WO2023189301A1 - Refrigerator oil, and working fluid composition - Google Patents

Refrigerator oil, and working fluid composition Download PDF

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Publication number
WO2023189301A1
WO2023189301A1 PCT/JP2023/008669 JP2023008669W WO2023189301A1 WO 2023189301 A1 WO2023189301 A1 WO 2023189301A1 JP 2023008669 W JP2023008669 W JP 2023008669W WO 2023189301 A1 WO2023189301 A1 WO 2023189301A1
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acid
mass
ester
less
value
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PCT/JP2023/008669
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French (fr)
Japanese (ja)
Inventor
祐也 水谷
由真 関
素也 岡崎
英俊 尾形
昌輝 川口
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Ｅｎｅｏｓ株式会社
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Priority to CN202380021354.1A priority Critical patent/CN118679235A/en
Publication of WO2023189301A1 publication Critical patent/WO2023189301A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/02—Materials undergoing a change of physical state when used
    • C09K5/04—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/08—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing oxygen
    • C10M105/32—Esters
    • C10M105/38—Esters of polyhydroxy compounds
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M129/00—Lubricating compositions characterised by the additive being an organic non-macromolecular compound containing oxygen
    • C10M129/02—Lubricating compositions characterised by the additive being an organic non-macromolecular compound containing oxygen having a carbon chain of less than 30 atoms
    • C10M129/04—Hydroxy compounds
    • C10M129/10—Hydroxy compounds having hydroxy groups bound to a carbon atom of a six-membered aromatic ring
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C10M169/04—Mixtures of base-materials and additives

Definitions

  • the present invention relates to refrigeration oil and working fluid compositions.
  • Refrigerating machines such as refrigerators, car air conditioners, room air conditioners, and vending machines are equipped with a compressor to circulate refrigerant within the refrigeration cycle.
  • the compressor is then filled with refrigerating machine oil for lubricating the sliding members.
  • Refrigeration oils generally contain base oils and additives selected depending on the desired properties.
  • Patent Document 1 discloses a refrigerating machine oil whose base oil is an ester of a specific polyhydric alcohol, a carboxylic acid, and an ester having a peroxide value of 1 meq/kg or less.
  • antioxidants are one of the additives commonly used with base oil in refrigeration oil, but according to the study of the present inventors, when a specific ester is used as the base oil, the ester's It has been found that antioxidants may be easily consumed depending on the properties. If the antioxidant is easily consumed, the amount of antioxidant remaining in the refrigerating machine oil decreases, and there is a risk that the originally expected antioxidant function will not be fully exhibited. In addition, especially when a phenolic antioxidant is used as the antioxidant, quinone compounds are generated as the antioxidant is consumed, which may cause coloration.
  • one aspect of the present invention is to provide a refrigerating machine oil that can suppress consumption of antioxidants.
  • One aspect of the present invention is a refrigerated oil containing, as a base oil, an ester of a trihydric alcohol and a fatty acid having 14 to 20 carbon atoms, and an antioxidant, and the peroxide value of the ester is 5 mg/kg or more. It's machine oil.
  • the value of peroxide value (mg/kg) x acid value (mgKOH/g) of the ester may be 100 or less.
  • the value of peroxide value (mg/kg) x acid value (mgKOH/g) of the ester may be 5 or more.
  • Fatty acids having 14 to 20 carbon atoms may include oleic acid.
  • the antioxidant is 2,6-di-tert. -butyl-4-methylphenol.
  • Another aspect of the present invention is a working fluid composition containing the above-mentioned refrigeration oil and a refrigerant.
  • the refrigerant may include hydrocarbons.
  • One embodiment of the present invention is a refrigerating machine oil containing, as a base oil, an ester of a trihydric alcohol and a fatty acid having 14 to 20 carbon atoms, and an antioxidant.
  • a trihydric alcohol is an alcohol that has three hydroxyl groups.
  • the trihydric alcohol may be an aliphatic alcohol.
  • Examples of trihydric alcohols include trimethylolethane, trimethylolpropane, trimethylolbutane, glycerin, and 1,3,5-pentanetriol.
  • the trihydric alcohol is preferably trimethylolpropane.
  • the fatty acid having 14 to 20 carbon atoms may be a saturated fatty acid or an unsaturated fatty acid.
  • the C14 to C20 fatty acids preferably include unsaturated fatty acids, more preferably unsaturated fatty acids having 18 carbon atoms (C18 unsaturated fatty acids), and even more preferably oleic acid.
  • the content of unsaturated fatty acids is 70% by mass or more, 75% by mass or more, 80% by mass or more, or 85% by mass or more, based on the total amount of C14 to C20 fatty acids. It may be 95% by mass or less, 93% by mass or less, or 90% by mass or less.
  • the C14-C20 fatty acid further includes a saturated fatty acid having 14-20 carbon atoms (hereinafter also referred to as "C14-C20 saturated fatty acid”) in addition to oleic acid.
  • C14-C20 saturated fatty acids include tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptahexadecanoic acid, octadecanoic acid, nonadecanoic acid and eicosanoic acid. These C14 to C20 saturated fatty acids may be linear or branched.
  • the C14-C20 saturated fatty acid preferably includes at least one selected from the group consisting of linear C14-C20 saturated fatty acids, and more preferably linear tetradecanoic acid (myristic acid) and linear hexadecanoic acid. (palmitic acid), and linear octadecanoic acid (stearic acid), and more preferably linear tetradecanoic acid (myristic acid), linear hexadecanoic acid (palmitic acid), acid), and linear octadecanoic acid (stearic acid).
  • linear tetradecanoic acid myristic acid
  • linear hexadecanoic acid palmitic acid
  • acid linear octadecanoic acid
  • the C14-C20 fatty acid further contains, in addition to oleic acid, an unsaturated fatty acid having 14-20 carbon atoms other than oleic acid (hereinafter also referred to as "C14-C20 unsaturated fatty acid").
  • C14-C20 unsaturated fatty acids other than oleic acid may have, for example, 1 to 4, 1 to 3, 1 to 2, or 1 carbon-carbon unsaturated bonds.
  • C14-C20 unsaturated fatty acids other than oleic acid examples include physeteric acid, myristoleic acid, palmitoleic acid, heptadecenylenic acid, petroselaidic acid, elaidic acid, vaccenic acid, linoleic acid, linoleraidic acid, hyragonic acid, and linolenic acid. , and arachidonic acid.
  • the C14 to C20 unsaturated fatty acids other than oleic acid preferably include at least one selected from the group consisting of unsaturated fatty acids having 16 to 18 carbon atoms, and more preferably include palmitoleic acid.
  • the C14-C20 fatty acids in addition to oleic acid, further include both C14-C20 saturated fatty acids and C14-C20 unsaturated fatty acids other than oleic acid.
  • the C14 to C20 saturated fatty acids preferably include at least one selected from the group consisting of linear C14 to C20 saturated fatty acids and at least one selected from the group consisting of unsaturated fatty acids having 16 to 18 carbon atoms, More preferably, it contains at least one selected from the group consisting of myristic acid, palmitic acid, and stearic acid, and palmitoleic acid, and even more preferably, it contains myristic acid, palmitic acid, stearic acid, and palmitoleic acid.
  • the content of C14-C20 saturated fatty acids may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and 15% by mass or less, 12% by mass or less, based on the total amount of C14-C20 fatty acids. , or 10% by mass or less.
  • the content of C14-C20 unsaturated fatty acids other than oleic acid may be 1% by mass or more, 3% by mass or more, or 4% by mass or more, and 10% by mass or less, based on the total amount of C14-C20 fatty acids. , 8% by mass or less, or 6% by mass or less.
  • each fatty acid mentioned above is measured by the following procedure.
  • the ester is dissolved in ethanol and subjected to alkaline hydrolysis, followed by trimethylsilyl (TMS) derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA).
  • TMS trimethylsilyl
  • BSTFA N,O-bis(trimethylsilyl)trifluoroacetamide
  • BSTFA N,O-bis(trimethylsilyl)trifluoroacetamide
  • the type of fatty acid constituting the ester is confirmed as a TMS derivatized product by GC/MS analysis of the obtained TMS derivatized fatty acid.
