin represented by the formula (1) (carbon number 8 to 30).

[0040] The α-olefin may be a linear or branched α-olefin. The paraffin may be a linear or branched paraffin, or may include a cycloaliphatic paraffin having 1 to 6 rings (which may have substituents). The aromatic compound may include an aromatic compound having 1 to 6 rings (which may have substituents).

[0041] In one embodiment, the content of the olefin represented by the formula (1) in the base oil (A) for refrigeration oil also depends on the manufacturing method of the olefin represented by the formula (1) and its yield. Based on the total amount of the base oil (A) for refrigeration oil, it may be 50% by mass or more, 60% by mass or more, or 70% by mass or more, and may be 100% by mass or less, 90% by mass or less, or 80% by mass or less. In addition, based on the total amount of the base oil (A) for refrigeration oil, the content of the olefin represented by the formula (1) in the base oil (A) for refrigeration oil may be 50 mol% or more, 60 mol% or more, or 70 mol% or more, and may be 100 mol% or less, 90 mol% or less, or 80 mol% or less.

[0042] In another embodiment, based on the total amount of the base oil (A) for refrigeration oil, the content of the olefin represented by the formula (1) in the base oil (A) for refrigeration oil may be 5% by mass or more, 10% by mass or more, 20% by mass or more, or 30% by mass or more, and may be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less. In addition, based on the total amount of the base oil (A) for refrigeration oil, the content of the olefin represented by the formula (1) in the base oil (A) for refrigeration oil may be 5 mol% or more, 10 mol% or more, 20 mol% or more, or 30 mol% or more, and may be 70 mol% or less, 60 mol% or less, 50 mol% or less, or 40 mol% or less.

[0043] When the base oil (A) for refrigeration oil contains α-olefins and / or paraffins as the hydrocarbon oils of the aforementioned sub-components in addition to the olefins represented by the formula (1), in one embodiment, the total amount of the olefins, α-olefins and paraffins represented by the formula (1) can preferably be 70% by mass or more, 80% by mass or more, 90% by mass or more, or 98% by mass or more based on the total amount of the base oil (A) for refrigeration oil. At this time, the content of α-olefins can preferably be 50% by mass or less, 20% by mass or less, 10% by mass or less, or less than 10% by mass based on the total amount of the base oil (A) for refrigeration oil.

[0044] In another embodiment, the total amount of the olefins, α-olefins and paraffins represented by the formula (1) can preferably be 70 mol% or more, 80 mol% or more, 90 mol% or more, or 98 mol% or more based on the total amount of the base oil (A) for refrigeration oil. At this time, the content of α-olefins can preferably be 50 mol% or less, 20 mol% or less, 10 mol% or less, or less than 10 mol%.

[0045] The content of the aromatic compound as the aforementioned sub-component can preferably be 2% by mass or less, 1% by mass or less, 0.5% by mass or less, or less than 0.5% by mass based on the total amount of the base oil (A) for refrigeration oil, and can preferably be 2 mol% or less, 1 mol% or less, 0.5 mol% or less, or less than 0.5 mol%.

[0046] The iodine value (gI2 / 100g) of the base oil (A) for refrigeration oil can be 10 or more, 30 or more, 50 or more, or 60 or more, and can be 150 or less, 120 or less, or 100 or less. The iodine value in this specification refers to the iodine value measured according to JIS K0070-1992.

[0047] It should be noted that the iodine value is a value measured in the form of the reaction amount of iodine per 100g of the sample (gI2 / 100g). In a hydrocarbon with an average molecular weight M, for 1 mole of the sample having an average of n double bonds, n moles of iodine (254×n (gI2)) react, so it can be expressed by the following formula.

[0048] Iodine value = 254×n×100 / M (gI2 / 100g)

[0049] Therefore, the number n of double bonds contained on average in 1 molecule of the sample (hereinafter also referred to as "n value") can be expressed by n = iodine value (gI2 / 100g) × M / 25400.

[0050] The n value can preferably be 0.1 or more, 0.3 or more, 0.5 or more, or 0.6 or more, and can be 1.5 or less, 1.2 or less, 1 or less, or 0.9 or less.

