Lubricant oil composition for compression refrigerator

Abstract

It is to provide a lubricating oil composition for a compression refrigerator, which is excellent in the thermal/chemical stability even when used in a compression refrigerator that uses a saturated fluorinated hydrocarbon refrigerant having a lower global warming potential and a fewer carbon atoms, by including in a base oil an organic compound having a double bond in a molecule, which is at least one kind selected from an organic compound having at least two non-conjugated double bonds in the molecule, a terpene compound having a double bond in the molecule, and C.sub.12 to C.sub.30 aliphatic unsaturated hydrocarbon having one double bond in the molecule.

Claims

1. A composition, comprising a lubricating oil and a refrigerant, wherein: the lubricating oil comprises: a base oil; an organic compound having a double bond, which consists of -pinene, -pinene, or both; and at least one epoxy compound selected from the group consisting of a glycidyl ester, an alkyl glycidyl ether and an alkylene glycol glycidyl ether; the refrigerant consists of difluoromethane; the refrigerant is the only saturated fluorinated compound in the composition; the base oil consists of at least one polyvinyl ether; a content of the organic compound having a double bond is 0.1% by mass or more and 5% by mass or less based on a total mass of the composition; and a content the at least one epoxy compound is 0.05% by mass or more and 6% by mass or less based on the total mass of the composition.

2. The composition according to claim 1, further comprising a compound having a 1,4-diene structure.

3. The composition according to claim 1, wherein the composition comprises the organic compound having a double bond in an amount of from 0.1% by mass to 3% by mass based on a total amount of the composition.

4. The composition according to claim 1, wherein the base oil consists of a polyvinyl ether.

5. The composition according to claim 1, wherein the base oil has a kinematic viscosity of from 1 mm.sup.2/s to 50 mm.sup.2/s at 100 C.

6. The composition according to claim 1, wherein the base oil has a number average molecular weight of from 300 to 3000.

7. The composition according to claim 1, wherein the base oil has a viscosity index of 60 or more.

8. The composition according to claim 1, further comprising: at least additive selected from the group consisting of an extreme pressure agent, an oiliness agent, an antioxidant, an acid scavenger, a metal deactivator, and an antifoaming agent.

9. The composition according to claim 1, wherein the composition is suitable for a car air conditioner, an electric car air conditioner, a gas heat pump, an air conditioner, a refrigerator, an automatic vending machine, a show case, a hot-water supply system, a freezing and heating system, or any combination thereof.

10. The composition according to claim 1, wherein the composition is suitable for a hot-water supply system having a moisture content of 300 ppm by mass or less and a residual air partial pressure of 10 kPa or less.

11. The composition according to claim 1, wherein the composition is suitable for a freezing and heating system having a moisture content of 300 ppm by mass or less and a residual air partial pressure of 10 kPa or less.

12. The composition according to claim 1, wherein the base oil has an ASTM color of 1 or less.

13. The composition according to claim 1, wherein the organic compound having a double bond is -pinene.

Description

EXAMPLE

(1) Hereinafter, the invention will be described in more detail with reference to Examples. However, the invention is not at all limited to these examples.

(2) Properties of the base oil and various characteristics of the lubricating oil composition for refrigerators were obtained according to the procedure shown below.

(3) <Properties of Base Oil>

(4) (1) Kinematic Viscosity at 100 C.

(5) The kinematic viscosity at 100 C. was measured according to JIS K 2283-1983 by using a glass capillary viscometer.

(6) (2) Number Average Molecular Weight

(7) The number average molecular weight was measured by gel permeation chromatography (GPC). The GPC was conducted using HLC-8120GPC, SC-8020 (trade name, manufactured by TOSOH Corporation), THF (tetrahydrofuran) as an eluting solution, and an IR detector. From the result, based on a calibration curve due to polystyrene reference sample, the number average molecular weight was obtained.

(8) (3) Flashing Point

(9) The flashing point was measured according to JIS K 2265 (C.O.C method).

(10) (4) Viscosity Index

(11) The viscosity index was measured according to JIS K 2283.

(12) <Thermal Stability Test of Lubricating Oil Composition for Refrigerators>

(13) In a 200 mL autoclave, oil/refrigerant (ratio: 30 g/30 g, moisture content in oil: 500 ppm by mass), and a metal catalyst made of iron, copper and aluminum were charged and encapsulated, after keeping under condition of air pressure of 18.7 kPa, and temperature of 200 C. for 240 hr, oil appearance was visually observed, and the acid value was measured. The acid value was measured by an indicator method according to Petroleum products and lubricants-Neutralization Test Method stipulated by JIS K 2501.

(14) <Compounding Component>

(15) Kinds of respective components used to prepare the lubricating oil composition for a refrigerator are shown below.

