JPH10102079A - Lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition, having excellent stability and lubricity and suitably usable as a refrigerator oil for a refrigerator using a hydrofluorocarbon(HFC)-based refrigerant by using an alkylbenzene oil and a polyether-based oil as a base oil. SOLUTION: This composition comprises (A) an alkylbenzene oil and (B) a polyether based oil as a base oil. For example, the components can be mixed at a ratio within the range of 1-99wt.% component A to 99-1wt.% component B for use. Tricresyl phosphate (TCP) in an amount of 0.1-2.0wt.% based on the component B in the base oil is preferably added and an epoxy comprising 0.01-10wt.% glycidyl ether based on the component B is preferably added. Furthermore, carbodiimide in an amount of 0.01-10wt.% based on the component B is preferably added and a phenolic antioxidant as an additive in an amount of 0.01-1.0wt.% based on the component B is preferably added. Thereby, problems such as adverse effects, e.g. the occurrence of corrosion in a sliding part can be eliminated to expect stable operation of an apparatus for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition, and more particularly, to 1,1,1,2-tetrafluoroethane (hereinafter, R134a) alone or a mixture of R134a and difluoromethane (hereinafter, R-32). A mixed refrigerant with pentafluoroethane (hereinafter referred to as R-125);
The present invention relates to a lubricating oil composition excellent in stability and lubricity, which can be used favorably as a refrigerating machine oil of a refrigerating apparatus using an HFC-based refrigerant such as a refrigerant mixture of -32 and R-125.

[0002]

2. Description of the Related Art HFC refrigerants such as R134a described above have poor compatibility with refrigeration oils such as mineral oils and alkylbenzene oils, which may lead to poor oil return to the compressor and suction of separated refrigerants during stagnation startup. There was a problem that resulted in poor lubrication of the compressor.

[0003] For this reason, the present inventors have proposed that H
A polyol ester oil was studied as a refrigerating machine oil compatible with the FC refrigerant. However, when this polyol ester-based oil is used in a compressor, the temperature tends to rise due to friction and wear of the sliding members inside the compressor, and is hydrolyzed by the heat or decomposed by the action of iron oxide. As a result, fatty acids and metal soaps are produced, causing the sliding members to corrode due to the fatty acids and the like, and a sludge component being generated due to abrasion, thereby clogging capillary tubes and the like. There was a problem that the durability of the compressor was impaired, such as adverse effects on the organic materials such as the element magnet wire.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lubricating oil composition having excellent stability and lubricity, and to provide a refrigeration apparatus using an HFC-based refrigerant such as R134a as a refrigerant. Even when used as a refrigerating machine oil, it suppresses the generation of carboxylic acid due to thermal decomposition or hydrolysis due to frictional heat of the sliding member and the generation of sludge accompanying this, and the generation of corrosion of the sliding member and the capillary tube due to the sludge Lubricating oil with excellent stability and lubricity that can stably operate refrigeration equipment for a long period of time without any clogging and without adverse effects on organic materials such as magnet wires of electric elements of the compressor. It is to provide a composition.

[0005]

Means for Solving the Problems As a result of intensive studies on such problems, the present inventors have found that acetylbenzene oil having low compatibility with HFC-based refrigerants has good compatibility with HFC-based refrigerants.
Further, by using a polyether-based oil having better hydrolysis resistance than a polyol ester-based oil as a base oil, it is more preferable that a lubricating oil composition containing a specific additive added to this base oil has improved stability and lubricity. They have been found to be excellent and can be used as refrigerating machine oil of a refrigerating apparatus using an HFC-based refrigerant, and have completed the present invention.

For example, as a result of a durability test of a rotary compressor of a refrigerating apparatus, vanes and rollers as sliding members thereof are severely worn, the total acid value of the polyol ester-based oil is increased, and pits are generated on the roller surface. It was observed that corrosive wear occurred. The cause is that the polyol ester oil is hydrolyzed by the frictional heat of the sliding member to generate carboxylic acid, which corrodes the iron-based material or reacts with the iron-based material to form metal soap or sludge. I could guess.

The invention of claim 1 of the present invention is a lubricating oil composition having excellent stability and lubricity based on an alkylbenzene oil and a polyether-based oil used for an HFC refrigerant.

According to a second aspect of the present invention, there is provided a lubricating oil composition according to the first aspect, wherein 0.1 to 2.0% by weight of tricresylphosphorus based on the polyether-based oil in the base oil. It is characterized by adding an epoxy or carbodiimide composed of fate (TCP), glycidyl ether.

According to a third aspect of the present invention, there is provided the lubricating oil composition according to the first or second aspect, wherein the compressor, the condenser, the decompressor, and the evaporator each having a compressor section housed in a closed container. It is characterized in that it is used as refrigerating machine oil to be sealed in the compressor of a refrigerating apparatus in which a refrigerating cycle is formed by sequentially connecting the refrigerating tubes.