[0051] The kinematic viscosity at 40°C of each of the olefin represented by Formula (1) and the base oil (A) for a refrigerator may be 1 mm 2 / s or more, 1.5 mm 2 / s or more, or 2 mm 2 / s or more, and may be less than 20 mm 2 / s, 15 mm 2 / s or less, 10 mm 2 / s or less, 7 mm 2 / s or less, 5 mm 2 / s or less, 4.5 mm 2 / s or less, 4 mm 2 / s or less, 3.5 mm 2 / s or less, or 3 mm 2 / s or less. The kinematic viscosity in this specification refers to the kinematic viscosity measured in accordance with JIS K2283:2000.

[0052] The kinematic viscosity at 100°C of each of the olefin represented by Formula (1) and the base oil (A) for a refrigerator may be 0.5 mm 2 / s or more, 0.7 mm 2 / s or more, or 0.8 mm 2 / s or more, and may be 10 mm 2 / s or less, 5 mm 2 / s or less, 3 mm 2 / s or less, 2 mm 2 / s or less, 1.5 mm 2 / s or less, 1.2 mm 2 / s or less, or 1 mm 2 / s or less.

[0053] The flash point of each of the olefin represented by Formula (1) and the base oil (A) for a refrigerator may be 70°C or more, 80°C or more, or 100°C or more, and may be 160°C or less, 150°C or less, or 140°C or less. The flash point in this specification refers to the flash point measured by the Cleveland open cup (COC) method described in JIS K2265-4:2007.

[0054] The biomass content of each of the olefin represented by Formula (1) and the base oil (A) for a refrigerator may be 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more, and may be 100%.

[0055] The biobased degree conceptually represents the proportion (%) of the carbon amount derived from biomass resources (or renewable resources) in the total organic carbon amount in a sample. When the substrate is 100% derived from biomass resources, a value of 100% can be expected; when the substrate is 100% derived from petroleum resources, a value of 0% can be expected; and in the case of a mixture, a value corresponding to the proportion of its carbon amount can be expected.

[0056] The biobased degree refers to the "Biobased Carbon Content" determined by the method of ASTM D6866-21 "Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis" and is calculated by the following formula.

[0057] Biobased Carbon Content (%) = pMC / REF(pMC)

[0058] Here, pMC represents the %Modern Carbon value calculated by 14Aspl / 14Astd×100, REF(pMC) represents the pMC corresponding to the production year, 14Aspl represents the 14 C / 12 C ratio of the sample, and 14Astd represents the 14 C / 12 C ratio of the reference material. When the calculated biobased degree exceeds 100%, the biobased degree of this sample is regarded as 100%.

[0059] Another embodiment of the present invention is a refrigerating oil containing the above-mentioned base oil (A) for refrigerating oil. The above-mentioned base oil (A) for refrigerating oil is included in the refrigerating oil as the base oil constituting the refrigerating oil. The refrigerating oil may contain the base oil as the main component. Based on the total amount of the refrigerating oil, the content of the base oil may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 95% by mass or more.

[0060] The base oil constituting the refrigerating oil may contain only the aforementioned base oil (A) for refrigerating oil, or in addition to the aforementioned base oil (A) for refrigerating oil, it may further contain a base oil different from the aforementioned base oil (A) for refrigerating oil (hereinafter also referred to as "base oil (B)").

[0061] The base oil (B) can be a hydrocarbon oil, a mineral oil or a synthetic hydrocarbon oil. Examples of the mineral oil include paraffinic or naphthenic mineral oils obtained by appropriately combining usual petroleum refining processes (such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay treatment, distillation, etc.) and refining using crude oil or its distillation residue as a raw material. Examples of the synthetic hydrocarbon oil include polyalphaolefins or their hydrogenated products, normal paraffins, isoparaffins, alkylbenzenes, alkylnaphthalenes, etc.

[0062] The base oil (B) is preferably an isoparaffin. The isoparaffin can be, for example, an isoparaffin obtained by appropriately combining components containing normal paraffins obtained by a dewaxing process in a petroleum refining process, Fischer-Tropsch synthesis, etc., or polymers of olefins such as ethylene, propylene, butene, diisobutene, etc., and refining through hydrocracking, hydroisomerization, hydrodewaxing, hydrorefining, distillation, etc.

[0063] There is no particular limitation on the kinematic viscosity of the base oil (B), and it can be appropriately selected according to the required kinematic viscosity of the refrigeration oil. The kinematic viscosity of the base oil (B) at 40 °C can be, for example, 1 mm 2 / s or more, 1.5 mm 2 / s or more, or 2 mm 2 / s or more, and can be 1000 mm 2 / s or less, 100 mm 2 / s or less, less than 20 mm 2 / s, 15 mm 2 / s or less, 10 mm 2 / s or less, 7 mm 2 / s or less, 5 mm 2 / s or less, 4.5 mm 2 / s or less, 4 mm 2 / s or less, 3.5 mm 2 / s or less, or 3 mm 2 / s or less.

