JP2000169868A - Refrigerator oil composition and lubrication method using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating machine oil composition having good lubricating performance and sealability and capable of long-term stable use in a compression refrigeration cycle using a refrigerant containing CO ₂ as a main component, and the composition. And a lubrication method using the same. SOLUTION: (1) It is composed of a refrigerant mainly composed of CO ₂ and a lubricating oil composition, wherein the lubricating oil composition mainly comprises an ester oil and has a kinematic viscosity at 100 ° C of 5.5 to 30 m.
m ² / s, and 0.005 to 5
A refrigerating machine oil composition containing an extreme pressure agent and / or an acid scavenger by weight, and (2) a lubricating method using the refrigerating machine oil composition in a compression refrigerating cycle having an oil separator and / or a hot gas line. Is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating machine oil composition, and more particularly, to a refrigerating machine oil composition using a refrigerant containing CO ₂ as a main component, and a lubricating method using the composition, particularly an oil separator. And / or a lubrication method in a compression refrigeration cycle having a hot gas line.

[0002]

2. Description of the Related Art In general, a compression refrigerating cycle of a refrigerating machine, for example, a compression refrigerating machine including a compressor, a condenser, an expansion valve, and an evaporator, uses a mixed liquid of refrigerant and lubricating oil in a closed system. Is circulated. In such a compression refrigerator, dichlorodifluoromethane (R-12) or chlorodifluoromethane (R-22) is conventionally used as a refrigerant.
Chlorofluorocarbon is used, and
A number of lubricating oils have been produced and used therewith. However, these fluorocarbon compounds, which have been conventionally used as refrigerants, may cause environmental pollution such as destruction of the ozone layer present in the stratosphere when released into the atmosphere. Regulations on its use are becoming more stringent. For this reason, hydrogen-containing Freon compounds such as hydrofluorocarbons and hydrochlorofluorocarbons have been attracting attention as new refrigerants. This hydrogen-containing Freon compound, especially 1,
Hydrofluorocarbons represented by 1,1,2-tetrafluoroethane (R-134a) do not have a risk of destruction of the ozone layer, but have a long life in the atmosphere, and are therefore likely to affect global warming. In recent years, use of a natural refrigerant having no such a problem has been considered.

On the other hand, carbon dioxide gas is harmless to the environment, is excellent in terms of safety for humans, and has a pressure close to an economically optimum level, and is extremely small compared to conventional refrigerants. It has advantages such as pressure ratio, excellent compatibility with ordinary oils and the structural materials of the machine, easily available everywhere, and does not require collection and is very inexpensive. Has been commonly used as a refrigerant. However, when such carbon dioxide gas is used as a refrigerant, lubricating with a conventionally used lubricating oil as a lubricating oil for a refrigerator results in inferior lubricity and insufficient wear resistance, and as a result stable The property deteriorates and long-term stable use becomes impossible. Further, the system using carbon dioxide gas has a problem that the discharge pressure is higher than the system using R-134a or the like, and as a result, the viscosity of the lubricating oil decreases and the sealing performance of the system deteriorates.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made from the above viewpoint, and has a good lubricating performance and sealability and a long-term stability in a compression refrigeration cycle using a refrigerant mainly composed of CO _2. It is an object of the present invention to provide a refrigerating machine oil composition that can be used and a lubrication method using the composition.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that the object of the present invention can be effectively achieved by using a lubricating oil composition comprising a specific lubricating base oil and an additive. It has been found that the present invention can be achieved, and the present invention has been completed. That is, the present invention comprises (1) a refrigerant mainly composed of CO ₂ and a lubricating oil composition, wherein the lubricating oil composition mainly comprises an ester oil and has a kinematic viscosity at 100 ° C. of 5.
A base oil of 5 to 30 mm ² / s;
A refrigerating machine oil composition containing from 005 to 5% by weight of an extreme pressure agent and / or an acid scavenger; and (2) a compression refrigeration cycle having an oil separator and / or a hot gas line. _A lubricating oil composition comprising a refrigerant having ₂ as a main component, the lubricating oil composition having an ester oil as a main component, and having a kinematic viscosity at 100 ° C of 5.5 to 30 mm ² /
s and 0.005 to 5% by weight based on the base oil
A lubricating method characterized by using a refrigerating machine oil composition containing an extreme pressure agent and / or an acid scavenger.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The refrigerating machine oil composition of the present invention comprises a refrigerant mainly composed of CO ₂ and a lubricating oil composition, and the lubricating oil composition mainly comprises an ester oil and has a kinematic viscosity at 100 ° C. of 5.5 to 5.5. It is characterized by containing a base oil of 30 mm ² / s and an extreme pressure agent and / or an acid scavenger of 0.005 to 5% by weight based on the base oil. The refrigerant of CO ₂ used in the present invention as a main component, in addition to the case of directly using the CO _2, which hydrocarbon, R-134
A mixture of a fluorinated hydrocarbon (or a chlorofluorocarbon) such as a and a refrigerant such as ether can be used.

