JPH06192671A - Lubricating oil for refrigerator - Google Patents

Abstract

PURPOSE:To obtain an oil with a wide range of temperature at which it is compatible with a hydrogen-containing halohydrocarbon refrigerant and a high viscosity index by adding a specified copolymer to a lubricating oil for a refrigerator in which the abovementioned refrigerant is used. CONSTITUTION:An alkyl fumarate copolymer comprising 1-50mol% structural units of formula I and 50-99mol% structural units of formula II (wherein R is 3-8 C alkyl) is added to a lubricating oil for a refrigerator in which a hydrogen-containing halohydrocarbon refrigerant [e.g. R134a (CF3CH2F)] is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating machine lubricating oil using a CFC alternative refrigerant, and more particularly to a refrigerating machine lubricating oil using a hydrogen-containing halogenated hydrocarbon refrigerant.

[0002]

2. Description of the Related Art Conventionally, as a refrigerant used in refrigerators such as building air conditioners, refrigerators and air conditioners, R11
Freon-based refrigerants such as ₃ F) and R 12 (CCl ₂ F ₂ ) have been used. However, these fluorocarbons in the form of substituting all of the hydrocarbons with halogens containing chlorine are subject to global regulation because they lead to ozone depletion in the stratosphere. Therefore, for example, R22 (CHClF ₂ ) or R2 is used as an alternative CFC-based refrigerant that does not damage the ozone layer.
123 (CF ₃ CHCl ₂ ) R141b, (CCl ₂ FC
H ₃ ), R134a (CF ₃ CH ₂ F), R152a (CHF ₂
Hydrogen-containing halogenated hydrocarbon refrigerants such as CH ₃ ) have been developed. Among them, non-chlorinated halogenated hydrocarbons,
For example, R134a (CF ₃ CH ₂ F), R152a (CHF ₂ C
H ₃ ) etc. are regarded as influential.

Refrigerant lubricating oils generally have a wide compatibility temperature range with a refrigerant (compatibility), that is, no clouding occurs at high temperatures (the refrigerant has a high solvability with respect to the lubricating oil), and a molecule of the lubricating oil. High polarity, no precipitation of lubricating oil at low temperature (high solubility of lubricating oil in refrigerant, small molecular weight of lubricating base oil) are required, and it is suitable for various refrigerators. Since the kinematic viscosity ranges are different from each other, it is required to have a kinematic viscosity corresponding to each range.

Naphthenic mineral oils, paraffinic mineral oils, alkylbenzenes, polyglycol mineral oils, ester oils and the like have been used as lubricating oils for conventional freon-based refrigerants. It is almost incompatible and cannot be used. Therefore, polyalkylene glycol-based and polyol polyester-based lubricating oils have been developed. However, all of them have low compatibility with CFC substitute for high kinematic viscosity products, and have high hygroscopicity with polyalkylene glycol-based lubricating oils, which causes problems such as rusting.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention provides a lubricating oil suitable for a refrigerator using a hydrogen-containing halogenated hydrocarbon-based alternative CFC refrigerant, particularly a non-chlorine halogenated hydrocarbon refrigerant. With the goal.

[0006]

The present invention relates to a refrigerating machine lubricating oil using a hydrogen-containing halogenated hydrocarbon refrigerant, which has the following formula (Formula 3):

[0007]

[Chemical 3] 1 to 50 mol% of the structural unit represented by the following formula (Formula 4):

[0008]

[Chemical 4] (Wherein R is each independently a linear or branched alkyl group having 3 to 8 carbon atoms), and a fumaric acid alkyl ester copolymer containing 50 to 99 mol% of the structural unit represented by The lubricating oil for refrigerators is characterized by containing.

The fumaric acid alkyl ester copolymer used in the lubricating oil of the present invention has the structural units represented by the above (formula 3) and (formula 4) in its structure. Here, examples of R include a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group and the like, and structural isomers thereof, which may be linear or branched. Preferably R is an n-butyl group. R may be the same or different. When the structural unit represented by (Chemical Formula 3) is more than 50 mol%, that is, when the number of units derived from diethyl fumarate is more than the number of units derived from dialkyl fumarate ester, the viscosity index extremely decreases. I will end up. The copolymer can be any copolymer such as a random copolymer or a block copolymer.

