JPH0797589A - Refrigerator oil composition - Google Patents

Abstract

PURPOSE:To obtain a refrigerator oil composition having excellent lubricity and insulation properties by adding a phosphoric ester to an ester oil for refrigerator oil and specifying the concentrations of sodium and/or potassium. CONSTITUTION:(A) An ester oil as a refrigerator oil (polyol esters, polycarboxylic esters, fumarate oligomers, carbonic esters, hydroxypivalic esters) is combined with (B) a phosphoric ester (benzyl diphenyl phosphate) in an amount of 0.01 to 5wt.%, preferably 0.1 to 3wt.% based on the component (A), and the concentration of sodium and/or potassium is set to less than 0.1ppm. It is suitably used in refrigerators employing a nonchlorine and fluorine- containing refrigerant such as 1, 1, 1, 2-tetrafluoro-ethane (R134a).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a refrigerating machine oil composition having excellent lubricity and insulation.

[0002]

_2. Description of the Related Art Refrigerators are conventionally used as refrigerants such as R11 (CCl ₃ F), R12 (CCl ₂ F ₂ ) and R123 (CF ₃ C).
Although chlorine-containing refrigerants such as HCl ₂ ) and R22 (CHClF ₂ ) are used, the development of alternative CFCs has become urgent due to environmental issues.
Recently, a chlorine-free fluorine-containing refrigerant such as 1.1.1.2-tetrafluoroethane (R134a) has begun to attract attention, and it has been proposed to use an ester oil compatible with R134a etc. as a refrigerating machine oil.

On the other hand, with the recent increase in efficiency of refrigerators,
Refrigerating machine oils are required to have thermal stability, and ester oils having excellent thermal stability are also used in this respect. However, ester oil has a problem that it is susceptible to hydrolysis when water is present in the system. Further, in a refrigerator refrigerator having a hermetic compressor, since the motor is in the refrigerating machine oil, the refrigerating machine oil is 1 × 10 ¹³ Ωcm (25 ° C.) or more,
A volume resistivity of preferably 5 × 10 ¹³ Ωcm (25 ° C.) or higher, more preferably 1 × 10 ¹⁴ Ωcm (25 ° C.) or higher is required. However, most of commercially available ester oils do not meet this requirement, and ester oils having high insulating properties are required.

[0004]

The present invention is based on R134a.
An object of the present invention is to provide a refrigerating machine oil composition that uses a non-chlorine fluorine-containing refrigerant such as, and is particularly excellent in lubricity and insulation.

[0005]

A refrigerating machine oil composition of the present invention is a refrigerating machine oil composition containing ester oil as a refrigerating machine oil and a phosphoric acid ester compound added thereto.
Alternatively, the potassium concentration is 0.1 ppm or less.

Examples of the ester oil which is a refrigerating machine oil include ester oils of polyol esters, polycarboxylic acid esters, fumaric acid ester oligomers, carbonic acid esters, hydroxybivalic acid esters and combinations thereof. First, the polyol esters will be exemplified. (1) Polyol esters of an aliphatic polyhydric alcohol and a linear or branched fatty acid.

Examples of the aliphatic polyhydric alcohol forming the polyesters include trimethylolpropane, ditrimethylolpropane, trimethylolethane, ditrimethylolethane, pentaerythritol, dipentaerythritol, tripentaerythritol, and the like fatty acid. Can have 3 to 12 carbon atoms, preferred fatty acids are propionic acid, butyric acid, valeric acid,
Hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, isovaleric acid, neopentanoic acid, 2-methylbutyric acid,
2-ethylbutyric acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2'-dimethyloctanoic acid, 2-butyloctanoic acid, 3,5,5-trimethylhexanoic acid Etc.

Further, partial esters of an aliphatic polyhydric alcohol and a linear or branched fatty acid can also be used. As this aliphatic polyhydric alcohol, trimethylolpropane,
Ditrimethylolpropane, trimethylolethane, ditrimethylolethane, pentaerythritol, dipentaerythritol, tripentaerythritol and the like can be used. Fatty acids having 3 to 9 carbon atoms, such as propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, 2-methylhexanoic acid,
2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2'-dimethyloctanoic acid, 2
-Butyloctanoic acid, 3,5,5-trimethylhexanoic acid and the like.