According to a fourth aspect of the present invention, there is provided the lubricating oil composition according to any one of the first to third aspects, wherein the base oil further comprises 0.01 to 1.
It is characterized in that it contains 0% by weight of a phenolic antioxidant.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyether oil used as a base oil in the present invention is not particularly limited. Specifically, for example, a polyvinyl ether-based oil represented by the following general formula (1) can be preferably used. In the formula, R _{1 to} R ₃ each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, which may be the same or different. R ₄ represents a hydrocarbon group having 1 to ₄ carbon atoms. n is an integer of 1 or more.

[0012]

Embedded image

In the present invention, the ratio of the alkylbenzene oil to the polyether-based oil in the base oil is not particularly limited, and may be, for example, a mixture of alkylbenzene oil of 1 to 99% by weight and polyether-based oil of 99 to 1% by weight. Can be used. 0.1 to 2.0% by weight based on the polyether oil in the base oil
It is preferable to add tricresyl phosphate (TCP), but if it is less than this range, a phosphoric acid film is not formed properly by TCP, so that lubricity is reduced,
Abrasion occurs in the boundary lubrication region and deterioration of the base oil occurs. Exceeding this range causes corrosion and abrasion due to TCP, and decomposed products of TCP adversely affect the base oil to accelerate the deterioration of the base oil.

It is preferable to add 0.01 to 10% by weight of an epoxy composed of glycidyl ether to the polyether-based oil in the base oil, but if it is less than this range, the effect of the epoxy will not be exhibited. Poor thermochemical stability. If it exceeds this range, the epoxy may polymerize, become sludge and deposit. The preferred range of addition of the epoxy to the polyether-based oil in the base oil is 0.1 to
2.0% by weight.

It is preferable to add 0.01 to 10% by weight of carbodiimide with respect to the polyether-based oil in the base oil. Poor nature. If the amount exceeds this range, carbodiimide may polymerize, form sludge and accumulate, or deteriorate stability. The preferred addition range of carbodiimide to the polyether-based oil in the base oil is 0.1 to 2.0% by weight, more preferably 0.1 to 2.0% by weight.
The range is from 0.5 to 0.5% by weight.

It is preferable to add a phenolic antioxidant as an additive to the base oil for the purpose of preventing oxidative deterioration during long-term storage, and the amount thereof is based on the amount of the polyether oil in the base oil. It is 0.01 to 1.0% by weight, more preferably 0.05 to 0.3% by weight. Antioxidants include 2,6-di-t-butyl-paracresol,
6-di-t-butyl-phenol, 2,4,6-tri-
T-butyl-phenol and the like can be used.

Preferably, a benzotriazole-based copper deactivator is added to the base oil, if necessary, in an amount of 1 to 100 ppm with respect to the polyether-based oil in the base oil. More preferably, it is 5 to 50 ppm. As the benzotriazole-based copper deactivator, for example, specifically, 5-methyl-1H-benzotriazole, 1-dioctylaminomethylbenzotriazole and the like can be used.

Other known additives may be added to the lubricating oil composition of the present invention without departing from the gist of the present invention.

Hereinafter, the present invention will be described with reference to FIGS. FIG. 1 shows a hermetic electric compressor a for compressing and discharging an evaporated HFC-based refrigerant to a condenser, a condenser b for condensing and liquefying the refrigerant, a capillary tube c for reducing the pressure of the refrigerant, and evaporating the liquefied refrigerant. 1 shows a refrigeration cycle of a refrigeration apparatus formed by connecting evaporators d and the like to be successively connected by a refrigerant pipe. The type of the hermetically sealed electric compressor a is not particularly limited, and specific examples include a rotary compressor, a reciprocating compressor, a vibration compressor, a multi-vane rotary compressor, a scroll compressor, and the like. Examples can be given. Hereinafter, the case where the lubricating oil composition of the present invention is used for a rotary compressor shown in FIGS. 2 and 3 and a reciprocating compressor shown in FIG. 4 will be described.

FIG. 2 is a longitudinal sectional view of the rotary compressor.
FIG. 3 is a cross-sectional view of the rotary compressor. 2 and 3
In the figure, reference numeral 1 denotes a closed container, in which an electric element 2 is accommodated on the upper side, and a rotary compression element 3 driven by the electric element is accommodated on the lower side. The electric element 2 includes a stator 5 having a winding 4 insulated with an organic material and a rotor 6 provided inside the stator. The rotary compression element 3 includes a cylinder 7 and a roller 10 that rotates along an inner wall of the cylinder 7 by an eccentric portion 9 of a rotation shaft 8.
A vane 12 is pressed against the peripheral surface of the roller and is pressed by a spring 11 so as to partition the inside of the cylinder 7 into a suction side and a discharge side, and seals an opening of the cylinder 7 while supporting the rotating shaft 8. Upper bearing 13 and lower bearing 14.

