阅读说明：本技术 冷冻机油和冷冻机用工作流体组合物 (Refrigerator oil and working fluid composition for refrigerator ) 是由 奈良文之 庄野洋平 大城户武 尾形英俊 于 2018-11-19 设计创作，主要内容包括：一种冷冻机油,其含有：润滑油基础油；包含硫和磷作为构成元素的第一极压剂；和,包含磷而不包含硫作为构成元素的第二极压剂,所述冷冻机油的100℃下的运动粘度为0.5mm<Sup>2</Sup>/s以上且2.5mm<Sup>2</Sup>/s以下。(A refrigerator oil, comprising: a lubricant base oil; a first extreme pressure agent containing sulfur and phosphorus as constituent elements; and a second extreme pressure agent containing phosphorus without containing sulfur as a constituent element, the refrigerating machine oil having a movement at 100 ℃The viscosity is 0.5mm 2 2.5mm of more than s 2 The ratio of the water to the water is less than s.)

1. A refrigerator oil, comprising: a lubricant base oil; a first extreme pressure agent containing sulfur and phosphorus as constituent elements; and a second extreme pressure agent containing phosphorus without containing sulfur as a constituent element, the refrigerating machine oil having a kinematic viscosity at 100 ℃ of 0.5mm²2.5mm of more than s²The ratio of the water to the water is less than s.

2. The refrigerator oil according to claim 1, wherein the total amount of the first extreme-pressure agent and the second extreme-pressure agent is 0.1 mass% or more and 5 mass% or less, based on the total amount of the refrigerator oil.

3. The refrigerator oil according to claim 1 or 2, wherein the content of the first extreme pressure agent is 5% by mass or more and 20% by mass or less based on the total amount of the first extreme pressure agent and the second extreme pressure agent.

4. The refrigerator oil according to any one of claims 1 to 3, wherein the content of the first extreme pressure agent is 0.01 mass% or more and 2 mass% or less based on the total amount of the refrigerator oil.

5. A working fluid composition for refrigerators comprising:

refrigerating machine oil comprising a lubricating base oil, a first extreme-pressure agent containing sulfur and phosphorus as constituent elements, and a second extreme-pressure agent containing phosphorus without containing sulfur as constituent elements, the refrigerating machine oil having an operation at 100 ℃The dynamic viscosity is 0.5mm²2.5mm of more than s²(ii) less than s; and the combination of (a) and (b),

a refrigerant.

Technical Field

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

Background

Refrigerators, air conditioners and other refrigerators include: a compressor for circulating a refrigerant in the refrigerant cycle system. The compressor is filled with a refrigerating machine oil for lubricating the sliding member. In general, as the viscosity of the refrigerating machine oil is lower, the stirring resistance and the friction of the sliding portion can be reduced, and therefore, the reduction in the viscosity of the refrigerating machine oil is related to the energy saving of the refrigerating machine. Patent document 1 discloses a predetermined refrigerator oil having VG3 or more and VG8 or less, for example.

Disclosure of Invention

Problems to be solved by the invention

However, if the viscosity of the refrigerating machine oil is low, it becomes difficult to maintain the oil film in the sliding portion, and therefore, there is a concern that the wear resistance cannot be maintained. Further, since the refrigerating machine oil is compatible with the refrigerant in the refrigerator, the viscosity at the time of use is greatly reduced as compared with the refrigerating machine oil itself, the lubrication condition changes from the fluid lubrication region to the mixed lubrication and/or boundary lubrication region, and the frequency of contact between the sliding materials increases. Therefore, a kinematic viscosity of 2.5mm, in particular at 100 ℃²Less than or equal to 2.0mm²The use of ultra-low viscosity refrigerating machine oils, such as those having a viscosity of not more than s, has not been achievedThe study was conducted sufficiently. In particular, even under severe lubrication conditions such as mixed lubrication and boundary lubrication conditions using such a refrigerating machine oil having an extremely low viscosity, it is extremely difficult to obtain a refrigerating machine oil having high wear resistance.