[0007] The viscosity of the base oil of the lubricating oil composition constituting the present invention has a kinematic viscosity at 100 ° C of 5.5 to 30 mm ² /.
s are used. 4. Kinematic viscosity at 100 ° C.
5~30mm ² / s, particularly 7.5~20.5mm ² / s
Is preferred in terms of the efficiency and lubricity of the compressor. Ester oils which are the main components of the base oil include polyhydric alcohol esters, aliphatic or aromatic polycarboxylic esters, alicyclic polycarboxylic esters, other organic carboxylic esters, carbonate esters, and fumaric acid. Ester oils such as ester oligomers, hydroxypivalic acid esters and combinations thereof can be mentioned. It will be described in order.

Polyhydric Alcohol Esters Polyhydric alcohol esters include esters of aliphatic polyhydric alcohols with linear or branched fatty acids. Aliphatic polyhydric alcohols forming the ester include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol,
Examples include trimethylolethane, ditrimethylolethane, trimethylolpropane, ditrimethylolpropane, glycerin, pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol and the like.

As the fatty acid, those having 3 to 12 carbon atoms can be used. Preferred fatty acids are propionic acid, butyric acid, pivalic acid, valeric acid, caproic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, and the like. 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 can be mentioned. Note that a partial ester of an aliphatic polyhydric alcohol and a linear or branched fatty acid can also be used.

As esters of these aliphatic polyhydric alcohols and linear or branched fatty acids, particularly preferred are pentaerythritol, dipentaerythritol and tripentaerythritol having 5 to 12 carbon atoms, more preferably 5 to 12 carbon atoms. 5-9 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-butyloctanoic acid And esters with 3,5,5-trimethylhexanoic acid.

In addition, aliphatic polyhydric alcohols having 3 to 3 carbon atoms
A partial ester with a linear or branched fatty acid of 9;
Complex esters with aliphatic or aromatic dibasic acids can also be used. In this complex ester, a fatty acid having preferably 5 to 7 carbon atoms, more preferably 5 or 6 carbon atoms, may be used. As such fatty acid, valeric acid, hexanoic acid, isovaleric acid, 2-methylbutyric acid, 2-ethylbutyric acid or a mixture thereof is used, and those having 5 and 6 carbon atoms in a weight ratio of 10: Fatty acids mixed at a ratio of 90 to 90:10 can be suitably used. Aliphatic dibasic acids used for esterification with polyhydric alcohols along with this fatty acid include succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, and tridecanediacid. Acid and docosannadioic acid; and phthalic acid and isophthalic acid as aromatic dibasic acids. In the esterification reaction for preparing a complex ester, first, a polyhydric alcohol and a dibasic acid are reacted at a predetermined ratio to partially esterify, and then the partial ester may be reacted with a fatty acid. The reaction order of the basic acid and the fatty acid may be reversed, or the dibasic acid and the fatty acid may be mixed and subjected to esterification. Further, the following general formula (I)

[0012]

Embedded image

(Wherein, R ^{1 to} R ³ are alkyl groups having 1 to 13 carbon atoms, those having 4 or more carbon atoms all have one or more branches, and the total carbon number of R ^{1 to} R ³ is The polyhydric alcohol ester obtained by reacting the acid fluoride represented by the formula (3) with a polyhydric alcohol has a low saturated moisture absorption and can be suitably used (JP-A-9-157219).

Aliphatic or aromatic polycarboxylic acid ester As the dicarboxylic acid ester, a dialkyl ester of an aliphatic or aromatic dicarboxylic acid (having 16 to 22 carbon atoms)
Can be mentioned. Examples of the aliphatic dicarboxylic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, tridecandioic acid, and docosanedioic acid, and aromatic Examples of dicarboxylic acids include phthalic acid and isophthalic acid. On the other hand, the alcohol component is an alcohol having 5 to 8 carbon atoms, such as amyl alcohol, hexyl alcohol, heptyl alcohol, and octyl alcohol. Preferred esters include dioctyl adipate, diisoheptyl adipate, dihexyl sebacate, diheptyl succinate, dioctyl phthalate, diisoheptyl phthalate, and diisoamyl phthalate.

