JPH0532985A - Refrigerator oil composition - Google Patents

Abstract

(57) [Summary] [Structure] (a) A specific ester oil and / or complex ester oil, and (b) the following general formula R ₁ [O (PO) _l (EO) _m R ₂ ] _n (wherein R ₁ is an n-valent group of an aliphatic hydrocarbon having 1 to 10 carbon atoms, PO is an oxypropylene group, EO is an oxyethylene group, R ₂ is a hydrogen atom or an alkyl group, and R ₁ and R ₂
Is 10 or less, l is an integer of 1 or more, m
Is an integer not exceeding 0 or l, and n is an integer of 1 to 6)
A refrigerating machine oil composition for a refrigerant containing trifluoromethane and / or pentafluoroethane as a main component, which is a mixture of a polyether compound having an average molecular weight of more than 300 and not more than 2000. [Effects] Excellent compatibility with new refrigerants such as trifluoromethane and pentafluoroethane, and good lubricity and thermal stability. Lubricating oil for refrigerators using such new refrigerants and refrigerants containing them. Can be preferably used as.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating machine oil composition for a novel refrigerant, and more specifically, it contains monochlorodifluoromethane (hereinafter referred to as a refrigerant containing chlorine, which is considered to decompose and destroy the ozone layer). , R-22) and other non-chlorine-containing hydrofluorocarbons such as trifluoromethane (hereinafter referred to as R-3).
2) or pentafluoroethane (hereinafter, R-1
The present invention relates to a refrigerating machine oil composition having excellent compatibility with a refrigerant containing 25) and excellent properties such as lubricity and stability.

[0002]

2. Description of the Related Art Generally, a compression type refrigerator comprises a compressor, a condenser, an expansion valve and an evaporator, and a mixture of a refrigerant and a lubricating oil lubricates the inside of this sealed system. Refrigerant and lubricating oil
In the lubrication process, the temperature in the compressor is 50 ° C. or higher, and the temperature in the refrigerant unit is about −40 ° C., so it is necessary to be compatible with each other in the temperature range of −40 ° C. to + 50 ° C. without being separated from each other. Is. If layer separation occurs during the operation of the refrigerator, seizure of the compressor and reduction in the efficiency of the evaporator are caused, and the life and efficiency of the device are significantly adversely affected.

Further, it is important for refrigerating machine oil to have a viscosity capable of retaining an oil film necessary for lubrication particularly at high temperatures. Usually, the viscosity of the lubricating oil before mixing with the refrigerant is about 2 to 50 cSt at 100 ° C. If the viscosity is lower than this, the oil film becomes thin and lubrication failure tends to occur, and if it is higher, the heat exchange efficiency decreases. Since the refrigerating machine oil is used in a wide temperature range, its viscosity index is preferably high, and a viscosity index of 40 or more is usually required. Furthermore, as other performances, stability in a CFC atmosphere, low hygroscopicity for preventing the valve from closing due to freezing in the expansion valve, and high electrical insulation in the case of a compressor with a built-in motor are required.

On the other hand, chlorofluoroalkanes and hydrochlorofluoroalkanes, which are usually called CFCs, are widely used as refrigerants for refrigerators. Among them, R-22 is particularly often used for air conditioners and industrial purposes. However, since hydrochlorofluoroalkanes containing chlorine in the molecule like R-22 may cause environmental pollution such as destruction of the ozone layer together with chlorofluoroalkanes, their regulations have recently been globally regulated. It tends to be severe. Therefore, as a new refrigerant, hydrofluorocarbon R-32 containing no chlorine is used.
And R-125, and further, 1,1-difluoroethane (hereinafter abbreviated as R-152a), 1,1,1,2-
A mixed refrigerant with tetrafluoroethane (hereinafter abbreviated as R-134a) or the like has been proposed. These refrigerants are less likely to destroy the ozone layer, and can replace the R-22 with almost no change in the structure of the conventional refrigerator, so that the room air conditioner and the industrial refrigerator are used. Is expected to be put into practical use.

