JPH08127791A - Lubricating oil composition for refrigerator - Google Patents

Abstract

PURPOSE: To provide a lubricating oil compsn. improved in lubricity, chlorofluorocarbon stability, electrical insulating properties, and resistance to wear by adding a specific phosphoric ester compd. to a lube base oil for a refrigerator wherein a hydrofluorocarbon is used as the refrigerant. CONSTITUTION: For example, 4-amino-1-butanol, conc. sulfuric acid and triethylamine are added to a soln. of bis(p-nitrophenyl) phosphate monohydrate in pyridine. The resulting mixture is refluxed, then stripped of the solvent, and mixed with water and barium hydroxide for neutralization to obtain a phosphoric ester compd. having an aminoalkyl group (s) in the molecule and represented by the general formula (wherein R1 and R2 are each H or 1-18C aminoalkyl, but are not simultaneously H). 0.05-5wt.% phosphoric ester thus obtd. is added to a lube base oil for a refrigerator wherein a hydrofluorocarbon is used as the refrigerant.

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 which uses Freon as a refrigerant.
The present invention relates to a lubricating oil composition suitable for use in compressing an alternative CFC-based refrigerant such as 2-tetrafluoroethane (R134a).

[0002]

2. Description of the Related Art Conventionally, in a refrigerator or a refrigerator system such as a refrigerator or an air conditioner, a CFC containing fluorine and chlorine as a refrigerant, for example, chlorofluorocarbon (CFC).
R11 (trichloromonofluoromethane) and R1
2 (dichlorodifluoromethane), R22 (monochlorodifluoromethane), which is hydrochlorofluorocarbon (HCFC), and the like are used. Further, as refrigerating machine lubricating oils to be used with them, known are paraffinic and naphthenic mineral oils, and alkylbenzene and ester synthetic oils. R11, R12
Chlorine contained in the molecule such as has a preferable effect of preventing abrasion by reacting with the metal on the sliding surface in the refrigerator system. However, this type of CFC compound
When released into the atmosphere, most of it is not decomposed, destroys the ozone layer in the stratosphere, and adversely affects biological systems, and its use is being regulated internationally. for that reason,
Studies have been widely conducted on alternative CFC substances that do not contain chlorine.

As an alternative to R11 and R12, R1
Hydrogen-containing fluorohydrocarbons such as 34a (1,1,1,2-tetrafluoroethane) have been proposed. R134
Since a has almost the same physical properties as R12 and an ozone depletion potential of zero, it has been noted, but a suitable lubricating oil to be used with it has not been found yet. Therefore, development of a lubricating oil that can be used in a refrigerator using this refrigerant has become an important issue. Hydrogen-containing fluorohydrocarbons, which do not have chlorine atoms in the molecule, do not act as extreme pressure agents on the refrigerant.Therefore, lubricants used in refrigeration systems that use hydrogen-containing fluorohydrocarbons have extreme pressure agents. Is essential.

As a refrigerating machine oil using hydrogen-containing fluorohydrocarbon as a refrigerant, a base oil containing an oxygen-containing compound as a main component, a phosphate triester having a hydrocarbon group or an oxygen-containing hydrocarbon group as an essential component, and a halogen It has been proposed to add a contained phosphoric acid triester, an acidic phosphoric acid ester, and an acidic phosphoric acid ester amine salt as an extreme pressure agent (JP-A-5-230487). However, these halogen-containing phosphoric acid triesters, acidic phosphoric acid esters, and acidic phosphoric acid ester amine salts are liable to cause a corrosion reaction, and when a corrosion reaction occurs, there is a drawback that remarkable wear is caused to a metal part in the refrigerator. there were.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a lubricating oil composition for a refrigerating machine, which improves the lubricity of a refrigerating machine oil using hydrogen-containing fluorohydrocarbon as a refrigerant and has excellent wear resistance. To aim.

[0006]

[Means for Solving the Problems]
As a result of intensive research to develop a lubricating oil for refrigerating machines, which has excellent lubrication performance in hydrogen-containing fluorohydrocarbon refrigerants such as 134a and which is also effective in wear resistance, It was found that the above object can be achieved by adding a phosphoric acid ester compound having an aminoalkyl group, and the present invention has been completed. That is, the present invention provides a base oil of a refrigerating machine oil having a hydrogen-containing fluorohydrocarbon as a refrigerant with a phosphoric acid ester compound represented by the following general formula (1) having an aminoalkyl group in the molecule of 0.05 Provided is a refrigerator lubricating oil containing 5% by weight to 5% by weight.

[0007]

Embedded image

In the formula, R ₁ and R ₂ may be the same or different and each represents hydrogen or an aminoalkyl group having 1 to 18 carbon atoms, and is not hydrogen at the same time.

[0009]

The lubricating oil of the present invention having the above structure has excellent lubricity,
Moreover, it has excellent performance as a lubricating oil for refrigerators, such as stability against CFCs, electrical insulation, and abrasion resistance. If the addition amount of the above-mentioned phosphoric acid ester compound to the base oil of the refrigerating machine oil is less than 0.05% by weight, the antiwear property is deteriorated, and the addition amount is 5% by weight.
If it exceeds, there is a problem of metal corrosion.

Examples of the lubricating base oil for refrigerators containing the phosphoric acid ester compound having an aminoalkyl group of the present invention include the following refrigerator oils conventionally used or mixtures thereof. That is, as the conventional refrigerating machine oil, for example, paraffin-based, naphthene-based mineral oil, alkylbenzenes, polybutenes, α-olefin oligomers, polyalkylene glycols, diesters, polyol esters, phosphoric acid esters, silicic acid esters. Examples thereof include silicones, silicones, polyphenyl ethers and perfluoropolyethers. Among these lubricating base oils for refrigerators, ester-based oils or polyalkylene glycol-based oils are most suitable in view of compatibility with hydrogen-containing fluorohydrocarbons that are refrigerants. As the ester oil, for example, a polyol ester or a complex ester can be used.