The above-mentioned fumaric acid alkyl ester copolymer can contain other copolymerization components in addition to the structural units represented by (Chemical Formula 3) and (Chemical Formula 4) as long as it is 20 mol% or less. . Examples of such other copolymerization component include butene and styrene.

The fumaric acid alkyl ester copolymer can be produced, for example, as follows. First, diethyl fumarate and an alkyl fumarate ester are mixed as raw materials in a ratio such that the amount of diethyl fumarate is 50 mol% or less. Here, it is known that the polymerization of fumaric acid ester occurs after the isomerization of maleic acid ester (Acta Polymerica 39 (1988) No. 1, 5-8), so the corresponding diethyl maleate and alkyl maleate Esters can also be used as raw materials. Next, the raw material is polymerized in the presence of a polymerization initiator. When starting from the corresponding maleic acid diethyl and maleic acid alkyl ester, an isomerization catalyst (eg, morpholine, piperidine, etc.) is additionally allowed to coexist. The details of the polymerization reaction can follow the method described in the above-mentioned document.

As the polymerization initiator used in the polymerization reaction, known compounds can be used, for example, azo compounds such as azonitrile compounds, azoamidine compounds, cyclic azoamidine compounds, azoamide compounds, alkylazo compounds, ketone peroxides, peroxyketals. Examples include peroxide-based polymerization initiators such as hydroperoxide, dialkyl peroxide, diacyl peroxide, diperoxydicarbonate, and peroxyester.

The polymerization initiator is at least 1/1 with respect to the raw material.
It is preferably used in a molar ratio of 00. Further, in order to improve the yield, it is preferable to add the initiator to the polymerization reaction system not batchwise but batchwise or continuously.
The polymerization temperature is preferably 50 to 180 ° C.

The polymerization reaction system may further contain a solvent.
As the solvent, those generally used for radical polymerization,
For example, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, p-xylene, o-xylene, benzene, toluene, tetrahydrofuran and the like can be used.

The degree of polymerization of the fumarate ester copolymer is adjusted so as to have an appropriate kinematic viscosity as a refrigerator lubricating oil described later, but the molecular weight of the refrigerator lubricating oil is preferably 400 to 2000. , And more preferably 400
˜1600. The kinematic viscosity is 2-100 cst
It is preferably in the range of (100 ° C.). When the molecular weight is large, the viscosity index is improved, but it tends to be solid at room temperature and the compatibility with the refrigerant tends to be lowered.

In the lubricating oil of the present invention, one type of fumaric acid ester copolymer may be used, or two or more types of copolymers having different structures, molecular weights and the like may be used. For example, mainly the fumaric acid ester copolymer having the above-mentioned molecular weight range, and further having a molecular weight of 3,000 to 1,000.
It is preferable to add a small amount of the fumaric acid ester polymer of 0 because the kinematic viscosity and the viscosity index are improved.

Further, in addition to the fumarate ester copolymer satisfying the above conditions, a fumarate ester polymer having another structural unit can be added. A preferable fumaric acid ester polymer is, for example, the following formula (Formula 5) disclosed in Japanese Patent Application No. 3-344484:

[0018]

[Chemical 5] (In the formula, R ₁ and R ₂ each independently have 1 carbon atom.
9 is a linear or branched alkyl group, an allyl group or an optionally substituted polyalkylene oxide group, R ₃ is an alkylene group, a substituted alkylene group or an alkylene oxide group, and m is 0. As described above, n is an integer of 1 or more, and R ₃ is 50 mol% or less of the whole)
A fumaric acid ester polymer represented by

The refrigerating machine lubricating oil of the present invention contains, for the purpose of adjusting the kinematic viscosity and viscosity index thereof for various refrigerating machines, in addition to the above-mentioned fumarate ester copolymer, for example, an organic compound. Lubricating oil components for refrigerators that have been conventionally used, such as carboxylic acid ester, polyalkylene glycol, alkylbenzene, and mineral oil, can be mixed and used at a desired ratio. Particularly preferable as the refrigerator lubricating oil of the present invention is, in addition to the above-described fumarate ester copolymer, a kinematic viscosity range at 100 ° C. of 2 to
It contains an organic carboxylic acid ester of 30 cst and / or a polyalkylene glycol. The organic carboxylic acid ester and / or polyalkylene glycol is preferably added in a proportion of 1 part by weight or less relative to 1 part by weight of the fumarate ester copolymer. If the amount of the organic carboxylic acid ester and / or the polyalkylene glycol is too large, the high temperature side compatibility tends to deteriorate and the viscosity tends to decrease.

