JP2910164B2 - Lubricating oil composition for refrigerator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lubricating oil for a refrigerator.

[Prior art] Conventionally, lubricating oils for refrigerators include naphthenic mineral oils, paraffinic mineral oils, alkylbenzene-based synthetic oils, poly-
Alpha-olefin-based synthetic oils are known and are used for the purpose of preventing friction, wear, seizure and the like in a sliding portion of a compressor.

The properties required for lubricating oil for refrigerators, unlike general lubricating oil, involve contact with chlorofluorocarbon as a refrigerant, so that the stability to the refrigerant is excellent, the solubility with the refrigerant is excellent, It does not dissolve polymer materials such as packings used as a material.

For dichlorodifluoromethane (hereinafter, referred to as R12) conventionally used as a refrigerant, naphthene-based mineral oil, paraffin-based mineral oil, alkylbenzene-based synthetic oil, poly-α-olefin-based synthetic oil, etc. meet the above-mentioned requirements. It satisfies the conditions and can be used without trouble. However, it was pointed out that R12 could destroy the ozone layer and have a serious adverse effect on the environment.
1,1,1,2-tetrafluoroethane (hereinafter referred to as R134a)
Has been proposed. However, conventional naphthenic mineral oils, paraffinic mineral oils, alkylbenzene synthetic oils, poly-α-olefin synthetic oils and the like cannot be used in R134a and cannot be used.

In order to solve this problem, it is proposed in US Pat. No. 4,755,316 to use a polyalkylene glycol-based oil as a lubricant, and in Japanese Patent Application No. 1-122947 to use a fluorosilicone oil. These lubricating oils dissolve well in R134a and solve the above-mentioned problems.However, during use, a trace amount of acid derived from R134a is generated, which causes corrosion of equipment and deterioration of lubrication performance. I understand.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned drawbacks in the prior art, and satisfies the basic conditions required for a refrigerator lubricant, and has a trace acid content derived from R134a. Accordingly, it is an object of the present invention to provide a lubricating oil composition for a refrigerator, which does not cause corrosion of equipment and deterioration of lubrication performance.

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and has a fluorine-containing base in which a group having an epoxy structure is bonded to 100 parts by weight of a lubricating base oil used in a refrigerator. An object of the present invention is to provide a lubricating oil composition for a refrigerator, comprising a polysiloxane compounded in a proportion of 0.00001 to 10 parts by weight.

In the lubricating oil composition of the present invention, a base oil (lubricating base oil)
There is no particular limitation, and mineral oil and synthetic oil may be used alone or as a mixture of both. But R134a
It is desirable to use a polyalkylene glycol-based oil or a fluorosilicone oil from the viewpoint of solubility in water.

Next, in the lubricating oil composition of the present invention, it is necessary to mix a fluorine-containing polysiloxane having a group having an epoxy structure bonded to the base oil. There are various types, and usually, fluorine-containing polysiloxane represented by the following general formula can be used.

Wherein R ^f is a perfluoroalkyl group, R ¹ is E or
CH ₃ and E are groups having an epoxy structure, n and p are each an integer of 1 or more, and m is an integer of 0 or more. Where R ^f is R134
The chain length and the amount introduced may be determined within the range of ensuring the solubility for a. However, it is generally difficult to ensure the solubility of a perfluoroalkyl group having 3 or less carbon atoms, and a perfluoroalkyl group having 4 or more carbon atoms. It is better to use a group.

E represents a group having an epoxy structure. Specifically, glycidoxymethyl group, β-glycidoxyethyl group, γ-glycidoxypropyl group, δ-glycidoxybutyl group, β -(3,4-epoxycyclohexyl) ethyl group, β- (3,4-epoxyphenyl) ethyl group and the like can be exemplified.

n, m, p may be an integer satisfying the above conditions, but R13
As the lubricant for 4a, one having a viscosity at 100 ° C. of 1 to 10 cst is usually used as a suitable lubricant, so that n, m, and p are preferably selected so as to satisfy the conditions. In the range, the epoxy value is 0.01-0.5 gram equivalent / 100g especially
It is better to choose p so that 0.02-0.4 gram equivalent / 100 g. If the epoxy value is less than this, the effect of capturing the acid content becomes insufficient. Conversely, if the epoxy group is introduced more than this, the solubility is reduced and various inconveniences occur.