  • each fatty acid is quantified by GC analysis under the following GC conditions.
  • GC conditions ⁇ Column: DB-5, 50°C ⁇ 320°C (15°C/min) ⁇ Injection: 300°C, 1 ⁇ L, split ratio 50:1 ⁇ Detector: FID, 320°C - Standard sample for calibration curve: Palmitic acid (reagent) is used for C14 fatty acids and C16 fatty acids, and stearic acid (reagent) is used for C18 fatty acids. Note that fatty acid ethylation may be generated during the TMS derivatization process, and the amount of fatty acid is calculated by adding up the amount of fatty acid TMS derivatization and the amount of fatty acid ethylation.
  • the peroxide value of the ester of trihydric alcohol and C14 to C20 fatty acid is 5 mg/kg or more, preferably 10 mg/kg or more, 15 mg/kg or more, 20 mg/kg or more, from the viewpoint of suppressing antioxidant consumption. kg or more, or 25 mg/kg or more.
  • the peroxide value of the ester may be 400 mg/kg or less, 350 mg/kg or less, or 320 mg/kg or less.
  • the peroxide value in this specification means the peroxide value measured in accordance with JPI-5S-72.
  • the peroxide value of the ester is within the above range and the acid value of the ester is also within an appropriate range.
  • the value of peroxide value (mg/kg) x acid value (mgKOH/g) of the ester is preferably 1 or more, more preferably 3, from the viewpoint of further suppressing consumption of the antioxidant. above, more preferably 5 or more, 6 or more, 7 or more, or 8 or more, preferably 150 or less, more preferably 130 or less, even more preferably 100 or less, 90 or less, 80 or less, 70 or less, It may be 60 or less, or 50 or less.
  • the acid value of the ester is preferably 1 mgKOH/g or less, more preferably 0.6 mgKOH/g or less, still more preferably 0.5 mgKOH/g or less, from the viewpoint of suppressing consumption of the antioxidant more preferably. It may be 4 mgKOH/g or less, or 0.35 mgKOH/g or less, preferably 0.03 mgKOH/g or more, more preferably 0.05 mgKOH/g or more, still more preferably 0.08 mgKOH/g or more, 0.1 mgKOH /g or more, or 0.12 mgKOH/g or more.
  • the acid value in this specification means the acid value measured in accordance with JIS K2501:2003.
  • the C14 to C20 fatty acid constituting the ester is a C14 to C20 fatty acid with a biomass degree of 50% or more, preferably a biomass degree of 50% or more.
  • An example of this method is to perform ester synthesis using a C14 to C20 unsaturated fatty acid so as to obtain a desired acid value, and then to contact it with air for a certain period of time so as to obtain a desired peroxide value.
  • the peroxide value of the ester can be changed to the peroxide value of the ester synthesized by the usual method. tends to be higher than that.
  • the treatment can be carried out under the necessary conditions. You can do this as appropriate.
  • the biomass degree in this specification conceptually indicates the ratio (%) of the amount of carbon derived from biomass resources (or renewable resources) to the total amount of organic carbon in a sample.
  • the biomass degree is 100% when the base material is 100% derived from biomass resources, and 0% when the base material is 100% derived from petroleum resources. In the case of mixtures of base materials, values are expected depending on the proportion of carbon derived from biomass resources.
  • pMC is the % Modern Carbon value calculated as 14Aspl/14Astd x 100
  • REF (pMC) is the pMC value according to the year of production
  • 14Aspl is the 14C / 12C ratio of the sample
  • 14Astd is the 14C /12C ratio of the standard material. 12 C ratio, and if the calculated value of biomass degree exceeds 100%, it is considered as 100% (see the above test method etc. for details).
  • the biomass degree of the ester or the refrigerating machine oil containing the same may preferably be 50% or more, 70% or more, 80% or more, 85% or more, or 100%, and from the economic point of view, preferably 95% or more. % or less or 92% or less.
  • the content of the ester of trihydric alcohol and C14 to C20 fatty acid is 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, based on the total amount of refrigerating machine oil. It may be % by mass or more.
  • the refrigeration oil may further contain other base oils than the ester of trihydric alcohol and C14 to C20 fatty acid.
  • Other base oils may be, for example, hydrocarbon oils or oxygenated oils.
  • the hydrocarbon oil include mineral oil, olefin polymers, naphthalene compounds, alkylbenzenes, and the like.
  • oxygen-containing oils include monoesters (esters of monoalcohols), polyol esters other than esters of trihydric alcohols and C14 to C20 fatty acids (esters of polyols having two or more hydroxyl groups), esters such as complex esters, and polyesters such as complex esters.
  • Examples include ethers such as alkylene glycol, polyvinyl ether, polyphenyl ether, and perfluoroether.
  • antioxidants contained in the refrigerating machine oil include phenolic antioxidants and amine antioxidants.
  • examples of the phenolic antioxidant include 2,6-di-tert. -butyl-p-cresol, 2,6-di-tert. -butyl-phenol, and 4,4'-methylenebis(2,6-di-tert.-butyl-phenol).
  • examples of the amine antioxidant include alkyldiphenylamine, naphthylamine, and the like.
  • the antioxidant preferably includes a phenolic antioxidant, more preferably 2,6-di-tert. - Contains butyl-4-methylphenol.
  • the content of the antioxidant may be 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more, and 3% by mass or less, 2% by mass, based on the total amount of refrigerating machine oil. or less, or 1% by mass or less.
  • the refrigeration oil may further contain additives other than antioxidants.
  • additives other than antioxidants include acid scavengers, antiwear agents, oil agents, antifoaming agents, metal deactivators, and viscosity index improvers.
  • the total content of additives other than antioxidants is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and 5% by mass or less or 2% by mass, based on the total amount of refrigerating machine oil. It may be less than % by mass.
  • the refrigeration oil preferably further contains an acid scavenger, more preferably an epoxy acid scavenger.
  • an acid scavenger examples include glycidyl ester compounds, glycidyl ether compounds, and alicyclic epoxy compounds.
  • the content of the acid scavenger may be 0.1% by mass or more and 3% by mass or less based on the total amount of refrigerating machine oil.
  • the refrigeration oil preferably further contains an anti-wear agent, more preferably a phosphorus-based anti-wear agent.
  • the phosphorus-based wear inhibitor include orthophosphoric acid ester compounds, phosphorous acid ester compounds, and thiophosphoric acid ester compounds.
  • the phosphorus anti-wear agent is preferably an orthophosphoric acid ester compound, more preferably at least one selected from tricresyl phosphate, triphenyl phosphate, trialkyl phosphate, and tri(alkylphenyl) phosphate.
  • the content of the anti-wear agent may be 0.1% by mass or more and 3% by mass or less based on the total amount of refrigerating machine oil.
  • the kinematic viscosity of the refrigerating machine oil at 40° C. may be 10 mm 2 /s or more, 20 mm 2 /s or more, 30 mm 2 /s or more, or 40 mm 2 /s or more, and 400 mm 2 /s or less, and 300 mm 2 /s or more. s or less, 200 mm 2 /s or less, 100 mm 2 /s or less, or 60 mm 2 /s or less.
  • the kinematic viscosity of the refrigerating machine oil at 100° C. is 4 mm 2 /s or more, and may be 6 mm 2 /s or more, 8 mm 2 /s or more, or 9 mm 2 /s or more, and 40 mm 2 /s or less, 25 mm 2 /s or more. s or less, 15 mm 2 /s or less, 12 mm 2 /s or less, or 10 mm 2 /s or less.
  • the viscosity index of the refrigerating machine oil may be 110 or more, 140 or more, 150 or more, 160 or more, or 170 or more, and may be 300 or less, 250 or less, or 220 or less.
  • kinematic viscosity and viscosity index refer to kinematic viscosity and viscosity index measured in accordance with JIS K2283:2000.
