JP2000096071A - Lubricating oil for refrigerator using dimethyl ether as refrigerant - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When used with dimethyl ether refrigerant,
To provide a lubricating oil having excellent lubricity, refrigerant compatibility, stability and the like. SOLUTION: A lubricating oil for a refrigerator using dimethyl ether as a refrigerant, comprising a hydrocarbon-based oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating oil for a refrigerator, and more particularly to a lubricating oil useful for a refrigerator using dimethyl ether (DME) as a refrigerant.

[0002]

2. Description of the Related Art Due to the recent problem of depletion of the ozone layer, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) which have been conventionally used as refrigerants for refrigeration equipment are subject to regulation.
FC (hydrofluorocarbon) is being used as a refrigerant. However, such HFC refrigerants also have problems such as high global warming ability, and the search for alternative refrigerants in place of these CFC-based refrigerants is being promoted. Among them, harmlessness to the environment, safety, from the viewpoint of availability, dimethyl ether (DME: CH ₃ -O
-CH ₃ ) has attracted attention. With the replacement of refrigerants with DME, development of refrigeration oils for DME refrigerants is underway.

[0003] Performances required for refrigerating machine oil include lubricity, refrigerant compatibility, stability, and the like, and these characteristics greatly vary depending on the type of coexisting refrigerant.
Since DME has a different chemical property from conventional chlorofluorocarbon-based refrigerants, refrigeration oil used in conventional chlorofluorocarbon-based refrigerants cannot be applied as it is, and there is still no DME refrigerant having excellent performance as a refrigeration oil for refrigerants. Not developed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and when used with a DME refrigerant, has excellent lubricity, refrigerant compatibility, and stability. The purpose is to provide oil.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, the present inventors have found that refrigeration using DME excellent in the above-mentioned various performances as a refrigerant by containing a hydrocarbon-based oil is used. It has been found that lubricating oil for machinery can be obtained.

That is, the present invention is a lubricating oil for a refrigerator using dimethyl ether (DME) as a refrigerant, characterized by containing a hydrocarbon-based oil.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.

The hydrocarbon oil used in the lubricating oil of the present invention includes naphthenic and paraffinic mineral oils, olefin polymers, naphthalene compounds, alkylbenzenes, and mixtures of two or more of these.

As the mineral oil, a lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of a paraffin-based crude oil, an intermediate-based crude oil or a naphthenic-based crude oil is subjected to solvent removal,
Paraffinic or naphthenic mineral oil obtained by appropriately combining one or more purification means of solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment Can be mentioned.

[0010] Among these mineral oils, it is preferable to use highly refined mineral oil from the viewpoint of better stability. As the highly refined mineral oil used in the present invention,
The non-aromatic unsaturated component (unsaturation degree) is preferably 10% or less. If the degree of unsaturation is more than 10%, sludge may be generated and capillaries may be clogged. From this point, in the present invention, the above-mentioned degree of unsaturation is more preferably 5% or less, still more preferably 1% or less, and most preferably 0.1% or less. Specific examples of such highly refined mineral oil include, for example, a distillate obtained by distilling a paraffinic-based crude oil, an intermediate-based crude oil or a naphthenic-based crude oil under normal pressure, or a residual oil obtained by atmospheric distillation under reduced pressure. Refined oil obtained by refining an oil according to a conventional method, deep-dewaxed oil obtained by further deep-dewaxing after refining, and hydrogenated oil obtained by hydrogenation treatment can be given. .
The purification method at this time is not particularly limited, and various methods are used.

Usually, (a) hydrogenation treatment, (b) dewaxing treatment (solvent dewaxing or hydrogenation dewaxing), (c) solvent extraction treatment, (d) alkali washing or sulfuric acid washing treatment, (e) clay The processing is performed alone or in combination in an appropriate order. It is also effective to repeat the same process in a plurality of stages. For example, a method of hydrotreating a distillate, or a method of performing alkali washing or sulfuric acid washing after hydrogenation, a method of performing a dewaxing process after hydrotreating a distillate, After the solvent extraction treatment, a method of hydrotreating, a two-stage or three-stage hydrotreating of the distillate, or a method of alkali washing or sulfuric acid washing thereafter, and further, a treatment as described above to Then, there is a method of dewaxing again to obtain deeply dewaxed oil.

Among the above-mentioned methods, the highly refined mineral oil used in the present invention includes naphthenic mineral oil and mineral oil obtained by deep dewaxing, because of its low-temperature fluidity and no wax precipitation at low temperatures. It is suitable. This deep dewaxing is performed by a solvent dewaxing method under severe conditions, a catalytic dewaxing method using a zeolite catalyst, or the like.