The present invention has been made in view of such circumstances, and an object thereof is to provide: a refrigerating machine oil having a low viscosity and high wear resistance even under severe lubricating conditions such as mixed lubrication and/or boundary lubrication conditions, and a working fluid composition for a refrigerating machine containing the same.

Means for solving the problems

The present invention provides a refrigerator oil, which contains: a lubricant base oil; a first extreme pressure agent containing sulfur and phosphorus as constituent elements; and a second extreme pressure agent containing phosphorus without containing sulfur as a constituent element, the refrigerating machine oil having a kinematic viscosity at 100 ℃ of 0.5mm²2.5mm of more than s²The ratio of the water to the water is less than s.

The total amount of the first extreme-pressure agent and the second extreme-pressure agent is preferably 0.1 mass% or more and 5 mass% or less, based on the total amount of the refrigerating machine oil.

The content of the first extreme-pressure agent is preferably 5 mass% or more and 20 mass% or less based on the total amount of the first extreme-pressure agent and the second extreme-pressure agent.

The content of the first extreme pressure agent is preferably 0.01 mass% or more and 2 mass% or less based on the total amount of the refrigerator oil.

Further, the present invention provides a working fluid composition for a refrigerator, comprising: the refrigerator oil of the present invention described above; and, a refrigerant.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided: a refrigerating machine oil which has a low viscosity and is excellent in wear resistance even under severe lubricating conditions such as mixed lubrication and/or boundary lubrication conditions, and a working fluid composition for a refrigerating machine containing the refrigerating machine oil.

Drawings

Fig. 1 is a schematic diagram showing an example of the configuration of a refrigerator.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail.

The refrigerator oil of the present embodiment includes: a lubricant base oil; a first extreme pressure agent comprising sulfur and phosphorus; and, a second extreme pressure agent comprising phosphorus and no sulfur.

Examples of the lubricant base oil include mineral oils. Mineral oils can be obtained as follows: the lubricating oil fraction obtained by subjecting a crude oil such as a paraffinic or naphthenic crude oil to atmospheric distillation or vacuum distillation can be obtained by purifying the obtained lubricating oil fraction by a method such as solvent removal, solvent purification, hydrorefining, hydrocracking, solvent dewaxing, hydrodewaxing, clay treatment, or sulfuric acid washing. These purification methods can be used alone in 1 kind, or can be combined with 2 or more kinds and use. From the viewpoint of availability, it is preferable to select and use a low-viscosity lubricant base oil used for applications such as general solvents, diluents, and metal working oils.

The lubricant base oil may be formed of the above-mentioned mineral oil, and the ratio of the mineral oil may be usually 50 mass% or more, 70 mass% or more, or 90 mass% based on the total amount of the lubricant base oil. The mineral oil may further contain a hydrocarbon oil such as alkylbenzene or an oxygen-containing oil such as an ester, unless the effects of the present invention are significantly impaired.

The alkylbenzene may be at least 1 selected from the group consisting of alkylbenzene (a1) and alkylbenzene (a2) described below.

Alkylbenzene (a 1): an alkylbenzene having 1 to 4 alkyl groups having 1 to 19 carbon atoms and 9 to 19 carbon atoms in total (preferably an alkylbenzene having 1 to 4 alkyl groups having 1 to 15 carbon atoms and 9 to 15 carbon atoms in total)

Alkylbenzene (a 2): an alkylbenzene having 1 to 4 alkyl groups having 1 to 40 carbon atoms and having 20 to 40 total carbon atoms of the alkyl groups (preferably an alkylbenzene having 1 to 4 alkyl groups having 1 to 30 carbon atoms and having 20 to 30 total carbon atoms of the alkyl groups)

The ester may be, for example, an ester of a monohydric or dihydric alcohol with a fatty acid. The monohydric alcohol or dihydric alcohol may be, for example, an aliphatic alcohol having 4 to 12 carbon atoms. The fatty acid may be a C4-19 fatty acid, for example.