The esters of these aliphatic polyhydric alcohols with linear or branched fatty acids are particularly preferably pentaerythritol, dipentaerythritol, tripentaerythritol with 5 to 12 carbon atoms, and more preferably with 5 carbon atoms. 5 to 9 fatty acids such as valeric acid, hexanoic acid, heptanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2'-dimethyloctanoic acid, 2-butyloctane Examples thereof include esters composed of acid, 3,5,5-trimethylhexanoic acid, or a mixture thereof. These partial esters can be obtained by appropriately adjusting the number of reaction moles of the aliphatic polyhydric alcohol and the fatty acid to react.

(2) Neopentyl glycol as an aliphatic polyhydric alcohol and a linear or branched fatty acid having 6 to 9 carbon atoms such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, 2-ethylbutyric acid, It is also possible to use diesters with 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, 3,5,5-trimethylhexanoic acid and the like.

(3) Aliphatic polyhydric alcohol and carbon number 3 to
A partial ester of a linear or branched fatty acid of 9,
It is also possible to use complex esters with linear or branched aliphatic dibasic acids or aromatic dibasic acids. As such an aliphatic polyhydric alcohol, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol and the like can be used. Examples of the fatty acid having 3 to 12 carbon atoms include propionic acid, butyric acid, isobutyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, 2
-Methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2'-dimethyloctanoic acid, 2-butyloctanoic acid, 3,5,5-
Trimethylhexanoic acid or the like can be used.

In this complex ester, it is preferable to use a fatty acid having 5 to 7 carbon atoms, more preferably 5 to 6 carbon atoms. As such a fatty acid, valeric acid, hexanoic acid, isovaleric acid, 2-methylbutyric acid, 2-ethylbutyric acid or a mixture thereof is used,
Weight ratio of carbon number 5 and carbon number 6 is 10:90
Fatty acids mixed in a ratio of ˜90: 10 can be preferably used.

The aliphatic dibasic acids used for esterification with polyhydric alcohols together with this fatty acid include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecane. Diacid,
It is advisable to use tridecanedioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid, docosanedioic acid, etc. Also, as aromatic dibasic acid, phthalic acid, isophthalic acid, and aromatic tribasic acid, trimellitic acid, aromatic Examples of the tetrabasic acid include pyromellitic acid.

In the esterification reaction, first, a polyhydric alcohol is reacted with an aliphatic dibasic acid or an aromatic dibasic acid at a predetermined ratio to partially esterify it, and then the partially esterified product is reacted with a fatty acid. Alternatively, the reaction order of the acids may be reversed, or the acids may be mixed and subjected to esterification.

(4) Further, linear or branched dialkyl esters of aliphatic dibasic acids (having 16 to 22 carbon atoms) may be used. As the aliphatic dibasic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid,
Examples thereof include tridecanedioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid, docosanedioic acid, and those having properties equivalent to these. Preferred aliphatic dibasic acids are succinic acid, adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid and the like.

The alcohol component is an alcohol having 5 to 8 carbon atoms, specifically amyl alcohol, hexyl alcohol, heptyl alcohol and octyl alcohol, and isomers thereof, preferably isoamyl alcohol and isohexyl alcohol. And octyl alcohol. Specific examples include dioctyl adipate, di-isoheptyl adipate, dihexyl sebacate, and diheptyl succinate.

(5) Dialkyl esters of aromatic dibasic acids (having 18 to 26 carbon atoms) can also be used. Aromatic dibasic acids include phthalic acid, isophthalic acid,
Examples of the alcohol component in the dialkyl ester include alcohols having 5 to 8 carbon atoms such as amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, and isomers thereof. Preferred alcohols include isoamyl alcohol, isoheptyl alcohol and octyl alcohol. Aromatic diesters include dioctyl phthalate, diisoheptyl phthalate, diisoamino phthalate and the like.

(6) As alcohol components, monohydric alcohols selected from methanol, ethanol, propanol, butanol, etc. and their isomers, trihydric alcohols such as glycerin, trimethylolpropane and ethylene oxide, propylene oxide, etc. 1 mol to 1 of alkylene oxide selected from butylene oxide, amylene oxide, etc., and isomers thereof.
0 mol, preferably 1 to 6 mol of adduct is used.

As the organic carboxylic acid ester, an alkylene oxide adduct of a monohydric alcohol is adipic acid,
Pimelic acid, suberic acid, azelaic acid, sebacic acid,
There are diesters obtained by esterification with an aliphatic dibasic acid such as undecanedioic acid, dodecanedioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid and docosanedioic acid, or an aromatic dibasic acid such as phthalic acid.