[0013] The olefin polymer may have 2 to 1 carbon atoms.
And a product obtained by polymerizing the olefin of No. 2 and a product obtained by hydrogenating the olefin.
Polybutene, polyisobutene, oligomers of polyolefins having 5 to 12 carbon atoms (polyalphaolefin), ethylene-propylene copolymers, and hydrogenated products thereof are preferably used.

The method for producing the olefin polymer is not particularly limited, and it can be produced by various known methods. As an example of this, for example, poly-α-olefin is produced from α-olefin produced from ethylene by a known polymerization method such as Ziegler catalyst method, radical polymerization method, aluminum chloride method, boron fluoride method and the like. .

[0015] The naphthalene compound is not particularly limited as long as it has a naphthalene skeleton.

Embedded image (In the above formula (1), R ¹ , R ² , R ³ and R ⁴ may be the same or different and each represents a hydrogen atom or a carbon atom having 1 to 1 carbon atoms.
10 hydrocarbon groups and R ¹ , R ² , R ³ and R ⁴
Is 1 to 10).

R ¹ , R ² , R ³ and R ^{4 in} the compound of the formula (1) may be the same or different and are each a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms. Is shown. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an aryl group, an alkylaryl group, an aralkyl group and the like.

Preferred examples of the hydrocarbon group represented by R ¹ , R ² , R ³ and R ^{4 in} the compound of the formula (1) include, for example, methyl, ethyl, n-propyl, isopropyl Group, linear or branched butyl group,
1-8 carbon atoms such as a linear or branched pentyl group, a linear or branched hexyl group, a linear or branched heptyl group, a linear or branched octyl group; Alkyl group; ethenyl group (vinyl group), 1-propenyl group, 2
-Propenyl group (allyl group), 1-methylethenyl group (isopropenyl group), linear or branched butenyl group, linear or branched pentenyl group, linear or branched hexenyl group , A linear or branched heptenyl group, a linear or branched octenyl group, etc.
Alkenyl group having 8 to 8 carbon atoms such as phenyl group, tolyl group, xylyl group, ethylphenyl group and vinylphenyl group;
And aralkyl groups having 7 to 8 carbon atoms such as a benzyl group, a 1-phenylethyl group and a 1-phenylethyl group (phenethyl group). Further, among these, an alkyl group having 1 to 8 carbon atoms and an alkenyl group having 2 to 8 carbon atoms are particularly preferable, and among them, branched ones are preferable.

The compound of the formula (1) has a total carbon number of R ¹ , R ² , R ³ and R ⁴ of 1 to 10, preferably 1 to 10.
8 Within this range, R ¹ , R ² , R ³ and R ⁴ may be the same or different. That is, as the compound of the formula (1), R ¹ , R ² , R ³ and R ⁴ may be all hydrocarbon groups, or R ¹ , R ² ,
At least one of R ³ and R ⁴ may be a hydrocarbon group, and the other may be a hydrogen atom. Among these, from the viewpoint of compatibility with the refrigerant, ^{1 to 1} of R ¹ , R ² , R ³ and R ⁴ .
It is preferred that three are hydrocarbon groups and the others are hydrogen atoms, and that the total number of carbon atoms is 3 to 8.

When ^{two of} R ¹ , R ² , R ³ and R ⁴ are hydrocarbon groups, the combination is not particularly limited,
It is also possible that two hydrocarbon groups are bonded to the same condensed ring (benzene ring) such that R ¹ and R ² are hydrocarbon groups, or that R ¹ and R ³ are hydrocarbon groups. In addition, one in which one hydrocarbon group is bonded to each different condensed ring (benzene ring) may be used.