Examples of the polycarboxylic acid constituting the trivalent or higher polycarboxylic acid ester include aliphatic polycarboxylic acids such as 1,2,3,4-butanetetracarboxylic acid, trimellitic acid, and pyromellitic acid. Aromatic polycarboxylic acids can be mentioned. As the alcohol, a monohydric alcohol having a linear or branched alkyl group having 3 to 12 carbon atoms, or H- (AO) _n -R ( _where A represents 2 to 8 carbon atoms)
R is an alkyl group having 1 to 10 carbon atoms, n
Is an integer of 1 to 10). A polycarboxylic acid ester obtained by subjecting the above-mentioned polycarboxylic acid and alcohol to an esterification reaction, or obtained by further adding a polyhydric alcohol such as ethylene glycol or propylene glycol to the above-mentioned polycarboxylic acid and alcohol and carrying out an esterification reaction. Complex esters can be used.

Alicyclic polycarboxylic acid ester The alicyclic polycarboxylic acid ester is represented by the following general formula (II):

[0017]

Embedded image

(Wherein, A represents a cyclohexane ring or a cyclohexene ring; R ⁴ represents a hydrogen atom or a methyl group; X represents a hydrogen atom or COOR ⁷ ; Y represents a hydrogen atom or COOR ⁸ ; R ⁵ To R ⁸ each have 3 carbon atoms
And represents an alkyl group having １８18 or a cycloalkyl group having 3 to 10 carbon atoms, which may be the same or different from each other. )). This ester is prepared by esterifying a predetermined acid component and an alcohol component according to a conventional method, preferably while heating and stirring under an inert gas atmosphere such as nitrogen, in the presence or absence of an esterification catalyst. .

Examples of the acid component include cycloalkane polycarboxylic acid or cycloalkene polycarboxylic acid and acid anhydrides thereof, and one or more compounds may be used as a mixture. Specifically, 1,2-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 1-cyclohexene-1,2-dicaronic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid , 3-
Methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 3-methyl-4-cyclohexene-1,2-dicarboxylic acid, 4-
Methyl-4-cyclohexene-1,2-dicarboxylic acid,
1,2,4-cyclohexanetricarboxylic acid, 1,3
5-cyclohexanetricarboxylic acid, 1,2,4,5-
Examples thereof include cyclohexanetetracarboxylic acid and acid anhydrides thereof. Among them, 1,2-cyclohexanedicarboxylic acid, 3-methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, and 4-cyclohexene -1,2-dicarboxylic acid, 3-
Methyl-4-cyclohexene-1,2-dicarboxylic acid,
4-Methyl-4-cyclohexene-1,2-dicarboxylic acids and their anhydrides are preferred.

The alcohol component may have 3 to 3 carbon atoms.
Examples thereof include 18 linear or branched aliphatic alcohols and alicyclic alcohols having 3 to 10 carbon atoms. Specific linear aliphatic alcohols include n-propyl alcohol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, n-undecanol, n-dodecanol, n-tetradecanol,
Examples thereof include n-hexadecanol and n-octadecanol.

Specific branched aliphatic alcohols include isopropanol, isobutanol, sec.
-Butanol, isopentanol, isohexanol,
2-methylhexanol, 2-methylheptanol, isoheptanol, 2-ethylhexanol, 2-octanol, isooctanol, 3,5,5-trimethylhexanol, isodecanol, isoundecanol, isotridecanol, isotetradecanol Examples include decanol, isohexadecanol, isooctadecanol, and 2,6-dimethyl-4-heptanol.

Further, examples of the alicyclic alcohol include cyclohexanol, methylcyclohexanol, dimethylcyclohexanol and the like. Among the alicyclic polycarboxylic acid esters obtained from the above polycarboxylic acids and alcohols, in particular, diisobutyl 1,2-cyclohexanedicarboxylate, dicyclohexyl 1,2-cyclohexanedicarboxylate, diisoheptyl 1,2-cyclohexanedicarboxylate 1,2-cyclohexanedicarboxylic acid (2-ethylhexyl), 1,2-cyclohexanedicarboxylic acid di (3,5,5-trimethylhexyl),
Di (2,6-dimethyl-4-heptyl) 1,2-cyclohexanedicarboxylate, diisodecyl 1,2-cyclohexanedicarboxylate, diisoundecyl 1,2-cyclohexanedicarboxylate, 4-cyclohexene-1,2-
Dicyclohexyl dicarboxylate, 4-cyclohexene-
Diisoheptyl 1,2-dicarboxylate, di (2-ethylhexyl) 4-cyclohexene-1,2-dicarboxylate, di (3,5,5-trimethylhexyl) 4-cyclohexene-1,2-dicarboxylate, 3-methyl −
1,2-cyclohexanedicarboxylic acid di (3,5,5-
Trimethylhexyl), 4-methyl-1,2-cyclohexanedicarboxylic acid di (3,5,5-trimethylhexyl), 3-methyl-4-cyclohexene-1,2-dicarboxylic acid di (3,5,5-trimethyl) Hexyl), 4-
Methyl-4-cyclohexene-1,2-dicarboxylic acid di (3,5,5-trimethylhexyl), 1,2,4,5
-Tetracyclohexanetetracarboxylic acid (3,5,5
-Trimethylhexyl).