Further, 1 to 10 of alkylene oxides of polyhydric alcohols such as glycerin and trimethylolpropane are used.
The molar adduct is a linear or branched fatty acid having 3 to 12 carbon atoms, for example, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, 2-methyl. Hexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid,
Esters obtained by esterification with 2,2′-dimethyloctanoic acid, 2-butyloctanoic acid or the like can be used.

As the fatty acid constituting the organic carboxylic acid ester, a linear or branched fatty acid can be used, but the branched fatty acid is more excellent in hydrolysis stability. The organic carboxylic acid ester may be used alone, but in order to adjust the viscosity range according to various uses described later, the organic carboxylic acid ester may be appropriately used in combination.

For example, in the case of the complex type organic carboxylic acid ester of the above (3) having a high viscosity, an ester oil of an aliphatic polyhydric alcohol and a fatty acid having 3 to 9 carbon atoms at 100 ° C. It is possible to adjust the viscosity range according to the application by adding one having a viscosity of 6 mm ² / s or less. When the viscosity is low, it is advisable to add polymers to the organic carboxylic acid ester oil to adjust the viscosity. The polymer preferably has a viscosity at 100 ° C. of 10 mm ² / s or more.

Examples of such a polymer include polyalkylmethacrylates (for example, an alkyl group having 1 to 8 carbon atoms).
), Polyalkylene glycol (for example, polypropylene glycol, a copolymer composed of a polyethylene glycol component and a polypropylene glycol component, a copolymer composed of a polypropylene glycol component and a polytetramethylene glycol component), neopentyl glycol and a fat. Group II dibasic acid polyesters represented by the following formula

[0024]

[Chemical 1]

And the like. The addition amount of the polymer is not particularly limited as long as an ester oil having a desired viscosity can be obtained, but is usually 1% by weight to 99% by weight.
Can be in the range of.

As the polyvalent carboxylic acid ester, polyvalent carboxylic acid is an aliphatic or fatty acid such as 1,2,3,4-butanetetracarboxylic acid, cyclohexanecarboxylic acid or 1,4-cyclohexanecarboxylic acid. Cyclic polycarboxylic acid or aromatic polycarboxylic acid such as trimellitic acid or pyromellitic acid, and the alcohol has 3 to 1 carbon atoms.
2 monohydric alcohols having a linear or branched alkyl group, or a general formula H- (AO) _n -R (wherein A is an alkylene group having 2 to 8 carbon atoms, and R is 1 to 10 carbon atoms). Alkyl group, n is an integer of 1 to 10) is a polyalkylene glycol monool, and polyvalent carboxylic acid esters obtained by esterifying these polyhydric alcohols with alcohol, or the above polyhydric alcohols. Examples thereof include complex esters obtained by adding a polyhydric alcohol such as ethylene glycol and propylene glycol to a carboxylic acid and an alcohol to cause an esterification reaction.

Next, the fumaric acid ester oligomer will be described. The fumarate ester oligomer is a homopolymer of a fumarate ester or a copolymer of a fumarate ester and an unsaturated aliphatic hydrocarbon, and is represented by the following formula. Both terminals in the following formula are the polymerization initiator residues used in the polymerization reaction, and the description thereof is omitted in the formula.

[0028]

[Chemical 2]

(In the formula, R ₁ and R ₂ are a linear or branched alkyl group having 1 to 9 carbon atoms, an allyl group or a terminal-substituted or unsubstituted polyalkylene oxide group, which may be the same or different. Well, R ₃ is an alkylene group, a substituted alkylene group or an alkylene oxide group, m is 0 or more, n is 1 or more, preferably an integer of 1 to 12, and R ₃ is 50 mol% or less of the whole. Specific examples thereof include an ester oligomer of diethyl fumarate and an ester oligomer of dibutyl fumarate.

The following structural formula

[0031]

[Chemical 3]

1 to 50 mol% of the structural unit represented by the following general formula

[0033]

[Chemical 4]

(In the formula, each R is independently a linear or branched alkyl group having 3 to 8 carbon atoms)
The fumaric acid alkyl ester copolymer containing 50 to 99 mol% of the structural unit represented by

Next, as the carbonic acid ester, a compound represented by the general formula

[0036]

[Chemical 5]

(In the formula, R ₁ is a linear or branched alkyl group having 2 to 10 carbon atoms, and R ₂ is 2 to 1 carbon atoms.
An alkylene group having 0 or a cycloalkylene group, n is an integer of 1 to 4), or a carbonic acid ester represented by the general formula

[0038]

[Chemical 6]

(In the formula, R ₁ is a polyhydric alcohol residue having 2 to 6 hydroxyl groups, R ₂ is a linear or branched alkyl group having 2 to 10 carbon atoms, and n is 2 to 6 Carbonates represented by (which is an integer) can be used. The above carbonic acid esters are produced by transesterification of dimethyl carbonate and alcohols in the presence of a basic catalyst.