[0064] The kinematic viscosity of the base oil (B) at 100 °C can be, for example, 0.5 mm 2 / s or more, 0.7 mm 2 / s or more, or 0.8 mm 2 / s or more, and can be 100 mm 2 / s or less, 10 mm 2 / s or less, 5 mm 2 / s or less, 3 mm 2 / s or less, 2 mm 2 / s or less, 1.5 mm 2 / s or less, 1.2 mm 2 / s or less, or 1 mm2 Below / s.

[0065] The flash point of the base oil (B) can be 70 °C or higher, 80 °C or higher, or 100 °C or higher, and can be 300 °C or lower, 160 °C or lower, 150 °C or lower, or 140 °C or lower.

[0066] The carbon number and average carbon number of the base oil (B) can be, for example, 10 or more, 12 or more, or 13 or more, and can be 40 or less, 30 or less, 20 or less, or 18 or less, respectively.

[0067] It should be noted that the carbon number and average carbon number of the olefin represented by formula (1) in this specification, the base oil (A) for refrigeration oil, the base oil (B), and the mixture of the base oil (A) for refrigeration oil and the base oil (B) can be obtained by a generally known method, for example, the hydrocarbon type analysis method (gas chromatography) of gas chromatography based on the following conditions. As long as the same results can be obtained, other methods can also be used.

[0068] (Gas chromatography conditions)

[0069] Column: Liquid phase non-polar column (length 30 m, inner diameter 0.25 mmφ, liquid phase thickness 0.1 μm)

[0070] Injection temperature: 350 °C

[0071] Detector: FID 360 °C

[0072] Temperature rising conditions: 50 °C to 350 °C (temperature rising rate: 6 °C / min)

[0073] Carrier gas: Helium

[0074] Injection method: Split injection Sample injection volume: 1 μL (10% toluene solution)

[0075] When the base oil constituting the refrigeration oil contains the base oil (A) for refrigeration oil and the base oil (B), the content of the base oil (B) based on the total amount of the base oil can be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, and can be 95% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less.

[0076] The kinematic viscosity at 40 °C of the base oil constituting the refrigeration oil can be 1 mm 2 / s or more, 1.5 mm 2 / s or more, or 2 mm 2 / s or more, and can be 20 mm 2 / s or less, 15 mm 2 / s or less, 10 mm2 / s or less, 7 mm 2 / s or less, 5 mm 2 / s or less, 4.5 mm 2 / s or less, 4 mm 2 / s or less, 3.5 mm 2 / s or less or 3 mm 2 / s or less.

[0077] The kinematic viscosity at 100 °C of the base oil constituting the refrigeration oil can be 0.5 mm 2 / s or more, 0.7 mm 2 / s or more or 0.8 mm 2 / s or more, and can be 10 mm 2 / s or less, 5 mm 2 / s or less, 3 mm 2 / s or less, 2 mm 2 / s or less, 1.5 mm 2 / s or less, 1.2 mm 2 / s or less or 1 mm 2 / s or less.

[0078] The flash point of the base oil constituting the refrigeration oil can be 70 °C or more, 80 °C or more or 100 °C or more, and can be 160 °C or less, 150 °C or less or 140 °C or less.

[0079] The biomass content of the base oil constituting the refrigeration oil can be 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more or 90% or more, and can be 100% or less, 90% or less, 80% or less, 70% or less, 60% or less or 50% or less.

[0080] The iodine value (gI2 / 100g) of the base oil constituting the refrigeration oil can be 5 or more, 10 or more or 15 or more, and can be 150 or less, 120 or less or 100 or less.

[0081] The n value (= iodine value (gI2 / 100g) × average molecular weight / 25400) of the base oil constituting the refrigeration oil can be 0.1 or more, 0.3 or more or 0.5 or more, and can be 1.5 or less, 1.2 or less or 1 or less.

[0082] In one embodiment, although the refrigeration oil, the base oil constituting the refrigeration oil, or the base oil (A) for refrigeration oil has the above-mentioned low viscosity, by containing the olefin represented by the formula (1), compared with the base oil containing only olefins other than the olefin (α-olefin) and the base oil containing only hydrocarbon oils other than olefins, the friction coefficient can be reduced.