  • Refrigerating machine oil is used together with a refrigerant. That is, another embodiment of the present invention is a working fluid composition containing refrigerating machine oil and a refrigerant.
  • the refrigerant preferably contains hydrocarbons.
  • the hydrocarbon is preferably a hydrocarbon having 2 to 4 carbon atoms.
  • the hydrocarbon is, for example, at least one selected from the group consisting of ethylene, ethane, propane (R290), propylene, cyclopropane, normal butane, isobutane (R600a), cyclobutane, and methylcyclopropane, preferably propane ( R290) or isobutane (R600a), more preferably propane (R290).
  • the refrigerant may consist only of hydrocarbons, or may further contain other refrigerants in addition to hydrocarbons.
  • the content of hydrocarbons 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, based on the total amount of the refrigerant.
  • the other refrigerants include saturated fluorinated hydrocarbons (HFC) such as R32, R134a, R125, R143a, and R152a, unsaturated fluorinated hydrocarbons (HFO) such as R1234yf and R1234ze, and perfluoroether.
  • HFC saturated fluorinated hydrocarbons
  • HFO unsaturated fluorinated hydrocarbons
  • R1234yf and R1234ze such as R1234yf and R1234ze
  • perfluoroether examples include fluorine ether, bis(trifluoromethyl)sulfide, trifluoroiodide me
  • the content of refrigerating machine oil in the working fluid composition may be 1 part by mass or more or 2 parts by mass or more, and 500 parts by mass or less or 400 parts by mass or less, based on 100 parts by mass of the refrigerant.
  • Trimethylolpropane and a mixture of C14-20 fatty acids with 100% biomass obtained from animal and vegetable oils C14 saturated fatty acids (myristic acid): about 0.2-2% by mass, C16 unsaturated fatty acids (palmitoleic acid)) : about 0.1 to 6% by mass, C16 saturated fatty acid (palmitic acid): about 4 to 6% by mass, C18 unsaturated fatty acid (oleic acid): about 87 to 93% by mass, C18 saturated fatty acid (stearic acid): 1 ⁇ 2% by mass)) (biomass degree approximately 90%) was synthesized to have an acid value of 0 to 0.5mgKOH/g, and the peroxide value was changed by changing the contact time with air, etc.
  • esters Five types were prepared and these esters were used as base oils 1 to 5. Peroxide value (measured according to JPI-5S-72), acid value (measured according to JIS K2501:2003), and peroxide value (mg/kg) x acid value (mgKOH/g) of each ester ) are shown in Table 1.
  • each refrigerating machine oil (30 g) whose water content was adjusted to 1000 ppm was weighed into an autoclave, and a catalyst (iron, copper, and aluminum wire, each with an outer diameter of 1.6 mm and a length of 50 mm) was added to the autoclave.
  • a stability test was conducted by enclosing R290 (30 g) as a refrigerant and then heating it at 175° C. for 168 hours.
  • the antioxidant content (mass) C0 in each refrigeration oil before the stability test and the antioxidant content (mass) C1 in each refrigeration oil after the stability test were determined using HPLC or GC.

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Abstract

A refrigerator oil comprising: an ester of a trivalent alcohol and a C14-20 fatty acid, as a base oil; and an oxidation inhibitor, wherein the peroxide value of the ester is at least 5mg/kg.

Description

冷凍機油及び作動流体組成物Refrigerating machine oil and working fluid composition
　本発明は、冷凍機油及び作動流体組成物に関する。 The present invention relates to refrigeration oil and working fluid compositions.
　冷蔵庫、カーエアコン、ルームエアコン、自動販売機などの冷凍機は、冷媒を冷凍サイクル内に循環させるための圧縮機を備える。そして、圧縮機には、摺動部材を潤滑させるための冷凍機油が充填される。冷凍機油は、一般的に、所望の特性に応じて選択される基油及び添加剤を含有している。 Refrigerating machines such as refrigerators, car air conditioners, room air conditioners, and vending machines are equipped with a compressor to circulate refrigerant within the refrigeration cycle. The compressor is then filled with refrigerating machine oil for lubricating the sliding members. Refrigeration oils generally contain base oils and additives selected depending on the desired properties.
　上記のような冷凍機油の基油として、例えば、多価アルコールとカルボン酸とのエステルがしばしば用いられる。例えば特許文献１には、特定の多価アルコールとカルボン酸とエステルであって、過酸化物価が１ｍｅｑ／ｋｇ以下であるエステルを基油とする冷凍機油が開示されている。 For example, an ester of a polyhydric alcohol and a carboxylic acid is often used as the base oil for the above-mentioned refrigerating machine oil. For example, Patent Document 1 discloses a refrigerating machine oil whose base oil is an ester of a specific polyhydric alcohol, a carboxylic acid, and an ester having a peroxide value of 1 meq/kg or less.
特開平６－２５６８３号公報Japanese Patent Application Publication No. 6-25683
　ところで、冷凍機油において、基油と共に一般的に用いられる添加剤の一つに酸化防止剤があるが、本発明者らの検討によれば、特定のエステルを基油として用いると、そのエステルの性状によって、酸化防止剤が消耗しやすい場合があることが判明した。酸化防止剤が消耗しやすいと、冷凍機油中に残存する酸化防止剤の量が減るため、本来期待される酸化防止機能が充分に発揮されないおそれがある。また、特に酸化防止剤としてフェノール系酸化防止剤を用いた場合には、酸化防止剤の消耗に伴ってキノン化合物類が生成されるため、着色の原因となり得る。 Incidentally, antioxidants are one of the additives commonly used with base oil in refrigeration oil, but according to the study of the present inventors, when a specific ester is used as the base oil, the ester's It has been found that antioxidants may be easily consumed depending on the properties. If the antioxidant is easily consumed, the amount of antioxidant remaining in the refrigerating machine oil decreases, and there is a risk that the originally expected antioxidant function will not be fully exhibited. In addition, especially when a phenolic antioxidant is used as the antioxidant, quinone compounds are generated as the antioxidant is consumed, which may cause coloration.
　そこで、本発明の一側面は、酸化防止剤の消耗を抑制することができる冷凍機油を提供することを目的とする。 Therefore, one aspect of the present invention is to provide a refrigerating machine oil that can suppress consumption of antioxidants.
　特許文献１に記載されているように、エステルの過酸化物価は小さいほどよいと考えられていた。しかし、本発明者らは、三価アルコールと炭素数１４～２０の脂肪酸とのエステルにおいては、過酸化物価が小さすぎると、当該エステルを基油として用い、添加剤として酸化防止剤を用いた場合に、酸化防止剤が消耗しやすいことを見出した。 As described in Patent Document 1, it was thought that the lower the peroxide value of the ester, the better. However, the present inventors found that when the peroxide value of an ester of a trihydric alcohol and a fatty acid having 14 to 20 carbon atoms is too low, the ester is used as a base oil and an antioxidant is used as an additive. It has been found that in some cases, antioxidants are easily consumed.
　本発明の一側面は、基油として、三価アルコールと炭素数１４～２０の脂肪酸とのエステルと、酸化防止剤と、を含有し、エステルの過酸化物価が５ｍｇ／ｋｇ以上である、冷凍機油である。 One aspect of the present invention is a refrigerated oil containing, as a base oil, an ester of a trihydric alcohol and a fatty acid having 14 to 20 carbon atoms, and an antioxidant, and the peroxide value of the ester is 5 mg/kg or more. It's machine oil.
　エステルの過酸化物価（ｍｇ／ｋｇ）×酸価（ｍｇＫＯＨ／ｇ）の値は、１００以下であってよい。エステルの過酸化物価（ｍｇ／ｋｇ）×酸価（ｍｇＫＯＨ／ｇ）の値は、５以上であってよい。炭素数１４～２０の脂肪酸は、オレイン酸を含んでよい。酸化防止剤は、２，６－ジ－ｔｅｒｔ．－ブチル－４－メチルフェノールを含んでよい。 The value of peroxide value (mg/kg) x acid value (mgKOH/g) of the ester may be 100 or less. The value of peroxide value (mg/kg) x acid value (mgKOH/g) of the ester may be 5 or more. Fatty acids having 14 to 20 carbon atoms may include oleic acid. The antioxidant is 2,6-di-tert. -butyl-4-methylphenol.