In addition, the general formula

[0041]

[Chemical 7]

(In the formula, R ₁ is a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₂ is 2-1 to 2 carbon atoms.
A linear or branched alkyl group having 0, m is 2 to 1
0 is an integer, n is an integer of 2 to 100, and -AO- is-.
CH ₂ —CH (CH ₃ ) —O— is preferable, and —CH
₂ -CH ₂ -O- any good. ) Carbonate esters represented by) can be used. The carbonic acid ester is obtained, for example, by reacting carbonic acid with alkylene oxide, and the amount of alkylene oxide added is 2
Those of about 3 mol are suitable. The addition form of alkylene oxide may be ethylene oxide alone or propylene oxide alone, or may be a mixture.

Next, the hydroxybivalic acid esters are represented by the general formula

[0044]

[Chemical 8]

(Wherein R and R'are linear or branched alkyl groups having 2 to 10 carbon atoms, and n is an integer of 1 to 5).

Such polyol polyesters are
Generally, it is obtained by subjecting alcohols and fatty acids to an esterification reaction in the presence of an acid catalyst such as phosphoric acid. According to this preparation method, the total acid value is 0.1 to 0.5 mg KOH / g, the ash content (sodium content, (Potassium, iron, titanium, silicon, etc.)
Of 5 to 50 ppm and water of 300 to 1000 ppm are obtained. Generally, the insulating property of lubricating oil is considered to change depending on the acid value and impurities in the oil, but in ester oil, the effect on the insulating property is surprisingly small even if the acid value is high. Not all ash in the interior correlates with insulation.

That is, regarding the factor substances that reduce the volume resistivity of the ester oil, the present inventors have paid particular attention to the sodium and potassium contents, and as a result of analyzing a trace amount of several orders from the normal analysis level, in the raw material or in the synthetic material. Of the ash that is considered to be mixed in by the catalyst used in the process, and further by the neutralizing agent used in the refining process, iron, titanium, silicon, etc. do not affect its insulating properties, but base oil It was found that when the total concentration of sodium and potassium in the ester oil is high, the total concentration of sodium and potassium in the refrigerating machine oil composition exceeds 0.1 ppm, and the insulation property is extremely lowered. .

Therefore, when purifying the polyol ester, fumaric acid ester oligomer, carbonic acid ester and hydroxybivalic acid ester in the present invention, it is preferable to adopt a refining means which does not contain a component which imparts insulation properties, and particularly sodium content Since it is difficult to remove by purification, an ester exhibiting high insulation can be obtained by a small number of purification steps by adopting a method of avoiding the use of a compound having sodium as a constituent element. As a method of avoiding the sodium content, it is useful to use calcium hydroxide or the like for neutralizing the free fatty acid after the esterification reaction.

Further, in refrigerating machine oil, a high acid value is not preferable because problems such as corrosion of metal parts occur. Therefore, the total acid value of the refrigerating machine oil is less than 0.1 mg KOH / g, preferably 0.05 mg KOH / g or less.

Further, in order to enhance the stability of the refrigerant, the peroxide value is 1 meq./Kg or less and the aldehyde value is 1 mg KOH /
The bromine number index is preferably 10 mg / 100 g or less.

The ester may be purified by contacting it with silica gel, activated alumina, activated carbon, zeolite or the like. The contact conditions at this time may be appropriately determined according to various situations, and the temperature is preferably 100 ° C. or lower. As another ester purification method, a method using an ion exchange resin or an inorganic ion exchanger (manufactured by Toagosei Kagaku) may be used although the cost is high.

Next, the refrigerating machine oil of the present invention is added with an antiwear agent, an antioxidant, a corrosion inhibitor, an antifoaming agent, a metal deactivator, a rust preventive agent, and the like. Its sodium and / or potassium concentration is important and it is necessary that the sodium and / or potassium concentration in the refrigerating machine oil composition does not exceed 0.1 ppm.