Examples of such organic carboxylic acid ester include those having high molecular polarity. (1) First, polyesters of an aliphatic polyhydric alcohol and a linear or branched fatty acid can be used.

As the aliphatic polyhydric alcohol forming such polyesters, trimethylolpropane,
Examples thereof include ditrimethylolpropane, trimethylolethane, ditrimethylolethane, pentaerythritol, dipentaerythritol, tripentaerythritol and the like. The fatty acid preferably has 3 to 12 carbon atoms, and preferable examples thereof include propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, Isovaleric acid, neopentanoic acid, 2-methylbutyric acid, 2-ethylbutyric acid,
Examples thereof include 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, isodecanoic acid, 2,2′-dimethyloctanoic acid, 2-butyloctanoic acid and the like.

Preferred polyesters of the above-mentioned aliphatic polyhydric alcohol and fatty acid include pentaerythritol, dipentaerythritol, tripentaerythritol and the like, or a mixture thereof, with 5 to 12 carbon atoms, more preferably 5 to 7 carbon atoms. 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, etc. Ester oils with these mixtures, which can improve the compatibility with the refrigerant, especially at low temperatures.

Further, partial esters of an aliphatic polyhydric alcohol and a linear or branched fatty acid can also be used. At this time, the above-mentioned polyhydric alcohol can be used as the polyhydric alcohol. The fatty acid preferably has 3 to 9 carbon atoms, and preferable examples thereof include propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, 2-methylhexanoic acid and 2-ethylhexanoic acid. , Isooctanoic acid, isononanoic acid and the like. These partial esters can be obtained by appropriately controlling the number of moles of the reaction between the aliphatic polyhydric alcohol and the fatty acid and causing the reaction. (2) Neopentyl glycol is used as the 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 , 2-methylhexanoic acid, 2-
It is also possible to use diesters with ethylhexanoic acid, isooctanoic acid, isononanoic acid and the like. (3) Partial esters of an aliphatic polyhydric alcohol and a linear or branched fatty acid having 3 to 12 carbon atoms, and a linear or branched aliphatic dibasic acid and / or aromatic polybasic acid It is also possible to use complex esters with basic acids.

Such aliphatic polyhydric alcohols include trimethylolpropane, trimethylolethane,
Pentaerythritol and dipentaerythritols can be used.

Examples of the linear or branched fatty acid having 3 to 12 carbon atoms include propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid and decanoic acid. , Dodecanoic 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, etc. can be used.

The complex esters preferably have 5 to 7 carbon atoms, more preferably 5 to 6 carbon atoms.
With the use of fatty acids of, the resulting ester oil may have improved compatibility with the refrigerant, especially at low temperatures. As such a fatty acid, isovaleric acid, valeric acid, hexanoic acid, 2-methylbutyric acid, 2-ethylbutyric acid or a mixture thereof is used, and those having 5 carbon atoms and 6 carbon atoms are contained in a weight ratio of 10 : 90-9
Fatty acids mixed in a ratio of 0:10 can be preferably used.

As the aliphatic dibasic acid that can be used for esterification with polyhydric alcohol together with this fatty acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid. , Dodecanedioic acid, tridecanedioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid, docosanedioic acid and the like. Further, examples of the aromatic dibasic acid include phthalic acid and isophthalic acid, examples of the aromatic tribasic acid include trimellitic acid, and examples of the aromatic tetrabasic acid include pyromellitic acid. To be

The fatty acid and the aliphatic dibasic acid and / or aromatic polybasic acid may be used in a ratio of 6: 1 (molar ratio), and in the esterification reaction, these acids (fatty acid, aliphatic or The ratio of the total amount of the aromatic polybasic acid) and the amount of the polyhydric alcohol used may be 7: 1.