In the lubricating oil composition of the present invention, the fluorine-containing polysiloxane to which the group having an epoxy structure is bonded is used in an amount of 0.00001 to 10 parts by weight, preferably 0.001 to 0.1 part by weight, based on 100 parts by weight of the base oil. Mix. If the compounding amount is less than this, the effect of trapping the acid content is not sufficient, and if the compounding amount is more than this, on the contrary, there arises inconvenience such as a decrease in electric characteristics.

The lubricating oil composition of the present invention contains a base oil and a fluorine-containing polysiloxane to which a group having an epoxy structure is bonded as described below. Further, if necessary, various additives such as antioxidant , An extreme pressure agent, an oil agent, a copper deactivator, and the like.

Here, as an antioxidant, 2,6-di-t-butyl-
phenol-based antioxidants such as p-cresol; 2,6-di-t-butyl-p-ethylphenol; 4,4-methylenebis- (2,6-di-t-butylphenol);
α-naphthylamine; octylated-phenyl-α-naphthylamine; mono-octylated diphenylamine; di-
There are amine antioxidants such as octylated diphenylamine.

Examples of the extreme pressure agent include a phosphorus-based extreme pressure agent and a sulfur-based extreme pressure agent. Of these, the phosphate-based extreme pressure agent is a phosphate-based extreme pressure agent, such as triphenyl phosphate, trecresil phosphate, and tris (isopropylphenyl). ) Phosphate, tributyl phosphate, trioctyl phosphate, triphenyl thiophosphate, tricresyl thiophosphate, and the like. Examples of the phosphite type include triphenyl phosphite,
Tricresyl phosphite, tris (nonylphenyl)
Examples include phosphite, trilauryl phosphite, tristearyl phosphite, and trithiophosphite. Specific examples of sulfur-based extreme pressure agents include di-
Lauryl thiopropionate, ditridecyl thiodipropionate, distearyl thiodibutyrate, thiophene, benzothiophene, dodecyl sulfite, stearyl mercaptan and the like can be mentioned.

Further, bis (2-ethylhexyl) is used as an oily agent.
Sebacate, bis (2-ethylhexyl) azelate and the like, as a copper deactivator benzotriazole,
Methylbenzotriazole, dimethylbenzotriazole, mercaptobenzothiazole and the like can be mentioned.

[Action] The lubricating composition for a refrigerator of the present invention contains a fluorine-containing polysiloxane to which a group having an epoxy structure is bonded. Here, the group having an epoxy structure captures a trace amount of acid derived from R134a and prevents corrosion of equipment, deterioration of lubrication performance, and the like. On the other hand, since it contains fluorine, its solubility in R134a is not impaired, and since it has a siloxane skeleton, it has good low-temperature properties.

[Examples] A lubricating oil composition was prepared by mixing a base oil shown in Table 1 with a predetermined ratio of a fluorinated polysiloxane to which a group having an epoxy structure shown in Table 2 was bonded. The composition was subjected to a shield tube test. The results are shown in Table 3.

The shield tube test was performed as follows.
That is, steel, copper and aluminum wire containing 10ml inner volume
Put 2 ml of sample oil into a glass pressure-resistant ampoule with a syringe,
Degassed. 5g of refrigerant R134a while cooling with liquid nitrogen
After putting, it sealed with the burner. The sealed ampule was left in a 175 ° C. oil bath for 480 hours. After the test, cool the ampoule with liquid nitrogen and open it.
After absorption in 0 ml of distilled water, the amount of hydrochloric acid generated was calculated by titration with a 0.1 N potassium hydroxide solution. Also,
The solubility of the lubricating oil composition in R134a was also observed.

[Effect of the Invention] As described above, the lubricating oil composition of the present invention has excellent high-temperature stability in the presence of various refrigerants such as Freon,
It can handle conversion to 34a.

Claims (1)

(57) [Claims] The present invention is characterized in that a fluorine-containing polysiloxane having a group having an epoxy structure bonded thereto is mixed in a proportion of 0.00001 to 10 parts by weight with 100 parts by weight of a lubricating base oil used in a refrigerator. Lubricating oil composition for refrigerators.