The above-mentioned alicyclic polycarboxylic acid ester may be mixed with another ester (hereinafter referred to as a combined ester) in order to improve the balance of physical properties such as volume resistivity and viscosity. As the combined ester,
Adipic acid esters, azelaic esters, sebacic esters, phthalic esters, trimellitic esters, and polyhydric alcohol esters can be exemplified. As a polyhydric alcohol component of the polyhydric alcohol ester,
Neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and the like can be mentioned. As the acid component, isobutyric acid, 2-ethylbutyric acid, isovaleric acid, pivalic acid, cyclohexanecarboxylic acid, 2-methylpentanoic acid, -Ethylpentanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid,
3,5,5-trimethylhexanoic acid and the like can be mentioned. The content of the combined ester in the lubricating oil is 10 to
90% by weight.

Other Organic Carboxylic Acid Esters As other organic carboxylic acid esters other than the above, alkylene oxide adducts of monohydric alcohols can be prepared by adding adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid And diesters obtained by esterification with an aliphatic dicarboxylic acid such as dodecane diacid, docosane diacid, or an aromatic dicarboxylic acid such as phthalic acid. Further, a 1 to 10 mol adduct of an alkylene oxide of a polyhydric alcohol such as glycerin or trimethylolpropane is used as a 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-methylhexanoic acid, 2-ethylhexanoic acid,
Isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2
And esters obtained by esterification with dimethyloctanoic acid, 2-butyloctanoic acid, and the like.

Carbonic acid ester As the carbonic acid ester, the following general formula (III)

[0026]

Embedded image

(Wherein, R ⁹ is an alkyl group having 2 to 10 carbon atoms, R ¹⁰ is an alkylene group or cycloalkylene group having 2 to 10 carbon atoms, and a is an integer of 1 to 4). Compound or the following general formula (IV)

[0028]

Embedded image

(Wherein, R ¹¹ is a polyhydric alcohol residue having a hydroxyl group having 2 to 6 carbon atoms, R ¹² is an alkyl group having 2 to 10 carbon atoms, and b is an integer of 2 to 6). Compounds to be used can be mentioned. The above carbonate ester is prepared by transesterification of dimethyl carbonate and alcohols in the presence of a basic catalyst. The following general formula (V)

[0030]

Embedded image

Wherein R ¹³ is an alkyl group having 1 to 10 carbon atoms, R ¹⁴ is an alkyl group having 2 to 10 carbon atoms, and c is 2
An integer of 10 to 10; d represents an integer of 2 to 100;
It is _{-CH 2 -CH (CH 3) -O-} , or -CH ₂ -C
H ₂ —O— is shown. ) Can also be used.
This carbonate is obtained, for example, by reacting carbonic acid with an alkylene oxide. The form of addition of the alkylene oxide may be ethylene oxide alone or propylene oxide alone, or may be a mixture.

The fumaric acid ester oligomer is a homopolymer of a fumaric acid ester or a copolymer of a fumaric acid ester and an unsaturated aliphatic hydrocarbon, and has the following formula (VI)

[0033]

Embedded image

(Wherein, R ¹⁵ represents an alkylene group, a substituted alkylene group or an alkylene oxide group, and R ¹⁶ and R ¹⁷ represent an alkyl group having 1 to 9 carbon atoms, an allyl group or a terminally substituted or unsubstituted polyalkylene oxide group. And they may be the same or different, e is 0 or more,
f represents an integer of 1 or more, and R ¹⁵ is 50 mol% or less of the whole. ). Specific examples include an ester oligomer of diethyl fumarate and an ester oligomer of dibutyl fumarate. In addition, both ends in the above formula (VI) are polymerization initiation residues used in the polymerization reaction, and the description thereof is omitted. In addition, the following structural formula (VII)

[0035]

Embedded image

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

[0037]

Embedded image

(Wherein R ¹⁸ and R ¹⁹ each have 3 carbon atoms)
~ 8 alkyl groups, which may be the same or different. )), And a fumaric acid alkyl ester copolymer containing 50 to 99 mol% of the structural unit represented by formula (1).