[0083] In addition to the above base oils, the refrigeration oil may also contain oxygenated oils. Examples of oxygenated oils include esters, ethers, carbonates, ketones, silicones, polysiloxanes, etc. It should be noted that the "esters" mentioned here do not include the polymers described later. Examples of esters include monoesters, polyol esters, aromatic esters, dibasic acid esters, complex esters, carbonates, and mixtures thereof. Examples of ethers include polyethylene ethers, polyalkylene glycols, polyphenylene ethers, perfluoroethers, etc. The oxygenated oil preferably contains a monoester of a monohydric aliphatic alcohol and a monobasic fatty acid, and may also contain the monoester and polyol esters of a dihydric to hexahydric alcohol and a monobasic fatty acid.

[0084] Examples of the monohydric aliphatic alcohol constituting the above esters include monohydric aliphatic alcohols having 1 to 20 carbon atoms, preferably 4 to 18 carbon atoms, and more preferably 4 to 12 carbon atoms. Examples of the monobasic fatty acid constituting the above esters include monobasic fatty acids having 1 to 20 carbon atoms, preferably 4 to 18 carbon atoms, and more preferably 4 to 12 carbon atoms. Examples of the dihydric to hexahydric alcohols constituting the above esters preferably include neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, etc.

[0085] From the viewpoint of improving wear resistance, the refrigeration oil preferably further contains an antiwear agent (also called an extreme pressure agent) as an additive. Examples of antiwear agents include phosphorus-containing antiwear agents. Examples of phosphorus-containing antiwear agents include phosphate esters, thiophosphate esters, acidic phosphate esters, amine salts of acidic phosphate esters, chlorinated phosphate esters, etc. The antiwear agent (preferably a phosphorus-containing antiwear agent) can be used alone or in combination of two or more. The phosphorus-containing antiwear agent is preferably selected from one or more of phosphate esters and thiophosphate esters.

[0086] Examples of phosphate esters include trialkyl phosphates, trialkenyl phosphates, and triaryl phosphates. Examples of trialkyl phosphates include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, tris(undecyl) phosphate, tris(dodecyl) phosphate, tris(tridecyl) phosphate, tris(tetradecyl) phosphate, tris(pentadecyl) phosphate, tris(hexadecyl) phosphate, tris(heptadecyl) phosphate, and tris(octadecyl) phosphate. Examples of trialkenyl phosphates include trioleyl phosphate. Examples of triaryl phosphates include triphenyl phosphate, tricresyl phosphate, tris(ethylphenyl) phosphate, tris(butylphenyl) phosphate, tris(xylenyl) phosphate, tolyldiphenyl phosphate, and (xylenyl)diphenyl phosphate. The phosphate ester is preferably a triaryl phosphate, more preferably selected from triphenyl phosphate and tricresyl phosphate, and further preferably tricresyl phosphate.

[0087] As the thiophosphate ester, for example, trialkyl thiophosphate, trialkenyl thiophosphate, and triaryl thiophosphate can be cited. As the trialkyl thiophosphate, for example, tributyl thiophosphate, tripentyl thiophosphate, trihexyl thiophosphate, triheptyl thiophosphate, trioctyl thiophosphate, trinonyl thiophosphate, tridecyl thiophosphate, tris(undecyl) thiophosphate, tris(dodecyl) thiophosphate, tris(tridecyl) thiophosphate, tris(tetradecyl) thiophosphate, tris(pentadecyl) thiophosphate, tris(hexadecyl) thiophosphate, tris(heptadecyl) thiophosphate, and tris(octadecyl) thiophosphate can be cited. As the trialkenyl thiophosphate, for example, trioleyl thiophosphate can be cited. As the triaryl thiophosphate, for example, triphenyl thiophosphate, tricresyl thiophosphate, tris(xylenyl) thiophosphate, tolyl diphenyl thiophosphate, and (xylenyl) diphenyl thiophosphate can be cited. The thiophosphate ester is preferably triphenyl thiophosphate.

[0088] Based on the total amount of the refrigeration oil, the content of the antiwear agent (preferably a phosphorus-containing antiwear agent) can be 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, and can be 5% by mass or less, 4% by mass or less, or 3% by mass or less.