Preferred examples of the naphthalene compound represented by the formula (1) include, for example, (n-propyl) naphthalene, isopropylnaphthalene, (n-
Butyl) naphthalene, isobutylnaphthalene, (sec
-Butyl) naphthalene, (tert-butyl) naphthalene, (sec-pentyl) naphthalene, (1-ethylpropyl) naphthalene, (tert-pentyl) naphthalene, (1-methylpentyl) naphthalene, (1-ethylbutyl) naphthalene, ( 1,1-dimethylbutyl) naphthalene, (1-ethyl-1-methylpropyl) naphthalene, (1-methylhexyl) naphthalene, (1-ethylpentyl) naphthalene, (1-propylbutyl) naphthalene, (1,1- Dimethylpentyl) naphthalene, (1
-Ethyl-1-methylbutyl) naphthalene, (1,1-
(Diethylpropyl) naphthalene, (1-methylheptyl) naphthalene, (1-ethylhexyl) naphthalene,
(1-propylpentyl) naphthalene, (1,1-dimethylhexyl) naphthalene, (1-ethyl-1-methylpentyl) naphthalene, (1-methyl-1-propylbutyl) naphthalene, (1,1-diethylbutyl) Naphthalene, ethylmethylnaphthalene, diethylnaphthalene,
Methyl (n-propyl) naphthalene, methyl isopropyl naphthalene, di (n-propyl) naphthalene, diisopropyl naphthalene, (n-butyl) methyl naphthalene, isobutyl methyl naphthalene, (sec-butyl)
Methylnaphthalene, (tert-butyl) methylnaphthalene, di (n-butyl) naphthalene, diisobutylnaphthalene, di (sec-butyl) naphthalene, di (ter
t-butyl) naphthalene, trimethylnaphthalene, triethylnaphthalene, ethyldimethylnaphthalene, diethylmethylnaphthalene, dimethyl (n-propyl) naphthalene, dimethylisopropylnaphthalene, methyldi (n
-Propyl) naphthalene, methyldiisopropylnaphthalene, (n-butyl) dimethylnaphthalene, isobutyldimethylnaphthalene, (sec-butyl) dimethylnaphthalene, (tert-butyl) dimethylnaphthalene, phenylnaphthalene, tolylnaphthalene, xylylnaphthalene, (ethylphenyl ) Naphthalene, (vinylphenyl) naphthalene, benzylnaphthalene, phenethylnaphthalene, (1-phenylethyl) naphthalene and the like.

The naphthalene compound may be not only a compound having a single structure but also a mixture of compounds having different structures as long as the compound satisfies the general formula (1).

The method for producing the above naphthalene compound is not particularly limited, and it can be produced by various known methods. Examples thereof include halogenated hydrocarbons having 1 to 10 carbon atoms, olefins having 2 to 10 carbon atoms or styrenes having 8 to 10 carbon atoms, such as sulfuric acid, phosphoric acid, silicotungstic acid, and hydrofluoric acid. And acid catalysts such as Friedel-Crafts catalyst which is a metal halide such as aluminum chloride and zinc chloride.

As the alkylbenzene, any one can be used. However, since the possibility of seizure of the refrigerating compressor during long-term operation is small, the component having a molecular weight of 200 to 350 is preferably 60% by mass or more. Is preferably at least 65% by mass, more preferably at least 70% by mass, particularly preferably at least 80% by mass, most preferably 100% by mass.

In addition, from the viewpoint that the anti-seizure property of the refrigerating compressor under long-term operation is particularly excellent, a component having a molecular weight of 200 to 300 as alkylbenzene is preferably 30% by mass or more, more preferably 35% by mass or more. It is particularly desirable that the content be 40% by mass or more.

The molecular weight of the alkylbenzene is from 200 to 35
The structure of the component 0 is not particularly limited as long as its molecular weight is within this range. However, from the viewpoint of long-term reliability of the refrigeration system, the component 0 has 1 to 4 alkyl groups having 1 to 19 carbon atoms, and The alkyl benzene (A) having a total carbon number of the group of 9 to 19 is preferable.
More preferably, it is an alkyl benzene having 1 to 4 alkyl groups of 15 to 15 and having a total carbon number of the alkyl groups of 9 to 15.

Examples of the alkyl group having 1 to 19 carbon atoms include a methyl group, an ethyl group, a propyl group (including all isomers) and a butyl group (including all isomers). , Pentyl group (including all isomers), hexyl group (including all isomers), heptyl group (including all isomers), octyl group (including all isomers), nonyl group (including all isomers) Decyl group (including all isomers), undecyl group (including all isomers), dodecyl group (including all isomers), tridecyl group (including all isomers), Tetradecyl group (including all isomers), pentadecyl group (including all isomers), hexadecyl group (including all isomers), heptadecyl group (including all isomers), octadecyl group (including Including isomers of all), including nonadecyl group (including all isomers) and the like.

The alkyl group may be linear or branched, but is preferably a branched alkyl group from the viewpoint of stability and viscosity characteristics, and particularly from the viewpoint of availability. More preferred are branched alkyl groups derived from oligomers of olefins such as propylene, butene, isobutylene, and the like.

The number of alkyl groups in the alkylbenzene of the above (A) is from 1 to 4, but from the viewpoint of stability and availability, alkylbenzenes having one or two alkyl groups, ie, monoalkylbenzene, dialkylbenzene Alkylbenzene, or a mixture thereof, is most preferably used.

As a matter of course, the alkylbenzene of (A) includes not only alkylbenzene having a single structure but also one to four alkyl groups having 1 to 19 carbon atoms, and the total number of carbon atoms of the alkyl group is As long as it is an alkylbenzene satisfying the condition of 9 to 19, a mixture of alkylbenzenes having different structures may be used.

