CN114258425A

CN114258425A - Refrigerator oil, working fluid composition for refrigerator, and refrigerator

Info

Publication number: CN114258425A
Application number: CN202080058987.6A
Authority: CN
Inventors: 庄野洋平; 奈良文之
Original assignee: Eneos Corp
Current assignee: Eneos Corp
Priority date: 2019-08-23
Filing date: 2020-07-28
Publication date: 2022-03-29
Also published as: WO2021039249A1; KR20220020931A; US20220298448A1; JP7421287B2; JP2021031580A

Abstract

The refrigerator oil of the present invention comprises: kinematic viscosity at 40 ℃ of 10mm²A lubricant base oil of less than s; and an oily agent containing at least 1 selected from the group consisting of ester oily agents and ether oily agents.

Description

Refrigerator oil, working fluid composition for refrigerator, and refrigerator

Technical Field

The invention relates to a refrigerator oil, a working fluid composition for a refrigerator, and a refrigerator.

Background

Refrigerators such as refrigerators include a refrigerant cycle system including a compressor, a condenser, an expansion mechanism (an expansion valve, a capillary tube), an evaporator, and the like, and cool the refrigerator by circulating a refrigerant in the refrigerant cycle system.

Examples of the compressor for a refrigerator include a rotary compressor and a piston/crank compressor. For example, in a piston-crank type compressor, a rotary motion of a motor is converted into a reciprocating motion by a connecting rod, and a piston connected to the connecting rod is reciprocated to compress a refrigerant. The refrigerating machine oil is sealed in the compressor together with the refrigerant, and lubricates sliding members such as a connecting rod and a piston. As a refrigerating machine oil, for example, patent document 1 below discloses a refrigerating machine oil containing a predetermined base oil, a phosphorus-based extreme pressure agent, and an ester-based additive.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2005/012469

Disclosure of Invention

Problems to be solved by the invention

Although the conventional refrigerating machine oil is effective for reducing friction in a fluid lubrication region, for example, there is still room for improvement in that the effect of reducing friction cannot be sufficiently obtained in a region where the slip speed is low, such as an elastic fluid lubrication region, a mixed lubrication region, or a boundary lubrication region.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a refrigerating machine oil having excellent friction characteristics in a region where a slip speed is low, a working fluid composition for a refrigerating machine containing the refrigerating machine oil, and a refrigerating machine filled with the refrigerating machine oil.

Means for solving the problems

The present invention provides a kind of refrigerating machine oil,it comprises the following components: kinematic viscosity at 40 ℃ of 10mm²A lubricant base oil of less than s; and an oily agent containing at least 1 selected from the group consisting of ester oily agents and ether oily agents.

The lubricant base oil may comprise a mineral oil.

The oily agent may comprise an ether oily agent.

The ether oily agent may be an alkyl or alkenyl glyceryl ether.

The present invention also provides a working fluid composition for a refrigerator, which comprises a refrigerant and the refrigerator oil of the present invention.

The present invention further provides a refrigerator including a refrigerant cycle system: the refrigerant circulation system is connected with a compressor, a condenser, an expansion mechanism and an evaporator in sequence by pipes, and the refrigerant circulation system is filled with a refrigerant and the refrigerator oil of the invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a refrigerator oil having excellent friction characteristics in a region where a slip speed is low, a working fluid composition for a refrigerator containing the refrigerator oil, and a refrigerator filled with the refrigerator oil.

Drawings

Fig. 1 is a schematic diagram showing an embodiment of a freezer.

Detailed Description

Embodiments of the present invention will be described in detail below.

The refrigerator oil of the present embodiment includes: kinematic viscosity at 40 ℃ of 10mm²A lubricant base oil of less than s; and an oily agent containing at least 1 selected from the group consisting of ester oily agents and ether oily agents.

The lubricant base oil may be any of mineral oil, synthetic oil, or a mixture of both, and preferably contains mineral oil from the viewpoint of exhibiting more excellent frictional properties in a region where the slip velocity is low. When the lubricant base oil contains a mineral oil, the content of the mineral oil may be 50 mass% or more, 70 mass% or more, or 90 mass% or more, based on the total amount of the lubricant base oil.