[0089] The refrigeration oil may further contain a polymer. The polymer may be, for example, a polymer having a kinematic viscosity at 40°C higher than that of the above base oil. As the polymer, a polymer containing an unsaturated carboxylic acid ester as a monomer unit can be cited. The polymer is obtained by polymerizing one or more monomers of an unsaturated carboxylic acid ester which is an ester of an unsaturated carboxylic acid and an alcohol.

[0090] The polymer is not particularly limited as long as it contains an unsaturated carboxylic acid ester as a monomer unit, and may further contain other monomers (monomers copolymerizable with the unsaturated carboxylic acid ester). That is, the polymer may be a homopolymer of one unsaturated carboxylic acid ester, a copolymer of two or more unsaturated carboxylic acid esters, or a copolymer of one or more unsaturated carboxylic acid esters and one or more other monomers.

[0091] The unsaturated carboxylic acid constituting the unsaturated carboxylic acid ester has at least one polymerizable unsaturated bond (polymerizable carbon-carbon double bond) and at least one carboxyl group. For example, it may be an unsaturated monocarboxylic acid having one polymerizable unsaturated bond and one carboxyl group, or an unsaturated dicarboxylic acid having one polymerizable unsaturated bond and two carboxyl groups. As the unsaturated monocarboxylic acid, acrylic acid, methacrylic acid (hereinafter, they will also be collectively referred to as “(meth)acrylic acid”), crotonic acid, etc. can be cited. As the unsaturated dicarboxylic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, etc. can be cited.

[0092] The alcohol that forms the unsaturated carboxylic acid ester can be, for example, an alcohol having 1 to 40 carbon atoms, preferably including an alcohol having 1 to 18 carbon atoms, and more preferably including an alcohol having 1 to 8 carbon atoms. These alcohols can be linear or branched. The alcohol can include an alcohol having 1 to 18 carbon atoms and an alcohol having 20 to 40 carbon atoms. These alcohols can be aliphatic alcohols.

[0093] When the unsaturated carboxylic acid ester is an unsaturated dicarboxylic acid ester, the unsaturated dicarboxylic acid ester preferably includes at least one selected from unsaturated dicarboxylic acid esters having a linear alkyl group with 4 to 10 carbon atoms.

[0094] The monomers other than the unsaturated carboxylic acid ester are not particularly limited, and examples thereof include the unsaturated carboxylic acids or their acid anhydrides exemplified as the unsaturated carboxylic acids constituting the above-mentioned unsaturated carboxylic acid esters, and unsaturated hydrocarbon compounds having a polymerizable unsaturated bond. The unsaturated hydrocarbon can be, for example, an unsaturated hydrocarbon compound having 2 to 20 carbon atoms, and preferably can be an α-olefin or styrene having 2 to 20 carbon atoms.

[0095] The polymer is preferably a copolymer of unsaturated carboxylic acid esters (two or more unsaturated carboxylic acid esters), or a copolymer of an unsaturated carboxylic acid ester (one or more unsaturated carboxylic acid esters) and an α-olefin (one or more α-olefins). The copolymer of unsaturated carboxylic acid esters is preferably a copolymer of (meth)acrylates. The copolymer of an unsaturated carboxylic acid ester and an α-olefin is preferably at least one selected from the copolymers of (meth)acrylates and α-olefins and the copolymers of unsaturated dicarboxylic acid esters and α-olefins, and more preferably a copolymer of an unsaturated dicarboxylic acid ester and an α-olefin.

[0096] Preferred examples of the unsaturated dicarboxylic acid ester in the copolymer of the unsaturated dicarboxylic acid ester and the α-olefin include, for example, monoesters or diesters of unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, etc. with aliphatic alcohols having 3 to 10 carbon atoms such as propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol. The aliphatic alcohol having 3 to 10 carbon atoms is preferably a linear aliphatic alcohol having 4 to 10 carbon atoms. The unsaturated dicarboxylic acid ester is preferably a maleate. Preferred examples of the maleate include dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dipentyl maleate, dihexyl maleate, diheptyl maleate, dioctyl maleate, didecyl maleate, etc.

[0097] When the above polymer is a copolymer, based on all the monomer units constituting the copolymer, the content of the unsaturated carboxylic acid ester can be 10 mol% or more, 30 mol% or more, or 50 mol% or more, and can be 90 mol% or less, 70 mol% or less, or 50 mol% or less.