Hydroxypivalic acid ester The hydroxypivalic acid ester is represented by the general formula (IX)

[0040]

Embedded image

(Wherein, R ²⁰ and R ²¹ represent an alkyl group having 2 to 10 carbon atoms, and g represents an integer of 1 to 5). The ester oils described in (1) to (4) may be used by mixing one kind or two or more kinds of the same kind of ester oil, or may be used by mixing different kinds of ester oils. It is necessary to adjust the kinematic viscosity of the base oil at 100 ° C. to 5.5 to 30 mm ² / s as described above. When the above ester oil is used as a base oil, if the viscosity is out of the range, it may be adjusted by adding another component. If the viscosity is high, for example,
An ester oil of an aliphatic polyhydric alcohol and a fatty acid having 3 to 9 carbon atoms having a kinematic viscosity at 100 ° C. of 6 mm ² / s or less can be appropriately added and adjusted to an appropriate range.
When the viscosity is low, the viscosity may be adjusted by adding polymers. The polymer preferably has a kinematic viscosity at 100 ° C. of 10 mm ² / s or more.

Examples of such polymers include polyalkyl methacrylates (for example, those having an alkyl group of 1 to 8), polyalkylene glycols (for example, polypropylene glycol, copolymers comprising a polypropylene glycol component and a polyethylene glycol component, polypropylene glycol). And a polyester of neopentyl glycol and an aliphatic dicarboxylic acid, represented by the following formula (X):

[0043]

Embedded image

(H is an integer of 1 to 20, i is 1 to 1
Indicates an integer of 0. And the like. The lubricating oil composition constituting the present invention is based on the above base oil,
It is prepared by blending 0.005 to 5% by weight of an extreme pressure agent and / or an acid scavenger with respect to the base oil. As the extreme pressure agent,
For example, sulfur-based extreme pressure agents such as sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiocarbamates, thioterpenes, and dialkylthiodipropionates can be mentioned. Here, sulfurized fats and oils are obtained by reacting sulfur and sulfur-containing compounds with fats and oils (lard oil, whale oil, vegetable oil, fish oil, etc.), and the sulfur content is not particularly limited,
Generally, those having 5 to 30% by weight are preferable. Specific examples include lard sulfide, rapeseed rapeseed oil, sulfide castor oil,
Sulfurized soybean oil, sulfurized rice bran oil and the like can be mentioned.
Examples of the sulfurized fatty acid include sulfurized oleic acid, and examples of the sulfurized ester include methyl sulfurized methyl oleate and sulfide of rice sulfide or the fatty acid octyl.

As the sulfurized olefin, for example, the following general formula (XI) R ²² -S _j -R ²³ ... (XI) (wherein R ²² is an alkenyl group having 2 to 15 carbon atoms, and R ²³ is Represents an alkyl group or an alkenyl group having 2 to 15 carbon atoms,
j represents an integer of 1 to 8. And the like. This compound is obtained by reacting an olefin having 2 to 15 carbon atoms or a di- to tetramer thereof with a sulfurizing agent such as sulfur or sulfur chloride. As the olefin, propylene, isobutene, diisobutene and the like are preferable.

The dihydrocarbyl polysulfide is represented by the following general formula (XII): R ²⁴ —S _k —R ²⁵ ... (XII) (wherein R ²⁴ and R ²⁵ are alkyl having 1 to 20 carbon atoms, respectively) A group or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms or an arylalkyl group having 7 to 20 carbon atoms, which may be the same or different, and k is And an integer of 2 to 8). Here, R ²⁴ and R ²⁵
When is an alkyl group, it is called an alkyl sulfide.

Specific examples of R ²⁴ and R ²⁵ in the general formula (XII) include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and s.
ec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups, cyclohexyl groups, cyclooctyl groups, phenyl groups, naphthyl groups , Tolyl, xylyl, benzyl, phenethyl and the like.

Examples of the dihydrocarbyl polysulfide include dibenzyl polysulfide and di-t.
Preferred examples include ert-nonyl polysulfide, didodecyl polysulfide, di-tert-butyl polysulfide, dioctyl polysulfide, diphenyl polysulfide, dicyclohexyl polysulfide, and the like.

Further, as thiocarbamates, for example, zinc dithiocarbamate and the like, as thioterpenes, for example, a reaction product of phosphorus pentasulfide and pinene,
As dialkylthiodipropionates, for example,
Examples thereof include dilauryl thiodipropionate and distearyl thiodipropionate.