　本発明の他の一側面は、上記の冷凍機油と、冷媒と、を含有する作動流体組成物である。冷媒は、炭化水素を含んでよい。 Another aspect of the present invention is a working fluid composition containing the above-mentioned refrigeration oil and a refrigerant. The refrigerant may include hydrocarbons.
　本発明の一側面によれば、酸化防止剤の消耗を抑制することができる冷凍機油を提供することができる。 According to one aspect of the present invention, it is possible to provide a refrigerating machine oil that can suppress consumption of antioxidants.
　以下、本発明の実施形態について詳細に説明する。本発明の一実施形態は、基油として、三価アルコールと炭素数１４～２０の脂肪酸とのエステルと、酸化防止剤と、を含有する冷凍機油である。 Hereinafter, embodiments of the present invention will be described in detail. One embodiment of the present invention is a refrigerating machine oil containing, as a base oil, an ester of a trihydric alcohol and a fatty acid having 14 to 20 carbon atoms, and an antioxidant.
　三価アルコールは、三つの水酸基を有するアルコールである。三価アルコールは、脂肪族アルコールであってよい。三価アルコールとしては、例えば、トリメチロールエタン、トリメチロールプロパン、トリメチロールブタン、グリセリン、及び１，３，５－ペンタントリオールが挙げられる。三価アルコールは、好ましくはトリメチロールプロパンである。 A trihydric alcohol is an alcohol that has three hydroxyl groups. The trihydric alcohol may be an aliphatic alcohol. Examples of trihydric alcohols include trimethylolethane, trimethylolpropane, trimethylolbutane, glycerin, and 1,3,5-pentanetriol. The trihydric alcohol is preferably trimethylolpropane.
　炭素数１４～２０の脂肪酸（以下「Ｃ１４～Ｃ２０脂肪酸」ともいう）は、飽和脂肪酸であっても不飽和脂肪酸であってもよい。Ｃ１４～Ｃ２０脂肪酸は、好ましくは不飽和脂肪酸、より好ましくは炭素数１８の不飽和脂肪酸（Ｃ１８不飽和脂肪酸）、更に好ましくはオレイン酸を含む。不飽和脂肪酸（好ましくはＣ１８不飽和脂肪酸、より好ましくはオレイン酸）の含有量は、Ｃ１４～Ｃ２０脂肪酸の合計量を基準として、７０質量％以上、７５質量％以上、８０質量％以上、又は８５質量％以上であってよく、９５質量％以下、９３質量％以下、又は９０質量％以下であってよい。 The fatty acid having 14 to 20 carbon atoms (hereinafter also referred to as "C14 to C20 fatty acid") may be a saturated fatty acid or an unsaturated fatty acid. The C14 to C20 fatty acids preferably include unsaturated fatty acids, more preferably unsaturated fatty acids having 18 carbon atoms (C18 unsaturated fatty acids), and even more preferably oleic acid. The content of unsaturated fatty acids (preferably C18 unsaturated fatty acids, more preferably oleic acid) is 70% by mass or more, 75% by mass or more, 80% by mass or more, or 85% by mass or more, based on the total amount of C14 to C20 fatty acids. It may be 95% by mass or less, 93% by mass or less, or 90% by mass or less.
　一実施形態において、Ｃ１４～Ｃ２０脂肪酸は、オレイン酸に加えて、炭素数１４～２０の飽和脂肪酸（以下「Ｃ１４～Ｃ２０飽和脂肪酸」ともいう）を更に含む。Ｃ１４～Ｃ２０飽和脂肪酸としては、テトラデカン酸、ペンタデカン酸、ヘキサデカン酸、ヘプタヘキサデカン酸、オクタデカン酸、ノナデカン酸及びエイコサン酸が挙げられる。これらのＣ１４～Ｃ２０飽和脂肪酸は、直鎖状であっても分岐状であってもよい。Ｃ１４～Ｃ２０飽和脂肪酸は、好ましくは直鎖状のＣ１４～Ｃ２０飽和脂肪酸からなる群より選ばれる少なくとも一種を含み、より好ましくは、直鎖状のテトラデカン酸（ミリスチン酸）、直鎖状のヘキサデカン酸（パルミチン酸）、及び直鎖状のオクタデカン酸（ステアリン酸）からなる群より選ばれる少なくとも一種を含み、更に好ましくは、直鎖状のテトラデカン酸（ミリスチン酸）、直鎖状のヘキサデカン酸（パルミチン酸）、及び直鎖状のオクタデカン酸（ステアリン酸）を含む。 In one embodiment, the C14-C20 fatty acid further includes a saturated fatty acid having 14-20 carbon atoms (hereinafter also referred to as "C14-C20 saturated fatty acid") in addition to oleic acid. C14-C20 saturated fatty acids include tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptahexadecanoic acid, octadecanoic acid, nonadecanoic acid and eicosanoic acid. These C14 to C20 saturated fatty acids may be linear or branched. The C14-C20 saturated fatty acid preferably includes at least one selected from the group consisting of linear C14-C20 saturated fatty acids, and more preferably linear tetradecanoic acid (myristic acid) and linear hexadecanoic acid. (palmitic acid), and linear octadecanoic acid (stearic acid), and more preferably linear tetradecanoic acid (myristic acid), linear hexadecanoic acid (palmitic acid), acid), and linear octadecanoic acid (stearic acid).
　他の一実施形態において、Ｃ１４～Ｃ２０脂肪酸は、オレイン酸に加えて、オレイン酸以外の炭素数１４～２０の不飽和脂肪酸（以下「Ｃ１４～Ｃ２０不飽和脂肪酸」ともいう）を更に含む。オレイン酸以外のＣ１４～Ｃ２０不飽和脂肪酸は、例えば、１～４個、１～３個、１～２個、又は１個の炭素－炭素不飽和結合を有していてよい。オレイン酸以外のＣ１４～Ｃ２０不飽和脂肪酸としては、例えば、フィセテリン酸、ミリストレイン酸、パルミトレイン酸、ヘプタデセニレン酸、ペトロセライジン酸、エライジン酸、バクセン酸、リノール酸、リノレライジン酸、ヒラゴニン酸、リノレン酸、及びアラキドン酸が挙げられる。オレイン酸以外のＣ１４～Ｃ２０不飽和飽和脂肪酸は、好ましくは、炭素数１６～１８の不飽和脂肪酸からなる群より選ばれる少なくとも一種を含み、より好ましくは、パルミトレイン酸を含む。 In another embodiment, the C14-C20 fatty acid further contains, in addition to oleic acid, an unsaturated fatty acid having 14-20 carbon atoms other than oleic acid (hereinafter also referred to as "C14-C20 unsaturated fatty acid"). C14-C20 unsaturated fatty acids other than oleic acid may have, for example, 1 to 4, 1 to 3, 1 to 2, or 1 carbon-carbon unsaturated bonds. Examples of C14-C20 unsaturated fatty acids other than oleic acid include physeteric acid, myristoleic acid, palmitoleic acid, heptadecenylenic acid, petroselaidic acid, elaidic acid, vaccenic acid, linoleic acid, linoleraidic acid, hyragonic acid, and linolenic acid. , and arachidonic acid. The C14 to C20 unsaturated fatty acids other than oleic acid preferably include at least one selected from the group consisting of unsaturated fatty acids having 16 to 18 carbon atoms, and more preferably include palmitoleic acid.
