JP2781766B2 - Tetrafluoroethane refrigerator composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composition for a tetrafluoroethane refrigerator, and more particularly to a composition for a tetrafluoroethane refrigerator comprising a specific polyether refrigerator oil and a tetrafluoroethane refrigerant, and a tetrafluoroethane refrigerator composition. The present invention relates to a polyether refrigerating machine oil (lubricating oil) for a refrigerator using an ethane refrigerant.

[0002]

2. Description of the Related Art Conventionally, R-12 (dichlorodifluoromethane) has been used as a good refrigerant in refrigeration cycles such as refrigerators and car air conditioners. But,
R-12 has the potential to destroy the stratospheric ozone layer and adversely affect ecosystems, and alternative materials are being investigated. As an alternative to R-12, R-134a (1,
(1,1,2-tetrafluoroethane) is considered to be the most influential, but 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 or paraffinic mineral oil cannot be used as the refrigerating machine oil for R-134a. As a substance relatively well compatible with R-134a, a polyether oil having a structure as shown in Table 1 below is known. (A) For example, Du Pont
Research Disclosure (17483 Oct. 1978). For (a), for example, USPat. 4,755,316
It is described in the specification.

[0003]

However, the polyethers shown in Table 1 have the disadvantage that they have high hygroscopicity and easily absorb moisture. An increase in moisture has adverse effects such as a decrease in insulation resistance and an increase in corrosiveness to metals.

[0004]

[Table 1]

* Hygroscopicity test method 15 g of oil confirmed to have a water content of 0.03% or less is placed in a petri dish having a diameter of 150 mm. While keeping the petri dish open, it is left to stand in a constant temperature room at room temperature of 20 ° C. and humidity of 50%. Assuming that the weight of the oil after 30 hours is Yg, the weight increase rate is determined by the following equation. Weight increase rate = (Y-15) / 15 × 100 [%]

[0006]

Means for Solving the Problems The present inventors have made intensive efforts to solve the above-mentioned problems, and as a result, have presumed that the high hygroscopicity of polyether oil is caused by terminal hydroxyl groups. Then, evaluation was performed as a refrigerating machine oil for R-134a using a polyether having a methyl group at the end. As a result, the polyether having a methyl group at the end is reduced in the amount of moisture absorption and the viscosity index is improved without impairing the compatibility with R-134a as compared with the polyether having a hydroxyl group. And completed the present invention. That is, the present invention provides the following general formula:

[0007]

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[In the formula, R ¹ represents an ethylene group or a propylene group, which are present together in a random or block manner. X ¹ represents a methyl group; X ² represents a residue obtained by removing a hydroxyl group from a dihydroxy compound having 2 or 3 carbon atoms;
³ represents a residue obtained by removing a hydroxyl group from a trihydroxy compound. l, m, and n are kinematic viscosities of the above compounds 10 to 3
It is a positive number that is 00 cSt (40 ° C.), and may be the same or different. A tetrafluoroethane-based refrigerator composition comprising at least one polyether selected from the group consisting of The present invention also provides a refrigerating machine oil for a tetrafluoroethane-based refrigerating machine comprising the above polyether.

X ¹ in the general formula is a residue obtained by removing a hydroxyl group from methanol, that is, a methyl group. X ² in the general formula is a residue obtained by removing a hydroxyl group from a dihydroxy compound having 2 or 3 carbon atoms, that is, an ethylene glycol residue (that is, an ethylene group), a propylene glycol residue (a 1,2-propylene glycol residue and 1 ,
3-propylene glycol residue) (that is, propylene group)
It is. X ³ in the general formula is a residue obtained by removing a hydroxyl group from a trihydroxy compound such as a glycerin residue or a trimethylolpropane residue. Also, the general formula
In the above, R ¹ represents an ethylene group or a propylene group, and these are present together in a random or block manner. That is, l, m or n R ¹ O in the formula
Each represents an oxyethylene group or an oxypropylene group, and when l, m or n are repeated, the oxyethylene group and the oxypropylene group are linked together in a random or block manner. In this case, those having an oxypropylene group as a main component are preferable. Further, a plurality of R ¹ in the general formula and may be the same or different.

The compound represented by the above general formula (1) is used as a refrigerating machine oil in order to sufficiently achieve functions such as friction, wear and seizure prevention in sliding parts of a compressor or the like.
Its kinematic viscosity is desirably 10 to 300 cSt (40 ° C.), preferably 15 to 200 cSt (40 ° C.).
It is preferable that the values of m and n are selected so as to be within such a viscosity range. The values of l, m and n are about 3 to 6
0, preferably 6 to 30, which may be the same or different.

