JP2001226690A - Lubricant composition for freezing device, and freezing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition which is used for freezing devices using refrigerants not containing chlorine and has excellent abrasion resistance and simultaneously excellent stability. SOLUTION: This lubricant composition for freezing devices using chlorine- free refrigerants, characterized by containing (1) 0.1 to 2.0 wt.% of a phosphate ester compound, (2) 0.05 to 2.0 wt.% of a thiobisphenol compound and (3) 0.05 to 2.0 wt.% of an acid scavenger.

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 for a refrigerating system using a refrigerant containing no chlorine such as hydrofluorocarbon, ammonia, carbon dioxide and hydrocarbon, and a refrigerating system. In particular, the present invention relates to a lubricating oil composition having excellent wear resistance suitable as a lubricating oil for refrigeration equipment such as refrigerators, car air conditioners, and room air conditioners, and a refrigeration apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, as lubricating oils for refrigeration systems such as refrigerators and air conditioners, mineral oils such as naphthenic and paraffinic oils, and synthetic oils such as alkylbenzenes and polyalphaolefins have been known. It is used to prevent wear, seizure and the like. Characteristics required for lubricating oil for refrigeration equipment include excellent stability with respect to the refrigerant due to contact with the refrigerant, and excellent solubility with the refrigerant. Conventionally, a Freon refrigerant containing chlorine has been often used as a refrigerant. For example, R11 (trichloromonofluoromethane) and R1
Chlorofluorocarbons such as 2 (dichlorodifluoromethane) and R22 (monochlorodifluoromethane)
Hydrochlorofluorocarbons have been used. For these chlorine-containing refrigerants, naphthenic mineral oils, paraffinic mineral oils, alkylbenzene synthetic oils, poly-α-olefin synthetic oils and the like have been used.

However, these chlorine-containing Freon refrigerants are:
In order to destroy the stratospheric ozone layer, its use has been regulated internationally. As an alternative chlorofluorocarbon refrigerant, chlorine such as R134a (1,1,1,2-tetrafluoroethane) has been used. , Or so-called natural refrigerants such as ammonia, carbon dioxide, and hydrocarbons are being used. For hydrofluorocarbon refrigerants,
Polyether synthetic oils such as PAG and polyol ester synthetic oils have been proposed. Polyether compounds have been proposed for ammonia refrigerants.

However, in the case of a refrigerant containing no chlorine, the extreme pressure effect of chlorine (improvement in lubricity) cannot be expected, so that poor lubrication tends to occur in bearings, pistons, seals, etc. of the refrigeration system, resulting in energy loss and increased wear. This can cause seizure and promote the decomposition of refrigerant and lubricating oil, causing corrosion.

[0005] In order to cope with these problems, conventionally, various kinds of wear resistance improvers such as sulfur-based and phosphorus-based have been added. However, conventionally used additives are problematic in that the effect of adding lubricity is small, the stability is poor, the solubility with a refrigerant is small, and the metal material is corrosive. In many cases, it may not always be sufficient for refrigeration equipment.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to develop a lubricating oil composition which is excellent not only in wear resistance but also in stability and is most suitable for a refrigeration system using a refrigerant containing no chlorine. .

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, as a lubricating oil composition for refrigeration equipment, mineral oil or synthetic oil was used as a base oil, and phosphorus was used as an additive. It has been found that the above problems can be solved by using an acid ester compound, a thiobisphenol compound and an acid scavenger in combination.

The present invention has been made based on this finding. In a lubricating oil for refrigeration equipment using a chlorine-free refrigerant, mineral oil and / or synthetic oil are used as a base oil, and (1) 0.1 to 2.0% by weight of a phosphoric ester compound; and (2) a thiobisphenol compound. 0.05 to 2.0% by weight (3) A lubricating oil composition for refrigeration equipment containing 0.05 to 2.0% by weight of an acid scavenger.