　他の一実施形態において、Ｃ１４～Ｃ２０脂肪酸は、オレイン酸に加えて、Ｃ１４～Ｃ２０飽和脂肪酸と、オレイン酸以外のＣ１４～Ｃ２０不飽和脂肪酸との両方を更に含む。Ｃ１４～Ｃ２０飽和脂肪酸は、好ましくは、直鎖状のＣ１４～Ｃ２０飽和脂肪酸からなる群より選ばれる少なくとも一種と、炭素数１６～１８の不飽和脂肪酸からなる群より選ばれる少なくとも一種とを含み、より好ましくは、ミリスチン酸、パルミチン酸、及びステアリン酸からなる群より選ばれる少なくとも一種と、パルミトレイン酸とを含み、更に好ましくは、ミリスチン酸、パルミチン酸、ステアリン酸、及びパルミトレイン酸を含む。 In another embodiment, the C14-C20 fatty acids, in addition to oleic acid, further include both C14-C20 saturated fatty acids and C14-C20 unsaturated fatty acids other than oleic acid. The C14 to C20 saturated fatty acids preferably include at least one selected from the group consisting of linear C14 to C20 saturated fatty acids and at least one selected from the group consisting of unsaturated fatty acids having 16 to 18 carbon atoms, More preferably, it contains at least one selected from the group consisting of myristic acid, palmitic acid, and stearic acid, and palmitoleic acid, and even more preferably, it contains myristic acid, palmitic acid, stearic acid, and palmitoleic acid.
　Ｃ１４～Ｃ２０飽和脂肪酸の含有量は、Ｃ１４～Ｃ２０脂肪酸の合計量を基準として、１質量％以上、３質量％以上、又は５質量％以上であってよく、１５質量％以下、１２質量％以下、又は１０質量％以下であってよい。オレイン酸以外のＣ１４～Ｃ２０不飽和脂肪酸の含有量は、Ｃ１４～Ｃ２０脂肪酸の合計量を基準として、１質量％以上、３質量％以上、又は４質量％以上であってよく、１０質量％以下、８質量％以下、又は６質量％以下であってよい。 The content of C14-C20 saturated fatty acids may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and 15% by mass or less, 12% by mass or less, based on the total amount of C14-C20 fatty acids. , or 10% by mass or less. The content of C14-C20 unsaturated fatty acids other than oleic acid may be 1% by mass or more, 3% by mass or more, or 4% by mass or more, and 10% by mass or less, based on the total amount of C14-C20 fatty acids. , 8% by mass or less, or 6% by mass or less.
　上述した各脂肪酸の含有量は、以下の手順で測定される。
　エステルをエタノールに溶解し、アルカリ加水分解処理した後、Ｎ，Ｏ－ビス（トリメチルシリル）トリフルオロアセトアミド（ＢＳＴＦＡ）を用いてトリメチルシリル（ＴＭＳ）誘導体化処理を行う。得られた脂肪酸のＴＭＳ誘導体化物をＧＣ／ＭＳ分析することにより、エステルを構成する脂肪酸の種類をＴＭＳ誘導体化物として確認する。次に、以下のＧＣ条件によるＧＣ分析にて、各脂肪酸を定量する。
（ＧＣ条件）
　・カラム：ＤＢ－５、５０℃→３２０℃（１５℃／ｍｉｎ）
　・インジェクション：３００℃、１μＬ、スプリット比５０：１
　・検出器：ＦＩＤ、３２０℃
　・検量線用標準試料：Ｃ１４脂肪酸、Ｃ１６脂肪酸についてはパルミチン酸（試薬）を、Ｃ１８脂肪酸についてはステアリン酸（試薬）を用いる。
なお、ＴＭＳ誘導体化処理の過程で、脂肪酸エチル化物が生成することがあるが、脂肪酸ＴＭＳ誘導体化物の量と脂肪酸エチル化物の量とを合算して当該脂肪酸の量として算出する。 The content of each fatty acid mentioned above is measured by the following procedure.
The ester is dissolved in ethanol and subjected to alkaline hydrolysis, followed by trimethylsilyl (TMS) derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). The type of fatty acid constituting the ester is confirmed as a TMS derivatized product by GC/MS analysis of the obtained TMS derivatized fatty acid. Next, each fatty acid is quantified by GC analysis under the following GC conditions.
(GC conditions)
・Column: DB-5, 50℃ → 320℃ (15℃/min)
・Injection: 300℃, 1μL, split ratio 50:1
・Detector: FID, 320℃
- Standard sample for calibration curve: Palmitic acid (reagent) is used for C14 fatty acids and C16 fatty acids, and stearic acid (reagent) is used for C18 fatty acids.
Note that fatty acid ethylation may be generated during the TMS derivatization process, and the amount of fatty acid is calculated by adding up the amount of fatty acid TMS derivatization and the amount of fatty acid ethylation.
　三価アルコールとＣ１４～Ｃ２０脂肪酸とのエステルの過酸化物価は、酸化防止剤の消耗を抑制できる観点から、５ｍｇ／ｋｇ以上であり、好ましくは、１０ｍｇ／ｋｇ以上、１５ｍｇ／ｋｇ以上、２０ｍｇ／ｋｇ以上、又は２５ｍｇ／ｋｇ以上であってもよい。エステルの過酸化物価は、４００ｍｇ／ｋｇ以下、３５０ｍｇ／ｋｇ以下、又は３２０ｍｇ／ｋｇ以下であってもよい。本明細書における過酸化物価は、ＪＰＩ－５Ｓ－７２に準拠して測定された過酸化物価を意味する。 The peroxide value of the ester of trihydric alcohol and C14 to C20 fatty acid is 5 mg/kg or more, preferably 10 mg/kg or more, 15 mg/kg or more, 20 mg/kg or more, from the viewpoint of suppressing antioxidant consumption. kg or more, or 25 mg/kg or more. The peroxide value of the ester may be 400 mg/kg or less, 350 mg/kg or less, or 320 mg/kg or less. The peroxide value in this specification means the peroxide value measured in accordance with JPI-5S-72.
　酸化防止剤の消耗を更に好適に抑制できる観点から、エステルの過酸化物価が上記の範囲でありつつ、エステルの酸価も適切な範囲であることが好ましい。具体的には、エステルの過酸化物価（ｍｇ／ｋｇ）×酸価（ｍｇＫＯＨ／ｇ）の値は、酸化防止剤の消耗を更に好適に抑制できる観点から、好ましくは１以上、より好ましくは３以上、更に好ましくは、５以上、６以上、７以上、又は８以上であってよく、好ましくは１５０以下、より好ましくは１３０以下、更に好ましくは、１００以下、９０以下、８０以下、７０以下、６０以下、又は５０以下であってよい。 From the viewpoint of further suppressing consumption of the antioxidant, it is preferable that the peroxide value of the ester is within the above range and the acid value of the ester is also within an appropriate range. Specifically, the value of peroxide value (mg/kg) x acid value (mgKOH/g) of the ester is preferably 1 or more, more preferably 3, from the viewpoint of further suppressing consumption of the antioxidant. above, more preferably 5 or more, 6 or more, 7 or more, or 8 or more, preferably 150 or less, more preferably 130 or less, even more preferably 100 or less, 90 or less, 80 or less, 70 or less, It may be 60 or less, or 50 or less.
　エステルの酸価は、酸化防止剤の消耗を更に好適に抑制できる観点から、好ましくは１ｍｇＫＯＨ／ｇ以下、より好ましくは０．６ｍｇＫＯＨ／ｇ以下、更に好ましくは、０．５ｍｇＫＯＨ／ｇ以下、０．４ｍｇＫＯＨ／ｇ以下、又は０．３５ｍｇＫＯＨ／ｇ以下であってよく、好ましくは０．０３ｍｇＫＯＨ／ｇ以上、より好ましくは０．０５ｍｇＫＯＨ／ｇ以上、更に好ましくは、０．０８ｍｇＫＯＨ／ｇ以上、０．１ｍｇＫＯＨ／ｇ以上、又は０．１２ｍｇＫＯＨ／ｇ以上であってよい。本明細書における酸価は、ＪＩＳ　Ｋ２５０１：２００３に準拠して測定された酸価を意味する。 The acid value of the ester is preferably 1 mgKOH/g or less, more preferably 0.6 mgKOH/g or less, still more preferably 0.5 mgKOH/g or less, from the viewpoint of suppressing consumption of the antioxidant more preferably. It may be 4 mgKOH/g or less, or 0.35 mgKOH/g or less, preferably 0.03 mgKOH/g or more, more preferably 0.05 mgKOH/g or more, still more preferably 0.08 mgKOH/g or more, 0.1 mgKOH /g or more, or 0.12 mgKOH/g or more. The acid value in this specification means the acid value measured in accordance with JIS K2501:2003.
