JPH03227397A - Lubricant for freezer - Google Patents

Abstract

PURPOSE:To obtain the subject lubricant having excellent miscibility with a fluorocarbon-based coolant not containing chlorine, low moisture absorption, high volume resistivity and capable of improving electrical insulation properties containing neopentyl polyol ester of a specific fatty acid. CONSTITUTION:The aimed lubricant contains neopentyl polyol ester of 2-6C fatty acid (preferably butanoic acid, pentanoic acid, 2-methyl propanoic acid or 2-methyl butanoic acid).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lubricant for refrigerators. Specifically, the present invention relates to a neopentyl polyol ester lubricant for refrigerators that has good compatibility with chlorine-free fluorocarbon refrigerants such as Freon 134a (Ll, 1,2-tetrafluoroethane) in refrigerators.

[Prior art and problems to be solved by the invention] Fluorocarbon compounds are excellent substances in terms of chemical stability, low toxicity, and nonflammability, and are widely used in fields such as refrigerants, aerosols, foaming, and cleaning. I've been exposed to it. However, in recent years, the production and consumption of certain types of fluorocarbons has been increasing, as fluorocarbons released into the atmosphere destroy the ozone layer in the stratosphere and cause global warming, the so-called "greenhouse effect." There is a growing movement to reduce

For this reason, progress is being made in the development of fluorocarbons that do not cause ozone layer depletion or the greenhouse effect, that is, fluorocarbons that do not contain chlorine in their molecules and are relatively easily decomposed.

Under these circumstances, Freon 134a, which has similar physical properties to Freon 12, was developed as a substitute for Freon 12 (dichlorodifluoromethane), which has been widely used as a refrigerant in household refrigerators, air conditioners, commercial small refrigerators, car air conditioners, etc. It was done.

However, since Freon 134a does not contain chlorine in its molecules, Freon 134a contains chlorine in its molecules, such as Freon 12.
The solubility is significantly different from that of Fluon 22 (monochlorodifluoromethane). Therefore, Freon 134a has poor compatibility with naphthenic mineral oil and alkylbenzene, which have been conventionally used as refrigeration oil, and causes problems such as poor oil return in the evaporator, seizure of the compressor, and abnormal vibration. There is a need to develop a refrigerating machine oil that has good compatibility with

Regarding the refrigerating machine oil using Freon 134a as a refrigerant, one using polyalkylene glycol with molecular weight of 2,000 or less and having two or more functionalities is proposed in US Pat. This may cause malfunction or blockage (moisture choke), promote the decomposition of fluorocarbons, and cause the generated hydrofluoric acid to corrode metal parts.

Furthermore, JP-A-55-155093 and JP-A-581
No. 5592 discloses a refrigerating machine lubricant containing neopentyl polyol ester, but these publications also disclose refrigerating machine lubricants that have good solubility in chlorine-free fluorocarbon refrigerants such as Freon 134a. There is no mention of drugs at all.

[Means for Solving the Problems] As a result of intensive studies on various synthetic lubricating oils, the present inventors found that a certain type of neopentyl polyol ester is particularly suitable for fluorocarbon-based refrigerants that do not contain chlorine (Freon 1
The present inventors have completed the present invention by discovering that they have excellent compatibility with fluorocarbons (such as 348), low hygroscopicity, excellent electrical insulation properties, and excellent stability against fluorocarbons.

That is, the refrigerating machine lubricant of the present invention is a refrigerating machine lubricant that uses a fluorocarbon-based refrigerant that does not contain chlorine, and is characterized by containing a neopentyl polyol ester of a fatty acid having 2 to 6 carbon atoms. shall be.

The chlorine-free fluorocarbon refrigerants used in the present invention include Freon 134 (1,L2,2-tetrafluoroethane), Freon 134a, and Freon 143 (CI).

2-trifluoroethane), Freon 143a (Ll, 1
Freon 152 (1,2-difluoroethane), Freon 152a (1,1-difluoroethane), etc. Among these, Freon 13
4a is preferable because it has similar physical properties to Freon 12, which is currently commonly used.

As the fatty acid to be used as a raw material for the neopentyl polyol ester of the present invention, one or more of linear saturated fatty acids having 2 to 6 carbon atoms, branched saturated fatty acids, etc. can be used. Such straight chain saturated fatty acids include acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, etc., and branched saturated fatty acids include 2-methylpropanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, Examples include triphthyl acetic acid, 2-methylpentanoic acid, 3-methylhentanoic acid, 4-methylpentanoic acid, 2-1,000 rubbutanoic acid, 2,2-dimethylbutanoic acid, and 3,3-dimethylbutanoic acid.

Among these, particularly preferred are butanoic acid, pentanoic acid,
These are fatty acids such as 2-methylpropanoic acid and 2-methylbutanoic acid.