Examples of the mineral oil include: the crude oil is subjected to atmospheric distillation and vacuum distillation to obtain a lubricant fraction, and the obtained lubricant fraction is subjected to refining treatment such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrotreating, sulfuric acid cleaning, clay treatment or the like alone or in combination of 2 or more kinds as appropriate, and paraffin-based mineral oil is particularly preferably used. These mineral oils may be used alone, or 2 or more kinds thereof may be used in combination at an arbitrary ratio.

% C of paraffinic mineral oil_PAnd% C_NRatio of (% C)_P/％C_N) Preferably greater than 1, more preferably 1.1 or more, and still more preferably 1.5 or more. % by weight of paraffinic mineral oil_P/％C_NIf the temperature is more than 1, the refrigerating machine oil has an improved flash point (for example, 100 ℃ or higher) and is excellent in friction characteristics. % C in the invention_PAnd% C_NRespectively, refer to values determined by the method (n-D-M Loop analysis) according to ASTM D3238-95 (2010).

Examples of the synthetic oil include synthetic hydrocarbon oils and oxygen-containing oils.

Examples of the synthetic hydrocarbon oil include alkylbenzenes, alkylnaphthalenes, Polyalphaolefins (PAOs), polybutenes, and ethylene- α -olefin copolymers.

Examples of the oxygen-containing oil include: esters, ethers, carbonates, ketones, silicones, polysiloxanes, and the like. Examples of the ester include: monoesters, polyol esters, aromatic esters, dibasic acid esters, complex esters, carbonates, and mixtures thereof. Among these, monoesters of 1-membered aliphatic alcohols and 1-membered fatty acids are preferably used, and if necessary, a mixture of the monoester and a polyol ester of 2 to 6-membered alcohols and 1-membered fatty acids is preferably used. Examples of the 1-membered aliphatic alcohol constituting such an ester include: 1-membered aliphatic alcohol having 1 to 20 carbon atoms, preferably 4 to 18 carbon atoms, and more preferably 4 to 12 carbon atoms. Examples of the 1-membered fatty acid constituting such an ester include: 1-membered fatty acid having 1 to 20 carbon atoms, preferably 4 to 18 carbon atoms, and more preferably 4 to 12 carbon atoms. Preferable examples of the 2-to 6-membered alcohol constituting such an ester include neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and the like. Examples of the ether include polyvinyl ether, polyalkylene glycol, polyphenylene ether, perfluoro ether, and a mixture thereof.

From the viewpoint of efficiently reducing the friction coefficient in a region where the slip velocity is low, the kinematic viscosity of the lubricant base oil at 40 ℃ needs to be 10mm²Less than s, preferably 5mm²Less than s, more preferably 4mm²The ratio of the water to the water is less than s. The lower limit of the kinematic viscosity at 40 ℃ of the lubricant base oil is not particularly limited, and may be, for example, 1mm²More than s or 1.5mm²More than s. The kinematic viscosity of the lubricant base oil at 100 ℃ is preferably 0.5mm²More preferably 1 mm/s or more²More than s. The kinematic viscosity of the lubricant base oil at 100 ℃ is preferably 3mm²Less than s, more preferably 2mm²The ratio of the water to the water is less than s. The kinematic viscosity of the present invention means a kinematic viscosity according to JIS K2283: kinematic viscosity measured at 2000.

The flash point of the lubricant base oil may be, for example, 100 ℃ or higher, 110 ℃ or higher, or 120 ℃ or higher from the viewpoint of safety. The flash point of the lubricant base oil may be, for example, 155 ℃ or lower or 145 ℃ or lower. The flash point of the present invention means a flash point according to JIS K2265-4: 2007 (Cleveland open cup (COC) method) determination of the flash point.

The pour point of the lubricant base oil is preferably-10 ℃ or lower, more preferably-20 ℃ or lower. The pour point of the present invention means that the pour point is measured according to JIS K2269: 1987 pour point.

The content of the lubricant base oil may be 50 mass% or more, 60 mass% or more, 70 mass% or more, 80 mass% or more, or 90 mass% or more based on the total amount of the refrigerator oil.