　エステルの過酸化物価及び酸価を上述した範囲に調整する方法としては、エステルを構成するＣ１４～Ｃ２０脂肪酸として、バイオマス度が５０％以上のＣ１４～Ｃ２０脂肪酸、好ましくはバイオマス度が５０％以上のＣ１４～Ｃ２０不飽和脂肪酸を用い、所望の酸価となるようにエステル合成を行い、所望の過酸化物価となるように一定時間空気と接触させる方法が挙げられる。このような脂肪酸を用いてエステルを合成し、エステルを空気と接触させることで（エステルと空気の接触時間が長いほど）、エステルの過酸化物価が通常の方法で合成されたエステルの過酸化物価よりも高くなる傾向にある。また、通常の冷凍機油用のエステルの合成時と比べ、エステルを合成した後に過度に酸価又は過酸化物価を低減するための処理を行わなくてもよく、当該処理は、必要に応じた条件で適宜行えばよい。 As a method for adjusting the peroxide value and acid value of the ester to the above-mentioned range, the C14 to C20 fatty acid constituting the ester is a C14 to C20 fatty acid with a biomass degree of 50% or more, preferably a biomass degree of 50% or more. An example of this method is to perform ester synthesis using a C14 to C20 unsaturated fatty acid so as to obtain a desired acid value, and then to contact it with air for a certain period of time so as to obtain a desired peroxide value. By synthesizing an ester using such a fatty acid and contacting the ester with air (the longer the contact time between the ester and the air), the peroxide value of the ester can be changed to the peroxide value of the ester synthesized by the usual method. tends to be higher than that. In addition, compared to the synthesis of esters for ordinary refrigeration oil, there is no need to perform excessive treatment to reduce the acid value or peroxide value after synthesizing the ester, and the treatment can be carried out under the necessary conditions. You can do this as appropriate.
　本明細書におけるバイオマス度は、概念的には、試料中の全有機炭素量に占めるバイオマス資源（又は再生可能資源）由来炭素量の割合（％）を示すものである。バイオマス度としては、バイオマス資源由来の基材１００％の場合には１００％の値が、石油資源由来の基材１００％の場合には０％が、バイオマス資源由来の基材と石油資源由来の基材の混合物の場合はそのバイオマス資源由来炭素量の割合に応じた値がそれぞれ期待される。
　また、未知試料のバイオマス度は、ＡＳＴＭ　Ｄ６８６６－２１“Standard Test Methods forDetermining the Biobased Content of Solid, Liquid, and Gaseous Samples UsingRadiocarbon Analysis”による方法で測定される“Biobased Carbon Content”を意味し、以下の式により算出される。
　バイオマス度（Biobased Carbon Content）（％）＝ｐＭＣ／ＲＥＦ（ｐＭＣ）
　ここで、ｐＭＣは１４Ａｓｐｌ／１４Ａｓｔｄ×１００で算出される% ModernCarbon値、ＲＥＦ（ｐＭＣ）は生産年に応じたｐＭＣ値、１４Ａｓｐｌは試料の１４Ｃ／１２Ｃ比、１４Ａｓｔｄは標準物質の１４Ｃ／１２Ｃ比をそれぞれ意味し、バイオマス度の算出値が１００％を超える場合は１００％とされる（詳細は上記試験法等参照）。 The biomass degree in this specification conceptually indicates the ratio (%) of the amount of carbon derived from biomass resources (or renewable resources) to the total amount of organic carbon in a sample. The biomass degree is 100% when the base material is 100% derived from biomass resources, and 0% when the base material is 100% derived from petroleum resources. In the case of mixtures of base materials, values are expected depending on the proportion of carbon derived from biomass resources.
In addition, the biomass content of an unknown sample means the "Biobased Carbon Content" measured by the method according to ASTM D6866-21 "Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis", and is calculated using the following formula: Calculated by
Biobased Carbon Content (%) = pMC/REF (pMC)
Here, pMC is the % Modern Carbon value calculated as 14Aspl/14Astd x 100, REF (pMC) is the pMC value according to the year of production, 14Aspl is the 14C / 12C ratio of the sample, and 14Astd is the 14C /12C ratio of the standard material. 12 C ratio, and if the calculated value of biomass degree exceeds 100%, it is considered as 100% (see the above test method etc. for details).
　エステル又はこれを含有する冷凍機油のバイオマス度は、好ましくは、５０％以上、７０％以上、８０％以上、８５％以上、又は１００％であってよく、経済性の点で、好ましくは、９５％以下又は９２％以下であってよい。 The biomass degree of the ester or the refrigerating machine oil containing the same may preferably be 50% or more, 70% or more, 80% or more, 85% or more, or 100%, and from the economic point of view, preferably 95% or more. % or less or 92% or less.
　三価アルコールとＣ１４～Ｃ２０脂肪酸とのエステルの含有量は、冷凍機油全量を基準として、５０質量％以上、６０質量％以上、７０質量％以上、８０質量％以上、９０質量％以上、又は９５質量％以上であってよい。 The content of the ester of trihydric alcohol and C14 to C20 fatty acid is 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, based on the total amount of refrigerating machine oil. It may be % by mass or more.
　冷凍機油は、三価アルコールとＣ１４～Ｃ２０脂肪酸とのエステル以外のその他の基油を更に含有してもよい。その他の基油は、例えば炭化水素油又は含酸素油であってよい。炭化水素油としては、鉱油、オレフィン重合体、ナフタレン化合物、アルキルベンゼン等が挙げられる。含酸素油としては、モノエステル（モノアルコールのエステル）、三価アルコールとＣ１４～Ｃ２０脂肪酸とのエステル以外のポリオールエステル（二つ以上の水酸基を有するポリオールのエステル）、コンプレックスエステル等のエステル、ポリアルキレングリコール、ポリビニルエーテル、ポリフェニルエーテル、パーフルオロエーテル等のエーテルが挙げられる。 The refrigeration oil may further contain other base oils than the ester of trihydric alcohol and C14 to C20 fatty acid. Other base oils may be, for example, hydrocarbon oils or oxygenated oils. Examples of the hydrocarbon oil include mineral oil, olefin polymers, naphthalene compounds, alkylbenzenes, and the like. Examples of oxygen-containing oils include monoesters (esters of monoalcohols), polyol esters other than esters of trihydric alcohols and C14 to C20 fatty acids (esters of polyols having two or more hydroxyl groups), esters such as complex esters, and polyesters such as complex esters. Examples include ethers such as alkylene glycol, polyvinyl ether, polyphenyl ether, and perfluoroether.
　冷凍機油に含まれる酸化防止剤としては、例えば、フェノール系酸化防止剤及びアミン系酸化防止剤が挙げられる。フェノール系酸化防止剤としては、例えば、２，６－ジ－ｔｅｒｔ．－ブチル－ｐ－クレゾール、２，６－ジ－ｔｅｒｔ．－ブチル－フェノール、及び４，４’－メチレンビス（２，６－ジ－ｔｅｒｔ．－ブチル－フェノール）が挙げられる。アミン系酸化防止剤としては、アルキルジフェニルアミン、ナフチルアミン等が挙げられる。酸化防止剤は、好ましくはフェノール系酸化防止剤を含み、より好ましくは２，６－ジ－ｔｅｒｔ．－ブチル－４－メチルフェノールを含む。 Examples of the antioxidants contained in the refrigerating machine oil include phenolic antioxidants and amine antioxidants. Examples of the phenolic antioxidant include 2,6-di-tert. -butyl-p-cresol, 2,6-di-tert. -butyl-phenol, and 4,4'-methylenebis(2,6-di-tert.-butyl-phenol). Examples of the amine antioxidant include alkyldiphenylamine, naphthylamine, and the like. The antioxidant preferably includes a phenolic antioxidant, more preferably 2,6-di-tert. - Contains butyl-4-methylphenol.