The composition of the present invention comprises a polyether represented by the above general formula (1) and tetrafluoroethane. Weight ratio of 1/99 to 99/1, preferably 5/95
６０60/40. In addition, this tetrafluoroethane is generally R134a, but it is added to 1,1,2,2.
A small amount of 2-tetrafluoroethane (R134) may be contained. The compounds of the general formulas (1) to (5) can be used alone or as a mixture thereof. The composition and the refrigerating machine oil (lubricating oil) of the present invention can be used for refrigerating in low to high temperature fields.
The present invention is particularly effective in the application of a refrigeration cycle for refrigeration and air conditioning, but can also be used for various other heat recovery technologies such as a Rankine cycle.

The composition and the refrigerating machine oil of the present invention are excellent in heat stability and do not require a stabilizer under normal use conditions, but are required to improve heat stability due to severe use conditions. Include phosphite compounds such as dimethyl phosphite, diisopropyl phosphite, and diphenyl phosphite; triphenoxy phosphine sulfide;
A small amount of a phosphine sulfide-based compound such as trimethylphosphine sulfide or a stabilizer such as glycidyl ethers may be added. Further, the general formula of the present invention ~
And a conventionally used naphthenic mineral oil, paraffinic mineral oil, alkylbenzene-based synthetic oil, poly-α-olefin-based synthetic oil, perfluoropolyether oil as a fluorine-based lubricant, fluorine-containing It is possible to use a mixture with silicone oil or a polyether oil other than the polyether oil of the present invention.

Various additives such as phenolic and amine-based antioxidants, sulfur and phosphorus-based extreme pressure additives, silicone-based defoamers, and metal deactivators such as benzotriazole are also used in the present invention. May be further added to the composition or the refrigerating machine oil. In the present invention, it is considered that by methylating the terminal hydroxyl group, hydrophilicity is reduced and hygroscopicity is reduced. In addition, it is considered that by methylating the terminal hydroxyl group, the interaction due to hydrogen bonding between molecules is reduced, and the viscosity index is improved.

[0014]

Next, the present invention will be described in more detail with reference to examples. Example 1 The following formula

[0015]

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The hygroscopicity, viscosity index, compatibility with R134a and kinematic viscosity at 40 ° C. of the polyether oil represented by the formula (1) were measured. The compatibility with R134a was measured by the following method. Method for Measuring Compatibility with R134a Polyether oil and R134a were mixed at a weight ratio of 15:85, sealed, the temperature was kept at 25 ° C., and the state was observed.

As a result, the weight increase rate showing hygroscopicity is 0.9.
%, A viscosity index of 245 and a kinematic viscosity of 101 c.
St (40 ° C.) and R134a dissolved and showed good compatibility. Here, the viscosity index is an index indicating the temperature dependency of the viscosity of the lubricating oil. The larger the value, the smaller the change in viscosity with temperature, and the better the lubricating performance.

Comparative Example 1

[0019]

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The hygroscopicity, viscosity index, compatibility with R134a and kinematic viscosity at 40 ° C. of the polyether oil represented by the following formula were measured in the same manner as in Example 1. As a result, the viscosity index was 228, the kinematic viscosity was 104 cSt (40 ° C.), and R1
34a and showed good compatibility. However, the rate of weight increase showing hygroscopicity was 2.9%, indicating a large amount of hygroscopicity.

[0021]

The composition and the refrigerating machine oil of the present invention have low hygroscopicity, so that the incorporation of moisture is reduced, so that the insulation resistance can be prevented from decreasing and the corrosion of copper, pipes and other metals due to moisture is prevented from progressing. can do. Further, since the viscosity index is high, a lubricating function such as friction, abrasion and prevention of seizure in a sliding portion of a compressor or the like can be sufficiently exhibited in a wide temperature range.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C10N 30:00 40:30 (56) References JP-A-2-305893 (JP, A) JP-A-2-102296 (JP, A) JP-A-1-259909 (JP, A) JP-A-1-198694 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10M 105/18 C09K 5/04 C10M 107 / 34 C10N 20:02 C10N 30:00 C10N 40:30

Claims (2)

(57) [Claims] [Claim 1] The following general formula: [Wherein, R ¹ represents an ethylene group or a propylene group, and these are present together in a random or block manner. X ¹ represents a methyl group, X ² represents a residue obtained by removing a hydroxyl group from a dihydroxy compound having 2 or 3 carbon atoms, and X ³ represents a residue obtained by removing a hydroxyl group from a trihydroxy compound. l, m,
n is a compound having a kinematic viscosity of 10 to 300 cSt.
(40 ° C.), which may be the same or different. ] A tetrafluoroethane-based refrigerator composition comprising at least one polyether selected from the group consisting of: and tetrafluoroethane. 2. A refrigerating machine oil for a tetrafluoroethane-based refrigerating machine comprising the polyether according to claim 1.