The alkylbenzene used in the present invention preferably contains less than 40% by mass, preferably less than 35% by mass, more preferably less than 30% by mass of a component having a molecular weight of less than 200 or having a molecular weight of more than 350. However, from the viewpoint of reliability during long-term operation of the compressor, these components are preferably alkylbenzenes having a molecular weight of more than 350 and 450 or less, and alkylbenzenes having a molecular weight of more than 350 and 430 or less. Is more preferable.

The structure of the alkylbenzene having a molecular weight of more than 350 and not more than 450 is not particularly limited as long as the molecular weight is within this range, but from the viewpoint of stability and availability, alkylbenzenes having 1 to 40 carbon atoms are preferred. Alkylbenzene (B) having 1 to 4 groups and a total carbon number of the alkyl group of 20 to 40 is preferable, and further having 1 to 4 alkyl groups of 1 to 30 carbon atoms, Further, it is more preferable that the alkyl group is an alkylbenzene having 20 to 30 carbon atoms in total.

Examples of the alkyl group having 1 to 40 carbon atoms include a methyl group, an ethyl group, a propyl group (including all isomers) and a butyl group (including all isomers). , Pentyl group (including all isomers), hexyl group (including all isomers), heptyl group (including all isomers), octyl group (including all isomers), nonyl group (including all isomers) Decyl group (including all isomers), decyl group (including all isomers), dodecyl group (including all isomers), tridecyl group (including all isomers), decyl group (including all isomers), Tetradecyl group (including all isomers), pentadecyl group (including all isomers), hexadecyl group (including all isomers), heptadecyl group (including all isomers), octadecyl group (including All isomers), nonadecyl group (including all isomers), icosyl group (including all isomers), henicosyl group (including all isomers), docosyl group (including all isomers) ), Tricosyl group (including all isomers), tetracosyl group (including all isomers), pentacosyl group (including all isomers), hexacosyl group (including all isomers), heptacosyl group (including all isomers) Octakosyl group (including all isomers), nonacosyl group (including all isomers), triacontyl group (including all isomers), hentriacontyl group (including all isomers) ), Dotriacontyl group (including all isomers), tritriacontyl group (including all isomers), tetratriacontyl group (including all isomers) Pentatriacontyl group (including all isomers), hexatriacontyl group (including all isomers), heptatriacontyl group (including all isomers), octatriacontyl group (Including all isomers), a nonatriacontyl group (including all isomers), and a tetracontyl group (including all isomers).

The alkyl group may be linear or branched, but is preferably a branched alkyl group from the viewpoint of stability and viscosity characteristics, and particularly from the viewpoint of availability. More preferred are branched alkyl groups derived from oligomers of olefins such as propylene, butene, isobutylene, and the like.

The number of alkyl groups in the alkylbenzene of the above (B) is from 1 to 4, but from the viewpoint of stability and availability, alkylbenzenes having one or two alkyl groups, ie, monoalkylbenzene, dialkylbenzene Alkylbenzene, or a mixture thereof, is most preferably used.

As a matter of course, the alkylbenzene of (B) includes not only an alkylbenzene having a single structure but also one to four alkyl groups having 1 to 40 carbon atoms, and the total number of carbon atoms of the alkyl groups is As long as the alkylbenzene satisfies the condition of 20 to 40, a mixture of alkylbenzenes having different structures may be used.

The method for producing the above-mentioned alkylbenzene is arbitrary, and is not limited at all. In general, it can be produced by the following synthesis method.

As the aromatic compound as a raw material, specifically, for example, benzene, toluene, xylene, ethylbenzene, methylethylbenzene, diethylbenzene, and a mixture thereof are used. Specific examples of the alkylating agent include linear or branched olefins having 6 to 40 carbon atoms obtained by polymerization of lower monoolefins (preferably propylene) such as ethylene, propylene, butene, and isobutylene. A linear or branched olefin having 6 to 40 carbon atoms obtained by pyrolysis of wax, heavy oil, petroleum fraction, polyethylene, polypropylene, etc .; separation of n-paraffin from petroleum fraction such as kerosene, gas oil And a linear olefin having 9 to 40 carbon atoms obtained by olefination with a catalyst; and mixtures thereof.

Examples of the alkylation catalyst for the alkylation include Friedel-Crafts type catalysts such as aluminum chloride and zinc chloride; acidic catalysts such as sulfuric acid, phosphoric acid, silicotungstic acid, hydrofluoric acid and activated clay. A known catalyst is used.

The above-mentioned alkylbenzene is, for example, separately prepared from a component having a molecular weight of 200 to 350 and a component having a molecular weight of 200.
It is also possible to obtain a mixture of components having a molecular weight of less than 350 or a molecular weight exceeding 350 at a ratio within the range specified in the present invention. However, an alkylbenzene mixture obtained by the method exemplified above or a commercially available alkylbenzene mixture is distilled. Separation by chromatography or chromatography with a molecular weight of 2
It is practically convenient to obtain a fraction containing 60% by mass or more of the components of 00 to 350.