In the esterification reaction, first, a polyhydric alcohol and an aliphatic dibasic acid and / or an aromatic polybasic acid are reacted at a predetermined ratio to partially esterify, and then the partially esterified product and a fatty acid are reacted. Alternatively, the reaction order of the acids may be reversed, or the acids may be mixed and subjected to esterification. (4) Linear or branched dialkyl esters of aliphatic dibasic acids (having 16 to 22 carbon atoms) may be used.

As the aliphatic dibasic acid, the aliphatic dibasic acid shown in (3) above can be used. Preferred aliphatic dibasic acids are succinic acid, adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, carboxyoctadecanoic acid, carboxymethyloctadecanoic acid and the like.
As the alkyl alcohol component, an alcohol having 5 to 8 carbon atoms can be used, and examples thereof include amyl alcohol, hexyl alcohol, heptyl alcohol and octyl alcohol, and isomers thereof, preferably isoamyl alcohol, isohexyl alcohol and octyl alcohol. Is. Specific examples include dioctyl adipate, diisoheptyl adipate, dihexyl sebacate, and diheptyl succinate. (5) Dialkyl esters of aromatic dibasic acids (having 18 to 26 carbon atoms) can also be used.

Examples of the aromatic dibasic acid include phthalic acid, isophthalic acid and their derivatives. Also,
As the alkyl alcohol component, the alcohol having 5 to 8 carbon atoms shown in (4) above can be used. Preferred alcohols are isoamyl alcohol, isoheptyl alcohol and octyl alcohol. Such diesters include dioctyl phthalate, diisoheptyl phthalate, diisoamyl phthalate and the like. (6) In addition, methanol as an alcohol component,
Monohydric alcohols selected from ethanol, propanol, butanol, etc. and their isomers, polyhydric alcohols such as glycerin, trimethylolpropane, etc. and, for example, selected from ethylene oxide, propylene oxide, butylene oxide, amylene oxide, etc. and their isomers. 1 to 10 mol, preferably 1 of alkylene oxide
It is also possible to use organic carboxylic acid esters using ~ 6 mol adducts.

As the acid for the alkylene oxide adduct of monohydric alcohol, the aliphatic dibasic acids and aromatic polybasic acids shown in (3) above can be used. Further, as the acid for the alkylene oxide adduct of polyhydric alcohol,
The linear or branched fatty acid having 3 to 12 carbon atoms shown in (1) above can be used.

As the fatty acid constituting the above-mentioned organic carboxylic acid ester, a linear or branched fatty acid can be used, but when a branched fatty acid is used, the hydrolysis stability is more excellent, Further, compatibility with a hermetic coil or the like can be achieved.

These organic carboxylic acid esters can be obtained by esterifying alcohols and fatty acids in the presence of an acid catalyst such as phosphoric acid. Normal,
Total acid value 0.1-0.5 mgKOH / g, peroxide value 0.
1-5 meq / kg, aldehyde value 0.1-5 mg KOH /
g, bromine number index 1-100 mg / 100g, ash content 5-50 ppm,
A water content of 300 to 1000 ppm is obtained.

However, if the total acid value of the refrigerating machine lubricating oil is high, problems such as corrosion of metal parts occur, and the refrigerating machine lubricating oil itself is hydrolyzed to function as a refrigerating machine lubricating oil. In general, in refrigerators and the like, the motor part is arranged in the lubricating oil, so that high insulation is required, so that the lubricating oil for refrigerators has a total acid value of 0. It is preferably not more than 05 mgKOH / g.

Further, the peroxide value, the aldehyde value, and the bromine number index are kept low in order to further improve the refrigerant stability, and the ash content is restrained in order to suppress sludge, etc. Therefore, it is preferable to suppress the water content. Therefore, by refining the above-mentioned esters obtained by a normal esterification reaction and adjusting the indexes showing the above-mentioned properties of the ester oil to a range suitable as a refrigerating machine oil, a more excellent refrigerating machine oil can be obtained. .

