JPH0381395A - Tetrafluoroethane composition for refrigerating machine - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in functions such as abrasion, friction and anti-seizing properties at a sliding part of a compressor, etc., and having low moisture absorption properties by mixing a specific polyether with tetrafluoroethane. CONSTITUTION:The title composition is obtained by mixing one or more ethers selected from the group consisting of ethers of formulae I-III [wherein R<1> is alkylene; R<2-4> are each alkanesulfonyl, arenesulfonyl or H provided that 2 or more of R<2-4> are not H atoms at the same time; l, m and n are each a positive number such that the kinematic viscosity may be 5-300cst (40 deg.C); X<1> is R<1> or the residue of a monohydroxy compound from which the hydroxyl group is removed provided that X<1> and R<1> are not H atoms at the same time: R<2> is the residue of a dihydroxy compound from which the hydroxyl groups are removed; and X<3> is the residue of a trihydroxy compound from which the hydroxyl groups are removed] with the tetrafluoroethane.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is directed to the refrigerant tetrafluoroethane, preferably 1,1,1,2-tetrafluoroethane (R-134
For a), from -20℃ or lower, +
The present invention relates to a composition for a refrigerator consisting of polyether and tetrafluoroethane, which are compatible in any ratio at temperatures of 40° C. or higher and have low hygroscopicity.

[Conventional technology]