[0009] 2. 2. The lubricating oil composition for a refrigeration unit according to the above 1, wherein the base oil is at least one selected from an ester compound, an ether compound, a poly-α-olefin, and an alkylbenzene.

[0010] 3. 3. The lubricating oil composition for a refrigeration unit according to the above 1 or 2, wherein the acid scavenger is at least one selected from an epoxy compound and a carbodiimide compound.

4. Wherein the refrigerant containing no chlorine is at least one selected from hydrofluorocarbons, ammonia, carbon dioxide, and hydrocarbons.
The lubricating oil composition for a refrigeration apparatus according to item 3,

5. It is intended to provide a refrigeration apparatus characterized by using the lubricating oil composition described in any one of 1 to 4 above.

(Function) The phosphate ester reacts with the metal on the surface of the sliding material to form a metal-phosphate film such as iron phosphate on the surface of the sliding material, thereby reducing the sliding resistance between the sliding materials. It acts to reduce friction and reduce friction. Thiobisphenol reacts with the metal on the sliding material surface in the same way as the phosphate ester, and forms a metal-sulfide film such as iron sulfide on the sliding material surface, reducing the sliding resistance between the sliding materials and friction. Has the function of reducing Since phosphoric acid esters and thiobisphenols have different temperatures at which they easily react with metals, a film is formed by using both in combination with one another even in a low temperature range where the reaction activity is low, and a film is formed. That is, it exhibits a friction reducing effect under a wide range of use conditions. The acid scavenger reacts with the acid in the lubricating oil, has the function of reducing the corrosiveness and catalytic activity of the acid, and has the effect of preventing corrosive wear. In particular, when used in combination with a phosphoric acid ester or thiobisphenol, it neutralizes phosphoric acid generated from the phosphoric acid ester and sulfuric acid generated from the liobisphenol, thereby suppressing the occurrence of corrosive wear.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be applied to a refrigeration system using a refrigerant containing no chlorine. Examples of the refrigerant containing no chlorine include hydrofluorocarbon, ammonia, carbon dioxide, and hydrocarbon. These refrigerants can be applied to one or a mixture of two or more thereof.

Examples of the hydrofluorocarbon include R-134a (1,1,1,2-tetrafluoroethane),
R-143a (1,1,2-trifluoroethane), R-125
(Pentafluoroethane), R-32 (difluoromethane)
Or a mixed refrigerant thereof.

As the hydrocarbon refrigerant, for example, one having 1 to carbon atoms
Five hydrocarbon compounds can be used. Specific examples include compounds such as methane, ethane, propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, cyclopropane, cyclobutane, and cyclopentane. It goes without saying that these compounds may be used alone or in combination of two or more.

As the base oil of the lubricating oil for the refrigeration system in the present invention, mineral oil or synthetic oil can be used, and a material having good compatibility with the refrigerant to be used may be appropriately selected. The mineral oil includes various types such as naphthenic mineral oil and paraffinic mineral oil. As the synthetic oil, it is preferable to use at least one selected from an ester compound, an ether compound, a polyalphaolefin, and an alkylbenzene.