The organic carboxylic acid 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, but the temperature is preferably 100 ° C. or lower.

Examples of the polyalkylene glycol which can be used in the present invention include homopolymers of alkylene glycols such as polyethylene glycol and polypropylene glycol, and copolymers of alkylene oxides such as ethylene oxide and propylene oxide. The terminal group may be substituted with a methyl group, an ethyl group, a propyl group, a butyl group or the like. Average molecular weight is usually 500-18
00, preferably 800 to 1600, and when it is less than 500, the compatibility with the refrigerant at high temperature is high, but the kinematic viscosity is low and the thermal stability tends to be low. If it exceeds 1800, the kinematic viscosity is high, but the compatibility with the refrigerant tends to decrease.

A viscosity index improver may be added to the lubricating oil for a refrigerator of the present invention for the purpose of obtaining desired kinematic viscosity and viscosity index required for various refrigerators. As such a viscosity index improver, a conventional one can be used, and examples thereof include polyolefin (for example, polybutene, poly α-olefin, ethylene / α-olefin copolymer and the like, including hydrogenated products), polymethacrylate (for example, methacrylate, Acrylic homopolymers and copolymers containing acrylic acid and methacrylic acid as components), polyisobutylene, polyalkylstyrene, ethylene-propylene copolymer, styrene-diene copolymer, styrene-maleic anhydride copolymer Examples include coalescence. The content of these viscosity index improvers is usually 0.1 to 20% by weight, preferably 1 to 10% by weight, based on the base oil.

The refrigerator lubricating oil of the present invention is usually (100
A kinematic viscosity range (at ° C.) Of 2 to 100 cst, preferably 2 to 80 cst, is used. When it is less than 2 cst, the compatibility with the refrigerant at high temperature is high, but the kinematic viscosity is low, the lubricity and sealing properties are deteriorated, and the thermal stability tends to be low. If it exceeds 100 cst, the compatibility with the refrigerant tends to decrease. However, even within this range, the range of kinematic viscosity used differs depending on the model used. For refrigerators, for example, it is 2 to 9 cst, preferably 3 to 7 cst. 7 to 4 for car air conditioners
It is 0 cst. Among car air conditioners, the reciprocating type compressor has 7 to 15 cst, preferably 8 to 11 cst, and the rotary type compressor has 15 to 40 cst, preferably 20 to 20 cst.
35 cst. In the refrigerator, if it exceeds 9 cst, there is a problem that the friction loss in the sliding portion becomes large. Further, in the reciprocating type car air conditioner, there is a problem that lubricity is deteriorated when it is less than 7 cst, and there is a problem that the friction loss in the sliding portion becomes large when it exceeds 15 cst. If it is less than cst, there is a problem that the sealing property is deteriorated.

Various additives usually used can be used in the lubricating oil for refrigerator of the present invention. As the antiwear agent, for example, a general formula (RO) ₃ P = S (wherein R is an alkyl group,
A compound represented by an allyl group or a phenyl group, which may be the same or different, for example, a sulfur-based antiwear agent such as trialkylphosphorothionate, triphenylphosphorothionate, and alkyldiallylphosphorothionate , Diphenyl sulfide, diphenyl disulfide, di n-butyl sulfide, di-n-butyl disulfide, di-tert-dodecyl disulfide, di-tert-
Sulfides such as dodecyl trisulfide, sulfurized spalm oil, sulfurized oils and fats such as sulfurized dipentene, thiocarbonates such as xanthic disulfide, zinc primary alkylthiophosphate, zinc secondary alkylthiophosphate, alkyl Examples include zinc thiophosphate antiwear agents and phosphorus antiwear agents such as zinc allylthiophosphate and zinc allylthiophosphate. Examples of phosphorus antiwear agents 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, dibutyl phenyl phenyl phosphate Phosphates such as phosphates and tributylphenyl phosphate, tris Sodium phosphite ester, phosphite ester such as diisopropyl phosphite ester, hexamethylphosphoric triamide, n-butyl-n-dioctylphosphinate, di-n-butylhexylphosphonate, amine dibutylphosphonate, dibutylphosphonate Other phosphorus compounds such as roamidate can be used.

