JPH0885798A - Refrigerating machine oil composition - Google Patents

Abstract

PURPOSE: To minimize the deterioration of a refrigerant cycle material due to moisture, reduce the evolution of oil sludge, and improve the reliability of refrigeration cycle by mixing an ester oil with a refrigerating machine oil having no ester group. CONSTITUTION: An ester oil (A) of the formula (R is a hydrocarbon group) having a molecular weight of 500-1,000 and a kinetic viscosity of 15-80cst (40 deg.C) is mixed with at least one refrigerating machine oil having no ester group (B) selected from naphthenic mineral oils, paraffinic mineral oils alkyl-benzene synthetic oils, polyether mineral oils and fluorocarbon synthetic oils, so that the ratio of A/B may become 1/1-9/1.

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 refrigerant compressor, and in particular, uses difluoromethane (hereinafter referred to as HFC32) alone or hydrofluorocarbon containing HFC32 (hereinafter referred to as HFC) as a refrigerant. The present invention relates to a refrigerating machine oil composition suitable for a refrigerant compressor.

[0002]

2. Description of the Related Art For an air conditioner, a refrigerator or the like, for example, a hermetic refrigerant compressor shown in FIG. 1 or a semi-hermetic refrigerant compressor (not shown) for a car air conditioner is provided in order to send cold air or hot air. Refrigerant compressors are used. As an example, a representative hermetic rotary refrigerant compressor whose longitudinal sectional view is shown in FIG. 1 will be described. A motor mechanism 4 composed of a stator 2 and a rotor 3, and a compression mechanism 5 under a lower portion of the motor mechanism 4 via a shaft 8 are provided inside a sealed casing 1. Refrigerating machine oil 9 is contained in the casing 1 in order to facilitate the operation of the sliding portion of the compression mechanism 5.
The refrigerant introduced from the supply pipe 6 through an accumulator (not shown) is compressed by the compression mechanism 5 driven by the motor mechanism 4 and once discharged into the casing 1, and then provided on the upper portion of the casing 1. It is supplied from the discharge pipe 7 to the refrigerator side. In addition, 10 is a bearing, 11
Is a sub bearing, 12 is a crank, 13 is a roller, 1
4 is a blade, and 15 is a spring.

Dichlorodifluoroethane (hereinafter, referred to as CFC12) and monochlorodifluoromethane (hereinafter, referred to as HCFC22) are mainly used as the refrigerant of such a hermetic refrigerant compressor, and the casing 1 contains The refrigerating machine oil used is naphthenic or paraffinic mineral oil that has lubricity and is soluble in CFC12 and HCFC22.

By the way, recently, it has been revealed that the release of CFCs from the above-mentioned CFC-based refrigerants leads to the destruction of the ozone layer and seriously affects the human body and biological systems.
CFC12, HCFC22, R-502, etc. containing chlorine cannot be used. HFC32, pentafluoroethane (hereinafter referred to as HFC125), 1,1,
1,2-tetrafluoroethane (hereinafter referred to as HFC134a), 1,1,1-trifluoroethane (hereinafter referred to as 143a), 1,1-difluoroethane (hereinafter referred to as HFC152a), etc., either alone or mixed. It is being examined so that it can be used. Further, development of refrigerating machine oil suitable for these refrigerants is desired.

Here, one of the necessary characteristics of the refrigerating machine oil is that it has compatibility with the refrigerant in order to improve the oil return in the refrigeration cycle. HFC32 alone,
Alternatively, HFCs containing HFC32 are hardly soluble in mineral oil, which is a conventional refrigerating machine oil, so ester-based oils, alkylene glycol-based oils, ether-based oils, fluorine-based oils, etc., which have compatibility with these, have been tried to be used. However, the use of ester oils is being considered.