The content of the hydrocarbon-based oil in the lubricating oil of the present invention is not particularly limited.
From the viewpoint of superiority in various performances such as chemical stability and electric insulation, the hydrocarbon oil is preferably contained in an amount of 50% by mass or more, more preferably 70% by mass or more, and more preferably 80% by mass, based on the total amount of the lubricating oil. More preferably, the content is more preferably 90% by mass or more.

The lubricating oil of the present invention contains the above-mentioned hydrocarbon-based oil. In addition to this, esters, polyglycols, polyvinyl ethers, ketones, polyphenyl ethers, silicones, polysiloxanes, perfluoro A synthetic oil containing oxygen such as ether may be used in combination. As the synthetic oil containing oxygen, among the above, esters, polyglycols, polyvinyl ethers,
Ketones are preferably used.

The lubricating oil of the present invention contains a hydrocarbon-based oil and, if necessary, a synthetic oil containing oxygen, and is mainly used as a base oil. The lubricating oil of the present invention can be suitably used in a state where no additives are added, but can be used in a form in which various additives are blended as required.

In order to further improve the wear resistance and load bearing capacity of the lubricating oil of the present invention, phosphate esters, acidic phosphate esters, amine salts of acidic phosphate esters, chlorinated phosphate esters and phosphite esters At least one phosphorus compound selected from the group consisting of:
These phosphorus compounds are esters of phosphoric acid or phosphorous acid with alkanols or polyether-type alcohols or derivatives thereof.

Specifically, for example, phosphate esters include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, and tridodecyl phosphate. , Tritridecyl phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl Phosphate, xylendiphenyl phosphate and the like. Examples of the acidic phosphate include monobutyl acid phosphate, monopentyl acid phosphate, monohexyl acid phosphate, monoheptyl acid phosphate, monooctyl acid phosphate,
Monononyl acid phosphate, monodecyl acid phosphate, monoundecyl acid phosphate,
Monododecyl acid phosphate, monotridecyl acid phosphate, monotetradecyl acid phosphate, monopentadecyl acid phosphate, monohexadecyl acid phosphate, monoheptadecyl acid phosphate, monooctadecyl acid phosphate, monooleyl acid phosphate, dibutyl acid diphosphate Acid phosphate, dihexyl acid phosphate, diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecyl acid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl acid
Examples thereof include dipentadecyl acid phosphate, dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, and dioleyl acid phosphate. Examples of the amine salt of the acidic phosphoric acid ester include the acidic phosphoric acid ester methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, Dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine,
Examples thereof include salts with amines such as tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, and trioctylamine. As chlorinated phosphates, tris-dichloropropyl phosphate, tris-chloroethyl phosphate,
Tris chlorophenyl phosphate, polyoxyalkylene bis [di (chloroalkyl)] phosphate and the like can be mentioned. As the phosphite, dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, dioleyl Phosphite, diphenyl phosphite, dicresyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl phosphite Phyto, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, tricresyl phosphite and the like. Also, a mixture of these can be used.

When these phosphorus compounds are blended with the lubricating oil of the present invention, the blending amount is not particularly limited, but usually,
An amount such that its content is 0.01 to 5.0% by mass, more preferably 0.02 to 3.0% by mass, based on the total amount of the lubricating oil (based on the total amount of the base oil and all the blending additives). It is desirable to add a phosphorus compound.

In the lubricating oil of the present invention, in order to further improve the stability, (1) phenylglycidyl ether type epoxy compound (2) alkyl glycidyl ether type epoxy compound (3) glycidyl ester type epoxy compound (4 ) Allyl oxirane compound (5) alkyl oxirane compound (6) alicyclic epoxy compound (7) epoxidized fatty acid monoester (8) epoxidized vegetable oil At least one epoxy compound selected from the group consisting of .

(1) Specific examples of the phenylglycidyl ether type epoxy compound include phenylglycidyl ether and alkylphenylglycidyl ether. The alkylphenyl glycidyl ether referred to herein includes those having 1 to 3 alkyl groups having 1 to 13 carbon atoms, among which those having one alkyl group having 4 to 10 carbon atoms, for example, n-butylphenyl glycidyl Ether, i-butylphenyl glycidyl ether,
sec-butylphenyl glycidyl ether, tert
-Butylphenyl glycidyl ether, pentyl phenyl glycidyl ether, hexyl phenyl glycidyl ether, heptyl phenyl glycidyl ether, octyl phenyl glycidyl ether, nonyl phenyl glycidyl ether, decyl phenyl glycidyl ether and the like can be exemplified as preferable ones.