The refrigerator oil of the present embodiment includes at least 1 oily agent selected from the group consisting of ester oily agents and ether oily agents.

The ester oil-based agent may be a natural product (usually, a product contained in a natural oil or fat derived from animals, plants, or the like) or a synthetic product, and is preferably a synthetic ester from the viewpoints of stability of the obtained refrigerator oil, uniformity of the ester component, and the like.

The synthetic ester as the ester oiliness agent can be obtained by, for example, reacting an alcohol with a carboxylic acid. The alcohol may be a 1-membered alcohol or a polyhydric alcohol. The carboxylic acid may be a monobasic acid or a polybasic acid.

The combination of the alcohol and the carboxylic acid in the ester oily agent is arbitrary and is not particularly limited, and examples thereof include esters based on the combinations of the following (i) to (vii).

(i) Esters of 1-membered alcohols with monobasic acids

(ii) Esters of polyhydric alcohols with monobasic acids

(iii) Esters of 1-membered alcohols with polybasic acids

(iv) Esters of polyhydric alcohols with polybasic acids

(v) Mixed esters of mixtures of 1-and polyhydric alcohols with polybasic acids

(vi) Mixed esters of polyols with mixtures of monobasic and polybasic acids

(vii) Mixed esters of mixtures of 1-and polyhydric alcohols with mixtures of monobasic and polybasic acids

The esters (ii) to (vii) may be full esters obtained by esterifying all of the hydroxyl groups of the polyhydric alcohol or the carboxyl groups of the polybasic acid, or partial esters partially remaining in the form of hydroxyl groups or carboxyl groups, and are preferably partial esters from the viewpoint of more efficiently achieving low friction in a region where the slip velocity is low.

The 1-membered alcohol constituting the ester oiliness agent is usually a 1-membered alcohol having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and such an alcohol may be a straight-chain alcohol or a branched-chain alcohol, or may be a saturated alcohol or an unsaturated alcohol. As the 1-membered alcohol, for example, methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, and a mixture thereof are preferably used.

As the polyol constituting the ester oiliness agent, a2 to 10-membered polyol, preferably a2 to 6-membered polyol is usually used. As the polyhydric alcohol, for example, glycerin, sorbitol, sorbitan, ethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, and a mixture thereof can be preferably used.

In addition, as the monobasic acid constituting the ester oiliness agent, a fatty acid having 2 to 24 carbon atoms is generally used, and the fatty acid may be a straight chain fatty acid, a branched chain fatty acid, a saturated fatty acid, or an unsaturated fatty acid. As the monobasic acid, for example, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, linoleic acid, linolenic acid, and the like are preferably used.

The polybasic acid constituting the ester oiliness agent includes dibasic acid, trimellitic acid, and the like, and in view of precipitation resistance under a refrigerant atmosphere and at low temperature, dibasic acid is preferable. The dibasic acid can be any of chain dibasic acid and cyclic dibasic acid. In the case of a chain dibasic acid, the compound may be linear or branched, and may be saturated or unsaturated. The polybasic acid is preferably a chain dibasic acid having 2 to 16 carbon atoms, and for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and a mixture thereof can be preferably used.

Specific examples of preferable ester oil agents include: and glycerol monooleate, glycerol dioleate, glycerol trioleate and mixtures thereof, sorbitan monooleate, sorbitan dioleate, sorbitan trioleate and mixtures thereof, among them, from the viewpoint of more efficiently exerting low friction in a region where the slip velocity is low, it is preferable to use an ester oil based on a partial ester, and in particular, it is preferable to use glycerol monooleate and glycerol dioleate based on glycerol monooleate.

From the viewpoint of more efficiently achieving low friction in a region where the slip velocity is low, the saponification value of the ester oil agent is preferably 100mgKOH/g or more, more preferably 130mgKOH/g or more, preferably 200mgKOH/g or less, and more preferably 185mgKOH/g or less. The iodine value of the ester oil agent is not particularly limited, but in the case of an oily agent having an unsaturated bond, it is preferably 50 or more, more preferably 60 or more, and preferably 100 or less, more preferably 80 or less. Here, the saponification value and the iodine value refer to the saponification value and the iodine value measured in accordance with JIS K0070 (1992).