In the present invention, a phosphoric acid ester-based compound is added. Since the phosphoric acid ester-based compound is usually produced by a dehydrochlorination reaction of phosphorus oxychloride and phenol or alcohol, sodium is used in the neutralization step. It has been found that the concentration of sodium and / or potassium is high, and even the additive increases the concentration of sodium and / or potassium in the entire refrigerator oil composition.

Examples of such phosphoric acid ester compounds include benzyl diphenyl phosphate, allyl diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, ethyl diphenyl phosphate, tributyl phosphate, dibutyl phosphate, cresyl diphenyl. Phosphate, dicresyl phenyl phosphate, ethyl phenyl diphenyl phosphate, diethyl phenyl phenyl phosphate, propyl phenyl diphenyl phosphate, dipropyl phenyl phenyl phosphate, triethyl phenyl phosphate, tripropyl phenyl phosphate, butyl phenyl diphenyl phosphate ,
Examples thereof include phosphoric acid esters such as dibutylphenyl phenyl phosphate and tributyl phenyl phosphate, and triphosphorous acid esters such as triisopropyl phosphite and diisopropyl phosphite.

In the production of these phosphoric acid ester compounds, it is preferable to use those produced by adopting a neutralizing and refining means that does not leave sodium and / or potassium components as in the case of the above-mentioned ester oil. preferable. Further, the sodium and / or potassium concentration may be a concentration such that, when added to refrigerating machine oil as an additive, the sodium and / or potassium concentration in the entire composition is 0.1 ppm or less.

In addition to these, as the phosphorus compound, hexamethylphosphoric triamide, n-butyl-n
Other phosphorus compounds such as dioctyl phosphinate, di-n-butylhexyl phosphonate, amine dibutyl phosphonate, dibutyl phosphoramidate can be used.

As an antiwear agent, a general formula (RO) ₃ P
= S (wherein R is an alkyl group, an allyl group or a phenyl group and may be the same or different), and specifically, trialkylphosphorothionate, triphenylphosphorothionate, alkyldiallylphos Phorothionate, diphenyl sulfide, diphenyl disulfide, di-n-butyl sulfide, di-n-butyl disulfide, di-tert-dodecyl disulfide, di-tert-dodecyl trisulfide, sulfalized spalm oil, sulfalized dipentene It is also possible to use xanthic disulfide zinc primary alkylthiophosphate, zinc secondary alkylthiophosphate, zinc alkyl-allylthiophosphate, zinc allylthiophosphate.

The various antiwear agents may be used in an amount of 0.01 to 5% by weight, preferably 0.1 to 3% by weight, based on the ester oil and the like. The above anti-wear agents may be used alone or in combination of two or more.

As the antioxidant, for example, di (alkylphenyl) amine (wherein the alkyl group has 4 to 2 carbon atoms)
0), phenyl-α-naphthylamine, alkyldiphenylamine (the alkyl group has 4 to 20 carbon atoms), N-nitrosodiphenylamine, phenothiazine, N, N′-dinaphthyl-p-phenylenediamine, acridine, N-
Amine-based antioxidants such as methylphenothiazine, N-ethylphenothiazine, dipyridylamine, diphenylamine, phenolamine, and 2,6-di-t-butyl-α-dimethylaminoparacresol, 2.6-di-t-
Butyl paracresol, 4.4'-methylene bis (2.
6-di-t-butylphenol), 2.6-di-t-butyl-4-N, N-dimethylaminomethylphenol,
2.6-Di-t-butylphenol and other phenolic antioxidants, organic iron salts such as iron octoate, ferrocene and iron naphthoate, and organic such as cerium naphthoate and cerium toluate Organic metal compound-based antioxidants such as cerium salts and organic zirconium salts such as zirconium octoate, and phosphites such as tridi-t-butylphenyl phosphite and trioctyl phosphite may be used. The above-mentioned antioxidants may be used alone, or may be used in combination of two or more so as to exert a synergistic effect.
The ratio of the antioxidant used is 0.001 with respect to the refrigerator oil.
~ 5 wt%, preferably 0.01-2 wt% may be used.

As a corrosion inhibitor, isostearate, n
-Octadecyl ammonium stearate, duomin T.deolate, lead naphthenate, sorbitan oleate,
Pentaerythrit oleate, oleyl sarcosine,
Alkyl succinic acid, alkenyl succinic acid and their derivatives are used, and their usage ratio is 0.0 with respect to the refrigerating machine oil.
It is recommended to use 01 to 1.0% by weight, preferably 0.01 to 0.5% by weight.