Particularly, a synthetic oil is preferable, and an ester compound or an ether compound is preferable. As the ester compound, a polyol ester, a complex ester, and the like obtained by an esterification reaction between a polyhydric alcohol and a monocarboxylic acid are preferable. Typical examples of the polyhydric alcohol include neopentyl polyols such as neopentyl glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol. Monocarboxylic acids include pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2,2-dimethylbutanoic acid, 3-dimethylbutanoic acid, 3,3-dimethylbutanoic acid, 2-ethylbutanoic acid, heptanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 5-methylhexanoic acid, 2,2- Dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 2,4-dimethylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 2,2,3-trimethylbutanoic acid, 2-ethyl-3methylbutanoic acid, Octanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 2,2-dimethylhexanoic acid, 2,3-dimethylhexanoic acid, 2,4-dimethyl Hexanoic acid, 3,3-dimethylhexanoic acid, 3,5-dimethylhexanoic acid, 2-
Ethylhexanoic acid, 3-ethylhexanoic acid, 2,2,3
-Trimethylpentanoic acid, 2,3,3-trimethylpentanoic acid, 2-ethyl-2-methylpentanoic acid, 2-ethyl-3-methylpentanoic acid, 3-ethyl-2-methylpentanoic acid, nonanoic acid, 2-methyloctanoic acid , 3-methyloctanoic acid, 2,2-dimethylheptanoic acid, 2,3-dimethylheptanoic acid, 3,5-dimethylheptanoic acid, 2-ethylheptanoic acid, 3-ethylheptanoic acid, 2,2,4-trimethyl Hexanoic acid, 2,4,4-trimethylhexanoic acid, 3,3,5-trimethylhexanoic acid, 3,5,5-
Trimethylhexanoic acid, 2-ethyl-2-methylhexanoic acid, 2-ethyl-4-methylhexanoic acid, 4-ethyl-2
Methylhexanoic acid, 3-ethyl-5 methylhexanoic acid,
5-ethyl-3-methylhexanoic acid, 2-propylhexanoic acid, 3-propylhexanoic acid, 2,2,4,4-tetramethylhexanoic acid, and the like.

Various ether compounds can be used. As a typical example, the following general formula X [-O- (AO) n-R] m (1) (wherein, X: a hydrocarbon group in which a hydroxyl group is removed from a monol or polyol, A: A polyether compound represented by an alkylene group having 2 to 4 carbon atoms, R: hydrogen or an alkyl group having 1 to 10 carbon atoms, m: valence of X, and n: a positive number of 2 or more.

As the base oil, one of the above mineral oils or synthetic oils is used.
The species or a combination of two or more species may be used as appropriate.

The following additives are added to the above base oil. (1) Phosphate Ester Compound The phosphate ester compound is represented by (R ¹ O) (R ² O) (R ³ O) P ＝ O [wherein R ¹ , R ² , and R ^{3 each} have 6 to 6 carbon atoms. 12
Which may be the same or different, respectively). Specifically, for example, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, and the like can be given. Particularly, tricresyl phosphate and triphenyl phosphate are preferable. The phosphate compound is used in an amount of 0.1 to 2.0% by weight, preferably 0.2% by weight, based on the base oil.
１．０1.0% by weight. If the addition amount is too small, there is no effect, and if it is too large, the stability is deteriorated and the deterioration of the refrigerating machine oil is undesirably accelerated.

(2) Thiobisphenol compound The thiobisphenol compound is generally represented by the following chemical formula. HO-Ph-S-Ph-OH [including derivatives in which a substituent is bonded to a phenyl group] Specifically, 4,4-thiobis (3-methyl-6-
Tert-butylphenol), 4,4-thiobis (2,6-tert-butylphenol) and the like. The thiobisphenol compound is used in an amount of 0.05 to 2.0% by weight, preferably 0.1 to 2.0% by weight of the base oil.
Add 1.0% by weight. If the addition amount is too small, there is no effect, and if it is too large, the stability is deteriorated and the deterioration of the refrigerating machine oil is undesirably accelerated.

(3) Acid scavenger An acid scavenger is a compound having a functional group reactive with water or a carboxyl group, which reacts with water in a lubricating oil to prevent a hydrolysis reaction. Alternatively, it is an additive that is added so that the fatty acid does not act as a catalyst for the hydrolysis reaction by reacting with the fatty acid. In particular,
For example, an epoxy compound or a carbodiimide compound is preferable, and examples thereof include 2-ethylhexylglycidyl ether, epoxidized cyclohexylcarbinol, and di (alkylphenyl) carbodiimide. The acid scavenger is added in an amount of 0.05 to 2.0% by weight, preferably 0.1 to 1.0% by weight, based on the base oil. If the addition amount is too small, there is no effect, and if it is too large, the stability is deteriorated and the deterioration of the refrigerating machine oil is undesirably accelerated.