(2) Specific examples of the alkyl glycidyl ether type epoxy compound include decyl glycidyl ether, undecyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, 2-ethylhexyl glycidyl ether, neoethyl Pentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether,
Examples thereof include 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl ether, polyalkylene glycol monoglycidyl ether, and polyalkylene glycol diglycidyl ether.

(3) As the glycidyl ester type epoxy compound, specifically, phenyl glycidyl ester,
Examples thereof include an alkyl glycidyl ester and an alkenyl glycidyl ester, and preferred examples include glycidyl-2,2-dimethyloctanoate, glycidyl benzoate, glycidyl acrylate, and glycidyl methacrylate.

(4) As the allyloxirane compound, specifically, 1,2-epoxystyrene, alkyl-1,
Examples thereof include 2-epoxystyrene.

(5) As the alkyloxirane compound,
Specifically, 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxynonane, 1,2 -Epoxydecane, 1,2-epoxyundecane, 1,2-epoxidedodecane, 1,2-
Epoxy tridecane, 1,2-epoxytetradecane,
1,2-epoxypentadecane, 1,2-epoxyhexadecane, 1,2-epoxyheptadecane, 1,1,2
-Epoxy octadecane, 2-epoxynonadecane,
Examples thereof include 1,2-epoxyicosane.

(6) Specific examples of the alicyclic epoxy compound include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate. , Bis (3,4-epoxycyclohexylmethyl) adipate, exo-2,3-epoxynorbornane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (7-oxabicyclo [4.1. 0] Hept-3-yl) -spiro (1,3-
Dioxane-5,3 '-[7] oxabicyclo [4.
1.0] heptane, 4- (1′-methylepoxyethyl) -1,2-epoxy-2-methylcyclohexane,
4-epoxyethyl-1,2-epoxycyclohexane and the like can be exemplified.

(7) Specific examples of the epoxidized fatty acid monoester include epoxidized fatty acids having 12 to 20 carbon atoms and alcohols or phenols having 1 to 8 carbon atoms,
Examples thereof include esters with alkylphenol. Particularly, butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and butylphenyl esters of epoxystearic acid are preferably used.

(8) Specific examples of the epoxidized vegetable oil include epoxy compounds of vegetable oils such as soybean oil, linseed oil, and cottonseed oil.

Among these epoxy compounds, preferred are phenylglycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, alicyclic epoxy compounds and epoxidized fatty acid monoesters. Among them, a phenyl glycidyl ether type epoxy compound and a glycidyl ester type epoxy compound are more preferable, and phenyl glycidyl ether, butyl phenyl glycidyl ether, alkyl glycidyl ester and a mixture thereof are particularly preferable.

When these epoxy compounds are blended with the lubricating oil of the present invention, the amount of the compound is not particularly limited, but is usually based on the total amount of the lubricating oil (based on the total amount of the base oil and all of the additives). Of the epoxy compound is desirably 0.1 to 5.0% by mass, more preferably 0.2 to 2.0% by mass.

Of course, two or more of the above phosphorus compounds and epoxy compounds may be used in combination.

In order to further enhance the performance of the lubricating oil of the present invention, if necessary, a conventionally known refrigerating machine oil additive, for example, di-tert-butyl-p-
Phenolic antioxidants such as cresol and bisphenol A; amine antioxidants such as phenyl-α-naphthylamine and N, N-di (2-naphthyl) -p-phenylenediamine; and wear prevention such as zinc dithiophosphate. Agent,
Chlorinated paraffins, extreme pressure agents such as sulfur compounds, oil agents such as fatty acids, silicone-based defoamers, metal deactivators such as benzotriazole, viscosity index improvers, pour point depressants,
Additives such as detergents and dispersants may be used alone or in combination of several types. The total amount of these additives is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less based on the total amount of the lubricating oil (based on the total amount of the base oil and all the additives).

The kinematic viscosity of the lubricating oil of the present invention is not particularly limited, but the kinematic viscosity at 40 ° C. is preferably 3 to 100 m.
m ² / s, more preferably 4~50mm ² / s, and most preferably, to 5 to 40 mm ² / s. Also,
The kinematic viscosity at 100 ° C. is preferably 1 to ²⁰ mm ² /
s, more preferably ² to 10 mm ² / s.

The volume resistivity of the lubricating oil of the present invention is not particularly limited, but is preferably 1.0 × 10 ¹² Ω · cm or more, more preferably 1.0 × 10 ¹³ Ω · cm or more, and most preferably. It can be 1.0 × 10 ¹⁴ Ω · cm or more. In particular, when used for hermetic refrigerators, high electrical insulation tends to be required. In the present invention, the volume resistivity represents a value at 25 ° C. measured according to JIS C 2101 “Testing method for electric insulating oil”.