The upper bearing 13 is provided with a discharge hole 15 communicating with the discharge side of the cylinder 7. A discharge valve 16 for opening and closing the discharge hole 15 and a discharge muffler 17 are attached to the upper bearing 13 so as to cover the discharge valve.

The roller 10 is formed of an iron-based material such as cast iron, and the vane 12 is formed of an iron-based material such as an iron-based material, a composite material of aluminum and carbon, and a steel surface-treated with chromium nitride. .

An HFC-based refrigerant, for example, a refrigerant mixture of three kinds of R134a, R32 and R125 or a refrigerant mixture of two kinds of R32 and R125 is sealed in the bottom of the closed container 1.

The epoxy glycidyl ether is selected from the group of hexyl glycidyl ether, 2-ethylhexyl glycidyl ether, isooctadecyl glycidyl ether and the like.

The oil 18 lubricates the sliding surface between the roller 10 and the vane 12, which are sliding members of the rotary compression element 3.

As described above, the refrigerant flowing into the cylinder 7 of the rotary compression element 3 and compressed by the cooperation of the rollers 10 and the vanes 12 is, for example, R407C [R134a and R32C].
Refrigerant mixture of R32 and R125] or R410A [R32 and R1
25 mixed refrigerant].

Reference numeral 19 denotes a suction pipe which is attached to the closed vessel 1 and guides the refrigerant to the suction side of the cylinder 7, and 20 is attached to the upper wall of the closed vessel 1 and is compressed by the rotary compression element 3 via the electric element 2. This is a discharge pipe for discharging the refrigerant to the outside of the closed container 1.

In the rotary compressor using the lubricating oil composition of the present invention as the refrigerating machine oil, the refrigerant flowing from the suction pipe 19 to the suction side in the cylinder 7 is supplied to the roller 10 and the vane 1.
2 and is compressed in cooperation with the discharge valve 16 through the discharge hole 15.
Is discharged and discharged into the discharge muffler 17. The refrigerant in the discharge muffler is discharged from the discharge pipe 20 to the outside of the closed container 1 via the electric element 2. The oil 18 is supplied to a sliding surface of a sliding member such as the roller 10 and the vane 12 of the rotary compression element 3 to perform lubrication. Further, the refrigerant compressed in the cylinder 7 is prevented from leaking to the low pressure side.

FIG. 4 is an explanatory sectional view of a reciprocating compressor. Reference numeral 1a denotes a closed container, in which a motor unit 2a disposed on the lower side and a reciprocating compression unit 3a disposed on the upper side are accommodated. The reciprocating compression section 3a and the electric motor section 2a are elastically attached to the inner wall of the closed casing 1a. The motor unit 2a includes a stator 5a having a winding 4a wound therein,
A rotor 6a disposed inside the stator, and a rotating shaft 8a inserted into the center of the rotor and supported by bearings 13a.
It is composed of

The reciprocating compressor 3a includes a cylinder 7a, a piston 25 fitted in a crank pin 24 of the rotary shaft 8a in the cylinder and reciprocating therewith, a valve seat 26 provided on an end face of the cylinder 7a, And a cylinder head 27 that is attached to the cylinder 7a. A discharge valve (not shown) for opening and closing a discharge port is attached to the valve head 26 on the cylinder head 27 side.

In the reciprocating compressor using the lubricating oil composition of the present invention as a refrigerating machine oil, the three-component mixture H flowing into the cylinder 7a by the reciprocating sliding of the piston 25 is used.
The FC-based refrigerant is compressed in the cylinder 7a, and is discharged to an external refrigerant circuit (not shown) by opening a discharge valve.

Then, the oil 18a put in the bottom of the sealed container 1a fills the inside of the lubricating oil cup from the hole 29 of the lubricating oil cup 28, and has a hollow lubricating oil passage 30 in the central part of the lubricating oil cup 28. The rotary shaft 8a has a rotary shaft 8a. The oil 18a is sucked up by a vacuum phenomenon caused by a vortex generated at the upper open end by the high-speed rotation of the rotary shaft 8a, and circulates through sliding parts such as the piston 25 / cylinder 7a and the rotary shaft 8a / bearing 13a. Self-lubrication to lubricate.