　酸化防止剤の含有量は、冷凍機油全量を基準として、０．０１質量％以上、０．０５質量％以上以上、又は０．１質量％以上であってよく、３質量％以下、２質量％以下、又は１質量％以下であってよい。 The content of the antioxidant may be 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more, and 3% by mass or less, 2% by mass, based on the total amount of refrigerating machine oil. or less, or 1% by mass or less.
　冷凍機油は、酸化防止剤以外の添加剤を更に含有してもよい。酸化防止剤以外の添加剤としては、酸捕捉剤、摩耗防止剤、油性剤、消泡剤、金属不活性化剤、粘度指数向上剤などが挙げられる。酸化防止剤以外の添加剤の合計の含有量は、冷凍機油全量を基準として、好ましくは０．１質量％以上、より好ましくは０．５質量％以上であってよく、５質量％以下又は２質量％以下であってよい。 The refrigeration oil may further contain additives other than antioxidants. Examples of additives other than antioxidants include acid scavengers, antiwear agents, oil agents, antifoaming agents, metal deactivators, and viscosity index improvers. The total content of additives other than antioxidants is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and 5% by mass or less or 2% by mass, based on the total amount of refrigerating machine oil. It may be less than % by mass.
　冷凍機油は、好ましくは酸捕捉剤、より好ましくはエポキシ系酸捕捉剤を更に含有する。エポキシ系酸捕捉剤としては、例えば、グリシジルエステル化合物、グリシジルエーテル化合物、及び脂環式エポキシ化合物が挙げられる。酸捕捉剤の含有量は、冷凍機油全量を基準として、０．１質量％以上であってよく、３質量％以下であってよい。 The refrigeration oil preferably further contains an acid scavenger, more preferably an epoxy acid scavenger. Examples of the epoxy acid scavenger include glycidyl ester compounds, glycidyl ether compounds, and alicyclic epoxy compounds. The content of the acid scavenger may be 0.1% by mass or more and 3% by mass or less based on the total amount of refrigerating machine oil.
　冷凍機油は、好ましくは摩耗防止剤、より好ましくはリン系摩耗防止剤を更に含有する。リン系摩耗防止剤としては、例えば、正リン酸エステル化合物、亜リン酸エステル化合物、及びチオリン酸エステル化合物が挙げられる。リン系摩耗防止剤は、好ましくは正リン酸エステル化合物であり、より好ましくは、トリクレジルホスフェート、トリフェニルホスフェート、トリアルキルホスフェート、及びトリ（アルキルフェニル）ホスフェートから選ばれる少なくとも一種である。摩耗防止剤の含有量は、冷凍機油全量を基準として、０．１質量％以上であってよく、３質量％以下であってよい。 The refrigeration oil preferably further contains an anti-wear agent, more preferably a phosphorus-based anti-wear agent. Examples of the phosphorus-based wear inhibitor include orthophosphoric acid ester compounds, phosphorous acid ester compounds, and thiophosphoric acid ester compounds. The phosphorus anti-wear agent is preferably an orthophosphoric acid ester compound, more preferably at least one selected from tricresyl phosphate, triphenyl phosphate, trialkyl phosphate, and tri(alkylphenyl) phosphate. The content of the anti-wear agent may be 0.1% by mass or more and 3% by mass or less based on the total amount of refrigerating machine oil.
　冷凍機油の４０℃における動粘度は、１０ｍｍ２／ｓ以上、２０ｍｍ２／ｓ以上、３０ｍｍ２／ｓ以上、又は４０ｍｍ２／ｓ以上であってよく、４００ｍｍ２／ｓ以下であり、３００ｍｍ２／ｓ以下、２００ｍｍ２／ｓ以下、１００ｍｍ２／ｓ以下、又は６０ｍｍ２／ｓ以下であってよい。 The kinematic viscosity of the refrigerating machine oil at 40° C. may be 10 mm 2 /s or more, 20 mm 2 /s or more, 30 mm 2 /s or more, or 40 mm 2 /s or more, and 400 mm 2 /s or less, and 300 mm 2 /s or more. s or less, 200 mm 2 /s or less, 100 mm 2 /s or less, or 60 mm 2 /s or less.
　冷凍機油の１００℃における動粘度は、４ｍｍ２／ｓ以上であり、６ｍｍ２／ｓ以上、８ｍｍ２／ｓ以上、又は９ｍｍ２／ｓ以上であってよく、４０ｍｍ２／ｓ以下、２５ｍｍ２／ｓ以下、１５ｍｍ２／ｓ以下、１２ｍｍ２／ｓ以下、又は１０ｍｍ２／ｓ以下であってよい。 The kinematic viscosity of the refrigerating machine oil at 100° C. is 4 mm 2 /s or more, and may be 6 mm 2 /s or more, 8 mm 2 /s or more, or 9 mm 2 /s or more, and 40 mm 2 /s or less, 25 mm 2 /s or more. s or less, 15 mm 2 /s or less, 12 mm 2 /s or less, or 10 mm 2 /s or less.
　冷凍機油の粘度指数は、１１０以上、１４０以上、１５０以上、１６０以上、又は１７０以上であってよく、３００以下、２５０以下、又は２２０以下であってよい。 The viscosity index of the refrigerating machine oil may be 110 or more, 140 or more, 150 or more, 160 or more, or 170 or more, and may be 300 or less, 250 or less, or 220 or less.
　本明細書における動粘度及び粘度指数は、ＪＩＳ　Ｋ２２８３：２０００に準拠して測定される動粘度及び粘度指数を意味する。 In this specification, kinematic viscosity and viscosity index refer to kinematic viscosity and viscosity index measured in accordance with JIS K2283:2000.
　冷凍機油は、冷媒と共に用いられる。すなわち、本発明の他の一実施形態は、冷凍機油と、冷媒と、を含有する作動流体組成物である。 Refrigerating machine oil is used together with a refrigerant. That is, another embodiment of the present invention is a working fluid composition containing refrigerating machine oil and a refrigerant.
　冷媒は、好ましくは炭化水素を含む。炭化水素は、好ましくは炭素数２～４の炭化水素である。炭化水素は、例えば、エチレン、エタン、プロパン（Ｒ２９０）、プロピレン、シクロプロパン、ノルマルブタン、イソブタン（Ｒ６００ａ）、シクロブタン、及びメチルシクロプロパンからなる群より選ばれる少なくとも１種であり、好ましくはプロパン（Ｒ２９０）又はイソブタン（Ｒ６００ａ）であり、より好ましくはプロパン（Ｒ２９０）である。 The refrigerant preferably contains hydrocarbons. The hydrocarbon is preferably a hydrocarbon having 2 to 4 carbon atoms. The hydrocarbon is, for example, at least one selected from the group consisting of ethylene, ethane, propane (R290), propylene, cyclopropane, normal butane, isobutane (R600a), cyclobutane, and methylcyclopropane, preferably propane ( R290) or isobutane (R600a), more preferably propane (R290).
　冷媒は、炭化水素のみからなっていてよく、炭化水素に加えて、他の冷媒を更に含んでもよい。炭化水素の含有量は、冷媒全量を基準として、５０質量％以上、６０質量％以上、７０質量％以上、８０質量％以上、９０質量％以上、又は９５質量％以上であってよい。当該他の冷媒としては、例えば、Ｒ３２、Ｒ１３４ａ、Ｒ１２５、Ｒ１４３ａ、Ｒ１５２ａ等の飽和フッ化炭化水素（ＨＦＣ）、Ｒ１２３４ｙｆ、Ｒ１２３４ｚｅ等の不飽和フッ化炭化水素（ＨＦＯ）、パーフルオロエーテル等の含フッ素エーテル、ビス（トリフルオロメチル）サルファイド、三フッ化ヨウ化メタン、アンモニア（Ｒ７１７）、二酸化炭素（Ｒ７４４）等が挙げられる。 The refrigerant may consist only of hydrocarbons, or may further contain other refrigerants in addition to hydrocarbons. The content of hydrocarbons 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, based on the total amount of the refrigerant. Examples of the other refrigerants include saturated fluorinated hydrocarbons (HFC) such as R32, R134a, R125, R143a, and R152a, unsaturated fluorinated hydrocarbons (HFO) such as R1234yf and R1234ze, and perfluoroether. Examples include fluorine ether, bis(trifluoromethyl)sulfide, trifluoroiodide methane, ammonia (R717), carbon dioxide (R744), and the like.