The water content of the lubricating oil of the present invention is not particularly limited, but can be preferably 200 ppm or less, more preferably 100 ppm or less, most preferably 50 ppm or less based on the total amount of the lubricating oil. In particular, when used for hermetic refrigerators, the water content is required to be low from the viewpoint of the effect on oil stability and electrical insulation.

Although the total acid value of the lubricating oil of the present invention is not particularly limited, it is preferably 0.1 mg KOH /% in order to prevent corrosion of metals used in refrigerators or pipes.
g, more preferably 0.05 mgKOH / g or less. In addition, in this invention, the total acid value represents the value of the total acid value measured based on JISK2501 "Petroleum products and lubricating oils-neutralization number test method".

The ash content of the lubricating oil of the present invention is not particularly limited. However, in order to enhance the stability of the lubricating oil of the present invention and suppress the generation of sludge, the content is preferably 100 ppm or less, more preferably 50 ppm or less. Can be. In the present invention, ash is defined by JIS K2272.
Shows the value of ash measured according to "Test method for ash content and sulfated ash content of crude oil and petroleum products".

The refrigerant used in the refrigerator using the lubricating oil of the present invention is dimethyl ether (DME).
Or a mixture with other refrigerants. Other refrigerants include hydrofluorocarbons, hydrocarbons, carbon dioxide, ammonia and the like.

As the hydrofluorocarbon refrigerant,
Hydrofluorocarbons having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms, are mentioned. Specifically, for example, difluoromethane (HFC-32), trifluoromethane (HFC-32)
23), pentafluoroethane (HFC-125),
1,1,2,2-tetrafluoroethane (HFC-13
4), 1,1,1,2-tetrafluoroethane (HFC
-134a), 1,1,1-trifluoroethane (HF
C-143a), 1,1-difluoroethane (HFC-
152a) or a mixture of two or more thereof. These refrigerants are appropriately selected depending on the application and required performance, for example, HFC-32 alone;
HFC-23 alone; HFC-134a alone; HFC-1
25 alone; HFC-134a / HFC-32 = 60 to 8
0% by mass / 40 to 20% by mass of a mixture; HFC-32 /
HFC-125 = 40 to 70% by mass / 60 to 30% by mass
HFC-125 / HFC-143a = 40 to
60% by mass / 60 to 40% by mass of a mixture; HFC-13
4a / HFC-32 / HFC-125 = 60% by mass / 3
0% by mass / 10% by mass mixture; HFC-134a / H
FC-32 / HFC-125 = 40 to 70% by mass / 15
-35% by weight / 5-40% by weight mixture; HFC-12
5 / HFC-134a / HFC-143a = 35-55
A preferable example is a mixture of mass% / 1 to 15 mass% / 40 to 60 mass%. More specifically,
HFC-134a / HFC-32 = 70/30% by weight mixture; HFC-32 / HFC-125 = 60/40% by weight mixture; HFC-32 / HFC-125 = 50 /
50% by weight mixture (R410A); HFC-32 / H
FC-125 = 45/55% by weight mixture (R410
B); HFC-125 / HFC-143a = 50/50
% By weight mixture (R507C); HFC-32 / HFC
-125 / HFC-134a = 30/10/60% by mass
HFC-32 / HFC-125 / HFC-1
34a = 23/25/52% by mass of a mixture (R407
C); HFC-32 / HFC-125 / HFC-134
a = 25/15/60% by weight mixture (R407E);
HFC-125 / HFC-134a / HFC-143a
= 44/4/52% by mass (R404A).

As the hydrocarbon refrigerant, 25 ° C., 1
A gas at atmospheric pressure is preferably used. Specifically, it is an alkane, cycloalkane, alkene or a mixture thereof having 1 to 5, preferably 1 to 4 carbon atoms. Specific examples include methane, ethylene, ethane, propylene, propane, cyclopropane, butane, isobutane, cyclobutane, methylcyclopropane, and a mixture of two or more of these. Among these, propane, butane, isobutane or a mixture thereof is preferred.

The mixing ratio of DME to hydrofluorocarbon and / or hydrocarbon is not particularly limited, but is preferably 1 to 200 parts by weight, more preferably 1 to 200 parts by weight, as the total amount of hydrofluorocarbon and hydrocarbon per 100 parts by weight of DME. 10 to 100 parts by weight are used.

The lubricating oil of the present invention is usually present in the refrigerator in the form of a fluid composition for a refrigerator as described above alone or mixed with DME and other refrigerants. The mixing ratio of the lubricating oil and the refrigerant in this composition is not particularly limited, but the lubricating oil is preferably 1 to 500 parts by weight, more preferably 2 to 100 parts by weight of the refrigerant.
400 parts by weight.