[0098] When the above polymer is a copolymer of an unsaturated carboxylic acid ester and an α-olefin, the molar ratio of the unsaturated carboxylic acid ester / α-olefin is not particularly limited, and can preferably be 1 / 9 or more, more preferably 3 / 7 or more, preferably 9 / 1 or less, and more preferably 7 / 3 or less.

[0099] The number average molecular weight (Mn) of the polymer is preferably 300 or more, more preferably 1000 or more, further preferably 1500 or more, can be 2000 or more, 3000 or more, or 4000 or more, preferably 500000 or less, more preferably 50000 or less, further preferably 30000 or less, and can be 20000 or less, 15000 or less, or 10000 or less.

[0100] The weight average molecular weight (Mw) of the polymer is preferably 400 or more, more preferably 1000 or more, further preferably 2000 or more, particularly preferably 3000 or more, can be 4000 or more, 5000 or more, 6000 or more, 7000 or more, 8000 or more, or 9000 or more, preferably 10000000 or less, more preferably 100000 or less, further preferably 50000 or less, particularly preferably 30000 or less, and can be 20000 or less.

[0101] The Mw / Mn of the polymer is preferably 1.2 or more, more preferably 1.5 or more, further preferably 1.7 or more, particularly preferably 2 or more, preferably 5 or less, more preferably 3.5 or less, further preferably 3 or less, and can be 2.5 or less.

[0102] It should be noted that the "weight average molecular weight (Mw)" and "number average molecular weight (Mn)" in this specification refer to the weight average molecular weight and number average molecular weight in terms of polystyrene obtained by gel permeation chromatography (GPC) using an APC XT column manufactured by Waters Corporation and tetrahydrofuran as the mobile phase (standard substance: polystyrene).

[0103] The viscosity index of the polymer is preferably 80 or more, more preferably 140 or more, can be 180 or more or 200 or more, preferably 400 or less, more preferably 300 or less, and can be 250 or less. The viscosity index in this specification refers to the viscosity index measured in accordance with JIS K2283:2000.

[0104] The polymer of the present embodiment can be added as a polymer additive to a refrigeration oil. In addition to the polymer, the polymer additive may further contain other components other than the polymer, such as a diluent oil, in order to improve the operability during synthesis, transportation, etc. The physical properties of the above polymer (number-average molecular weight (Mn), weight-average molecular weight (Mw), Mw / Mn, kinematic viscosity at 100 °C, kinematic viscosity at 40 °C, viscosity index, and residual carbon component) can also be replaced by the physical properties of the polymer additive in the state added to the refrigeration oil. However, when the polymer additive contains other components other than the polymer, the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the polymer additive refer to the values measured excluding the other components.

[0105] When calculating the average molecular weights of the polymer in the polymer additive or the refrigeration oil containing the same, a sample obtained by separating and removing the above other components from the polymer additive or the refrigeration oil containing the same by rubber membrane dialysis or the like can be used, and the average molecular weights of the polymer can be calculated by the above gel permeation chromatography. Alternatively, the polymer additive or the refrigeration oil containing the same can be used, and during the calculation of the average molecular weights using the above gel permeation chromatography, the peak components attributable to the above other components can be excluded, and the average molecular weights of the polymer can be calculated.

[0106] As more specific examples of the polymer (polymer additive) described above, copolymers of (meth)acrylates, copolymers of (meth)acrylates and α-olefins, copolymers of maleates and α-olefins, etc. can be cited.

[0107] Based on the total amount of the refrigeration oil, the content of the polymer can be 0.1% by mass or more, 0.5% by mass or more, or 0.8% by mass or more, and can be 20% by mass or less, 5% by mass or less, 2% by mass or less, or 1% by mass or less.

[0108] In addition to the above components, the refrigeration oil may further contain other additives. As other additives, antioxidants, acid scavengers, oxygen scavengers, metal deactivators, pour point depressants, detergents / dispersants, antifoaming agents, etc. can be cited. Based on the total amount of the refrigeration oil, the total content of the other additives can be 10% by mass or less or 5% by mass or less.

[0109] The kinematic viscosity of the refrigeration oil at 40 °C can be 1 mm 2 / s or more, 1.5 mm 2 / s or more, or 2 mm 2 / s or more, and can be 20 mm 2 / s or less, 15 mm 2 / s or less, 10 mm 2 / s or less, 7 mm 2 / s or less, 5 mm 2 / s or less, 4.5 mm 2 / s or less, 4 mm 2 / s or less, 3.5 mm 2 / s or less or 3 mm 2 / s or less.