[0006]

However, since the ester type oil has a high water absorption (or hygroscopicity), the water mixed in the refrigeration cycle causes freezing in the capillary tube and the refrigerant / ester type refrigerating machine oil. Hydrolysis occurs. When the refrigerant decomposes, strong acid components such as hydrochloric acid and hydrofluoric acid are produced, and when the ester oil is decomposed, carboxylic acids, which are weak acids, are produced. These serve as a hydrolysis catalyst for the ester bond present in the ester oil. In addition, refrigeration oil is
The frictional heat generated by the sliding portion causes thermal deterioration and the like, and deteriorated substances of oil are generated. These deteriorated substances circulate in the refrigeration cycle together with the compressed refrigerant, and accumulate in the capillary tube having an extremely small inner diameter (for example, φ1.0 mm or less), resulting in the problem that the refrigerant circulation is hindered and cooling failure occurs. is there.

Further, from the viewpoint of lubricity, conventional mineral oil type refrigerating machine oil contains a cyclic compound, and the oil film forming ability was relatively high, whereas ester type oil contained a cyclic compound. Since it is a chain compound that does not exist, there is a problem that an appropriate oil film thickness cannot be maintained under severe sliding conditions.

Furthermore, as a refrigerant, conventional CFC12 or HCFC2 is used.
When 2 is used, chlorine (Cl) atoms in CFC12 and HCFC22 react with iron (Fe) atoms of the metal substrate to form an iron chloride film with good wear resistance, whereas HFC32 alone or
When HFC containing HFC32 is used, there is also a problem in terms of lubrication that a self-lubricating film such as iron chloride is not formed due to the absence of chlorine (Cl) atoms.

Thus, when HFC32 alone which is a refrigerant replacing CFC, HCFC or the like, or HFC containing HFC32 and the ester oil is applied to the refrigeration cycle, when the same ester-based refrigerating machine oil is used, There is a problem that defects occur in component parts and quality and durability are greatly reduced.

The present invention has been made to cope with such a problem, and the hygroscopicity and the reactivity with water are lowered, the refrigeration cycle material is less likely to be deteriorated by water, and the generation of oil sludge is reduced. Therefore, it is an object of the present invention to provide a refrigerating machine oil composition that can improve the reliability of the refrigeration cycle as a result.

[0011]

The refrigerating machine oil composition of the present invention is a refrigerating machine oil composition of a refrigerant compressor in which a compression mechanism is housed in a closed container and HFC32 alone or HFC containing HFC32 is used as a refrigerant. In the above, the ester-based oil is mixed with a refrigerating machine oil containing no ester group.

Here, the refrigerating machine oil containing no ester group is characterized by comprising at least one mineral oil selected from naphthenic mineral oil and paraffinic mineral oil.

Further, it is characterized in that it is at least one kind of synthetic oil selected from alkylbenzene synthetic oil, polyether synthetic oil and fluorine synthetic oil.

Further, it is characterized by comprising a mixed oil of the above-mentioned mineral oil and synthetic oil.

The mixing ratio of the ester-based oil and the refrigerating machine oil containing no ester group is such that (ester-based oil) / (refrigerating machine oil containing no ester group) = 1/1 to 9/1. .

In the refrigerating machine oil composition of the present invention prepared by blending an ester oil with a mineral oil, a fluorine-based synthetic oil is further added.
It is characterized by containing 0.01 to 10% by volume.

Examples of HFCs containing HFC32 according to the present invention include mixed refrigerants such as HFC32 / HFC125 and HFC32 / HFC125 / HFC134a.

The ester oil according to the present invention is compatible with HFC32 alone or HFC containing HFC32.
An ester compound obtained from a polyol such as di-, tri- or tetraol. Examples of ester oils derived from tetraol include those represented by the following general formula, which are suitable for the present invention.

Embedded image Here, R represents a hydrocarbon group. The ester oil that can be used in the refrigerator oil composition of the present invention preferably has a molecular weight of about 500 to 1000 and a kinematic viscosity of about 15 to 80 centistokes (40 ° C).

The naphthenic mineral oil and the paraffinic mineral oil according to the present invention are composed of a naphthenic base oil and a paraffinic base oil. For example, as the naphthenic mineral oil, Suniso 3GS, Suniso 4GS and the like (manufactured by Nippon Sun Oil Co., Ltd.) Examples of the paraffinic mineral oil include S-15 and S-32 (manufactured by Japan Energy Co.). These may be a single oil or a mixed oil, and may be mixed with an ester oil.