In the present invention, wear resistance and acid value stability can be simultaneously provided by using the above-mentioned phosphate compound, thiobisphenol compound and acid scavenger in combination. The lubricating oil composition of the present invention may contain known lubricating oil additives necessary for imparting overall performance. For example, amine-based antioxidants, anti-wear agents such as zinc dithiophosphate, chlorinated paraffins, extreme pressure agents such as sulfur compounds, oily agents such as fatty acids, silicone-based antifoaming agents and the like can be added in usual amounts. Within the range, it is possible to mix several kinds or to mix them alone.

The lubricating oil composition of the present invention can be used not only for the lubricating oil for refrigerators, but also for turbine oil, hydraulic oil and the like. In particular, if used in a refrigeration system that uses a chlorine-free refrigerant, it will exhibit extremely high lubrication performance,
The life and reliability of the refrigerator are greatly improved. Therefore, car air conditioners having reciprocating or rotary compressors, air conditioners, dehumidifiers, refrigerators, freezers, refrigerators,
It is particularly preferably used for cooling devices for vending machines, showcases, chemical plants and the like.

[0026]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to the examples. Base oils and additives used in Examples and Comparative Examples are as follows.

Base oil: B-1) pentaerythritol and 2-ethylhexanoic acid and
Polyol ester composed of 3,5,5 trimethylhexanoic acid (2 ethylhexanoic acid: 3,5,5 trimethylhexanoic acid = 1:
1, viscosity: 68 mm ² / s @ 40 ° C., total acid value: 0.01 mgKOH / g) B-2) CH ₃ O (PO) _m (EO) _n H (PO: polyoxypropylene group, EO: polyoxyethylene) Group, m: n = 8: 2, viscosity: 49mm ² / s @ 40 ° C, total acid value: 0.01mg
KOH / g) B-3) poly α-olefin ^{(viscosity: 91 mm 2 / s @ 40} ℃, total acid number: 0.01mgKOH / g) B-4 ) branched alkylbenzenes ^{(viscosity: 45 mm 2 / s @ 40} ℃ , Total acid value: 0.01mgKOH / g)

Additives: (1) phosphate compound: P-1) tricresyl phosphate (TCP) P-2) triphenyl phosphate (TPP) (2) thiobisphenol compound: T-1) 4, 4'thiobis (3 methyl 6-tert-butylphenol) T-2) 4,4'thiobis (2,6 tert-butylphenol) (3) acid scavenger: A-1) 2-ethylhexyl glycidyl ether A-2) epoxidized cyclohexyl Carbinol A-3) Di (alkylphenyl) carbodiimide For comparison with thiobisphenol, T-3) 4,4'dithiobis (2,6 tert-butylphenol) was prepared. The compositions of the lubricating oil compositions of Examples and Comparative Examples are shown in Tables 1 and 2.

[0029]

[Table 1]

[0030]

[Table 2]

Using the lubricating oil compositions of these Examples and Comparative Examples, tests were conducted under the following conditions. Falex wear test: ASTM D2670 compliant / standard test piece (SAE3135 / AISI C-1
137) / 60 ° C / 290rpm / 1112N × 30min

SRV test: 60 ° C./frequency 50 Hz / amplitude 1.0 mm / 667 N × 30 min

Shield tube test (confirmation of stability): Test A: (HFC refrigerant) Moisture in oil: 500 ppm, sample / R134a = 7 ml / 3 ml, catalyst: F
e, Cu, Al, temperature: 175 ° C, time: 14 days Test B: (ammonia refrigerant) Moisture in oil: 500ppm, sample / R717 = 7ml / 3ml, catalyst: Fe,
Al, temperature: 150 ° C, time: 14 days

Compressor durability test: Moisture in oil: 1500 ppm, refrigerant: R407C, no dryer, Pd = 3
MPa, Ps = 0.5MPa, temperature on shell: 120 ° C, time: 330h

Table 3 shows the test results of the lubricating oil compositions of Examples and Comparative Examples when B-1 was used as the base oil. For the shield tube test, test A (H
FC refrigerant).