[0110] The kinematic viscosity of the refrigeration oil at 100 °C can be 0.5 mm 2 / s or more, 0.7 mm 2 / s or more or 0.8 mm 2 / s or more, and can be 10 mm 2 / s or less, 5 mm 2 / s or less, 3 mm 2 / s or less, 2 mm 2 / s or less, 1.5 mm 2 / s or less, 1.2 mm 2 / s or less or 1 mm 2 / s or less.

[0111] In one embodiment, although the refrigeration oil has a low viscosity as described above, by containing a base oil containing an olefin represented by formula (1) and a hydrocarbon oil other than the olefin, the friction coefficient can be reduced as compared with the case of containing a base oil containing only an α-olefin or a base oil containing only a hydrocarbon oil other than the olefin represented by formula (1).

[0112] The pour point of the refrigeration oil can be 10 °C or less, 0 °C or less, -10 °C or less, -20 °C or less, -30 °C or less, or -40 °C or less. The pour point in this specification refers to the pour point measured according to JIS K2269:1987.

[0113] From the viewpoint of further reducing the friction coefficient, the iodine value (gI2 / 100 g) of the refrigeration oil can be 2 or more, 5 or more, 10 or more, 15 or more, or 20 or more, and can be 75 or less, 70 or less, 65 or less, 60 or less, or 55 or less.

[0114] The refrigeration oil can exist in a refrigerating machine having a refrigerant cycle system including a compressor, a condenser, an expansion mechanism, and an evaporator in a state of a working fluid composition mixed with a refrigerant. That is, another embodiment of the present invention is a working fluid composition containing the above refrigeration oil and a refrigerant. The content of the refrigeration oil in the working fluid composition can be 1 part by mass or more or 2 parts by mass or more with respect to 100 parts by mass of the refrigerant, and can be 500 parts by mass or less or 400 parts by mass or less.

[0115] Examples of the refrigerant include hydrocarbons, saturated fluorohydrocarbons, unsaturated fluorohydrocarbons, fluorine-containing ethers such as perfluoroethers, bis(trifluoromethyl)sulfide, trifluoroiodomethane, ammonia, and carbon dioxide.

[0116] The refrigerant preferably contains a hydrocarbon. Based on the total amount of the refrigerant, the content of the hydrocarbon may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more. The refrigerant may also consist only of a hydrocarbon.

[0117] The hydrocarbon is preferably a hydrocarbon having 1 to 5 carbon atoms, more preferably a hydrocarbon having 2 to 4 carbon atoms. Examples of the hydrocarbon include methane, ethylene, ethane, propylene, propane (R290), cyclopropane, n-butane, isobutane (R600a), cyclobutane, methylcyclopropane, 2-methylbutane, and n-pentane. The refrigerant may contain two or more of these hydrocarbons. The refrigerant preferably contains a hydrocarbon that is a gas at 25°C and 1 atm, more preferably contains propane, n-butane, isobutane, 2-methylbutane, or a mixture thereof.

[0118] Examples

[0119] Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples.

[0120] To the following base oils 1 to 4, a phosphorus-containing antiwear agent (phosphate ester and thiophosphate ester) and a copolymer of maleic acid ester and an α-olefin having 8 to 10 carbon atoms (Mn: 8300, Mw: 12800, Mw / Mn: 1.5) were added in a total amount of 2.7% by mass (based on the total amount of the refrigeration oil), and refrigeration oils of Example 1, Example 2, Reference Example 1, and Reference Example 2 shown in Table 1 were respectively prepared.

[0121] (Base oil 1)

[0122] A hydrocarbon oil containing the olefin represented by the formula (1) as a main component (raw material: derived from vegetable oil, content of the olefin represented by the formula (1): 70 mol% or more (the balance is paraffin and less than 10 mol% of α-olefin), kinematic viscosity at 40°C: 2.7 mm 2 / s, kinematic viscosity at 100°C: 1.2 mm 2 / s, flash point: 136°C, biomass degree: 100%, R 1 、R 2 and R 3 The total carbon number of the alkyl groups shown: 12 to 16, the average of the total carbon number: 14, average molecular weight: 226, iodine value (gI2 / 100g): 94.6, n value: 0.84, pour point: -15°C)

[0123] (Base oil 2)