In refrigeration cycles such as refrigerators and car air conditioners, R
-12 (dichlorodifluoromethane) has been used as a good refrigerant. However, R-12 can destroy the ozone layer in the stratosphere and have a negative impact on biological systems, so alternatives are being considered. R-134a is considered to be the most promising substitute for R-12;
Naphthenic mineral oil and paraffinic mineral oil, which are common refrigeration oils for R-12, are not compatible with R-134a. Therefore, naphthenic mineral oil,
Paraffinic mineral oil cannot be used. Polyether oils having the structures shown in Table 1 are known as substances that are relatively compatible with R-134a. Regarding (a), for example, Du Pont's Re5ea
rchDisclosure(174830ct, 19
78). Regarding (b), for example, U
, S. Pat, No. 4.755°316. [Problems to be Solved by the Invention] However, the polyethers shown in Table 1 had the following problems.・Insufficient compatibility with R-134a - In order to demonstrate lubricity, which is the most important role of refrigeration oil, R-1
It is necessary to be compatible with R-134a and circulate within the system together with R-134a. (7), C45 refrigerating machine oil is, for example, 4
When the kinematic viscosity at 0° C. is 100 cst, the high temperature critical temperature (see notes in Table 1) is as shown in Table 1. The compatibility cannot be said to be sufficient. - Highly hygroscopic - Refrigerating machine oil (7), C4) has high hygroscopicity and easily absorbs moisture. Contamination with moisture causes negative effects such as a decrease in insulation resistance and an increase in corrosiveness to metals. Table 1 Conventional polyether oil and High temperature critical temperature (*) High temperature critical temperature: Oil and R-134a are mixed at a weight ratio of 15:85 and sealed. As the temperature is increased, the temperature at which turbidity or two-layer separation begins is called the high temperature critical temperature. The better the compatibility, the higher the high-temperature critical temperature. [Means for Solving the Problems] In solving the above-mentioned problems, the present inventors presumed that the high hygroscopicity of polyether oil is caused by the terminal hydroxyl groups. Therefore, using a polyether with a number of terminal hydroxyl groups in the range of 1 to 3, and using a compound in which all or part of each terminal hydroxyl group was converted into a sulfonic acid ester, we evaluated it as a refrigerating machine oil for R-134a. was carried out. As a result, not only hygroscopicity is improved, but R
It was discovered that the compatibility with -134a and the viscosity index were also improved, and the present invention was completed. That is, the present invention is based on the following general formula (%) [wherein R1 is an alkylene group, R'', R'', R' is alkanesulfonyl, arenesulfonyl or hydrogen, R
R, R1, and R4 may be the same or different (however, two or more selected from R'', R'', and R' may not be hydrogen at the same time) β. m and n are the kinematic viscosity of the above compounds (■ to ■) of 5 to 300 cst
(40°C), and may be the same or different. XI is hydrogen, alkanesulfonyl, arenesulfonyl, or a residue of a monohydroxy compound from which the hydroxyl group has been removed. (However, Xl and R1' do not become hydrogen at the same time.) X2 is the residue of a dihydroxy compound from which the hydroxyl group has been removed. x3 is the residue of the trihydroxy compound from which the hydroxyl group has been removed. The present invention relates to a tetrafluoroethane-based refrigerator composition comprising at least one polyether selected from the following and tetrafluoroethane. XI in the general formula (2) is hydrogen, a sulfonyl group, or a residue of a monohydroxy compound from which the hydroxyl group has been removed. When a sulfonyl group is represented by -SQ or -A, A is preferably an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, or an aryl group such as a phenyl group. The residue of the monohydroxy compound excluding the hydroxyl group is preferably an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a 2-ethylhexyl group, a nonyl group, or an aryl group such as a phenyl group. As x3 in the general formula (■), a residue from which the hydroxyl group of a dihydroxy compound such as an ethylene glycol residue or a propylene glycol residue has been removed is preferable;
3 is preferably a residue from which the hydroxyl group of a trihydroxy compound has been removed, such as a glycerin residue or a trimethylolpropane residue. R1 in the general formulas Φ~■ is an alkylene group such as an ethylene group, a propylene group, a butylene group, a tetramethylene group, etc., and these may be used alone or together in a random or block form, and when they exist together, It is preferable that the main component is a propylene group. General formula■～
R' in (2) may be the same or different. Rx, Rs, and R4 in the general formulas Φ to 2 are alkanesulfonyl, arenesulfonyl, or hydrogen as described above, and these may be the same or different. However, XI and R3 do not become hydrogen at the same time. Also, Rm, Rm,
Two or more elements selected from f<4 do not become hydrogen at the same time. Usually, when synthesizing the compounds represented by the general formulas (1), (2), and (2), the number of active hydrogen groups in the corresponding initiators is 1 and 2.3, respectively. Using an initiator with the number of active hydrogen groups of 4 or more, the kinematic viscosity is 12c, which is the general kinematic viscosity of refrigeration oil for car air conditioners and refrigerators.
st (40°C) to 200cst (40°C), 12. The number of m and n, that is, the number of moles of alkylene oxide added, becomes too small, which is undesirable because the lubricating performance deteriorates. The compounds represented by the general formulas Φ to ■ have a kinematic viscosity of 5 to 300 cst (40 °C), preferably 12
~200 cst (40°C) is desirable, and the molecular weight in the general formula Φ~■ or (1, m, n
It is preferable to select a value that falls within such a viscosity range. 12. The values of m and n are approximately 3 to 60, preferably 6 to 30, and may be the same or different. The weight ratio of the compounds represented by the above general formulas (1) to (2) and R134a is 1/99 to 99/1, preferably 5/95 to 60.
/40. R134a may contain a small amount of 1,1,2,2-tetrafluoroethane (R134). Compounds of the general formulas Φ to (■) can be used alone or as a mixture thereof. The composition of the present invention is particularly effective in refrigeration cycle applications for freezing, refrigeration, and air conditioning in the low to high temperature fields, but can also be used in various other heat recovery technologies such as Rankine cycles. be. The composition of the present invention has excellent thermal stability and does not require a stabilizer under normal usage conditions, but when it is necessary to improve thermal stability due to harsh usage conditions, dimethyl phosphite , phosphite compounds such as diisopropyl phosphite and diphenyl phosphite, phosphine sulfide compounds such as triphenoxyphosphine sulfide and trimethylphosphine sulfide, and other stabilizers such as glycidyl ethers in an amount of 0.01 to 10% by weight.
It is sufficient to add a certain amount. In addition, the compounds represented by the general formulas Φ to ■ of the present invention and conventionally used naphthenic mineral oils, paraffinic mineral oils,
Can be mixed with alkylbenzene-based synthetic oil, poly-α-olefin-based synthetic oil, perfluoropolyether oil which is a fluorinated lubricating oil, fluorine-containing silicone oil, or polyether oil other than the polyether oil of the present invention. It is. Additionally, various additives such as phenol-based or amine-based antioxidants, sulfur- or phosphorus-based extreme pressure additives, silicone-based antifoaming agents, or metal deactivators such as benzotriazole may be added to the composition of the present invention. It may be further added. [Function] In the present invention, it is thought that by converting the terminal hydroxyl group into a sulfonic acid ester, hydrophilicity is reduced and hygroscopicity is reduced. Further, although the mechanism of compatibilization between the oil of the present invention and the refrigerant tetrafluoroethane is not necessarily clear, it is believed that a certain interaction between the sulfonic group of the sulfonic acid ester group and tetrafluoroethane is involved. It is thought that there are. [Example] Examples 1 to 5, Comparative Examples 1 to 5 Structure of oil used in Examples 1 to 5 and Comparative Examples 1 to 5, R-
Table 2 shows the results of compatibility with 134a, hygroscopicity, and kinematic viscosity at 40°C. Hygroscopicity test method: 15 g of oil, which has been confirmed to have a moisture content of 0.03% or less, is placed in a petri dish with a diameter of 150 mm. The petri dish is left open in a constant temperature room with a room temperature of 20°C and a humidity of 50%. When the weight of oil after 30 hours is Yg, the weight increase rate is expressed by the following formula [Effect of the invention]

Claims (1)

[Claims] 1. The following general formula (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (3) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R^1 is an alkylene group, R^2, R^3, R^
4 is alkanesulfonyl, arenesulfonyl, or hydrogen, and R^2, R^3, and R^4 may be the same or different. (However, two or more selected from R^2, R^3, and R^4 will not become hydrogen at the same time.) l, m, and n represent compounds (1) to (3) whose kinematic viscosity is 5. ~300cst(
40° C.), and may be the same or different. X^1 is hydrogen, alkanesulfonyl, arenesulfonyl, or a residue of a monohydroxy compound from which the hydroxyl group has been removed. (
However, X^1 and R^2 do not become hydrogen at the same time. ) X^2 is the residue of a dihydroxy compound from which the hydroxyl group has been removed. X^3 is the residue of the trihydroxy compound from which the hydroxyl group has been removed. ] A tetrafluoroethane-based refrigerator composition comprising at least one polyether selected from the following and tetrafluoroethane.