JP2901330B2 - Lubricant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a lubricating oil for a compressor using 1,1,1,2-tetrafluoroethane refrigerant as an alternative chlorofluorocarbon,
The present invention relates to a lubricating oil for a compressor having excellent stability and compatibility when coexisting in a compressor.

[Prior art] R12 as a refrigeration refrigerant for electric refrigerators and car air conditioners
(Dichlorofluoromethane) is used, but stratospheric ozone depletion has recently become a social issue, and 1,1,1,2-tetrafluoroethane (R134a) has been attracting attention as an alternative chlorofluorocarbon.

However, conventional lubricating oil for compressors cannot be used because of its poor compatibility with R134a.

[Problem to be Solved by the Invention] The present invention provides a lubricating oil for a compressor suitable for using R134a as a refrigerant.

[Means for Solving the Problems] In order to solve the above problems, the present inventors have studied various synthetic oils and found that the compound represented by the general formula (A)
It has been found that 1,1,1,2-tetrafluoroethane (R134a) is excellent as a lubricating oil for refrigerators.

(However, R _{1 to} R ₃ and R _{4 to} R ₆ are selected from an alkyl group or a hydrogen residue, and at least two or more are alkyl groups in the group, and the alkyl groups may be the same or different. R ₇ is an alkylene group, an arylene group or an aralkylene group.) Generally, R134a is used as a lubricating oil for a compressor using R134a.
Of good hydrolysis resistance and thermal stability as well as having a pour point of -10 ° C or less, preferably -20 to -60 ° C, and a dynamic point at 100 ° C. It is necessary that the viscosity be in the range of 1 to 50 cSt, preferably 3 to 40 cSt. If the pour point is higher than −10 ° C., the lubricating oil may be solidified at a low temperature, which is not preferable.

Further, if the kinematic viscosity at 100 ° C is less than 1 cSt, it becomes impossible to maintain the hermeticity of the compressor.
If it exceeds 50 cSt, the viscosity becomes too high and the lubricity deteriorates. Further, the viscosity index, which is an index of the viscosity temperature gradient, is preferably 100 or more. The compound of the general formula (A) of the present invention satisfies these conditions.

The compound represented by the formula (A) used in the present invention is generally a compound represented by the following formulas (B) and (C) in a ratio of 2: 1.
It is obtained by reacting at a (molar ratio) ratio.

(However, R _{1 to} R ₃ and R _{4 to} R ₆ are each selected from an alkyl group or a hydrogen residue, and at least two or more alkyl groups in the group may be the same or different. R ₇ is an alkylene group, an arylene group or an aralkylene group.) The compound of the formula (B) is Or And glycerin There is a method of obtaining by reacting with the above, but the former is superior in terms of the ease of reaction.

Specific examples of each compound are shown below. As pivalic acid, 2,2-dimethylbutanoic acid, 2,2-dimethylpentanoic acid, 2-ethyl-2-methylbutanoic acid,
2,2,4,4-tetramethylpentanoic acid, neononanoic acid, neodecanoic acid, 2-isopropyl-2,3-dimethylbutanoic acid, 2-ethyl-2,3,3-trimethylbutanoic acid, 2,2,3 ,Four
-Tetramethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, 2-isopropyl-2,3,5,5-tetramethylhexanoic acid, 2,3,4-trimethyl-2-neopentylpentanoic acid , 2,2,4,4,6,6-hexamethylheptanoic acid, 2,
2,4-trimethyl-2-tert-pentylpentanoic acid, 2
-Ethyl-2,3,3,5,5-pentamethylhexanoic acid, 2-
Examples thereof include ethylhexanoic acid, 2-methylhexanoic acid, 2-methylheptanoic acid, 2-ethylheptanoic acid, and 2-ethylbutanoic acid.

May be the same or different. Further, this is obtained as a mixture from a practical point of view, and is often used as it is.

as well as Is a glycidyl ester of the acids described above.

Next, the compound represented by the formula (C) is a polyisocyanate compound, and examples thereof include hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and diphenylmethane diisocyanate.

The reaction of the formulas (B) and (C) is usually carried out at a temperature of from 60 to 160 ° C, but if necessary, the reaction may be further carried out by raising the temperature to about 200 ° C.