In order to produce a refrigerating machine oil having properties described later, the properties of a lubricant base oil as a main component (for example, 90 mass% or more) are preferably equivalent to those of the refrigerating base oil unless otherwise specified in the present specification. Therefore, the ranges of properties of the individual items of the refrigerating machine oil described later can be understood as ranges of the individual items of the lubricating base oil contained in the refrigerating machine oil unless otherwise specified in the present specification. For example, the distillation property of the lubricant base oil by GC distillation is not particularly limited as long as the distillation property of the refrigerator oil falls within the range described below. Initial boiling point IBP to 90% distillation temperature T for lubricant base oil₉₀The above-mentioned limitations and the regulations relating thereto are understood to be substantially the same as or within ± 5 ℃ of the distillation properties of the refrigerating machine oil described later, for example, so as to be less susceptible to the additive formulation. The distillation end point EP of the lubricant base oil may be, for example, 450 ℃ or lower and 95% distillation temperature T₉₅For example, 410 ℃ or lower.

The kinematic viscosity at 40 ℃ of the lubricant base oil may be, for example, 2.0mm²2.5mm over/s²More than s, or 2.7mm²Is not less than s, for example, 4.5mm²Less than s, 4.0mm²Less than s, or 3.5mm²The ratio of the water to the water is less than s. The kinematic viscosity at 100 ℃ of the lubricant base oil may be, for example, 0.5mm²0.6mm over/s²0.8mm over/s²More than s, or 1.0mm²Is more than or equal to s, and can be, for example, 2.5mm²2.0mm below/s²1.5mm below/s²Less than s, or 1.3mm²The ratio of the water to the water is less than s. The kinematic viscosity in the present invention is a value in accordance with JIS K2283: 2000, measured kinematic viscosity.

The sulfur content of the lubricant base oil may be, for example, 0.05% by mass or less, 0.02% by mass or less, or 0.01% by mass or less, and may be less than 0.02% by mass. The sulfur content of the lubricant base oil may be less than 0.0001% by mass, and may be, for example, 0.0001% by mass or more, 0.0005% by mass or more, or 0.001% by mass or more, from the viewpoint of further improving the effect of the combination with the first extreme pressure agent and the second extreme pressure agent. The sulfur content in the present invention is defined by JIS K2541-6: 2013 by the ultraviolet fluorescence method.

The content of the lubricant base oil may be, for example, 50 mass% or more, 60 mass% or more, 70 mass% or more, 80 mass% or more, 90 mass% or more, or 95 mass% or more, and may be, for example, 99.5 mass% or less, 99 mass% or less, or 98.5 mass% or less, based on the total amount of the refrigerator oil.

The refrigerator oil of the present embodiment contains a first extreme pressure agent and a second extreme pressure agent.

The first extreme-pressure agent is an extreme-pressure agent containing sulfur and phosphorus as constituent elements in the same molecule, and examples of such extreme-pressure agents include thiophosphates and the like.

Examples of the thiophosphate include tributyl thiophosphate, tripentyl thiophosphate, trihexyl thiophosphate, triheptyl thiophosphate, trioctyl thiophosphate, trinonyl thiophosphate, tridecyl thiophosphate, triundecyl thiophosphate, tridodecyl thiophosphate, tritridecyl thiophosphate, tritetradecyl thiophosphate, tripentadecyl thiophosphate, trihexadecyl thiophosphate, triheptadecyl thiophosphate, trioctadecyl thiophosphate, triolenyl thiophosphate, triphenyl thiophosphate, tricresyl thiophosphate, trixylyl thiophosphate, tolyldiphenyl thiophosphate, and ditolyl diphenyl thiophosphate. Among them, triphenyl thiophosphate is preferred.

The second extreme pressure agent contains phosphorus in the same molecule and does not contain sulfur as a constituent element, and examples of such extreme pressure agents include sulfur-free phosphoric acid esters, acidic phosphoric acid esters, amine salts of acidic phosphoric acid esters, chlorinated phosphoric acid esters, and phosphorous acid esters.