[0124] α-olefin with 16 carbon atoms (1-hexadecene (reagent), kinematic viscosity at 40 °C: 2.6 mm 2 / s, kinematic viscosity at 100 °C: 1.1 mm 2 / s, flash point: 135 °C, biogenicity: 0%, iodine value (gI2 / 100g): 113, n value: 1.0, pour point: 2.5 °C)

[0125] (Base oil 3)

[0126] An alkane-based base oil mainly composed of isoparaffins obtained by hydrocracking / isomerization / refining of an alkane component synthesized from carbon monoxide and hydrogen through the Fischer-Tropsch reaction and fractionation (aromatic component < 0.5 mass%, ASTM color: 0, kinematic viscosity at 40 °C: 2.2 mm 2 / s, kinematic viscosity at 100 °C: 0.98 mm 2 / s, biogenicity: 0%, flash point: 120 °C, carbon number 13 - 16, average carbon number: 14, n value: 0, pour point < -45 °C)

[0127] (Base oil 4)

[0128] A base oil obtained by mixing 20% by mass of the above base oil 1 and 80% by mass of the above base oil 3 (kinematic viscosity at 40 °C: 2.3 mm 2 / s, kinematic viscosity at 100 °C: 1.0 mm 2 / s, flash point: 123 °C, biogenicity: 20%, iodine value (gI2 / 100g): 19, n value: 0.17, pour point: -40 °C)

[0129] (Evaluation of friction characteristics)

[0130] The friction characteristics of each refrigeration oil obtained as follows were evaluated.

[0131] Using an MTM (Mini Traction Machine) test machine (manufactured by PCS Instruments), the coefficient of friction (μ) was measured under the following conditions. The results are shown in Table 1. The smaller the coefficient of friction, the better the friction characteristics.

[0132] Ball and disk: Standard test piece (AISI 52100 standard)

[0133] Test temperature: 40 °C

[0134] Sliding speed: 0.3 - 0.9 m / s (partial excerpt)

[0135] Load: 10 N

[0136] Slip ratio: 30%

[0137] It should be noted that as the sliding speed, the value of |U D -U B | (m / s) is used. Here, U D is the speed (m / s) of the disk of the sliding part, and U B is the speed (m / s) of the ball of the sliding part.

[0138] [Table 1]

[0139]

[0140] (Evaluation of stability)

[0141] A autoclave test using base oil 1 or base oil 4 and R600a as the refrigerant was carried out. Specifically, 30 g of a base oil with the water content in the base oil adjusted to less than 10 ppm and iron, copper, and aluminum catalysts (each 0.6 mmφ×30 mm) were placed in a glass container inside a pressure-resistant container with an internal volume of 200 ml, and 30 g of R600a was sealed under vacuum. The base oil after being held at 175°C for 2 weeks was recovered, and the hue (ASTM color) and acid value of the base oil were measured. For base oil 1 and base oil 4, the hue was L0.5 in both cases, and the acid value was less than 0.01 mgKOH / g, confirming that there was no problem with stability.

[0142] (Low-temperature precipitation test in the coexistence of refrigerant)

[0143] A low-temperature precipitation test using the refrigeration oil of Example 1 or Example 2 and the hydrocarbon refrigerant R600a as the refrigerant was carried out. Specifically, a working fluid composition mixed in such a way that the refrigeration oil / refrigerant ratio (mass ratio) was 2 / 8 was prepared, and the low-temperature precipitation test according to Appendix A of JIS K2211 (2009) was carried out. These working fluids did not produce hairy precipitates, granular precipitates, blurring, or turbidity even when cooled to -55°C, and no tendency to precipitate at low temperatures was confirmed.

Claims

1. A base oil for refrigeration oil, which contains an olefin represented by the following formula (1), In the formula, R 1 represents an alkyl group, and one of R 2 and R 3 represents an alkyl group, and the other of R 2 and R 3 represents a hydrogen atom or an alkyl group.

2. The base oil according to claim 1, wherein, The average carbon number of the base oil is 8 or more and 30 or less.

3. The base oil according to claim 1, wherein The biogenicity of the base oil is 10% or more.

4. The base oil according to claim 1, which further contains a hydrocarbon oil other than the olefin.

5. A refrigeration oil, which contains the base oil according to any one of claims 1 to 4 and an additive.

6. The refrigeration oil according to claim 5, which is used together with a refrigerant containing a hydrocarbon.

7. A working fluid composition, which contains the refrigeration oil according to claim 5 and a refrigerant.

8. The working fluid composition according to claim 7, wherein The refrigerant contains a hydrocarbon.

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