Examples of the extreme pressure agent include phosphoric acid esters, acidic phosphoric acid esters, phosphite esters, acidic phosphite esters, thiophosphoric acid esters, thioacidic phosphoric acid esters, and amine salts thereof. Examples of the phosphorus-based extreme pressure agent such as the above-mentioned reaction product of phosphorus pentasulfide and pinene such as phosphorus sulfide terpenes can be given. Here, phosphate ester, acid phosphate ester, phosphite ester,
And the acidic phosphite are represented by the following general formula (XIII)
(XVII).

[0051]

Embedded image

[0052]

Embedded image

[0053]

Embedded image

[0054]

Embedded image

[0055]

Embedded image

In the above general formulas (XIII) to (XVII),
R²⁶~ R²⁸Is an alkyl group having 4 to 30 carbon atoms, alkenyl
Group, alkylaryl group and arylalkyl group
Then R ²⁶~ R²⁸May be the same or different. phosphoric acid
As esters, triaryl phosphate, tria
Lucyl phosphate, trialkylaryl phosphate
G, triarylalkyl phosphate, trialkenyl
Such as triphosphate.
Phenyl phosphate, tricresyl phosphate, ben
Zirdiphenyl phosphate, ethyldiphenylphospho
Phosphate, tributyl phosphate, ethyl dibutyl phosphate
Fate, cresyl diphenyl phosphate, dicledge
Phenyl phosphate, ethyl phenyl diphenyl pho
Sulfate, diethylphenylphenyl phosphate,
Propylphenyl diphenyl phosphate, dipropyl
Phenyl phenyl phosphate, triethyl phenyl phosphate
Sulfate, tripropylphenyl phosphate, spot
Ruphenyl diphenyl phosphate, dibutyl phenyl
Phenyl phosphate, tributyl phenyl phosphate
, Trihexyl phosphate, tri (2-ethylhexyl)
(Sil) phosphate, tridecyl phosphate, trila
Uryl phosphate, trimyristyl phosphate,
Lipalmityl phosphate, tristearyl phosphate
And trioleyl phosphate
You.

As the acidic phosphoric acid ester, specifically, for example, 2-ethylhexyl acid phosphate,
Ethyl acid phosphate, butyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate, tridecyl acid phosphate, stearyl acid phosphate, isostearyl acid phosphate, and the like can be given.

As the phosphite, specifically,
For example, triethyl phosphite, tributyl phosphite, triphenyl phosphite, tricresyl phosphite, tri (nonylphenyl) phosphite, tri (2
-Ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphenylisodecyl phosphite, tristearyl phosphite, trioleyl phosphite,
Examples thereof include 2-ethylhexyldiphenyl phosphite.

Specific examples of the acidic phosphite include dibutyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, distearyl hydrogen phosphite, and diphenyl hydrogen phosphite. . Examples of the thiophosphate and the thioacid phosphate include those corresponding to the above-described phosphate and acid phosphate, respectively.

Further, examples of the amines which form an amine salt with these include, for example, general formula (XVIII), R _m NH _3-m ... (XVIII) (where R is an alkyl group having 3 to 30 carbon atoms) Or an alkenyl group, an aryl group or an aralkyl group having 6 to 30 carbon atoms, or a hydroxyalkyl group having 2 to 30 carbon atoms, and m represents 1, 2 or 3. When there are a plurality of Rs, a plurality of Rs are Mono-substituted amine, di-substituted amine or tri-substituted amine represented by the following formula: The alkyl group or alkenyl group having 3 to 30 carbon atoms in R in the general formula (XVIII) is
It may be linear, branched, or cyclic.

Here, examples of the monosubstituted amine include butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, laurylamine, stearylamine, oleylamine, benzylamine, and the like. Examples include dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, distearylamine, dioleylamine, dibenzylamine, stearyl monoethanolamine, decyl monoethanolamine, hexyl monopropanolamine. Benzyl monoethanolamine, phenyl monoethanolamine, tolyl monopropanol and the like. Examples of trisubstituted amines include tributylamine, tripentylamine, trihexylamine, tricyclohexylamine, trioctylamine, trilaurylamine, tristearylamine, trioleylamine, tribenzylamine, dioleyl monoethanolamine, dilauryl.・ Monopropanolamine, dioctyl monoethanolamine,
Dihexyl monopropanolamine, dibutyl monopropanolamine, oleyl diethanolamine,
Examples include stearyl dipropanolamine, lauryl diethanolamine, octyl dipropanolamine, butyl diethanolamine, benzyl diethanolamine, phenyl diethanolamine, tolyl dipropanolamine, xylyl diethanolamine, triethanolamine, and tripropanolamine. it can.