[0005]

However, such R
-22 New refrigerants R-32 and R-12, which are regarded as substitutes
5 or the above mixed refrigerant containing them, the lubricating oil conventionally used with R-22, that is,
Paraffinic mineral oils, naphthenic mineral oils, alkylbenzenes, etc. have poor compatibility with new refrigerants and cannot be used at all.

Therefore, the present invention provides R-32 or R-12.
5 or its compatibility with mixed refrigerants containing them is good over the entire operating temperature range, has high stability in a CFC atmosphere, low hygroscopicity, high electric insulation, and is resistant to hydrolysis. It is intended to provide a good refrigerator oil composition.

[0007]

The present inventors have found that a refrigerating machine oil composition containing a mixed oil of a specific ester and a specific polyether compound as a main component contains R-32 or R-125, or these. It has been found that it has excellent compatibility with the mixed refrigerant and can meet the above-mentioned object, and thus completed the present invention. That is, the present invention provides (a) an ester oil synthesized from a polyhydric alcohol having 1 to 15 carbon atoms and a monohydric fatty acid having 3 to 18 carbon atoms and / or a polyhydric alcohol having 5 to 15 carbon atoms, and A complex ester oil synthesized from a mixed carboxylic acid of a monovalent fatty acid having 3 to 18 and a polybasic acid having 4 to 14 carbon atoms, and (b) the following general formula R ₁ [O (PO) _l (EO)] _m R ₂ ] _n (wherein R ₁ is an n-valent group of an aliphatic hydrocarbon having 1 to 10 carbon atoms, PO is an oxypropylene group, EO is an oxyethylene group, R ₂ is a hydrogen atom or an alkyl group, R ₁ and R ₂
Is 10 or less, 1 is an integer of 1 or more, m is 0 or an integer not exceeding 1, and n is an integer of 1 to 6), and the average molecular weight is more than 300 and 2000. With the following polyether compounds

The polyhydric alcohols used in the present invention include neopentyl glycol, trimethylolethane,
Polyhydric alcohols having a neo-type carbon structure such as trimethylolpropane, trimethylolbutane, pentaerythritol, dipentaerythritol and tripentaerythritol are preferred, and among them, neopentyl glycol, trimethylolpropane and pentaerythritol are particularly preferred. These polyhydric alcohols may be used alone or in combination of two or more for esterification.

Examples of monovalent fatty acids having 3 to 18 carbon atoms include propionic acid, isopropionic acid, butanoic acid,
Isobutanoic acid, pentanoic acid, isopentanoic acid, hexanoic acid, heptanoic acid, isoheptanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, 3,5,5-trimethylhexanoic acid, decanoic acid, undecanoic acid, lauric acid, myristin Acids, palmitic acid, palmitooleic acid, stearic acid, isostearic acid, linoleic acid, linolenic acid and the like. These monohydric fatty acids can be used in the esterification reaction either as a single oil or as a mixed oil of two or more kinds.

As the polybasic acid for obtaining the complex ester oil which can be used in the present invention, succinic acid, glutaric acid, adipic acid, pimelic acid,
Examples thereof include suberic acid, azelaic acid, sebacic acid, phthalic acid, maleic acid and trimellitic acid. When these polybasic acids and the above-mentioned monohydric fatty acids are simultaneously reacted with a polyhydric alcohol, a complex ester which is one of the materials for the refrigerator oil composition of the present invention can be synthesized.

In the refrigerator oil composition of the present invention, the polyether compound of the above formula is used as the other refrigerator oil material. R ₁ in the above formula is a hydrocarbon residue derived from an alkyl group having 1 to 10 carbon atoms or a dihydric alcohol having 2 to 10 carbon atoms, preferably a methyl group, an ethyl group, an ethylene group. , A propyl group, a propylene group, a trimethylene group, and a 1,2,3-propanetriyl group.