In the compound represented by the formula (A) of the present invention, R _{1 to} R ₃ and R _{4 to} R ₆ each may be such that at least two or more of them are alkyl groups within the group, but a higher hydrolysis resistance It is preferred that all three are alkyl groups.

In order to further enhance the performance of the compound represented by the formula (A) of the present invention, if necessary, other lubricating oils and lubricating oil additives such as antioxidants, viscosity index improvers, defoamers,
Metal deactivators and the like can be used.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

 The properties as a lubricating oil were measured by the following test methods.

1) Kinematic viscosity and viscosity index at 100 ° C .; JIS K2283 2) Pour point; JIS K2269 3) Compatibility with R-134a; 2: 8 between test oil and R-134a
(Weight), cooled to -20 ° C, separated
Those that do not separate are marked with ○.

4) Hydrolysis resistance: In the test according to ASTM D2619, the test oil having no change in the acid value was evaluated as ○, the change in the acid value within 5% as Δ, and the test value exceeding 5% as X.

Example 1 276 g of pivalic acid glycidyl ester and 2-ethyl-2
-260 g of methylbutanoic acid are reacted at 150 to 200 ° C until the acid value is 0.1 or less, then cooled to 120 ° C and added with 168 g of hexamethylene diisocyanate, and reacted until the conversion from the isocyanate value becomes 99% or more. Let it. The properties of the obtained product as a lubricating oil were measured and found to be as follows.

・ Kinematic viscosity at 100 ° C .: 28 cst ・ Viscosity index: 112 ・ Pour point: -17.5 ° C. ・ Compatibility with R-134a: ○ ・ Hydrolysis resistance: ○ Example 2 Cardura E (product of Shell Chemical Co., Ltd.) Name: carbon number 10
Glycidyl ester of neo acid) and 116 g of 2,2-dimethylbutanoic acid are added and reacted in the same manner as in Example 1.

Next, 84 g of hexamethylene diisocyanate is added at 120 ° C., and the mixture is reacted until the conversion from the isocyanate value becomes 99% or more. The properties of the obtained product as a lubricating oil were measured as follows.

・ Kinematic viscosity at 100 ° C .: 25 cst ・ Viscosity index: 123 ・ Pour point: −32.5 ° C. ・ Compatibility with R-134a: ○ ・ Hydrolysis resistance: ○ Example 3 250 g of Kajura E and 144 g of 2-ethylhexanoic acid To 150
Reaction at ~ 200 ° C until the acid value is 0.1 or less, then 12
After cooling to 0 ° C, 125 g of methylenebis (4-phenylene isocyanate) was added, and the reaction rate from the isocyanate value was reduced.
React until 99% or more. The properties of the obtained lubricating oil are as follows.

・ Kinematic viscosity at 100 ° C .: 38 cst ・ Viscosity index: 105 ・ Pour point: −25 ° C. ・ Compatibility with R-134a: ○ ・ Hydrolysis resistance: △ Example 4 Equatate 9G (by Idemitsu Petrochemical Co., Ltd.) Trade name: glycidyl ester of neo acid having 9 carbon atoms) 226 g and 144 g of 2-ethylhexanoic acid are reacted at 150 to 200 ° C. until the acid value becomes 0.1 or less, then cooled to 120 ° C. and 84 g of hexamethylene diisocyanate And react until the reaction rate from the isocyanate value becomes 99% or more. The properties of the obtained lubricating oil are as follows.

・ Kinematic viscosity at 100 ° C .: 31 cst ・ Viscosity index: 118 ・ Pour point: −27.5 ° C. ・ Compatibility with R-134a: ○ ・ Hydrolysis resistance: △

Claims (2)

(57) [Claims] 1. A lubricating oil characterized by using a compound represented by the general formula (A) as a base oil. (However, R _{1 to} R ₃ and R _{4 to} R ₆ are selected from an alkyl group or a hydrogen residue, and at least two or more are alkyl groups in each group, and the alkyl groups may be the same or different. R ₇ comprises an alkylene group, an arylene group or an aralkylene group.) 2. The lubricating oil according to claim ₁ , wherein all of R _{1 to} R ₆ in the general formula (A) are alkyl groups, and the alkyl groups may be the same or different.