Examples of the etheric oil agent include an etherate of a3 to 6-membered aliphatic polyhydric alcohol, a two-molecule condensate or a three-molecule condensate of a3 to 6-membered aliphatic polyhydric alcohol, and the like.

Specific examples of the 3 to 6-membered aliphatic polyol include: glycerin, sorbitol, trimethylolpropane, erythritol, pentaerythritol, and the like. Specific examples of the di-molecular condensate and tri-molecular condensate of a 3-to 6-membered aliphatic polyhydric alcohol include: diglycerol, bissorbitol, triglycerol, trisorbitol, ditrimethylolpropane, dipentaerythritol, tritrimethylolpropane, tripentaerythritol, etc.

Specific examples of preferred etheric oily agents include alkyl or alkenyl glyceryl ethers, including: alkyl or alkenyl monoglyceryl ether, alkyl or alkenyl polyglyceryl ether having an alkyl or alkenyl group having 4 to 20 carbon atoms, preferably 8 to 18 carbon atoms, and more specifically, for example: lauryl (mono or poly) glyceryl ether, myristyl (mono or poly) glyceryl ether, palmityl (mono or poly) glyceryl ether, stearyl (mono or poly) glyceryl ether, oleyl (mono or poly) glyceryl ether, etc., and preferable examples thereof include oleyl (mono or di) glyceryl ether. From the viewpoint of more efficiently exhibiting low friction in a region where the slip velocity is low, such an ether oil-based agent preferably has a hydroxyl group in the molecule, and the hydroxyl value thereof is preferably 50mgKOH/g or more, more preferably 100mgKOH/g or more, further preferably 200mgKOH/g or more, particularly preferably 250mgKOH/g or more, preferably 400mgKOH/g or less, and more preferably 320mgKOH/g or less. Here, the hydroxyl value is a hydroxyl value measured in accordance with JIS K0070 (1992).

The oily agent may further contain other oily agents in addition to the ester oily agent and the ether oily agent. Examples of such an oily agent include: 1-polyol oily agents, carboxylic acid oily agents, and the like. Examples of the 1-membered alcohol oily agent include the 1-membered alcohols exemplified in the description of the ester oily agent. Examples of the carboxylic acid oil-based agent include the monobasic acids and the polybasic acids exemplified in the description of the ester oil-based agent.

The total content of the oiliness agents is not particularly limited, and is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more, based on the total amount of the refrigerating machine oil, from the viewpoint of further improving the frictional characteristics of the refrigerating machine oil, and is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 1% by mass or less, and particularly preferably 0.2% by mass or less, from the viewpoint of preventing precipitation under a refrigerant atmosphere and at a low temperature.

The refrigerator oil of the present embodiment may further contain other additives in addition to the above components within a range not significantly impairing the effects of the present invention. Examples of the other additives include antioxidants, acid scavengers, extreme pressure agents, antifoaming agents, metal deactivators, anti-wear agents, viscosity index improvers, pour point depressants, clarifying dispersants, and the like. The content of these additives may be 10% by mass or less or 5% by mass or less based on the total amount of the refrigerator oil.

Examples of the antioxidant include a phenol-based antioxidant and an amine-based antioxidant. Examples of the phenol antioxidant include: 2, 6-di-t-butyl-p-cresol (DBPC), 2, 6-di-t-butylphenol, 4' -methylenebis (2, 6-di-t-butylphenol), and the like. Examples of the amine-based antioxidant include: phenyl-alpha-naphthylamines, dialkylated diphenylamines, and the like. These antioxidants may be used alone in 1 kind or in combination of 2 or more kinds.

Examples of the acid scavenger include epoxy compounds (epoxy acid scavengers). Examples of the epoxy compound include: glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, aryl oxirane compounds, alkyl oxirane compounds, alicyclic epoxy compounds, epoxidized fatty acid monoesters, epoxidized vegetable oils, and the like. These acid scavengers can be used alone in 1 kind or in combination in 2 or more kinds. The refrigerator oil further contains an acid scavenger, and thus the hydrolytic stability can be further improved. This is particularly pronounced in the case of lubricant base oils comprising esters.