In the above formula, l is an integer of 1 or more, m is 0 or an integer not exceeding 1, and n is an integer of 1 to 6,
l, m and n are polyether compounds having an average molecular weight of 30.
More than 0 and not more than 2000, preferably 400
~ 1800 is selected.

Further, the bond between 1 oxypropylene group and m oxyethylene group in the above formula may be either block copolymerization or random copolymerization. In addition, n R _{2 s} may be the same or different, and this is n
The same applies to the number of l and the number of m.

The polyether compound represented by the above formula used in the present invention preferably has a kinematic viscosity at 100 ° C. adjusted to 2 to 15 cSt in order to maintain lubricity and compatibility. Further, such polyether compounds may be used alone or in combination of two or more kinds.

The mixing ratio of the ester and the polyether in the refrigerating machine oil composition of the present invention is selected so that the characteristics of each base material can be sufficiently exhibited. Preferably, it is in the range of 95 to 5 parts by weight of polyether with respect to 5 to 95 parts by weight of ester. This ratio may be appropriately selected according to the type of refrigerant and the required specifications of the equipment used.

The refrigerating machine oil composition of the present invention is applied to R-32, R-
When added as a lubricating oil for a refrigerant such as 125, the addition amount thereof varies depending on the type of the refrigerant and the refrigerator oil composition and the type of the refrigerator, but is usually 90 to 10 parts by weight of the refrigerant for the refrigerator oil composition. 10 to 90 parts by weight is preferable.

The refrigerating machine oil composition of the present invention is R-32.
Or a refrigerating machine oil composition for a refrigerant containing R-125, wherein the refrigerant is R-32 simple substance, R-125 simple substance, R-
32 and R-125, or R-1
52a and / or a mixture containing R-134a, and further R-124, R-124a, R-142b, R-.
The refrigerating machine oil composition of the present invention can be used even in a mixture with 143, R-143a, R-218 and the like.

The refrigerator oil composition according to the present invention comprises
Needless to say, a lubricating oil such as a synthetic oil or a mineral oil can be appropriately mixed in a range satisfying the function as a refrigerating machine oil, and conventionally, various known additives used in a refrigerating machine oil, for example, phosphorus-based materials. Addition of load-bearing additives, antioxidants such as amines and phenols, metal deactivators such as benzotriazole, defoaming agents such as silicones, oily agents such as carboxylic acids, and rust preventives such as alkenylsuccinic acid. can do.

[0019]

The dihydric or higher polyhydric alcohol, which is a raw material for the alcohol component for synthesizing the ester oil constituting the refrigerator oil composition of the present invention, must have a carbon number of 15 or less. In a polyhydric alcohol having 16 or more carbon atoms, the hydrocarbon portion of the alcohol itself becomes too large, and the synthesized ester has poor compatibility with new refrigerants such as R-32 and R-125, and refrigerating machine oil. Is not preferable.

Further, in the present invention, as an ester oil, the above monohydric fatty acid having 3 to 18 carbon atoms and 4 to 1 carbon atom are added.
A mixed carboxylic acid obtained by mixing the polybasic acid of 4 as an acid component,
A complex ester oil synthesized by reaction with a polyhydric alcohol having 5 to 15 carbon atoms can be used.
A polybasic acid having 3 or less carbon atoms is a special product, is difficult to obtain at low cost, and is inferior in the stability of the ester after synthesis, and thus is not preferable as a raw material for complex ester oil synthesis according to the present invention. Further, a polybasic acid having 15 or more carbon atoms is not preferable because the compatibility with R-32, R-125 and the like is significantly reduced. The polybasic acid preferably has 4 to 14 carbon atoms, and in order to ensure compatibility with R-32, R-125 and the like in a wider temperature range, it has 4 carbon atoms.
Those of 10 are particularly preferable.