Silicone is preferably used as the defoaming agent, and the proportion of the defoaming agent used is 0.0001 to 0.
003% by weight, preferably 0.0001 to 0.001% by weight may be used.

As the metal deactivator, for example, benzotriazole thiadiazole, thiadiazole derivative, triazole, triazole derivative, dithiocarbamate and the like may be used in addition to the triazole derivative in the present invention, and the ratio thereof is base oil. 0.01% by weight to 10% by weight, preferably 0.01% by weight to 1.0%
It is advisable to use% by weight.

As the rust preventive, for example, succinic acid, succinic acid ester, oleic acid beef tallow amide, barium sulfonate, calcium sulfonate, etc. may be used, and the use ratio thereof is 0.01% by weight to 10% by weight, preferably 0.1% by weight. It is advisable to use 01% to 1.0% by weight.

Next, the viscosity range of the refrigerator oil composition of the present invention will be described. The viscosity range of the refrigerator oil of the present invention is 4
10-500 mm ² / s at 0 ° C, preferably 20-4
It is 80 mm ² / s.

Refrigerating machine oil, eg 40 ° C. for refrigerators
Viscosity at the ^{10mm 2 / s ~40mm 2 / s} , preferably 1
5mm ² / s ~35mm are those of ² / s, also, as a refrigerating machine for refrigerating machine oil in the car air conditioner 40mm ² / s ~500
mm ² / s is recommended, and 40 mm ² / for car air conditioners and reciprocating type compressors.
s to 120 mm ² / s, preferably 80 mm ² / s to 100 mm ² /
s, 80 for rotary type compressors
^{mm 2 / s ~500mm 2 / s} , preferably 100mm ² / s ~45
Those having a viscosity range of 0 mm ² / s are preferably used.

When the viscosity range is less than 10 mm ² / s, the viscosity is too low even if the compatibility with the refrigerant at high temperature is high, the lubricity and sealing characteristics are poor, and the thermal stability is low. It is not preferable, and if it exceeds 500 mm ² / s, the compatibility with the refrigerant decreases, which is not preferable. Even within this range, the viscosity range used varies depending on the model used as described above, and for refrigerators, there is a problem that the friction loss in the sliding portion becomes large when it exceeds 40 mm ² / s. . Furthermore,
In the reciprocating type car air conditioner, if it is less than 40 mm ² / s, there is a problem of lubricity, and if it exceeds 120 mm ² / s, there is a problem that friction loss in the sliding part is large.
Also, for rotary type air conditioners, 80 mm ² / s
If it is less than 500 mm ² / s, there is a problem of sealing characteristics, and if it exceeds 500 mm ² / s, there is a problem of compatibility with the refrigerant.

Although the case where an ester oil is used as the refrigerating machine oil in the refrigerating machine oil composition has been described above, when the polyalkylene glycol is used as the refrigerating machine oil, the sodium and / or potassium concentration is similarly lowered. Good to do.

[0068]

INDUSTRIAL APPLICABILITY The present invention relates to a base oil in a refrigerating machine oil composition and an additive, and a sodium content in an ash content which is considered to be mixed in a raw material or a neutralizing agent used in a refining process. It is based on the finding that the insulating property is extremely reduced when the total concentration of potassium exceeds 0.1 ppm.

That is, the refrigerating machine oil composition of the present invention is a refrigerating machine oil composition in which ester oil is used as a refrigerating machine oil and a phosphoric acid ester compound is added, so that the sodium and / or potassium concentration is 0.1 ppm or less. × 10 ¹³ Ω
cm (25 ° C.) or higher, preferably 5 × 10 ¹³ Ωcm (25
C.) or more, more preferably 1 × 10 ¹⁴ Ωcm (25 ° C.) or more, and a refrigerating machine oil composition having excellent insulating properties can be obtained.