[0033]

EXAMPLES The present invention will be described below in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. (Example 1) An endurance test was performed under the following test conditions using a bench stand test device in which a rotary compressor, a condenser, an expansion valve, and an evaporator were connected by piping, and the vanes, rollers, and rotation of the rotary compressor were tested. The degree of wear of sliding parts such as shafts and bearings was measured, and the acid value of the base oil was measured. Pressure conditions: High pressure 27 to 28 kg / cm ² · G, Low pressure: 4.6 kg / cm ² · G Operating frequency: 100 HZ, Operating time: 1000 hr, Refrigerant: R407C manufactured by DuPont [52:23 between R134a, R32 and R125 : 25 mixed refrigerant] Case upper temperature: 95 to 100 ° C Each material of the sliding portion is as follows. Vane: High Speed Tool Steel Roller: Cast Iron Composition (wt%): T.V. C (total carbon): 3.2 to 3.6 Si: 2.2 to 2.9, Mn: 0.6 to 1.0, P: 0.18max, S: 0.08max Ni: 0.1 to 0.2, Cr: 0.20max MO: 0.07 to 0.2, Ti: 0.25max The balance is iron

Lubricating oil composition (oil) having a viscosity of VG15
20% by weight of an alkylbenzene oil and 80% by weight of a polyvinyl ether-based oil having a viscosity of VG68 as a base oil, and 0.1 to 2.0% by weight of tricresylphosphor based on the polyether-based oil in the base oil. Fate (TCP) and 0.01-10
An additive containing an additive (EP) with epoxy by weight. Furthermore, 0.05 to 0.3% by weight of 2,6
-Di-t-butyl-paracresol has been added.

Table 1 shows the test results. The numbers in Table 1 represent the degree of wear and the total acid value in a five-point scale.
5 is bad, 3 is an acceptable range, and 1 is good.

Comparative Example 1 A test was performed in the same manner as in Example 1 except that only the alkylbenzene oil used in Example 1 was used as a base oil. Table 1 shows the results.

Comparative Example 2 A test was conducted in the same manner as in Example 1 except that only the polyether-based oil used in Example 1 was used as a base oil. Table 1 shows the results.

Comparative Example 3 A test was performed in the same manner as in Example 1 except that a polyol ester oil was used in combination with an alkylbenzene oil instead of the polyether oil used in Example 1. Table 1 shows the results.

[0039]

[Table 1]

As can be seen from Table 1, in Example 1, both the abrasion degree and the acid value of the sliding portion were low and good (all at level 1), whereas in Comparative Example 1, the rotary compression of alkylbenzene oil was performed. The return to the machine was poor and the degree of wear of the sliding part was high. In Comparative Example 2, the acid value of the polyether-based oil was high,
Sludge generation was observed on the vane surface. In Comparative Example 3, the acid value of the base oil was increased, and generation of sludge was observed on the vane surface.

[0041]

According to the present invention, the lubricating oil composition of the present invention is excellent in stability and lubricity. When the lubricating oil composition of the present invention is used as a refrigerating machine oil for a refrigerating device using an HFC-based refrigerant, there is no occurrence of corrosion of a sliding member or clogging of a capillary tube or the like due to a sludge, and a magnet wire for an electric element of a compressor. There is no problem such as adverse effects on organic materials, and stable operation can be performed for a long time.

[Brief description of the drawings]

FIG. 1 is a refrigeration circuit diagram of a refrigeration apparatus.

FIG. 2 is a longitudinal sectional view of a rotary compressor used in the present invention.

FIG. 3 is a cross-sectional view of the rotary compressor of FIG. 2;

FIG. 4 is a longitudinal sectional view of a reciprocating compressor used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Closed container 2 Electric element 2a Electric motor part 3 Rotary compression element 3a Reciprocating compression part 4, 4a Winding 5, 5a Stator 6, 6a Rotor 7, 7a Cylinder 8, 8a Rotating shaft 9 Eccentric part 10 Roller 11 Spring 12 vane 13 upper bearing 13a bearing 14 lower bearing 15 discharge hole 16 discharge valve 17 discharge muffler 18, 18a oil 19 suction pipe 20 discharge pipe 24 crank pin 25 piston 26 valve seat 27 cylinder head 28 lubricating oil cup 29 hole 30 lubricating oil passage

Claims (4)

[Claims] 1. A lubricating oil composition having excellent stability and lubricity based on an alkylbenzene oil and a polyether oil used for an HFC-based refrigerant. 2. An epoxy or carbodiimide comprising tricresyl phosphate (TCP) or glycidyl ether in an amount of 0.1 to 2.0% by weight based on the polyether oil in the base oil. Claim 1
The lubricating oil composition according to the above. 3. A refrigerating machine oil to be sealed in the compressor of a refrigerating apparatus in which a refrigerating cycle is formed by connecting a compressor, a condenser, a decompressor, and an evaporator, in which a compressor section is housed in a closed container, in order by a refrigerant pipe. 3. The lubricating oil composition according to claim 1, which is used. 4. The base oil according to claim 1, further comprising 0.01 to 1.0% by weight of a phenolic antioxidant based on the polyether oil in the base oil. A lubricating oil composition according to claim 3.