Among these phosphorus-based extreme pressure agents, tricresyl phosphate, tri (nonylphenyl) phosphite, dioleyl hydrogen phosphite, 2-ethylhexyl diphenyl phosphite, etc. are preferred in terms of extreme pressure properties and friction characteristics. preferable. In the present invention, one kind of the above extreme pressure agent may be used, or two or more kinds thereof may be used in combination. In addition, the compounding amount is 0.00
A range of 5 to 5% by weight is preferred. If the amount is less than 0.005% by weight, extreme pressure properties and friction characteristics may be insufficient, and if it exceeds 5% by weight, sludge generation may be promoted.

Next, the acid scavenger is blended in the refrigerator oil composition for the purpose of hydrolytic stability.
For example, epoxy compounds such as phenyl glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α-olefin oxide, and epoxidized soybean oil can be used. Among them, phenyl glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, and α-olefin oxide are preferred from the viewpoint of compatibility.

In the present invention, one kind of the above acid scavenger may be used, or two or more kinds thereof may be used in combination. Further, the compounding amount is preferably in the range of 0.005 to 5% by weight based on the base oil. If the amount is less than 0.005% by weight, the acid capturing ability may not be exhibited, and if it exceeds 5% by weight, sludge may be generated. When both the extreme pressure agent and the acid scavenger are used, the total amount is in the range of 0.005 to 5% by weight based on the base oil.

The lubricating oil composition constituting the refrigerating machine oil composition of the present invention further includes a lubricating oil composition as long as the object of the present invention is not impaired.
If necessary, various known additives such as phenol-based and amine-based antioxidants, copper deactivators such as benzotriazole and derivatives thereof, and defoamers such as silicone oil and fluorinated silicone oil are appropriately added. Can be blended. These additives are used in the lubricating oil composition in an amount of 0.5 to 1%.
It is contained in an amount of 0% by weight.

In the present invention, the amount of the CO ₂ refrigerant and the lubricating oil composition used is preferably in the range of 99/1 to 10/90 by weight of the refrigerant / lubricating oil composition. When the amount of the refrigerant is less than the above range, the refrigerating capacity is reduced, and when it is more than the above range, the lubricating performance is undesirably reduced. From such a viewpoint, the weight ratio of the refrigerant / lubricating oil composition is more preferably in the range of 95/5 to 30/70.

The refrigerating machine oil composition of the present invention can be used for various refrigerating machines, but is particularly preferably applied to a compression refrigerating cycle of a compression refrigerating machine. In particular, the refrigerating machine oil composition of the present invention exerts its effects effectively when applied to, for example, a compression refrigeration cycle having an oil separator and / or a hot gas line as shown in each of FIGS. . Usually, a compression refrigeration cycle is a compressor-condenser-
It consists of an expansion valve and an evaporator. Lubricating oil for refrigerators
Generally, a refrigerant having good compatibility with a refrigerant used in a refrigerator is used. However, when a refrigerant mainly containing carbon dioxide gas is used in the above refrigeration cycle, if the refrigerator is lubricated with a generally used lubricating oil, wear resistance is insufficient or stability is insufficient. Could not be used for a long period of time. In particular, this tendency is remarkable when a capillary tube is used as an expansion valve as in a refrigeration cycle of an electric refrigerator or a small air conditioner. Therefore, the lubrication method of the present invention provides a lubricating oil composition having a lubricating oil composition of 100 ° C. when operating a compression refrigeration cycle having an oil separator and / or a hot gas line using a refrigerant containing carbon dioxide as a main component. Characterized in that a composition containing a base oil having a kinematic viscosity of 5.5 to 30 mm ² / s and an extreme pressure agent and / or an acid scavenger in an amount of 0.005 to 5% by weight based on the base oil is used. It is assumed that.

[0068]

EXAMPLES Next, 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 4 and Comparative Examples 1 and 2 To a base oil having the properties shown in Table 1, 1% by weight of tricresyl phosphate (TCP) and 1.5% by weight of α-olefin oxide (based on the base oil) The lubricating oil compositions to which Examples 1 and 2) and 1.5% by weight of phenylglycidyl ether (Examples 3 and 4 and Comparative Examples 1 and 2) were added were evaluated by performing the tests described above. The results are shown in Table 2.