Examples of the extreme pressure agent include phosphorus-containing extreme pressure agents. Examples of the phosphorus-containing extreme pressure agent include: phosphoric acid esters, acidic phosphoric acid esters, amine salts of acidic phosphoric acid esters, chlorinated phosphoric acid esters, phosphorous acid esters, thiophosphoric acid esters, dithiophosphoric acid esters, dithiophosphorylated carboxylic acids, and the like. The phosphate is preferably triphenyl phosphate (TPP), tricresyl phosphate (TCP) or triphenyl thiophosphate (TPPT). These extreme pressure agents may be used alone in 1 kind or in combination of 2 or more kinds.

As the defoaming agent, any compound generally used as a defoaming agent for a refrigerator oil can be used, and examples thereof include silicones such as dimethyl silicone and fluorosilicone. Compounds optionally selected from 1 or 2 or more of these may be compounded.

From the viewpoint of energy saving and efficiency improvement of the refrigerator, the kinematic viscosity of the refrigerator oil at 40 ℃ is preferably 10mm²Less than s, more preferably 5mm²(ii) less than s, more preferably 4mm²The ratio of the water to the water is less than s. The lower limit of the kinematic viscosity of the refrigerating machine oil at 40 ℃ is not particularly limited, and may be, for example, 1mm²More than s or 1.5mm²More than s. The kinematic viscosity of the refrigerator oil at 100 ℃ is preferably 0.5mm²More preferably 1 mm/s or more²More than s. The kinematic viscosity of the refrigerator oil at 100 ℃ is preferably 3mm²Less than s, more preferably 2mm²The ratio of the water to the water is less than s.

The viscosity index of the refrigerator oil may be 70 or more and 200 or less. The viscosity index of the present invention means a viscosity index according to JIS K2283: viscosity index measured at 2000.

The pour point of the refrigerating machine oil is preferably-10 ℃ or lower, more preferably-20 ℃ or lower.

The volume resistivity of the refrigerating machine oil is preferably 1.0X 10⁹Omega · m or more, more preferably 1.0 × 10¹⁰Omega · m or more, and more preferably 1.0 × 10¹¹Omega · m or more. The volume resistivity of the present invention means a volume resistivity according to JIS C2101: volume resistivity at 25 ℃ measured 1999.

The water content of the refrigerator oil is preferably 200ppm or less, more preferably 100ppm or less, and further preferably 50ppm or less, based on the total amount of the refrigerator oil.

The acid value of the refrigerating machine oil is preferably 2.0mgKOH or less, more preferably 1.0mgKOH/g or less, and still more preferably 0.1mgKOH/g or less. The hydroxyl value of the refrigerator oil is usually 0 to 100mgKOH/g, preferably 50mgKOH/g or less, more preferably 20mgKOH/g or less, and still more preferably 5mgKOH/g or less.

The ash content of the refrigerator oil is preferably 100ppm or less, more preferably 50ppm or less. The ash content of the present invention means a content according to JIS K2272: 1998 ash content determined.

The refrigerating machine oil according to the present embodiment is generally present in a state of a working fluid composition for a refrigerating machine mixed with a refrigerant in a refrigerating machine. That is, the working fluid composition for a refrigerator according to the present embodiment contains the above-described refrigerator oil and a refrigerant. The content of the refrigerating machine oil in the working fluid composition for a refrigerator is 1-500 parts by mass or 2-400 parts by mass relative to 100 parts by mass of the refrigerant.

Examples of the refrigerant include: hydrocarbon refrigerants, saturated fluorinated hydrocarbon refrigerants, unsaturated fluorinated hydrocarbon refrigerants, fluorine-containing ether refrigerants such as perfluoroethers, bis (trifluoromethyl) sulfide refrigerants, methyl iodide trifluoride refrigerants, and natural refrigerants such as ammonia and carbon dioxide.