It is presumed that the complex ester has a structure in which a plurality of polyhydric alcohols and polybasic acids are alternately connected by ester bonds, and the remaining hydroxyl groups are esterified and blocked by monovalent fatty acids. The higher the ratio of polybasic acid to monovalent fatty acid, the larger the molecular weight and the higher the viscosity of the ester obtained. An ester having an arbitrary viscosity can be obtained by changing the proportion of the polybasic acid, but in order to avoid a viscosity that is too high, the proportion of the polybasic acid is preferably 80 mol% or less of the total acid. Further, the ester oil and complex ester oil of (a) of the present invention, when the total acid value or the hydroxyl value is high, the hydrolysis stability and thermal stability are lowered, and especially a high total acid value promotes corrosion. , Total acid value 1mg
KOH / g, total hydroxyl value 50 mg KOH / g or less.

Next, the reason for limiting the average molecular weight of the polyether compound of the above formula used as the other refrigerating machine oil material in the present invention to more than 300 and 2000 or less is as follows. That is, when the average molecular weight is 300 or less, the kinematic viscosity at 100 ° C. is 2 cSt or less, which cannot maintain sufficient lubricity. On the other hand, when the average molecular weight exceeds 2000, R-32, R-125, etc. This is because they are incompatible. Adjustment of such average molecular weight,
In the formula, the degree of polymerization of oxyethylene group and oxypropylene group and the addition amount of [O (PO) _l (EO) _m R ₂ ] (n)
Made by The added amount (n) is 1 to 6
It is necessary to be an integer, and when it exceeds 6, it is not general as a compound, and it is expensive and not economical.

[0023] R ₁ in the formula of the polyether compound used in the present invention, n-valent group of aliphatic hydrocarbons having 1 to 10 carbon atoms, also R ₂ represents a hydrogen atom or an alkyl group, and R ₁ It is necessary that the sum of carbon numbers of R ₂ is 10 or less. From the viewpoint of compatibility with R-32, R-125 and the like, the smaller the number of carbon atoms, the better the compatibility, R ₁ is more preferably an alkyl group having 1 to 4 carbon atoms, and R ₂ is a hydrogen atom or a carbon atom. Alkyl groups of the number 1 to 4 are more preferable, and if the number of carbon atoms is 10 or more, they are not compatible and cannot be used.
Even if the carbon number of R ₁ exceeds 10, it cannot be used because it becomes incompatible with R-32, R-125 and the like. Also, R ₁ and R ₂
The sum of the carbon numbers of 10 or less is R when it exceeds 10.
This is because the compatibility with -32, R-125 and the like is reduced and the practicality is lost.

In the present invention, an oxybutylene group or more,
That is, a polyether compound containing an oxyalkylene group having 4 or more carbon atoms cannot be used because it becomes incompatible with R-32, R-125 and the like. Further, the polyether compound containing only oxyethylene group has a high pour point and cannot be used alone, and the ratio of oxyethylene group and oxypropylene group is 5: 5 (molar ratio).
If the number of oxyethylene groups is changed to more than
That is, when l and m in the above formula have a relation of m> l, the low temperature characteristics such as pour point are deteriorated and finally solidified at room temperature, which is not preferable. On the other hand, a polyether compound containing only an oxypropylene group, that is, m in the above formula is zero can be used, but is preferably a copolymer of an oxyethylene group and an oxypropylene group. .

A feature of the present invention is that a mixed oil of an ester having a specific structure and a polyether is used as a refrigerant R-32 or R-125.
R-152a or R-
It is used as a lubricating oil for a refrigerator using a mixed refrigerant with 134a. The characteristics of the respective base materials, that is, high lubricity of ester, low hygroscopicity, high electric insulation, and high compatibility with R-32, R-125 of polyether, etc., are combined to provide an excellent overall performance. The point is that it is used as refrigerating machine oil. The refrigerating machine oil composition of the present invention is particularly excellent in compatibility with the refrigerant in a wide range from low temperature to high temperature and has high lubricity.