Examples of the phosphate ester include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate, tritridecyl phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, triolenyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylyl phosphate, cresyldiphenyl phosphate, and ditolyl phosphate. Among them, triphenyl phosphate and tricresyl phosphate are preferable. Examples of triphenyl phosphate include tris (butylphenyl) phosphate.

Examples of the acidic phosphate ester include monobutyl acid phosphate ester, monopentyl acid phosphate ester, monohexyl acid phosphate ester, monoheptyl acid phosphate ester, monooctyl acid phosphate ester, monononyl acid phosphate ester, monodecyl acid phosphate ester, monoundecyl acid phosphate ester, monododecyl acid phosphate ester, monotridecyl acid phosphate ester, monotetradecyl acid phosphate ester, monopentadecyl acid phosphate ester, monohexadecyl acid phosphate ester, monopecyl acid phosphate ester, monostearyl acid phosphate ester, monooleenyl acid phosphate ester, dibutyl acid phosphate ester, dipentyl acid phosphate ester, dihexyl acid phosphate ester, diheptyl acid phosphate ester, dioctyl acid phosphate ester, dinonyl acid phosphate ester, didecyl acid phosphate ester, diundecyl acid phosphate ester, didodecyl acid phosphate ester, dipentyl, Ditridecyl acid phosphate, ditetradecyl acid phosphate, dipentadecyl acid phosphate, dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, dioleyl acid phosphate, and the like.

Examples of the amine salt of the acidic phosphoric acid ester include salts with amines such as methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, and trioctylamine of the acidic phosphoric acid ester.

Examples of the chlorinated phosphate include tris dichloropropyl phosphate, tris chloroethyl phosphate, tris chlorophenyl phosphate, polyoxyalkylene bis [ di (chloroalkyl) ] phosphate, and the like. Examples of the phosphite ester include dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, dioleyl phosphite, diphenyl phosphite, ditolyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl phosphite, tridodecyl phosphite, triolenyl phosphite, triphenyl phosphite, and tritolyl phosphite.

From the viewpoint of further excellent wear resistance, the total amount of the first extreme pressure agent and the second extreme pressure agent may be, for example, 0.1 mass% or more, 1 mass% or more, 1.5 mass% or more, or 1.6 mass% or more, and may be, for example, 5 mass% or less, 3 mass% or less, 2.5 mass% or less, or 2 mass% or less, based on the total amount of the refrigerator oil.

The ratio of the content of the first extreme pressure agent based on the total amount of the first extreme pressure agent and the second extreme pressure agent may be, for example, 5 mass% or more, 8 mass% or more, or 10 mass% or more, and may be, for example, 20 mass% or less, 18 mass% or less, 15 mass% or less, or 14 mass% or less, from the viewpoint of further excellent wear resistance.

From the viewpoint of further excellent wear resistance, the content of the first extreme pressure agent may be, for example, 0.01 mass% or more, 0.05 mass% or more, or 0.1 mass% or more, and may be, for example, 2 mass% or less, 1 mass% or less, 0.5 mass% or less, or 0.4 mass% or less, based on the total amount of the refrigerator oil. From the viewpoint of further excellent wear resistance, the content of the second extreme pressure agent may be, for example, 0.5% by mass or more, 1% by mass or more, or 1.2% by mass or more, and may be, for example, 5% by mass or less, 3% by mass or less, 2% by mass or less, or 1.8% by mass or less, based on the total amount of the refrigerator oil.

The refrigerator oil may contain, for example, the following lubricating oil additives in addition to the above-described lubricating base oil, first extreme-pressure agent, and second extreme-pressure agent. Examples of the lubricating oil additive include an acid trapping agent, an antioxidant, an extreme pressure agent other than the first extreme pressure agent and the second extreme pressure agent, an oiliness agent, an antifoaming agent, a metal deactivator, an anti-wear agent, a viscosity index improver, a pour point depressant, and a detergent dispersant. The content of these lubricating oil additives may be 10 mass% or less or 5 mass% or less based on the total amount of the refrigerating machine oil.