The alkylbenzene synthetic oil according to the present invention is an aromatic compound having an alkyl group in its side chain and does not contain an ester group in its molecular structure. Specific examples include HAB-15 and HAB-32 (manufactured by Nippon Oil Co., Ltd.).

The polyether synthetic oil according to the present invention is
A compound composed of an ether bond and not having an ester group in its molecular structure. Specifically, FV-32 (made by Idemitsu Co., Ltd.) can be mentioned, for example.

The fluorine-based synthetic oil according to the present invention is HFC32.
It is compatible with HFCs alone or with HFCs including HFC32 and is represented by the following general formula.

Embedded image Here, n is preferably in the range of 5 to 10.

The mixing ratio of the ester oil according to the present invention and the oil having no ester group in the molecular structure of at least one kind selected from the above mineral oil and synthetic oil is a weight ratio (ester oil) / (Refrigerating machine oil containing no ester group)
= 1/1 to 9/1. Within this range, the water absorption of the ester-based oil can be suppressed, and the generation of oil deterioration substances and the like can be prevented.

In addition, a fluorine-based synthetic oil may be added to the refrigerating machine oil composition of the present invention containing an ester-based oil and a mineral oil in an amount of 0.01 to
By blending 10% by volume, the water absorption of the ester oil can be suppressed and the abrasion resistance can be improved even under severe sliding conditions. It is preferably 0.01 to 8% by volume, more preferably 0.01 to 5% by volume.

The refrigerating machine oil composition of the present invention contains sulfur, phosphorus and halogen extreme pressure additives as additives.
Alternatively, it may contain an abrasion resistance improver, an antioxidant, a hydrolysis inhibitor, a heat resistance improver, a corrosion inhibitor, and an antifoaming agent.

[0026]

[Function] HFC32 alone or as a combination with HFC32-containing HFC refrigerant, ester oil does not contain ester groups and is mixed with mineral oil or synthetic oil that has low hygroscopicity and low reactivity Hygroscopicity and reactivity of machine oil are reduced.

Further, by incorporating the fluorine-based oil, the hygroscopicity is reduced and the lubricity of the metal sliding member is improved.

As a result, the carbon sludge is reduced,
Further, by maintaining the lubricity, the refrigerating machine oil of the present invention can favorably maintain the function as a refrigerant compressor.

[0029]

EXAMPLES Examples of the present invention will be described in detail below. Examples 1 to 4 and Comparative Examples 1 to 2 As a refrigerating machine oil, a hindered ester oil (manufactured by Japan Energy Co.) and a naphthene mineral oil (Suniso 3GS, manufactured by Nippon San Oil Co., Ltd.) are in the ratios shown in Table 1. To prepare a refrigerating machine oil. The ester-based oil alone was used as Comparative Example 1 and the naphthene-based mineral oil was used as Comparative Example 2.

The mixed refrigerating machine oil thus obtained was evaluated by performing a hygroscopicity test and a shield tube test. In the hygroscopicity test, 1 kg of sample oil was left in an atmosphere of 80% humidity for 24 hours to measure the moisture absorption rate. The shield tube test was conducted as follows. Prepare 6 heat-resistant glass test tubes,
2 ml of the oils of Examples 1 to 4 and Comparative Examples 1 and 2 and copper, aluminum and iron pieces are put in each. Finally, add 1 ml of HFC32, thoroughly degas and dehydrate while cooling, and then seal the upper part of the test tube to make a shield tube. The oil moisture absorption was 200 ppm. The shield tube was placed in a constant temperature bath maintained at 175 ° C and heated for 500 hours. After 500 hours, the hue and precipitate of the refrigerating machine oil in the shield tube were observed. Table 1 shows the results of the hygroscopicity test and the shield tube test.

[0031]

[Table 1] From the results of Table 1, it was confirmed that when the mixing ratio of the ester oil was high, the moisture absorption rate was increased, the hue of the refrigerating machine oil became dark and the precipitate was apt to be generated.

When the refrigerating machine oils of Examples 1 to 4 and Comparative Examples 1 and 2 were enclosed in the refrigerant compressor shown in FIG. 1 and operated with HFC32 as the refrigerant, Comparative Example 2
In, the amount of oil in the refrigerant compressor decreased, and the oil return in the refrigeration cycle was not good.