　作動流体組成物における冷凍機油の含有量は、冷媒１００質量部に対して、１質量部以上又は２質量部以上であってよく、５００質量部以下又は４００質量部以下であってよい。 The content of refrigerating machine oil in the working fluid composition may be 1 part by mass or more or 2 parts by mass or more, and 500 parts by mass or less or 400 parts by mass or less, based on 100 parts by mass of the refrigerant.
　以下、実施例に基づいて本発明を更に具体的に説明するが、本発明は実施例に限定されるものではない。 Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the Examples.
　トリメチロールプロパンと、動植物油から得られたバイオマス度１００％の炭素数１４～２０の脂肪酸混合物（Ｃ１４飽和脂肪酸（ミリスチン酸）：０．２～２質量％程度、Ｃ１６不飽和脂肪酸（パルミトレイン酸）：０．１～６質量％程度、Ｃ１６飽和脂肪酸（パルミチン酸）：４～６質量％程度、Ｃ１８不飽和脂肪酸（オレイン酸）：８７～９３質量％程度、Ｃ１８飽和脂肪酸（ステアリン酸）：１～２質量％程度）とのエステル（バイオマス度約９０％）を酸価が０～０．５ｍｇＫＯＨ／ｇとなるように合成し、空気との接触時間等を変えて過酸化物価を変化させたエステル５種類を用意し、これらのエステルを基油１～５として用いた。各エステルの過酸化物価（ＪＰＩ－５Ｓ－７２に準拠して測定）、酸価（ＪＩＳ　Ｋ２５０１：２００３に準拠して測定）、及び、過酸化物価（ｍｇ／ｋｇ）×酸価（ｍｇＫＯＨ／ｇ）の値を表１に示す。 Trimethylolpropane and a mixture of C14-20 fatty acids with 100% biomass obtained from animal and vegetable oils (C14 saturated fatty acids (myristic acid): about 0.2-2% by mass, C16 unsaturated fatty acids (palmitoleic acid)) : about 0.1 to 6% by mass, C16 saturated fatty acid (palmitic acid): about 4 to 6% by mass, C18 unsaturated fatty acid (oleic acid): about 87 to 93% by mass, C18 saturated fatty acid (stearic acid): 1 ~2% by mass)) (biomass degree approximately 90%) was synthesized to have an acid value of 0 to 0.5mgKOH/g, and the peroxide value was changed by changing the contact time with air, etc. Five types of esters were prepared and these esters were used as base oils 1 to 5. Peroxide value (measured according to JPI-5S-72), acid value (measured according to JIS K2501:2003), and peroxide value (mg/kg) x acid value (mgKOH/g) of each ester ) are shown in Table 1.
（酸化防止剤の残存量の評価）
　基油１～５のそれぞれに対して、冷凍機油全量を基準として、酸化防止剤（２，６－ジ－ｔｅｒｔ．－ブチル－４－メチルフェノール）０．３質量％、酸捕捉剤（グリシジルネオデカノエート）０．７質量％、及び摩耗防止剤（トリクレジルフォスフェート）１質量％を添加して、実施例１～４及び比較例１の各冷凍機油を調製した。
　得られた各冷凍機油について、ＪＩＳ　Ｋ２２１１－０９（オートクレーブテスト）に準拠して安定性試験を実施した。具体的には、水分含有量を１０００ｐｐｍに調整した各冷凍機油（３０ｇ）をオートクレーブに秤取し、触媒（鉄、銅、アルミの線、いずれも外径１．６ｍｍ×長さ５０ｍｍ）と、冷媒としてＲ２９０（３０ｇ）とを封入した後、１７５℃で１６８時間加熱することにより、安定性試験を実施した。
　安定性試験前の各冷凍機油における酸化防止剤の含有量（質量）Ｃ０と、安定性試験後の各冷凍機油における酸化防止剤の含有量（質量）Ｃ１とを、それぞれＨＰＬＣ又はＧＣを用いて定量し、下記式により酸化防止剤の残存量を算出した。結果を表１に示す。
　　酸化防止剤の残存量（質量％）＝Ｃ１／Ｃ０×１００ (Evaluation of residual amount of antioxidant)
For each of base oils 1 to 5, 0.3% by mass of antioxidant (2,6-di-tert.-butyl-4-methylphenol) and 0.3% by mass of acid scavenger (glycidyl neonate) based on the total amount of refrigerating machine oil. Refrigerating machine oils of Examples 1 to 4 and Comparative Example 1 were prepared by adding 0.7% by mass of decanoate) and 1% by mass of an anti-wear agent (tricresyl phosphate).
A stability test was conducted on each of the obtained refrigerating machine oils in accordance with JIS K2211-09 (autoclave test). Specifically, each refrigerating machine oil (30 g) whose water content was adjusted to 1000 ppm was weighed into an autoclave, and a catalyst (iron, copper, and aluminum wire, each with an outer diameter of 1.6 mm and a length of 50 mm) was added to the autoclave. A stability test was conducted by enclosing R290 (30 g) as a refrigerant and then heating it at 175° C. for 168 hours.
The antioxidant content (mass) C0 in each refrigeration oil before the stability test and the antioxidant content (mass) C1 in each refrigeration oil after the stability test were determined using HPLC or GC. The residual amount of the antioxidant was calculated using the following formula. The results are shown in Table 1.
Remaining amount of antioxidant (mass%) = C1/C0 x 100

Claims (7)

  1. 　基油として、三価アルコールと炭素数１４～２０の脂肪酸とのエステルと、
    　酸化防止剤と、を含有し、
    　前記エステルの過酸化物価が５ｍｇ／ｋｇ以上である、冷凍機油。     As a base oil, an ester of a trihydric alcohol and a fatty acid having 14 to 20 carbon atoms;
    Contains an antioxidant,
    Refrigerating machine oil, wherein the ester has a peroxide value of 5 mg/kg or more.
  2. 　前記エステルの過酸化物価（ｍｇ／ｋｇ）×酸価（ｍｇＫＯＨ／ｇ）の値が１００以下である、請求項１に記載の冷凍機油。 The refrigeration oil according to claim 1, wherein the value of peroxide value (mg/kg) x acid value (mgKOH/g) of the ester is 100 or less.
  3. 　前記エステルの過酸化物価（ｍｇ／ｋｇ）×酸価（ｍｇＫＯＨ／ｇ）の値が５以上である、請求項１又は２に記載の冷凍機油。 The refrigerating machine oil according to claim 1 or 2, wherein the value of peroxide value (mg/kg) x acid value (mgKOH/g) of the ester is 5 or more.
  4. 　前記炭素数１４～２０の脂肪酸がオレイン酸を含む、請求項１～３のいずれか一項に記載の冷凍機油。 Refrigerating machine oil according to any one of claims 1 to 3, wherein the fatty acid having 14 to 20 carbon atoms contains oleic acid.
  5. 　前記酸化防止剤が２，６－ジ－ｔｅｒｔ．－ブチル－４－メチルフェノールを含む、請求項１～４のいずれか一項に記載の冷凍機油。 The antioxidant is 2,6-di-tert. The refrigerating machine oil according to any one of claims 1 to 4, comprising -butyl-4-methylphenol.
  6. 　請求項１～５のいずれか一項に記載の冷凍機油と、
    　冷媒と、
    を含有する、作動流体組成物。     Refrigerating machine oil according to any one of claims 1 to 5,
    refrigerant and
    A working fluid composition containing.
  7. 　前記冷媒が炭化水素を含む、請求項６に記載の作動流体組成物。 7. The working fluid composition of claim 6, wherein the refrigerant comprises a hydrocarbon.
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