[0026]

The present invention will be described in more detail with reference to the following examples. Examples 1 to 6 and Comparative Examples 1 to 7 Table 1 shows the structures and composition ratios of the oils (a to f) used in Examples 1 to 6, and the oils (g) used in Comparative Examples 1 to 7
Structures and types of ~ m) are shown in Table 2. The esters and polyethers used in the examples and comparative examples were trial products. As the paraffinic refrigerating machine oil in Table 2, Kyodo Sekiyu's Freol S32 was used, and as the branched chain alkylbenzene, Mitsubishi Petrochemical Co., Ltd. Company-made Pansolve H was used.

[0027]

[Table 1]

[0028]

R-3 of various sample oils shown in Table 1 and Table 2
2, refrigerating machine oils such as R-125 were evaluated, and the results are shown in Table 3. The outline of the test method used for such evaluation is as follows.

0.6 g of compatible test oil and 2.4 g of refrigerant (R-32, R-125, mixed refrigerant A, mixed refrigerant B and mixed refrigerant C) were sealed in a glass tube and then cooled at 1 ° C./min. Then, the temperature at which the two-layer separation occurred at a low temperature, that is, the two-layer separation temperature was measured. The mixed refrigerant A is 8: 2 (weight ratio, the same applies hereinafter) with R-32 and R-134a, and the mixed refrigerant B is R-32.
And R-125 and R-134a are mixed at 5: 4: 1.

Lubricity According to ASTM D-3233-7, Falex (F
alex) The baking load is controlled under a blown atmosphere of R-125 (7
It was measured at 0 ml / min). Thermal stability According to ANSI / ASHRAE 97-1983, 1 g of test oil, 1 g of refrigerants (R-32 and R-125), and a catalyst (each wire of iron, copper, and aluminum) were sealed in a glass tube and then at 175 ° C. After heating and 10 days later, the hue of the sample oil was judged by ASTM display. Put 60g of sample oil in a 100ml beaker with a hygroscopic property ,
The water concentration was measured after standing for 3 hours in an atmosphere of ℃ and 80% humidity.

[0032]

[Table 3]

From the evaluation results shown in Table 3, the refrigerating machine oil composition of the present invention shows that the refrigerating machine oil composition of the present invention has R-32 and R-125 more than conventional paraffinic refrigerating machine oil, branched chain alkylbenzene, ester simple substance, polyether simple substance, etc. It can be seen that such a refrigerant shows excellent overall performance.

[0034]

As described above, the refrigerating machine oil composition of the present invention is composed of a mixed oil of a specific ester oil and a polyether compound, and is suitable for refrigerants such as R-32 and R-125. And has excellent compatibility, lubricity, thermal stability, and the like, and thus the novel refrigerants R-32 and R-1
It can be suitably used as a lubricating oil for a refrigerator using 25 or a refrigerant containing these.

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Claims (2)

[Claims] 1. (a) An ester oil synthesized from a polyhydric alcohol having 1 to 15 carbon atoms and a monohydric fatty acid having 3 to 18 carbon atoms and / or a polyhydric alcohol having 5 to 15 carbon atoms, and 3 carbon atoms. Complex ester oil synthesized from a mixed carboxylic acid of a monohydric fatty acid having 18 to 18 and a polybasic acid having 4 to 14 carbon atoms, and (b) the following general formula R ₁ [O (PO) _l (EO) _m R ₂ ] _n (wherein R ₁ is an n-valent group of an aliphatic hydrocarbon having 1 to 10 carbon atoms, PO is an oxypropylene group, EO is an oxyethylene group, R ₂ is a hydrogen atom or an alkyl group, R _{2 1} and R ₂
Is 10 or less, 1 is an integer of 1 or more, m is 0 or an integer not exceeding 1, n is an integer of 1 to 6), and the average molecular weight is more than 300 and 2000. A refrigerating machine oil composition for a refrigerant containing trifluoromethane and / or pentafluoroethane, which contains a mixture of the following polyether compounds as a main component. 2. The refrigerant containing trifluoromethane and / or pentafluoroethane is a refrigerant containing 1,1-difluoroethane and / or 1,1,1,2-tetrafluoroethane. Refrigerating machine oil composition.