JPH02102296A - 1.1.1.2- Lubricating oil for refrigerators using tetrafluoroethane refrigerant - Google Patents

Abstract

PURPOSE:To obtain the title lubricating oil improved in both stability and compatibility when coexisting with a 1,1,1,2-tetrafluoroethane refrigerant by incorporating antioxidants and an abrasion inhibitor comprising a phosphorus compound into a specified polyoxyalkylene glycol oil. CONSTITUTION:A base oil (A) comprising a polyoxyalkylene glycol oil of formula I (wherein R1 to R4 are each H or a hydrocarbon group of formula II; n is 0 to 8; x+y>=1) having a kinematic viscosity (40 deg.C) of 10-220mm<2>/s is mixed with 0.01-10wt.% of one or more antioxidants (B) selected from phenolic, amine, phosphorus, and benzotriazole antioxidants (e.g., benzotriazole) and 0-10wt.% abrasion inhibitor (C) comprising a phosphorus compound (e.g., tricresyl phosphate).

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a lubricating oil for refrigerators that uses 1,1.1.2-tetrafluoroethane refrigerant, which is a substitute for CFCs, and which can coexist in refrigerators. The present invention relates to a high viscosity polyether-based synthetic oil lubricating oil for refrigerating machines that has excellent stability and compatibility.

[Conventional technology]

Conventionally, R11 (ccLp) is mainly used as a refrigerant for refrigerators.
) is used for air conditioners in buildings, etc., and R12 (CCt!z
F2) is used as a refrigerant for refrigerators such as electric refrigerators and car air conditioners, but stratospheric ozone depletion has recently become a social problem, and the development of alternative fluorocarbons has become urgent.

Therefore, R123 (CF, CO
Cl2) is under consideration, but it has the problem of being expensive and toxicity tests have not been conducted. On the other hand, as a substitute for R12, R22 (CHCffiPz) has begun to be considered due to its ease of decomposition, but due to its low boiling point, the pressure at room temperature is high, pressure resistance is required for the hardware, and the packing part, There is a problem that leakage occurs from the hose part, etc., and there is also a problem that the electrical insulation is poor. Also, like this R22, 1 is known as an alternative to R12.
, 1.1.2-tetrafluoroethane (R]34a) does not contain chlorine, which affects ozone destruction, due to its structure, and although no chronic toxicity tests have been conducted,
Although it has passed the subacute and sexual toxicity tests and its use is beginning to attract attention, it has the problem of poor compatibility with commonly used refrigeration oil.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a refrigerating machine lubricating oil suitable for using 1.1.1.2 tetrafluoroethane refrigerant as a CFC substitute.

[Means to solve the problem]

Refrigerator lubricating oils suitable for the 1.1.1.2-tetrafluoroethane refrigerant of the present invention have the formula: R, -0-(CH2-C1l-0), -(CH2-C
H-0)y-R.

R2R3 (However, R1, R2, R3, R1 are hydrogen, or C7H2□
Pl and R4 may be the same or different, n is 0 to 8, and x+y is 1 or more. ), and the kinematic viscosity at 40°C is 10 to 22.
0mm2/s, or this polyoxyalkylene glycol oil is mixed with at least one antioxidant selected from phenolic, amine, phosphorus, and benzotriazole antioxidants. .01-10% by weight, ■, phosphorus-based wear inhibitor 0-1
It is characterized by containing 0% by weight.

As the polyoxypropylene glycol oil used in the present invention, if both R2 and R3 are methyl groups, R
1. R4 is preferably hydrogen, and when R2 is hydrogen and R3 is a methyl group, RI% R4 is preferably an alkyl group, particularly preferably a methyl group or a butyl group. The average molecular weight is preferably about 900 to 1100, and x+y is preferably 14 to 18.

In addition, as for the viscosity characteristics, the kinematic viscosity at 40°C is 10
~220 mm2/s, preferably 15
~100 mm”/s.