These antiwear agents may be used alone or in combination of two or more. The proportion of the antiwear agent used is usually 0.01 to 5% by weight, preferably 0.1 to 3% by weight, based on the base oil.

Antioxidants may also be used, for example, amine-based antioxidants such as dioctyldiphenylamine, phenyl-α-naphthylamine, alkyldiphenylamine, N-nitrosodiphenylamine, 2,6-di-t-butylparacresol, 4,4'-Methylenebis (2,6-di-t-butylphenol), 2,6-di-t-butyl-α-dimethylamine para-cresol, 2,6-di-t-butylphenol and other phenolic antioxidants Examples thereof include phosphorus antioxidants such as agents, tris (2,4-di-t-butylphenyl) phosphite, trisnonylphenylphosphite, and triphenylphosphite. These may be used alone, but 2
It is also possible to use a combination of two or more species. The proportion of the antioxidant used is usually 0.01 to 10% by weight, preferably 0.01 to 1.0% by weight, based on the base oil.

Corrosion inhibitors may also be used, eg isostearates, n-octadecyl ammonium stearate, duomin T.diolate, lead naphthenate, sorbitan oleate, pentaerythritol oleate, oleyl sarcosine, alkylsuccinates. Examples thereof include acids, alkenylsuccinic acids, and derivatives thereof. These may be used alone or in combination of two or more. The proportion of the corrosion inhibitor used is usually 0.001 to 1.0% by weight, preferably 0.0 to 1.0% by weight, based on the base oil.
It is 1 to 0.5% by weight.

It is also possible to use an antifoaming agent such as silicone. The use ratio is usually 0.0001 to 0.003% by weight, preferably 0.00
It is from 01 to 0.001% by weight.

Further, a metal deactivator can be used, and examples thereof include benzotriazole, benzotriazole derivatives, thiadiazole, thiadiazole derivatives, triazole, triazole derivatives and dithiocarbamates. These may be used alone or in combination of two or more. The proportion of the metal deactivator used is usually 0.01 to 10% by weight, preferably 0.01 to 1.0% by weight, based on the base oil.

Further, a rust preventive can be used, and examples thereof include succinic acid, succinic acid ester, oleic acid tallow amide, barium sulfonate, calcium sulfonate and the like. These may be used alone or in combination of two or more. The proportion of the rust preventive used is usually 0.01 to 10% by weight, preferably 0.01 to 1.0% by weight, based on the base oil.

The lubricating oil for a refrigerator of the present invention can be used as a lubricating oil in a refrigerator used in a refrigeration system in a wide field such as a building or household air conditioner, a refrigerator, a freezer, a car air conditioner and the like.

Further, the lubricating oil of the present invention can be added as an additive to a lubricating oil for a refrigerator having other substances such as organic carboxylic acid ester, polyalkylene glycol, alkylbenzene and mineral oil as a base oil. .

[0050]

Since the lubricating oil for a refrigerator of the present invention uses the fumaric acid alkyl ester copolymer having the above-mentioned specific structure, it can be used as an alternative CFC-based refrigerant such as hydrogen-containing halogenated hydrocarbon, especially R134a. Wide compatible temperature range and high viscosity index. It is also thermally and chemically stable and has excellent lubricity.

The present invention will be described in more detail by the following examples.

[0052]

Example 1 A 200 ml single neck flask was charged with di-n-butyl fumarate 29.
4 mmol (67.1 g, 67.8 ml) and diethyl fumarate 196 mmol (33.8 g, 32.2 m).
l) was added (molar ratio 6: 4) and a cooling pipe was attached,
This was set in the oil bath. The temperature was maintained at 60 ° C. while stirring with a magnetic stirrer, and 20 mmol of 2,2′-azobisisobutyronitrile (AIBN) (3.
8 g) and 30 ml of tetrahydrofuran were added, and heating and stirring were continued at this temperature for 72 hours. Then, the light fraction was distilled off under reduced pressure to obtain 91.6 g of a polymer. Yield 91%.

The kinematic viscosity of the obtained polymer was measured to determine the viscosity index. A compatibility test was also conducted.
The results are shown in Table 1.