The kinematic viscosity of the refrigerator oil at 100 ℃ is 0.5mm²2.5mm of more than s²The ratio of the water to the water is less than s. From the viewpoint of further improving the balance between the wear resistance and the energy saving performance of the refrigerator, the kinematic viscosity of the refrigerator oil at 100 ℃ is preferably 0.6mm²2.0mm of more than s²Less than s, more preferably 0.8mm²1.5mm of a length of more than s²Less than s, more preferably 1.0mm²1.4mm of a length of more than s²The ratio of the water to the water is less than s.

The kinematic viscosity at 40 ℃ of the refrigerating machine oil may be, for example, 2.0mm²2.5mm over/s²More than s and 3.0mm²More than s, or 3.2mm²S, for example, may be 4.5mm²Less than s, 4.0mm²Less than s, or 3.5mm²The ratio of the water to the water is less than s.

From the viewpoint of further excellent wear resistance, the aniline point of the refrigerator oil may be, for example, 60 ℃ or higher, 70 ℃ or higher, 73 ℃ or higher, 76 ℃ or higher, or 80 ℃ or higher. The aniline point of the refrigerator oil may be, for example, 100 ℃ or lower, 95 ℃ or lower, or 90 ℃ or lower, from the viewpoint of suitability for organic materials such as PET (polyethylene terephthalate) materials and sealing materials used in refrigeration apparatuses (refrigerators). The aniline point in the present invention is defined as a value according to JIS K2256: 2013.

In view of the fact that the distillation properties (when not particularly described, the distillation properties by GC distillation are also referred to) of the refrigerator oil by gas chromatography distillation (hereinafter also referred to as GC distillation), from the viewpoint of further improving the balance between the low viscosity of the refrigerator oil and the lubricity and further maintaining the flash point at a relatively high level, it is preferable to increase the distillation temperature on the low boiling point side and maintain the distillation temperature on the high boiling point side within an appropriate range. Such a refrigerator oil is desired to have the distillation properties described below.

The refrigerator oil may have an initial boiling point IBP of, for example, 200 ℃ or higher, 210 ℃ or higher, 220 ℃ or higher, or 230 ℃ or higher, and may have a boiling point IBP of, for example, 260 ℃ or lower, 250 ℃ or lower, or 240 ℃ or lower.

5% distillation temperature T of refrigerator oil₅For example, it may be 205 ℃ or higher, 215 ℃ or higher, 225 ℃ or higher, or 235 ℃ or higher, and for example, it may be 265 ℃ or lower, 255 ℃ or lower, or 245 ℃ or lower.

10% distillation temperature T of refrigerator oil₁₀For example, the temperature may be 210 ℃ or higher, 220 ℃ or higher, 230 ℃ or higher, or 240 ℃ or higher, and for example, 270 ℃ or lower, 260 ℃ or lower, or 250 ℃ or lower.

50% distillation temperature T of refrigerator oil₅₀For example, it may be 230 ℃ or higher, 240 ℃ or higher, 250 ℃ or higher, or 260 ℃ or higher, and for example, it may be 310 ℃ or lower, 300 ℃ or lower, or 280 ℃ or lower.

70% distillation temperature T for refrigerator oil₇₀For example, from the viewpoint of lubricity and high flash point, it may be 250 ℃ or higher, 260 ℃ or higher, 270 ℃ or higher, or 280 ℃ or higher. Further, the 70% distillation temperature T of the refrigerator oil₇₀For example, from the viewpoint of reducing the viscosity, the temperature may be 340 ℃ or lower, 330 ℃ or lower, or 300 ℃ or lower.

90% distillation temperature T of refrigerator oil₉₀For example, 270 ℃ or higher, 280 ℃ or higher, 290 ℃ or higher, or 300 ℃ or higher, and from the viewpoint of further excellent abrasion resistance, 320 ℃ or higher, 330 ℃ or higher, or 340 ℃ or higher is particularly preferable. Further, the 90% distillation temperature T of the refrigerating machine oil₉₀For example, from the same viewpoint as above, it may be 400 ℃ or lower, 370 ℃ or lower, 360 ℃ or lower, or 355 ℃ or lower.