The properties and performance of the lubricating oil composition were determined according to the following methods. (1) Solubility Carbon dioxide gas was blown into 100 g of oil under a pressurized condition of 50 kg / cm ² , and the dissolved amount (% by weight) of carbon dioxide gas in the oil was measured. (2) Shield tube test The catalyst Fe / Cu / Al was put in a glass tube, and a sample was filled at a ratio of carbon dioxide / oil / water = 0.5 g / 4 g / 0.02 g and sealed. After holding at 175 ° C. for 10 days, the oil appearance,
The catalyst appearance, total acid value and the presence or absence of sludge were evaluated.

(3) Hygroscopicity test 10 g of oil was subjected to 85% RH. H. The amount of moisture absorption (% by weight) after standing at (30 ° C.) for 120 hours was determined. (4) Falex baking test The pin / block material was set to ASIC1137 / SAE3135 using a Falex tester. The pin / block was set, 200 g of the sample oil was put into the test container, and carbon dioxide gas was blown at 5 liter / h.
The seizure load was measured at 90 rpm at an oil temperature of 50 ° C.

[0071]

[Table 1]

[0072]

[Table 2]

Examples 5 to 8 and Comparative Examples 3 to 5 To the base oils shown in Table 1, 1% by weight of tricresyl phosphate (TCP) and 1.5% by weight of α-
The lubricating oil composition to which olefin oxide (Examples 5 and 6) and 1.5% by weight of phenylglycidyl ether (Examples 7 and 8 and Comparative Examples 3 and 4) were added was subjected to an actual machine test by the following method to evaluate. went. The results are shown in Table 3.

The actual test of the lubricating oil composition was carried out using the following compression refrigeration cycle. Compression refrigeration cycle method A: Compression refrigeration cycle of "compressor-condenser-expansion valve-evaporator" having an oil separator (see FIG. 2) The expansion valve used was a capillary tube type.

In the actual machine test, a refrigerating machine having an output of 100 W using carbon dioxide as a refrigerant was subjected to a refrigerating test for one year under the following conditions at a ratio of 70% by weight of carbon dioxide and 30% by weight of a lubricating oil composition. Carried out. Operating conditions Suction temperature: 0 ° C. Discharge temperature: 100 ° C. Condenser outlet temperature: 10 ° C. Evaluation method The operation was stopped when an abnormality occurred in the operating state, and each part was observed to investigate the cause.

[0076]

[Table 3]

[0077]

According to the present invention, a refrigerating machine oil composition which has good lubrication performance and sealability and can be used stably for a long period of time in a compression refrigeration cycle using a refrigerant containing CO ₂ as a main component. A lubrication method using the composition can be provided.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a “compressor-condenser-expansion valve-evaporator” compression refrigeration cycle having an oil separator and a hot gas line.

FIG. 2 shows a “compressor-condenser-expansion valve- having an oil separator.
It is a flowchart which shows an example of the compression refrigeration cycle of "evaporator."

FIG. 3 shows a “compressor-condenser- having a hot gas line.
It is a flowchart which shows an example of the compression refrigeration cycle of "expansion valve-evaporator."

FIG. 4 is a flowchart showing an example of a compression refrigeration cycle of “compressor-condenser-expansion valve-evaporator”.

[Explanation of symbols]

 1: Compressor 2: Condenser 3: Expansion valve 4: Evaporator 5: Oil separator 6: Hot gas line 7: Valve for hot gas line

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C10N 30:06 30:10 40:30

Claims (3)

[Claims] 1. A lubricating oil composition comprising a refrigerant mainly composed of CO ₂ and a lubricating oil composition, wherein the lubricating oil composition mainly comprises an ester oil and has a kinematic viscosity at 100 ° C. of 5.5 to 30 mm ² /
s and 0.005 to 5% by weight based on the base oil
A refrigerating machine oil composition comprising an extreme pressure agent and / or an acid scavenger. _{2. A} lubricating oil composition comprising a refrigerant mainly composed of CO ₂ and a lubricating oil composition, wherein the lubricating oil composition mainly comprises an ester oil and has a kinematic viscosity at 100 ° C. of 5.5 to 30 mm ² /
s and 0.005 to 5% by weight based on the base oil
A refrigerating machine oil composition for use in a compression refrigeration cycle having an oil separator and / or a hot gas line, comprising: an extreme pressure agent and / or an acid scavenger. 3. A compression refrigeration cycle having an oil separator and / or a hot gas line, comprising a refrigerant mainly composed of CO ₂ and a lubricating oil composition, wherein the lubricating oil composition mainly comprises an ester oil. Refrigeration containing, as components, a base oil having a kinematic viscosity at 100 ° C. of 5.5 to 30 mm ² / s, and an extreme pressure agent and / or an acid scavenger of 0.005 to 5% by weight based on the base oil. A lubricating method characterized by using a machine oil composition.