The yield was obtained as a ratio of the weight of the residue to the total weight of the starting ester monomers after removing the light components from the polymerization reaction system by distillation under reduced pressure. Further, the compatibility test was conducted as follows. That is, sample oil and a refrigerant (1,1,1,2-tetrafluoroethane, R134
2) in a) at a ratio of 15% by volume of sample oil
The glass tube was sampled and mixed so that the glass tube was placed in a constant temperature bath having a cooling device, and the separation temperature of the sample oil and the refrigerant at low temperature was measured. Next, the sample oil and the refrigerant are put into another glass tube, and the total amount of the sample oil is 10% by volume of 2 ml in total.
The glass tube was sampled and mixed so that the glass tube was placed in a constant temperature bath having a heating device, and the separation temperature of the sample oil and the refrigerant at high temperature was measured. Example 2 The amounts of di-n-butyl fumarate and diethyl fumarate were 402 mmol (91.8 g, 92.7 ml) and 45 mmol (7.7 g, 7.3 ml), respectively (molar ratio 9: 1). The polymerization reaction was performed in the same manner as in Example 1 except for the above. Thus, 89.6 g of a polymer was obtained. Yield 90%.

The kinematic viscosity of the obtained polymer was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Example 3 Instead of di-n-butyl fumarate and diethyl fumarate, 275 mmol of di-n-propyl fumarate (55.0
g, 55.0 ml) and diethyl fumarate (275 mmol, 47.3 g, 45.0 ml) were used (molar ratio 5: 5), and the polymerization reaction was performed in the same manner as in Example 1. Thus, 99.5 g of a polymer was obtained. Yield 97%.

The kinematic viscosity of the obtained polymer was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Example 4 Instead of di-n-butyl fumarate and diethyl fumarate, 190 mmol of di2-ethylhexyl fumarate (6
4.7 g, 68.8 ml) and diethyl fumarate 19
The polymerization reaction was carried out in the same manner as in Example 1 except that 0 mmol (32.8 g, 31.2 ml) was used (molar ratio 5: 5). Thus, 95.6 g of a polymer was obtained. Yield 98
%.

The kinematic viscosity of the obtained polymer was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Example 5 The polymer prepared in Example 2 and dimethyl ether of polypropylene glycol having a kinematic viscosity at 100 ° C. of 19 cst were mixed at a ratio of 80:20 (weight ratio) to prepare a lubricating oil.

The kinematic viscosity of the obtained lubricating oil was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Example 6 The polymer prepared in Example 2 and the ester reaction product of dipentaerythritol and hexanoic acid having a kinematic viscosity at 100 ° C. of 11 cst were mixed at a ratio of 80:20 (weight ratio). Then, it was used as a lubricating oil.

The kinematic viscosity of the obtained lubricating oil was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Comparative Example 1 A 200 ml single neck flask was charged with diethyl fumarate 610.
After adding millimolar (105 g, 100 ml) and attaching a cooling pipe, this was set in an oil bath. While stirring with a magnetic stirrer, keep the temperature at 80 ° C,
70 mmol (11.5 g) of 2,2'-azobisisobutyronitrile (AIBN) and 100 of methyl ethyl ketone
ml was added and heating and stirring was continued at this temperature for 24 hours. Then, the light fraction was distilled off under reduced pressure to obtain 97.8 g of a polymer. Yield 93%.

With respect to the obtained polymer, the kinematic viscosity was measured in the same manner as in Example 1 to obtain the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Comparative Example 2 A 200 ml one-necked flask was charged with di-n-butyl fumarate 43.
After adding 4 mmol (99 g, 100 ml) and attaching a cooling pipe, this was set in an oil bath. While stirring with a magnetic stirrer, keep the temperature at 90 ° C,
61 mmol (10.0 g) of 2,2'-azobisisobutyronitrile (AIBN) and methyl isobutyl ketone 8
0 ml was added and heating and stirring was continued at this temperature for 24 hours.
Then, the light fraction was distilled off under reduced pressure to obtain 84.9 g of a polymer. Yield 86%.