Examples 5 to 8 and Comparative Example 3 As a refrigerating machine oil, the ester-based oil and naphthene-based mineral oil of Example 1 and an alkylbenzene-based synthetic oil (HAB-15, manufactured by Nippon Oil Co., Ltd.) are shown in Table 2. To prepare a refrigerating machine oil. The alkylbenzene synthetic oil alone was used as Comparative Example 3. Regarding the obtained mixed refrigerating machine oil, Example 1
The hygroscopicity test was conducted under the same conditions and method as described above. The results are shown in Table 2.

[0034]

[Table 2] From the results of Table 2, it was confirmed that the moisture absorption rate tended to increase when the mixing ratio of the ester oil was high. Further, when the refrigerating machine oils of Examples 5 to 8 and Comparative Example 3 were enclosed in the refrigerant compressor shown in FIG. 1 and operated with HFC32 as the refrigerant, the oil amount in the refrigerant compressor in Comparative Example 3 decreased. Occurred and the oil return in the refrigeration cycle was not good.

Examples 9 to 15 As a refrigerating machine oil, 20% of a naphthenic mineral oil (Suniso 3GS, manufactured by Nippon San Oil Co., Ltd.) was mixed with the ester oil of Example 1.
A mineral oil mixed ester oil was prepared. Fluorine-based oil (Demnum S-65, manufactured by Daikin Industries, Ltd.) was blended with this mineral oil-mixed ester-based oil in a ratio shown in Table 3.

[Table 3] The water absorption and wear characteristics of the obtained mixed refrigeration oil were measured. As for the wear characteristics, the lubricity of the refrigerant, the refrigerating machine oil, and the metal material was evaluated by using a wear tester as shown in FIG. In this device, the test shaft 16 is sandwiched between V-blocks 17 and 17, the load due to the tightening of the V-block 17 is set to a constant value, and the test shaft 16 is rotated at a constant sliding speed condition of 290 rpm. A device for inspecting the amount of wear of the test shaft 16 after a predetermined time by blowing the refrigerant HFC32 while adjusting the temperature of the refrigerating machine oil.

The results of measurement of water absorption and wear are shown in FIGS. 3 and 4. The numbers in the figure indicate the numbers of the examples. From FIGS. 3 and 4, the water absorption amount decreases as the blending amount of the fluorine-based oil in the mineral oil mixed ester-based oil increases. Regarding lubricity, if the blending amount of fluorine-based oil in this mineral oil mixed ester-based oil is less than 0.01% by volume, the amount of wear of the metal sliding member increases, and the blending amount of fluorine-based oil is 1%.
At 0% by volume, the amount of wear was almost the same as 0.01% by volume. The wear amount showed the minimum value when the blending amount of the fluorinated oil was in the range of 0.01 to 5% by volume.

The refrigerating machine oil of Example 13 was enclosed in the actual refrigerant compressor together with the refrigerant HFC32, and the operation was performed for 2000 hours.
After the operation was completed, the change in the characteristics of the electric wire coating material of the motor coil, the insulating film, and the refrigerating machine oil itself was examined. As a result, all of them were very good in comparison with the initial performance. In addition, no significant wear was observed on the sliding member, and no generation of oil sludge was observed.

[0038]

The refrigerating machine oil composition of the present invention is a refrigerant compressor using HFC32 alone or HFC containing HFC32, and the refrigerating machine oil containing no ester group is mixed with the ester type oil. The hydrolysis of the can be suppressed.

Since the refrigerating machine oil composition of the present invention is a mixture of ester oil and mineral oil, the hygroscopicity and the reactivity with water are lowered, and the deterioration of the refrigeration cycle material due to the water is less likely to occur. Improves reliability. Further, an oil film of mineral oil is formed on the sliding surface of the refrigerant compressor, and the slidability is also improved. Furthermore, since the mixing ratio of the ester-based oil is high with respect to the mineral oil that is incompatible with the HFC-based refrigerant, the problem of oil return is unlikely to occur. In addition, since mineral oil is cheaper than ester oil, the cost of refrigerating machine oil can be reduced by blending mineral oil.