95% distillation temperature T of refrigerator oil₉₅For exampleFor example, 280 ℃ or higher, 290 ℃ or higher, 300 ℃ or higher, 310 ℃ or higher, or 330 ℃ or higher may be used, and from the viewpoint of further excellent abrasion resistance, 340 ℃ or higher, 350 ℃ or higher, or 360 ℃ or higher is particularly preferable. 95% distillation temperature T of refrigerator oil₉₅For example, the temperature may be 410 ℃ or lower, 400 ℃ or lower, 390 ℃ or lower, or 380 ℃ or lower.

The distillation end point EP of the refrigerator oil may be 390 ℃ or higher, 395 ℃ or higher, or 400 ℃ or higher, for example, from the viewpoint of lubricity. The end point EP of distillation of the refrigerator oil may be 440 ℃ or lower, 430 ℃ or lower, or 425 ℃ or lower, for example, from the viewpoint of lowering the viscosity.

From the viewpoint of further improving the balance between the low viscosity and the lubricity of the refrigerator oil and further maintaining the flash point at a high level, it is preferable to increase the distillation temperature on the low boiling point side and maintain the distillation temperature on the high boiling point side in an appropriate range as described above. In addition to the above, it is desirable to maintain a moderately narrow range as described below, and not to widen the distillation range, but to maintain an excessively narrow range.

90% distillation temperature T of refrigerator oil₉₀And 5% distillation temperature T₅Difference between (T)₉₀-T₅) For example, the temperature may be 40 ℃ or higher, 50 ℃ or higher, or 60 ℃ or higher, particularly preferably 80 ℃ or higher, or 100 ℃ or higher, and may be 200 ℃ or lower, 160 ℃ or lower, 150 ℃ or lower, 140 ℃ or lower, or 130 ℃ or lower, for example.

90% distillation temperature T of refrigerator oil₉₀Difference (T) from initial boiling point IBP₉₀-IBP) may be, for example, 40 ℃ or more, 50 ℃ or more, 60 ℃ or more, or 70 ℃ or more, particularly preferably 80 ℃ or more, or 100 ℃ or more, and may be, for example, 170 ℃ or less, 160 ℃ or less, 150 ℃ or less, or 140 ℃ or less.

95% distillation temperature T of refrigerator oil₉₅Difference (T) from initial boiling point IBP₉₅-IBP) may be, for example, 50 ℃ or more, 60 ℃ or more, 70 ℃ or more, or 80 ℃ or more, particularly preferably 100 ℃ or more, or 120 ℃ or more, and may be, for example, 180 ℃ or less, 170 ℃ or less, 160 ℃ or less, or 150 ℃ or less.

95% distillation temperature T for refrigerator oil₉₅And 90% distillation temperature T₉₀Difference between (T)₉₅-T₉₀) From the viewpoint of lubricity, the temperature may be, for example, 1 ℃ or higher, 3 ℃ or higher, 5 ℃ or higher, 10 ℃ or higher, or 20 ℃ or higher, and may be, for example, 100 ℃ or lower, 80 ℃ or lower, 50 ℃ or lower, or 40 ℃ or lower.

End point of distillation EP and 90% distillation temperature T for refrigerator oil₉₀Difference between (EP-T)₉₀) From the viewpoint of lubricity, it may be, for example, 30 ℃ or more, 50 ℃ or more, 60 ℃ or more, or 70 ℃ or more, may be, for example, 150 ℃ or less, 140 ℃ or less, 130 ℃ or less, or 120 ℃ or less, and may be, in particular, 100 ℃ or less, 90 ℃ or less, or 80 ℃ or less.

In the present invention, the initial boiling point, 5% distillation temperature, 10% distillation temperature, 50% distillation temperature, 70% distillation temperature, 90% distillation temperature and distillation end point respectively mean the initial boiling point, 5% volume distillation temperature, 10% volume distillation temperature, 50% volume distillation temperature, 70% volume distillation temperature, 90% volume distillation temperature, 95% volume distillation temperature and distillation end point measured according to the distillation test method by gas chromatography specified in ASTM D7213-05.