The hydrocarbon refrigerant is preferably a hydrocarbon having 1 to 5 carbon atoms, more preferably a hydrocarbon having 2 to 4 carbon atoms. Specific examples of the hydrocarbon include: methane, ethylene, ethane, propylene, propane (R290), cyclopropane, n-butane, isobutane (R600a), cyclobutane, methylcyclopropane, 2-methylbutane, n-pentane or mixtures of 2 or more thereof. Of these, preferred are hydrocarbon refrigerants that are gaseous at 25 ℃ under 1 atmosphere, and more preferred are propane, n-butane, isobutane, 2-methylbutane or mixtures thereof.

The saturated fluorinated hydrocarbon refrigerant is preferably a saturated fluorinated hydrocarbon having 1 to 3 carbon atoms, more preferably 1 to 2 carbon atoms. Specific examples of the saturated fluorinated hydrocarbon refrigerant include: difluoromethane (R32), trifluoromethane (R23), pentafluoroethane (R125), 1,1,2, 2-tetrafluoroethane (R134), 1,1,1, 2-tetrafluoroethane (R134a), 1,1, 1-trifluoroethane (R143a), 1, 1-difluoroethane (R152a), fluoroethane (R161), 1,1,1,2,3,3, 3-heptafluoropropane (R227ea), 1,1,1,2,3, 3-hexafluoropropane (R236ea), 1,1,1,3,3, 3-hexafluoropropane (R236fa), 1,1,1,3, 3-pentafluoropropane (R245fa) and 1,1,1,3, 3-pentafluorobutane (R365mfc), or a mixture of 2 or more thereof.

The saturated fluorinated hydrocarbon refrigerant is appropriately selected from the above depending on the application and the required performance. A saturated fluorinated hydrocarbon refrigerant such as R32 alone; r23 alone; r134a alone; r125 alone; r134a/R32 is a mixture of 60-80 mass%/40-20 mass%; R32/R125 is a mixture of 40-70 mass%/60-30 mass%; R125/R143a is a mixture of 40 to 60 mass%/60 to 40 mass%; r134a/R32/R125 ═ 60%/30%/10% by mass of the mixture; a mixture of R134a/R32/R125 in an amount of 40 to 70 mass%/15 to 35 mass%/5 to 40 mass%; and R125/R134a/R143a is 35-55 mass%/1-15 mass%/40-60 mass% of the mixture. The saturated fluorinated hydrocarbon refrigerant may further specifically be a mixture of R134a/R32 ═ 70/30 mass%; a mixture of R32/R125 ═ 60/40 mass%; a mixture (R410A) of R32/R125 ═ 50/50 mass%; a mixture (R410B) of R32/R125 ═ 45/55 mass%; a mixture (R507C) of R125/R143a ═ 50/50 mass%; a mixture of R32/R125/R134a ═ 30/10/60 mass%; a mixture of R32/R125/R134a ═ 23/25/52 mass% (R407C); a mixture of R32/R125/R134a ═ 25/15/60 mass% (R407E); R125/R134a/R143a ═ 44/4/52 mass% of the mixture (R404A).

The unsaturated fluorinated Hydrocarbon (HFO) refrigerant is preferably an unsaturated fluorinated hydrocarbon having 2 to 3 carbon atoms, more preferably fluoropropene, and still more preferably fluoropropene having a fluorine number of 3 to 5. The unsaturated fluorinated hydrocarbon refrigerant is preferably any 1 or a mixture of 2 or more of 1,2,3,3, 3-pentafluoropropene (HFO-1225ye), 1,3,3, 3-tetrafluoropropene (HFO-1234ze), 2,3,3, 3-tetrafluoropropene (HFO-1234yf), 1,2,3, 3-tetrafluoropropene (HFO-1234ye), and 3,3, 3-trifluoropropene (HFO-1243 zf). The unsaturated fluorinated hydrocarbon refrigerant is preferably 1 or 2 or more selected from the group consisting of HFO-1225ye, HFO-1234ze and HFO-1234yf from the viewpoint of the physical properties of the refrigerant. The unsaturated fluorinated hydrocarbon refrigerant may be vinyl fluoride, preferably 1,1,2, 3-trifluoroethylene.