The kinematic viscosity of the obtained polymer was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Comparative Example 3 A 200 ml one-necked flask was charged with diethyl fumarate 610.
After adding millimolar (105 g, 100 ml) and attaching a cooling pipe, this was set in an oil bath. The temperature was kept at 155 ° C while stirring with a magnetic stirrer to obtain 2,2'-azobisisobutyronitrile (AIBN) 7
0 mmol (11.5 g) and 100 ml of o-xylene
Was added and heating and stirring was continued at this temperature for 24 hours. Then, the light fraction was distilled off under reduced pressure to obtain 104.8 g of a polymer. Yield 100%.

The kinematic viscosity of the obtained polymer was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Comparative Example 4 In a 200 ml one-necked flask, di-n-butyl fumarate 43 was added.
After adding 4 mmol (99 g, 100 ml) and attaching a cooling pipe, this was set in an oil bath. While stirring with a magnetic stirrer, keep the temperature at 80 ° C,
2,2'-azobisisobutyronitrile (AIBN) 80 mmol (13.1 g) and tetrahydrofuran 10 m
1 was added and heating and stirring was continued at this temperature for 72 hours. Then, the light fraction was distilled off under reduced pressure to obtain 94.1 g of a polymer. Yield 95%.

The kinematic viscosity of the obtained polymer was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Comparative Example 5 In a 200 ml one-necked flask, di-n-propyl fumarate 4 was added.
After putting 99 mmol (100 g, 100 ml) and attaching a cooling pipe, this was set in an oil bath. While stirring with a magnetic stirrer, keeping the temperature at 135 ℃, 2,2'-azobisisobutyronitrile (AIBN)
70 mmol (11.5 g) and p-xylene 100 m
1 was added and heating and stirring was continued at this temperature for 24 hours. Then, the light fraction was distilled off under reduced pressure to obtain 24.8 g of a polymer. Yield 25%.

The kinematic viscosity of the obtained polymer was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1. Comparative Example 6 Into a 200 ml one-necked flask, 276 mmol of di2-ethylhexyl fumarate (94 g, 100 ml) was placed, and after a cooling pipe was attached, this was set in an oil bath.
While stirring with a magnetic stirrer, increase the temperature to 135 ° C.
, 2,2'-azobisisobutyronitrile (AIB
N) 46 mmol (7.6 g) and p-xylene 250
ml was added and heating and stirring was continued at this temperature for 8 hours. Then, the light fraction was distilled off under reduced pressure to obtain 54.8 g of a polymer. Yield 58%.

The kinematic viscosity of the obtained polymer was measured in the same manner as in Example 1 to determine the viscosity index. Also,
Compatibility tests were also conducted. The results are shown in Table 1.

[0066]

[Table 1]

[0067]

The refrigerating machine lubricating oil of the present invention is an alternative fluorocarbon refrigerant such as a hydrogen-containing halogenated hydrocarbon, especially R13.
Wide temperature range compatible with 4a and high viscosity index. Therefore, it is very useful industrially.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10M 105: 18) C10N 20:02 30:00 A 8217-4H 30:02 40:30 (72) Inventor Hiro, Ueno-cho, Saitama Prefecture, Nishi-tsurugaoka 1-3-1, Tonen Co., Ltd. (72) Inventor Takehisa Sato, Saitama-ken, Nishitsurugaoka, 1-3-1, Tonenka Co., Ltd. Research Institute (72) Inventor Toshiaki Kuribayashi 1-3-3 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Tonen Co., Ltd. Research Institute (72) Taisei Ueda 1-3, Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Prefecture No. 1 Tonen Co., Ltd. Research Institute

Claims (2)

[Claims] 1. A refrigerating machine lubricating oil using a hydrogen-containing halogenated hydrocarbon refrigerant, which has the following formula (Formula 1): [Chemical 2] (Wherein R is each independently a linear or branched alkyl group having 3 to 8 carbon atoms), and a fumaric acid alkyl ester copolymer containing 50 to 99 mol% of the structural unit represented by A refrigerating machine lubricating oil comprising: 2. The kinematic viscosity range at 100 ° C. is 2-3.
The refrigerator lubricating oil according to claim 1, further comprising an organic carboxylic acid ester of 0 cst and / or a polyalkylene glycol.