If the acid value of the ester oil in the refrigerator oil composition is high, problems such as corrosion of metal parts in the refrigerator occur, and the ester oil itself is hydrolyzed, so that the function as the refrigerator oil is improved. And the insulating property is also reduced. Therefore, the total acid number as ester oil is 0.1 mg.
The content is preferably less than KOH / g, and the water content is 500 ppm or less, preferably 100 ppm or less.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples. First, a method for testing a refrigerator oil composition will be described. (Sodium content, potassium content) Place 100 samples on a platinum dish.
After ashing the sample by collecting g and heating it in an electric furnace at 550 ° C. for about 1 day and night, 2 ml of 20% hydrochloric acid and 5 ml of pure water were added to the ash, and heated at 50 ° C. for 10 minutes with a hot plate. It was heated and used as a sample for analysis. Quantify 10 ml of this analytical sample into a volumetric flask,
Atomic absorption spectrometer (single drop method, 589.0 nm, flame photo analysis)
Was used to measure the concentration of sodium or potassium in the sample from the correspondence with the sodium or potassium standard solution for the calibration curve.

[0072]

Example 1 1 mol of pentaerythritol and 2-ethylhexanoic acid were subjected to a conventional esterification reaction [catalyst Ti
(OC ₄ H ₉ ) ₄ ], 56 g of potassium hydroxide was added to the obtained product to neutralize the catalyst, and the product was washed with distilled water for purification to obtain an ester oil. The physical properties of this ester oil are shown below. Volume resistivity: 1 × 10 ¹⁴ Ωcm (25 ° C.), sodium concentration 0.01 ppm, silicon content 0.02 ppm, acid value 0.0
1 mg KOH / g, potassium, iron and titanium were not detected.

To this ester oil, 2.0% by weight of tricresyl phosphate (sodium concentration 0.15 ppm) was added.
Was added to prepare a refrigerator oil composition. The sodium concentration in the obtained refrigerator oil composition was 0.013.
It was ppm.

[0074]

Example 2 To the ester oil prepared in Example 1, trioctyl phosphate [(C ₈ H ₁₇ O) ₃ -P = O, sodium concentration 0.32 ppm] was added at a ratio of 2.0% by weight. , A refrigerator oil composition was prepared. The sodium concentration in the obtained refrigerator oil composition was 0.016 ppm.

[0075]

Example 3 The ester oil prepared in Example 1 was added with (C ₁₈
H ₃₅ O) ₃ -P = O, sodium concentration 0.35 ppm) was added at a ratio of 2.0% by weight to prepare a refrigerator oil composition. The sodium concentration in the obtained refrigerator oil composition was 0.017 ppm.

[0076]

Example 4 The ester oil prepared in Example 1 was mixed with the compound represented by the following structural formula (sodium concentration: 0.28 ppm).
) Was added at a ratio of 2.0% by weight to prepare a refrigerator oil composition. The sodium concentration in the obtained refrigerator oil composition was 0.016 ppm.

[0077]

[Chemical 9]

[0078]

Example 5 The ester oil prepared in Example 1 was mixed with n-butoxyethyl phosphate [(C ₄ H ₉ —O—C ₂ H
_4- O-) _3- P = O, sodium concentration 0.35 ppm]
Was added at a ratio of 2.0% by weight to prepare a refrigerator oil composition. The sodium concentration in the obtained refrigerator oil composition was 0.017 ppm.

[0079]

Comparative Example 1 To the ester oil prepared in Example 1, tricresyl phosphate (5.2 ppm sodium concentration) was added at a ratio of 2.0% by weight to prepare a refrigerator oil composition. The sodium concentration in the obtained refrigerator oil composition was 0.114 ppm.

[0080]

Comparative Example 2 The ester oil prepared in Example 1 was added to the compound represented by the above [Chemical Formula 9] (sodium concentration: 6.6 ppm).
) Was added at a ratio of 2.0% by weight to prepare a refrigerator oil composition. The sodium concentration in the obtained refrigerator oil composition was 0.142 ppm.

[0081]

Comparative Example 3 The ester oil prepared in Example 1 was mixed with n-butoxyethyl phosphate [(C ₄ H ₉ —O—C ₂ H
_4- O-) _3- P = O, sodium concentration 5.8 ppm] was added at a ratio of 2.0% by weight to prepare a refrigerator oil composition. The sodium concentration in the obtained refrigerator oil composition was 0.126 ppm.

The volume resistivity of each of the above refrigerating machine oil compositions was measured. The results are shown in the table below.

[0083]

[Table 1]

As can be seen from the table, the refrigerator oil composition of the present invention has excellent insulation properties.

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Claims (1)

[Claims] 1. A refrigerating machine oil composition comprising an ester oil as a refrigerating machine oil and a phosphoric acid ester compound added thereto, wherein the sodium and / or potassium concentration is 0.1 ppm or less.