The sulfur content of the refrigerator oil may be, for example, 0.001 mass% or more, or 0.005 mass% or more, or, for example, 0.3 mass% or less, 0.1 mass% or less, or 0.05 mass% or less. The source component of the sulfur content of the refrigerator oil is not particularly limited, and it is preferable that the sulfur content of the refrigerator oil further contains a sulfur content derived from the lubricant base oil from the viewpoint of further excellent wear resistance. In the sulfur content of the refrigerator oil, the ratio of the sulfur content derived from the lubricant base oil may be, for example, 5 mass% or more, 10 mass% or more, or 20 mass% or more, and may be, for example, 50 mass% or less, 40 mass% or less, or 30 mass% or less.

The composition ratio of the refrigerating machine oil based on the ring analysis is preferably maintained in the following range from the viewpoint of further improving the balance between the low viscosity of the refrigerating machine oil and the lubricity and further maintaining the flash point at a high level.

% C of refrigerator oil_PFor example, the amount may be 15 or more, 40 or more, or 50 or more, and for example, 70 or less, 60 or less, or 55 or less.

% C of refrigerator oil_NFor example, it may be 30 or more, 35 or more, or 40 or more, and for example, it may be 85 or less, 70 or less, 60 or less, 50 or less, or 49 or less.

% C of refrigerator oil_NRelative to% C_PRatio of (% C)_N/％C_P) For example, it may be 0.5 or more, 0.6 or more, or 0.7 or more, and for example, it may be 4.5 or less, 2.0 or less, 1.4 or less, 1.3 or less, or 1.2 or less.

% C for refrigerator oil_AFor example, from the viewpoint of lubricity and stability, it may be 8 or less, 5 or less, or 3 or less, may be 0, and may be 0.5 or more, or 1 or more.

% C in the invention_P、％C_NAnd% C_ARespectively, the values determined by the method (n-D-M loop analysis) according to ASTM D3238-95 (2010).

The flash point of the refrigerating machine oil may be, for example, 100 ℃ or higher, 110 ℃ or higher, or 120 ℃ or higher from the viewpoint of safety, and may be, for example, 155 ℃ or lower, or 145 ℃ or lower from the viewpoint of forming a low-viscosity oil. The flash point in the present invention is a flash point measured according to JIS K2265-4: 2007 (the Cleveland Open Cup (COC) method).

The pour point of the refrigerator oil may be, for example, not higher than-10 ℃ or not higher than-20 ℃ or not higher than-50 ℃ or not higher than-40 ℃ from the viewpoint of purification cost. The pour point in the present invention is defined as follows according to JIS K2269: 1987 pour point.

The acid value of the refrigerator oil may be, for example, 1.0mgKOH/g or less, or 0.1mgKOH/g or less. The acid value in the present invention is a value determined according to JIS K2501: 2003, and acid value.

The volume resistivity of the refrigerating machine oil may be, for example, 1.0 × 10⁹1.0 × 10 of not less than omega.m¹⁰Omega · m or more, or 1.0 × 10¹¹Omega · m or more. The inventionThe volume resistivity in (1) is a volume resistivity in accordance with JIS C2101: 1999, volume resistivity at 25 ℃.

The water content of the refrigerator oil may be, for example, 200ppm or less, 100ppm or less, or 50ppm or less based on the total amount of the refrigerator oil.

The ash content of the refrigerating machine oil may be, for example, 100ppm or less or 50ppm or less. Ash in the present invention means ash content according to JIS K2272: 1998 ash content determined.

The refrigerating machine oil of the present embodiment is generally present in the 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 may be 1 to 500 parts by mass or 2 to 400 parts by mass with respect 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, difluoromethane iodide 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, and a mixture of 2 or more of these hydrocarbons. Among them, the hydrocarbon refrigerant is preferably a hydrocarbon refrigerant which is gaseous at 25 ℃ under 1 atmosphere, more preferably propane, n-butane, isobutane, 2-methylbutane or a mixture 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), and a mixture of 2 or more thereof.