Further, as the antioxidant, antioxidants commonly used in refrigeration oil can be used, such as benzotriazole, benzotriazole derivatives, thiadiazole, thiadiazole derivatives, triazole, triazole derivatives,
Metal deactivators (metal scavengers) such as dithiocarbamates
, and amine antioxidants such as dioctyl diphenylamine, phenyl-α-naphthylamine, alkyldiphenylamine, and N-nitrosodiphenylamine, 2゜6-
Phenolic antioxidants such as di-t-butyl para-cresol, 4.4゛methylenebis (2,6-di-t-butylphenol), 2.6-di-t-butylphenol, tris (2,4-di-t-butylphenyl) Phosphorous antioxidants such as phosphite, trisnonylphenylphosphite, and triphenylphosphite are preferably used, and the proportion of these is 0.01 to 10% by weight, preferably 0.01 to 10% by weight, based on the polyoxyalkylene glycol oil. 01～
It is preferable to use 1.0% by weight.

Furthermore, commonly used phosphorus-based wear inhibitors can be used, but tricresyl phosphate, tricresyl phosphate,
Trioleyl phosphite, dioleylhydrodiene phosphite, zinc thiophosphate, etc. are preferably used, and the proportion thereof is 0 to 10% by weight, preferably 0 to 1.0% by weight, based on the polyoxyalkylene glycol oil. good.

[Effect]

Refrigerators require airtightness against refrigerants, and generally high viscosity polyether synthetic oils have been developed. Further, the operating temperature thereof is usually -30 to 100°C, and the refrigerating machine oil is required to have good compatibility with the refrigerant, so that it does not separate and does not react with the refrigerant. If the compatibility with the refrigerant is poor, there is a problem of sintering in the high temperature section of the refrigerator.

In addition, some parts of the compressor have exposed metal surfaces, where refrigeration oil and refrigerant coexist, and when operated at high temperatures for long periods of time, chemical reactions occur due to the catalytic action of the metal, resulting in hydrochloric acid, etc. This formation causes corrosion of metal parts and generation of sludge, which causes refrigerator failure.

The present inventors have discovered that 1
．． 1.1.2-Tetrafluoroethane While examining the above conditions as a refrigerant, we found that polyoxyalkylene glycol oil is extremely compatible with the conventionally used R12 (CCffi□FZ). ) was found to be more thermally and chemically stable.

Although the detailed reason is not fully clear, the conventional R
11 (CCffifiF), also R12 (CCI
! ．． tF! ) etc., when the polyoxyalkylene glycol oil of the present invention is used as a base oil, its chemical structure does not contain chlorine and is substituted only with fluorine, which has a strong bonding force, so it is more thermally and chemically resistant. It appears to be stable.

The effectiveness of the composition of the present invention will be explained below using Examples and Comparative Examples.

[Example 1] Table 1 shows the results of a compatibility test of 1.1.1.2-tetrafluoroethane, which is a refrigerant in the present invention, with various base oils.

(Compatibility test method) Sample oil and refrigerant (1.1.1.2-tetrafluoroethane) were collected in a glass tube at a ratio of oil and refrigerant of 15:85 and 50:50 for a total of 10 ml. and mix.

Place the glass tube in a constant temperature bath at the specified temperature and observe whether the sample oil and refrigerant are separated. In addition, HLB indicates the balance between hydrophilicity and hydrophobicity, and HLB of 5 to 8 is particularly good.

From the test results shown in Table 1, it can be seen that 1.1.1.2-tetrafluoroethane has good compatibility with the polyoxyalkylene glycol oil of the present invention.

As a comparative example, the above mineral oils include paraffinic mineral oil,
and naphthenic mineral oil, and decene oligomer was used as the α-olefin oligomer. In addition, hard alkylbenzene is used as the alkylbenzene,
The diester is ditridecyl adipate (DTDA).
)It was used. In addition, in the monool form of polyoxyprolene gellicol, R is C. R9, x+y is 18, average molecular weight is 1100, kinematic viscosity at 40'C is 60mm''/
I used the one from s.

The polyoxyprolene gelyl diol of the present invention has x+y of 17, average molecular weight of 1000, and kinematic viscosity of 70 mm"/s at 40°C, and the end-capped polyoxyalkylene glycol of the present invention. As, R is C.R9, R'' is C1. , x is 9, y is 9
, the average molecular weight is 1000, and the kinematic viscosity at 40°C is 3 8 mm2/s.