The lubricating oil of the present invention is preferably used for an air conditioner or a refrigerator having a reciprocating or rotary hermetic compressor. The lubricating oil of the present invention is preferably used for air conditioners for automobiles, dehumidifiers, freezers, freezing and refrigerated warehouses, vending machines, showcases, cooling devices for chemical plants, and the like. Further, the lubricating oil of the present invention is preferably used for those having a centrifugal compressor.

[0070]

EXAMPLES Hereinafter, the content of the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 14 The base oils and additives shown below were blended as shown in Tables 1 to 3 to prepare sample oils of Examples 1 to 14, respectively. The properties (kinematic viscosities at 40 ° C. and 100 ° C., total acid value) of the obtained sample oils are shown in Tables 1 to 3.

[0072] Base Oil 1: paraffinic highly refined mineral oil (pour point: -50 ° C., aniline _{point: 110 ℃,% C A:} 0.
0,% C _N : 36.5,% C _P : 63.5), Base oil 2: Highly refined paraffinic mineral oil (pour point: -40)
° C, aniline point: 115 ° C,% C _A : 0.0,% C _N : 3
_{7.0,% C P: 63.0)} , the base oil 3: naphthenic mineral oil (pour point: -42.5 ° C., aniline _{point: 80 ℃,% C A:} 10.0,% C N: 43. 0,
% C _P: 47.0), the base oil 4: Naphthenic mineral oil (pour point: -40 ° C., aniline _{point: 85 ℃,% C A:} 12.0,% C N: 44.0,% C
_P : 44.0) Base oil 5: Poly-α-olefin (1-decene oligomer, number average molecular weight: 370) Base oil 6: Poly-α-olefin (1-decene oligomer, number average molecular weight: 510), Base oil 7: alkyl naphthalene (number average molecular weight: 20)
0), Base oil 8: alkyl naphthalene (number average molecular weight: 36)
0), base oil 9: alkylbenzene (number average molecular weight: 210), base oil 10: alkylbenzene (number average molecular weight: 270), additive 1: phenyl glycidyl ether, additive 2: tricresyl phosphate.

Next, the following tests were performed on the above sample oils.

(Compatibility test with refrigerant) JIS-K-22
11 According to the “refrigerant oil” “Test method for compatibility with refrigerant”, 27 g of each sample oil is blended with 3 g of DME refrigerant, and whether the refrigerant and the sample oil are mutually dissolved at 0 ° C. It was observed whether it had separated or clouded. Tables 1 to 3 show the obtained results.

(Insulation Characteristics Test) JIS-C-2101
The volume resistivity of each sample oil at 25 ° C. was measured according to “Electrical Insulating Oil Test Method”. Table 1 shows the obtained results.
3 is shown.

(Thermal Stability Test) In an autoclave, 90 g of each sample oil, 10 g of DME refrigerant and a catalyst (each wire of iron, copper and aluminum) were sealed, and then heated to 175 ° C. Appearance, appearance of catalyst, volume resistivity of sample oil,
The total acid number of the sample oil was measured. Tables 1 to 3 show the obtained results.

(Lubricity test) ASTM D 2670
In accordance with the “FALEX WEAR TEST”, the running-in operation was performed at 150 lb under the condition of the temperature of the sample oil of 100 ° C.
After one minute under load, the tester was operated under 250 lb load for 2 hours. The wear amount of the test journal (pin) after the test was measured for each sample oil. Tables 1 to 3 show the obtained results.

(Hydrolysis Stability Test) 90 g of sample oil, 0.1 g of water and 10 g of DME refrigerant were placed in a 300 ml glass test tube, and each of copper, iron and aluminum wires was put as a catalyst for promoting deterioration, and the mixture was put in a stainless steel autoclave.
Degradation by heating at 75 ° C. for 168 hours. The total acid value of each sample oil after the test was measured. The obtained results are shown in Tables 1 to 3 together with the total acid value before the test.

[0079]

[Table 1]

[0080]

[Table 2]

[0081]

[Table 3] As is evident from the results shown in Tables 1 to 3, the sample oils of Examples 1 to 14, which are the lubricating oils for refrigerators of the present invention, have lubricating properties, refrigerant compatibility, and heat when used with dimethyl ether refrigerant. All the performances of stability, electrical insulation, hydrolysis resistance and kinematic viscosity were excellent in a well-balanced manner.

[0082]

As described above, according to the lubricating oil for refrigerators of the present invention, when used with a dimethyl ether refrigerant, the lubricating oil, the compatibility with the refrigerant, and the required performance such as the stability are high. Performance can be achieved.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoshi Suda 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Japan Nippon Oil & Oil Co., Ltd. Central Research Laboratory F-term (reference) 4H104 BA02A BA03A BA06A CA01A DA02A LA04 PA20

Claims (1)

[Claims] 1. A lubricating oil for a refrigerator using dimethyl ether as a refrigerant, comprising a hydrocarbon-based oil.