Fig. 1 shows an example of a refrigerator in which the refrigerator oil or the working fluid composition for refrigerators according to the present embodiment can be suitably used. Fig. 1 is a schematic diagram showing an embodiment of a freezer. As shown in fig. 1, the refrigerator 10 includes at least: a compressor (refrigerant compressor) 1, a condenser (gas cooler) 2, an expansion mechanism (capillary tube, expansion valve, etc.) 3, and a refrigerant cycle 6 of an evaporator (heat exchanger) 4 are sequentially connected by piping through a flow path 5.

In the refrigerant cycle 6, first, the high-temperature refrigerant discharged from the compressor 1 into the flow path 5 becomes a high-density fluid (supercritical fluid or the like) in the condenser 2. Next, the refrigerant is liquefied through a narrow flow path having the expansion mechanism 3, and further gasified in the evaporator 4 to become a low temperature. The refrigeration of the refrigerator 10 utilizes a phenomenon in which the refrigerant takes heat from the surroundings when vaporized in the evaporator 4.

In the compressor 1, a small amount of refrigerant coexists with a large amount of refrigerating machine oil under high temperature conditions. The refrigerant discharged from the compressor 1 to the flow path 5 is gaseous, and contains a small amount (typically 1 to 10 vol%) of the refrigerator oil in the form of mist, and a small amount of the refrigerant is dissolved in the mist of the refrigerator oil (point a in fig. 1).

In the condenser 2, the gaseous refrigerant is compressed to form a high-density fluid, and a large amount of refrigerant coexists with a small amount of refrigerating machine oil under relatively high temperature conditions (point b in fig. 1). Further, a mixture of a large amount of refrigerant and a small amount of refrigerating machine oil is sent to the expansion mechanism 3 and the evaporator 4 in this order, rapidly becomes a low temperature (points c and d in fig. 1), and returns to the compressor 1 again.

As the compressor 1, the following compressors and the like can be exemplified: a high-pressure container type compressor in which: a motor including a rotor and a stator, a rotary shaft fitted to the rotor, and a compressor unit connected to the motor via the rotary shaft, wherein a high-pressure refrigerant gas discharged from the compressor unit is retained in a closed container; a low-pressure container type compressor in which: the high-pressure refrigerant gas discharged from the compressor unit is directly discharged to the outside of the sealed container. The compressor is not limited to a rotary compressor such as the compressor 1, and may be a reciprocating compressor such as a piston-crank type compressor, a screw type compressor, or a centrifugal type compressor, but a reciprocating compressor is particularly preferable. The sealed structure of the compressor may be any of an open type, a semi-sealed type, and a sealed type, but a sealed type is particularly preferable.

When the refrigerating machine oil or the working fluid composition for a refrigerator of the present embodiment is used in a refrigerator including a compressor operable under the condition that a sliding member slides in a region having a low sliding speed, for example, 0.4m/s or less, preferably 0.2m/s or less, and more preferably 0.1m/s or less, excellent friction characteristics can be obtained. The lower limit of the slip speed is not particularly limited, and may be, for example, 0m/s or more, or may be 0.001m/s or more. As such a refrigerator, for example, a refrigerator having a reciprocating or rotary hermetic compressor, a water heater, a freezer-refrigerator warehouse, a vending machine, a showcase, a refrigerator in a chemical plant, or the like, and a refrigerator having a centrifugal compressor, or the like is preferable. In the present specification, the "slip speed" of the compressor means a relative speed when 2 sliding agents slide along with the sliding, and the speed of the sliding material 1 in the sliding portion is U₁[m/s]The speed of the sliding material 2 is set to U₂[m/s]The formula (I) is as follows.

Slip speed ═ U₁-U₂|

In the above formula, U is₁And U₂The same value may be used, or any value may be 0.

Examples

The present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

[ Lubricant base oils ]

Lubricating base oils A1 to A3 shown below were prepared.