(16) (1) Base Oil A1: Poly(ethyl vinyl ether) (kinematic viscosity at 100 C.: 15.97 mm.sup.2/s, flashing point: 222 C., the number average molecular weight: 1250, viscosity index: 85) A2: Polypropylene glycol dimethyl ether (kinematic viscosity at 100 C.: 9.25 mm.sup.2/s, flashing point: 212 C., the number average molecular weight: 1139, viscosity index: 207) A3: Polypropylene glycol (PPG)/poly(ethyl vinyl ether) (PEV) copolymer (PPG/EVE molar ratio: 7/11)(kinematic viscosity at 100 C.: 9.56 mm.sup.2/s, flashing point: 218 C., the number average molecular weight: 1200, viscosity index: 140) A4: Pentaerythritol octanoic acid (C.sub.8 acid) nonanoic acid (C.sub.9 acid) ester (C.sub.8 acid/C.sub.9 acid molar ratio: 1/1.1) (kinematic viscosity at 100 C.: 9.64 mm.sup.2/s, flashing point: 268 C., the number average molecular weight: 670, viscosity index: 126)

(17) (2) Stabilizer (Organic Compound Having Double Bond in Molecule) B1: -pinene B2: 1,4-p-mentadiene B3: 1,4-cyclohexadiene B4: 1,4-hexadiene B5: 2,5-norbornadiene B6: 1-hexadecene

(18) (3) Additive

(19) With the following respective components, compounding amounts in an entire composition were set respectively to amounts (% by mass) shown in bracket, and the extreme pressure agent and defoaming agent (other additives) were added to be 1.10% by mass in total. Acid scavenger: 2-ethylhexyl glycidyl ether (0.3% by mass) Antioxidant: 2,6-di-t-butyl-4-methyl phenol (0.3% by mass) Extreme pressure agent: tricresyl phosphate (1.0% by mass) Antifoaming agent: silicone-based antifoaming agent (0.1% by mass)

Examples 1 to 9 and Comparative Examples 1 to 7

(20) Lubricating oil compositions for a refrigerator each having a composition shown in Table 1 and Table 2 were prepared, and with R32 (difluoromethane) or R410A [50:50 mixture by mass ratio of R32 and R125 (pentafluoroethane)] as a refrigerant, the thermal stability of the compositions were evaluated. Results thereof are shown in Table 1 and Table 2.

(21) TABLE-US-00001 TABLE 1 TABLE 1-1 Examples 1 2 3 4 5 6 7 8 9 Com- Base oil A1 97.3 97.3 97.3 97.3 97.3 97.3 pound- A2 97.3 ed A3 97.3 compo- A4 97.3 sition Stabilizer B1 1.0 1.0 1.0 1.0 (% by B2 1.0 mass) B3 1.0 B4 1.0 B5 1.0 B6 1.0 Antioxidant 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Acid scavenger 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Other additive 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 Thermal Refrigerant R32 stability test Acid value 0.71 0.81 0.82 0.86 0.79 1.02 0.78 0.75 0.82 (mgKOH/g) Oil appearance Pale Pale Pale Pale Pale Pale Pale Pale Pale yellow yellow yellow yellow yellow yellow yellow yellow yellow

(22) TABLE-US-00002 TABLE 2 Table 1-2 Comparative Examples 1 2 3 4 5 6 7 Com- Base A1 98.3 98.3 98.1 97.6 pounded oil A2 98.3 com- A3 98.3 position A4 98.3 (% by Antioxidant 0.3 0.3 0.5 0.3 0.3 0.3 0.3 mass) Acid scavenger 0.3 0.3 0.3 1.0 0.3 0.3 0.3 Other additive 1.1 1.1 1.1 1.1 1.1 1.1 1.1 Thermal Refrigerant R32 R410A R32 R32 R32 R32 R32 stability test Acid value 1.54 1.20 1.55 1.51 1.40 1.55 1.56 (mgKOH/g) Oil appearance Orange Yellow Orange Orange Orange Orange Orange

(23) From Table 1 and Table 2, the followings are found.

(24) In all of Examples 1 to 9 where a lubricating oil composition for a compression refrigerator of the invention was used in a system where R32 (difluoromethane) was used as a refrigerant, in thermal and oxidation stability test, oil appearance was excellent and also the acid value was low.

(25) By contrast, in Comparative Examples 1 to 7 where an organic compound (stabilizer) having a double bond in the molecule according to the invention was not used, not only the acid value was high, but also the oil appearance turned to yellow or orange.

(26) Further, Comparative Example 1 where the same lubricating oil composition for a compression refrigerator in the invention, in which the stabilizer was not used was used, and R32 (difluoromethane 100%) was used as the refrigerant compared poorly with Comparative example 2 where R410A (a refrigerant obtained by mixing R32 and R125 at a mass ratio of 50:50) was used as a refrigerant in that the acid value was high and oil appearance was orange or yellow.

INDUSTRIAL APPLICABILITY

(27) The lubricating oil composition for a compression refrigerator of the invention exhibits excellent thermal and oxidation stability when used in a compression refrigerator that uses a refrigerant that uses C.sub.1 to C.sub.3 saturated fluorinated hydrocarbon that is a refrigerant that is low in the global warming potent and can be used in particular in an air conditioner and a car air conditioner.