The phosphoric acid ester to be added to the refrigerating machine lubricating oil of the present invention is obtained by a conventional method for producing an ester, and in the aminoalkyl group thereof, the substitution position of the amino group is the terminal farthest from the phosphorus atom or the intermediate position. Either part is fine. The carbon number of the aliphatic hydrocarbon is 1-18, preferably 3-9. Specifically, aminomethyl group, aminoethyl group, aminopropyl group, aminobutyl group, aminopentyl group, aminohexyl group, aminoheptyl group, aminooctyl group, aminononyl group, aminodecyl group, aminoundecyl group, aminododecyl group. Group, aminotridecyl group, aminotetradecyl group, aminopentadecyl group, aminohexadecyl group, aminoheptadecyl group, aminooctadecyl group and the like.

The refrigerating machine lubricating oil of the present invention may be used in admixture with additives such as an antioxidant, an antifoaming agent, a metal deactivator, and a heat stability improver. it can. Examples of the antioxidant include 2,6-ditertiarybutyl-p-cresol and α-naphthylamine. Examples of the defoaming agent include silicone oils such as dimethylpolysiloxane and organosilicates such as diethyl silicate. Examples of the metal deactivator include benzotriazole. Examples of the thermal stability improver include phosphite compounds, phosphine sulfide compounds, and other glycidyl ethers.

[0013]

EXAMPLES The present invention will now be described in more detail with reference to examples. However, the present invention is not limited to the examples. Example 1 First, a phosphoric acid ester having an aminobutyl group was synthesized as follows. To a pyridine solution of 34 g (0.1 mol) of bis (p-nitrophenyl) phosphate monohydrate, 17.8 g (0.2 mol) of 4-amino-1-butanol was added.
Mol), concentrated sulfuric acid 14.7 g (0.15 mol), and triethylamine 10.1 g (0.1 mol) were added, and the mixture was refluxed for 3 hours. After removing the solvent, water and barium hydroxide were added for neutralization, and the mixture was concentrated, and the oily residue was recrystallized from ethanol. It was confirmed by NMR that the obtained phosphoric acid ester was an ester of aminobutanol.

This phosphoric ester having an aminobutyl group is used as a polyol ester oil (RB68 manufactured by Nippon Oil Co., Ltd.).
The lubricating oil containing 1000 ppm in the base) is sealed in a hermetic rotary refrigerant compressor, and HFC1 is used as a refrigerant.
34a (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was used and operated at 25 ° C. for 1000 hours. After the operation was completed, the electric wire covering material of the motor coil, the insulating paper, and the refrigerating machine oil itself were examined, and it was found that there was no abnormality in all and it was very good. No significant wear was observed on the sliding portions of the vanes and rollers, and sludge deposited in the oil was hardly observed.

Example 2 First, a phosphoric acid ester having an aminohexyl group was synthesized as follows. To a pyridine solution of 34 g (0.1 mol) of bis (p-nitrophenyl) phosphate monohydrate, 23.4 g (0.2 mol) of 6-amino-1-hexanol and 14.7 g (0. 1
5 mol), and triethylamine 10.1 g (0.1
Mol) was added and the mixture was refluxed for 3 hours. After removing the solvent, water and barium hydroxide were added for neutralization, and the mixture was concentrated and the oily residue was recrystallized from ethanol. The obtained phosphoric acid ester is an ester of aminohexanol.
Confirmed by

This phosphoric acid ester having an aminohexyl group is used as a polyol ester oil (RB68 manufactured by Nippon Oil Co., Ltd.).
base) containing 1000 ppm of lubricating oil,
Enclosed in hermetic rotary refrigerant compressor, HFC as refrigerant
Using 134a (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.), operation was performed at 25 ° C. for 1000 hours. After the operation is completed, the motor coil wire covering and insulating paper,
Further, when the refrigeration oil itself was examined, it was found that there was no abnormality in all and it was very good. No significant wear was observed on the sliding portions of the vanes and rollers, and sludge deposited in the oil was hardly observed.

[Comparative Example] Triphenyl phosphate was used as a polyol ester oil (RB68 ba manufactured by Nippon Oil Co., Ltd.).
se), 1000 ppm of lubricating oil is enclosed in a hermetic rotary refrigerant compressor, and HFC134 is used as a refrigerant.
a (manufactured by Mitsui DuPont Fluorochemicals),
The operation was performed at 25 ° C. for 1000 hours. After the operation was completed, remarkable roughness was confirmed on the surface of the vane.

[0018]

INDUSTRIAL APPLICABILITY As described above, the present invention has excellent lubricity and wear resistance for a refrigerator using hydrogen-containing fluorohydrocarbon 1,1,1,2-tetrafluoroethane as a refrigerant. A lubricating oil composition is provided.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C10N 30:06 30:08 40:30 (72) Inventor Katsuya Wakita 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial (72) Inventor Yusuke Ozaki 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Nobuo Sonoda 1006, Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A lubricating oil base oil for a refrigerator, which uses a hydrogen-containing fluorohydrocarbon as a refrigerant, and a phosphoric acid ester compound having an aminoalkyl group in the molecule represented by Chemical formula 1 in an amount of 0.05% by weight to. A lubricating oil composition for refrigerating machine oil, characterized in that 5% by weight is added. Embedded image (In the formula, R ₁ and R ₂ may be the same or different,
Each represents hydrogen or an aminoalkyl group having 1 to 18 carbon atoms and is not hydrogen at the same time. )