A1: paraffinic mineral base oil, kinematic viscosity at 40 ℃: 3.4mm²(s), kinematic viscosity at 100 ℃: 1.3mm²(s), pour point: -35 ℃, flash point: 131 ℃ and% C_P/％C_N＝1.2

A2: paraffinic mineral base oil, kinematic viscosity at 40 ℃: 2.4mm²(s), kinematic viscosity at 100 ℃: 1.0mm²(s), pour point: -25 ℃, flash point: 110 ℃ and% C_P/％C_N＝1.6

A3: ester-based base oils composed of the monoester of 2-ethylhexanol and 2-ethylhexanoic acid and the polyol ester of neopentyl glycol and 2-ethylhexanoic acid, kinematic viscosity at 40 ℃: 3.0mm²S, acid value below 0.01mgKOH/g, flash point 140 deg.C

[ refrigerating machine oil ]

In examples and comparative examples, refrigerating machine oils having compositions (mass% based on the total amount of the refrigerating machine oil) shown in table 1 were prepared using the following components as the above-described lubricating base oil and additives, respectively.

(oiliness agent)

B1: oleyl glyceryl ether (hydroxyl value: 300mgKOH/g)

B2: sorbitan monooleate (saponification number: 153mgKOH/g, iodine number: 68)

B3: glyceryl monooleate (saponification number: 154mgKOH/g, iodine number: 70)

(other additives)

C1: mixture of tricresyl phosphate, triphenyl thiophosphate and defoamer

C2: mixture of glycidyl decanoate and 2, 6-di-tert-butyl-p-cresol

[ evaluation of Friction characteristics ]

In order to evaluate the frictional properties of the refrigerator oils of examples and comparative examples, the following tests were carried out.

The coefficient of friction (. mu.) was measured under the following conditions using an MTM (Mini Traction machine) tester (PCS Instruments Co.). The results are shown in Table 1. The smaller the friction coefficient, the more excellent the friction characteristics.

Ball and disc: standard test strip (AISI52100 standard)

Test temperature: 40 deg.C

Slip speed: 0.003, 0.015, 0.03, 0.9m/s

Load loading: 10N

Slip ratio: 30 percent of

The slip speed is | U |_D-U_B|[m/s]The value of (c). Wherein, U_DIs the speed of the disk in the sliding part [ m/s ]]，U_BIs the speed [ m/s ] of the ball in the sliding part]。

[ Table 1]

The refrigerator oils of examples 1 to 6 exhibited excellent frictional characteristics in a region where the slip speed was low, as compared with the refrigerator oils of comparative examples 1 to 3. On the other hand, the refrigerator oils of comparative examples 1 to 3, which did not contain an ester oil-based agent and an ether oil-based agent as additives, exhibited a high friction coefficient in a region where the slip speed was low. In particular, as shown in comparative example 2, even when the kinematic viscosity of the refrigerating machine oil at 40 ℃ is reduced to achieve a low viscosity, the friction characteristics are improved in the region where the slip speed is high, but the friction characteristics are not improved in the region where the slip speed is low. It was confirmed that the refrigerator oil obtained by adding 0.1 mass% of the oil agent B1 to the refrigerator oil of comparative example 2 had a reduced friction coefficient particularly at a low slip speed of less than 0.1 m/s.

Description of the reference numerals

A1 … compressor, a2 … condenser, a3 … expansion mechanism, a 4 … evaporator, a 5 … flow path, a 6 … refrigerant cycle system, and a 10 … refrigerator.

Claims

1. A refrigerator oil, comprising: transportation at 40 deg.CThe dynamic viscosity is 10mm²A lubricant base oil of less than s; and the number of the first and second groups,

comprising at least 1 oily agent selected from the group consisting of ester oily agents and ether oily agents.

2. The refrigerator oil of claim 1 wherein the lubricant base oil comprises a mineral oil.

3. The refrigerator oil according to claim 1 or 2, wherein the oily agent comprises an ether oily agent.

4. The refrigerator oil of claim 3 wherein the ether oiliness agent is an alkyl or alkenyl glyceryl ether.

5. A working fluid composition for a refrigerator, comprising a refrigerant and the refrigerator oil according to any one of claims 1 to 4.

6. A refrigerator is provided with a refrigerant cycle system: a compressor, a condenser, an expansion mechanism, and an evaporator are sequentially connected to the refrigerant circulation system by piping, and a refrigerant and the refrigerator oil according to any one of claims 1 to 4 are filled in the refrigerant circulation system.