Since the refrigerating machine oil composition of the present invention is a mixture of ester oil and synthetic oil, the hygroscopicity and the reactivity with water are lowered, and the deterioration of the refrigeration cycle material due to the water is less likely to occur. Improves reliability. Also, H
Even if a synthetic oil that is not compatible with the FC-based refrigerant is mixed, the problem of oil return is unlikely to occur due to the high mixing ratio of the ester-based oil.

Since the refrigerating machine oil composition of the present invention is a mixture of an ester oil with a mineral oil and a synthetic oil, the hygroscopicity can be suppressed and the above effects can be obtained.

By setting the blending ratio to ester-based oil / refrigerating machine oil containing no ester group = 1/1 to 9/1, the hygroscopicity is further suppressed and deterioration of the refrigeration cycle material due to water is less likely to occur. , The reliability of the refrigeration cycle is improved. In addition, the oil return problem is less likely to occur.

Since the refrigerating machine oil composition of the present invention comprises 0.01 to 10% by volume of a fluorine-based synthetic oil mixed with a mineral oil-mixed ester type oil, the hygroscopicity and the reactivity with water are lowered, and the refrigeration cycle material due to the water is used. Deterioration is less likely to occur, oil sludge is reduced, and the reliability of the refrigeration cycle is improved. Further, the slidability of the refrigerant compressor is also improved.

As a result of the above, the refrigerator oil composition of the present invention is HF
It is possible to greatly improve the reliability and durability of the refrigerant compressor using CFC alone or HFC including HFC32.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a hermetic refrigerant compressor.

FIG. 2 is a sectional view of a main part of a wear tester.

FIG. 3 is a diagram showing water absorption characteristics of mixed refrigerating machine oil.

FIG. 4 is a diagram showing wear characteristics of mixed refrigerating machine oil.

[Explanation of symbols]

1 ... Casing, 2 ... Stator, 3 ......... Rotor, 4 ... Motor mechanism, 5 ... Compression mechanism, 6 ...
Supply pipe, 7 ... Discharge pipe, 8 ... Shaft, 9 ...
Refrigerating machine oil, 10 bearings, 11 sub bearings, 12 cranks, 13 rollers, 14 rollers
… Blade, 15 ……… Spring, 16 ……… Test shaft, 17 ……… V-block.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location C10M 105: 52) C10N 40:30 (72) Inventor Tatsuya Tsuda 3-3-9 Shimbashi, Minato-ku, Tokyo Toshiba Abu E Co., Ltd.

Claims (6)

[Claims] 1. A refrigerating machine oil composition of a refrigerant compressor, wherein a compression mechanism is housed in a closed container and difluoromethane alone or hydrofluorocarbon containing difluoromethane is used as a refrigerant, wherein the refrigerating machine oil composition is an ester type. A refrigerator oil composition comprising a mixture of oil and a refrigerator oil containing no ester group. 2. The refrigerating machine oil composition according to claim 1, wherein the ester group-free refrigerating machine oil is at least 1 selected from naphthenic mineral oils and paraffinic mineral oils.
A refrigerating machine oil composition comprising a seed mineral oil. 3. The refrigerating machine oil composition according to claim 1, wherein the refrigerating machine oil containing no ester group is at least one kind of synthetic oil selected from alkylbenzene synthetic oil, polyether synthetic oil and fluorine synthetic oil. A refrigerating machine oil composition, which is an oil. 4. The refrigerating machine oil composition according to claim 1, wherein the ester group-free refrigerating machine oil is at least 1 selected from naphthenic mineral oil and paraffinic mineral oil.
A refrigerating machine oil composition comprising one kind of mineral oil and at least one kind of synthetic oil selected from alkylbenzene synthetic oil, polyether synthetic oil and fluorine synthetic oil. 5. The refrigerating machine oil composition according to any one of claims 1 to 4, wherein a mixing ratio of the ester-based oil and the refrigerating machine oil containing no ester group is (the ester-based oil). / (Refrigerating machine oil containing no ester group) = 1/1 to 9/1. 6. The refrigerating machine oil composition according to claim 2, further comprising 0.01 to 10% by volume of a fluorine-based synthetic oil.