Furthermore, as a comparative example, as a monool form of polyoxyalkylene glycol, R is CaHq, χ is 11, and y is 1.
1. The average molecular weight is 1200, the kinematic viscosity at 40°C is 61 mm"/s, and as a polyoxyalkylene glycol diol, χ is 14 and y is 6.
The average molecular weight was 1000, and the kinematic viscosity at 40°C was 77 mm2/s.

[Example 2] Polyoxyprolene gelicol diol (1) of the present invention
and end-capped polyoxyalkylene glycol (II) as a base oil and 1.1.1.2 tetrafluoroethane as a refrigerant, and when no additives are added to a compatible solution of both, and the following: Regarding the case of refrigerant base oil composition (sample oil) containing additives, conventional R12
(CCLFz) A high temperature shield tube test was conducted using the refrigerant as a comparative example.

The additives, metal pieces, test containers, and test methods used here are as follows.

Additive/Antioxidant Henctriazole (BTA) 2.6-G t-butylbalacreso-71/(DBP
C) - Anti-wear agent tricresyl phosphini) (TCP) - Metal piece material: iron, copper, aluminum Shape: diameter 1.7 mm, length 40 mm - Test container glass tube - Test method (shielded tube test) glass tube Add 1 g of sample oil (■) or (II) to
After taking 1 g of F3) and 81 test pieces of iron, copper, and aluminum as metal pieces and melting them, 17
It was heated for 14 days (336 hours) at a temperature of 5°C. After the test was completed, the degree of discoloration of the sample oil was measured. In addition, the state of precipitates or metal pieces was observed. In addition, 0.1% by weight of the antioxidant pencitriazole or 2.6% by weight of the antioxidant pencitriazole was added to each of the above sample oils.
- 0.5% by weight of butyl para-cresol or 0.5% by weight of anti-wear agent tricresyl phosphate
The same test as above was conducted. The test results are shown in Table 2 below.

(Left below) Table 2 (Table 2) As can be seen from Table 2, the lubricating oil for refrigerators of the present invention and 1.
1.1.Compared to the conventional compatible solution with R12 (CC: 12F2), the compatible solution with 2-tetrafluoroethane has less hue deterioration after the test, and also generates less sludge after the test. It can be seen that it has excellent chemical and thermal stability.

Furthermore, it can be seen that even if the amount of additive added is reduced, the compatible solution of the present invention generates little sludge and has excellent chemical and thermal stability.

〔Effect of the invention〕

The refrigerating machine lubricating oil of the present invention is extremely compatible with 1.1.1.2-tetrafluoroethane as a refrigerant for the refrigerating machine, and its compatible solution is the conventional R12 (CCj2g
It generates less sludge and has excellent chemical and thermal stability than a compatible solution with 1.
When using 1.1.2-tetrafluoroethane, it becomes an excellent lubricating oil for refrigerators.

Claims (2)

[Claims] (1) Formula, ▲Mathematical formula, chemical formula, table, etc.▼ (However, R_1, R_2, R_3, R_4 are hydrogen or C
A hydrocarbon group represented by _nH_2_n_+_1,
R_1 and R_4 may be the same or different, and n is 0
~8, x+y is 1 or more. ) and has a kinematic viscosity of 10 to 220 mm^2/s at 40°C, 1.1.1.2-
Lubricating oil for refrigerators that use tetrafluoroethane refrigerant. (2) Formula, ▲Mathematical formula, chemical formula, table, etc.▼ (However, R_1, R_2, R_3, R_4 are hydrogen or C
A hydrocarbon group represented by _nH_2_n_+_1,
R_1 and R_4 may be the same or different, and n is 0
~8, x+y is 1 or more. ), and has a kinematic viscosity of 10 to 220 mm^2/s at 40° C. [1] Phenol-based, amine-based, phosphorus-based, benzotriazole-based antioxidants 1.1.1.2-Tetrafluor containing 0.01 to 10% by weight of at least one kind of antioxidant, [2] and 0 to 10% by weight of a phosphorus anti-wear agent. Lubricating oil for refrigerators that use ethane refrigerant.