[0036]

[Table 3]

In the examples, the amount of Falex wear, S
Both RV test wear scar diameters are small and have good wear resistance. Also,
The results of the shield tube test show that the stability is excellent. Further, in Example 2, the condition of the sliding surface was good in the compressor durability test, and the rise in the total acid value was small. On the other hand, in the comparative example, the abrasion is large and the stability is poor. In Comparative Examples 1, 3, and 5, there was a problem that the result of the compressor test was such that abrasion was large or the total acid value was increased. In addition, Comparative Example 6 in which phosphoric acid ester was excessively added and Comparative Example 7 in which disulfide was added instead of thiobisphenol had poor shield tube test results and were inferior in stability.

Table 4 shows the test results of the lubricating oil compositions of Examples and Comparative Examples when B-2 was used as the base oil. For the shield tube test, test A (H
FC refrigerant).

[0039]

[Table 4]

The examples have a smaller amount of Falex wear and better abrasion resistance than the comparative examples. Also, the results of the shield tube test show that the stability is excellent.

Further, Table 5 shows the results in the case of the shield tube test B in which an ammonia refrigerant was used as the refrigerant.

[0042]

[Table 5]

Even when an ammonia refrigerant was used, the results of the shield tube test were good in the examples.
On the other hand, in the comparative example, the occurrence of precipitation, an increase in the total acid value, and a blackening of the appearance of the catalyst were observed, indicating that the stability was poor.

Table 6 shows the test results of the lubricating oil compositions of Examples and Comparative Examples using B-3 and B-4 as base oils.

[0045]

[Table 6]

In the examples, the Falex abrasion amount is smaller and the abrasion resistance is better as compared with the comparative example. On the other hand, in the comparative example, seizure occurred, and the wear resistance was poor.

[0047]

The lubricating oil composition for refrigeration equipment of the present invention, which uses a phosphoric acid ester, thiobisphenol and an acid scavenger in combination, is excellent in abrasion resistance and stability as well as a refrigerant containing no chlorine. Most suitable for refrigeration equipment to be used. By using the lubricating oil composition of the present invention, friction, wear, seizure and the like in the compression sliding portion and the like are reduced, and the refrigerant and the decomposition of the lubricating oil, the corrosion of the device and the like are hardly generated, and the refrigerant containing no chlorine is used. Refrigeration equipment can be provided.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C10M 105: 32 C10M 105: 32 137: 04 137: 04 135: 20) 135: 20) C10N 30:06 C10N 30:06 30:12 30:12 40:30 40:30 F term (reference) 4H104 BA03A BA07A BB09C BB34A BB36A BE11C BG16C BH03C CA01A CB14A DA02A LA03 LA06 PA20

Claims (5)

[Claims] 1. A lubricating oil for refrigeration equipment using a chlorine-free refrigerant, wherein mineral oil and / or synthetic oil is used as a base oil, and (1) 0.1 to 2.0% by weight of a phosphoric ester compound. ) A lubricating oil composition for refrigeration equipment, comprising 0.05 to 2.0% by weight of a thiobisphenol compound (3) 0.05 to 2.0% by weight of an acid scavenger. 2. The lubricating oil composition for a refrigeration system according to claim 1, wherein the base oil is at least one selected from an ester compound, an ether compound, a poly-α-olefin, and an alkylbenzene. 3. The lubricating oil composition for a refrigeration system according to claim 1, wherein the acid scavenger is at least one selected from an epoxy compound and a carbodiimide compound. 4. The refrigerant containing no chlorine is at least one selected from hydrofluorocarbons, ammonia, carbon dioxide, and hydrocarbons.
4. The lubricating oil composition for a refrigeration apparatus according to 3. 5. A refrigeration apparatus using the lubricating oil composition according to claim 1.