The saturated fluorinated hydrocarbon refrigerant may be appropriately selected from those described 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 a mixture of 35 to 55 mass%/1 to 15 mass%/40 to 60 mass% of R125/R134a/R143 a. The saturated fluorinated hydrocarbon refrigerant may be more specifically 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); a mixture (R404A) of R125/R134a/R143a of 44/4/52 mass%, and the like.

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

Among these refrigerants, a refrigerant having a low Global Warming Potential (GWP) is preferable in order to reduce the influence on the global environment. Such a refrigerant includes, for example, at least 1 selected from unsaturated fluorinated hydrocarbon refrigerants and natural refrigerants such as R290 and R600a, and examples thereof include mixed refrigerants having a GWP of 1000 or less. The GWP of these refrigerants may be 500 or less, 100 or less, 50 or less, or 10 or less.

In terms of cooling capacity, the boiling point of these refrigerants is preferably 0 ℃ or lower and-60 ℃ or higher, for example. Among them, the compression ratio is low and the volume capacity is high, more preferably-30 ℃ or lower, and the pressure is low and the sliding loss of the compressor is small, more preferably-30 ℃ or higher. The refrigerant having a low compression ratio and a high volumetric capacity is, for example, R290 (boiling point: -42.1 ℃ C.), and the refrigerant having a low pressure and a small sliding loss of the compressor is, for example, R600a (boiling point: -11.6 ℃ C.). In particular, R600a is preferably used from the viewpoint of expecting an effect of improving the efficiency of the refrigerator due to a reduction in the sliding loss of the compressor in accordance with a reduction in the viscosity of the refrigerator oil.

The refrigerator oil and the working fluid composition for a refrigerator according to the present embodiment can be suitably used for refrigerators such as air conditioners having reciprocating and rotary hermetic compressors, refrigerators, open-type or hermetic automobile air conditioners, dehumidifiers, water heaters, freezers, refrigerated warehouses, vending machines, display cases, and chemical plants, refrigerators having centrifugal compressors, and the like.

Fig. 1 is a schematic diagram showing an example of a configuration of a refrigerator to which a refrigerator oil and a working fluid composition for a refrigerator according to the present embodiment are applied. As shown in fig. 1, the refrigerator 10 includes, for example, at least: the refrigerant compressor 1, the gas cooler 2, the expansion mechanism 3 (a capillary tube, an expansion valve, etc.), and the evaporator 4 are connected in this order by the flow path 5. In the above-described refrigerant cycle system, first, the high-temperature (generally 70 to 120 ℃) refrigerant discharged from the refrigerant compressor 1 into the flow path 5 becomes a high-density fluid (supercritical fluid or the like) in the gas cooler 2. Then, the refrigerant is liquefied through a narrow flow path of the expansion mechanism 3, and further vaporized in the evaporator 4 to a low temperature (normally-40 to 0 ℃).

In the refrigerant compressor 1 shown in fig. 1, a small amount of refrigerant coexists with a large amount of refrigerating machine oil under high temperature (generally 70 to 120 ℃). The refrigerant discharged from the refrigerant compressor 1 to the flow path 5 is gaseous, and contains a small amount (usually 1 to 10%) of the refrigerator oil in the form of mist, but a small amount of the refrigerant is dissolved in the mist of the refrigerator oil (point a in fig. 1). Next, in the gas cooler 2, the gaseous refrigerant is compressed to become a high-density fluid, and a large amount of refrigerant coexists with a small amount of refrigerating machine oil under a relatively high temperature condition (about 50 to 70 ℃) (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 (usually-40 to 0 ℃) (points c and d in fig. 1), and is returned to the refrigerant compressor 1 again.

The refrigerating machine oil and the working fluid composition for a refrigerator according to the present embodiment can be used together with the above-described refrigerant, and are particularly suitable for use together with a hydrocarbon refrigerant in terms of cold-temperature characteristics and compatibility at the time of mixing the refrigerant.