Further, the neopentyl polyol, which is the other raw material for the neopentyl polyol ester of the present invention, is a polyol having a neopentyl structure, that is, C-C-CI, and preferably has 4 or more hydroxyl groups in the molecule. For example, pentaerythritol, dipentaerythritol, tripentaerythritol, tetrapentaerythritol, ditrimethylolpropane, ditrimethylolethane, tritrimethylolpropane, tritrimethylolethane, etc. can be used, but among these, pentaerythritol, dipentaerythritol, tri Pentaerythritol can be preferably used for applications that require medium to high viscosity (e.g., car cooler refrigerators and rotary refrigerator refrigerators), and tripentaerythritol is most preferred for applications that require particularly high viscosity. .

In addition, ditrimethylolpropane, ditrimethylolethane, tritrimethylolpropane, and tritrimethylolethane can be particularly preferably used in applications requiring low viscosity (for example, reciprocating refrigerators).

Furthermore, if the number of hydroxyl groups in the molecule is less than 3, Freon 13
Poor solubility with 4a (not very preferred).

The linear saturated fatty acid or branched saturated fatty acid having 2 to 6 carbon atoms and the neopentyl polyol can each be used singly or as a mixture of two or more, and by a normal esterification reaction or transesterification reaction, The neopentyl polyol ester of the present invention can be obtained.

The neopentyl polyol ester of the present invention preferably consists only of neopentyl polyol esters of the above-mentioned fatty acids having 2 to 6 carbon atoms. When using a fatty acid containing 2 to 6 carbon atoms, it shall contain at least 20 mol% of all fatty acids, and the average number of carbon atoms in the fatty acid per 1 hydroxyl group of neopentyl polyol shall be 6. It is preferable to adjust the composition of the raw fatty acid so that it is as follows.

Although the refrigerating machine lubricant of the present invention may be composed only of the above-mentioned neopentyl polyol ester, it may be used in combination with known refrigerating machine lubricants such as mineral oil, alkylbenzene, polyalkylene glycol, etc. Additionally, known additives for lubricants for refrigerators using Freon as a refrigerant, such as phosphoric acid esters such as tricresyl phosphate, phosphorous esters such as triethyl phosphite, epoxidized soybean oil, bisphenol A diglycidyl ether, etc. An epoxy compound, an organic tin compound such as dibutyltin laurate, an antioxidant such as α-naphthylbenzylamine, phenothiazine, BHT, etc. may be added within the range of usual addition amounts.

〔Effect of the invention〕

The refrigerating machine lubricant of the present invention can be used within the temperature range of -50 to 60°C, which is the actual operating temperature range of the refrigerating machine lubricant, and contains a fluorocarbon-based refrigerant that does not contain chlorine, such as Freon 134a,
They dissolve completely in virtually all ranges (1:99 to 99:1).

Further, the refrigerator lubricant of the present invention has low hygroscopicity and high volume resistivity, unlike polyalkylene glycol-based refrigerator lubricants. Therefore, by using the refrigerator lubricant of the present invention, it is possible to solve the problem of hygroscopicity, which has been thought to be the cause of troubles in refrigerators, and also improve electrical insulation.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples.

In the following Examples and Comparative Examples, Sample 1-1.9 shown below was used as a lubricant.

Sample 1 A mixture of DPET (dipentaerythritol) as neopentyl polyol and hexanoic acid and 2-methylpentanoic acid as fatty acids (the molar ratio of fatty acids is 50:
Neopentyl polyol ester obtained using 50).

Kinematic viscosity at 40°C 59cst, pour point -47.5°C
, the average number of carbon atoms in fatty acids per hydroxyl group in neopentyl polyol is 6°.Sample 2 DPET (dipentaerythritol) is used as neopentyl polyol, and a mixture of hexanoic acid, 2-methylpentanoic acid, and 2-methylbutanoic acid is used as fatty acid ( The neopentyl polyol ester was obtained using a blending molar ratio of fatty acids of 40:30:30.

Kinematic viscosity at 40°C 69 cst, pour point -45°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 5.7° Sample 3 DPET (dipentaerythritol) as neopentyl polyol, as fatty acid A mixture of hexanoic acid and 2-methylbutanoic acid (mole ratio of fatty acids is 50:
Neopentyl polyol ester obtained using 50).

Kinematic viscosity at 40°C 71 cst, pour point -45°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 5.5° Sample 4 DPET (dipentaerythritol) as neopentyl polyol, as fatty acid Neopentyl polyol ester obtained using 2-methylbutanoic acid.

40"C kinematic viscosity 79 cst, pour point -40'C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 5° Sample 5 DPET (dipentaerythritol) as neopentyl polyol, hexanoic acid as fatty acid and a mixture of 2-methylpropanoic acid (the molar ratio of fatty acids is 50:
Neopentyl polyol ester obtained using 50).

Kinematic viscosity at 40°C 68 cst, pour point -45°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 5° Sample 6 PET (pentaerythritol) as neopentyl polyol, butanoic acid and Mixture of 2-methylpropanoic acid (molar ratio of fatty acids is 50:50)
) neopentyl polyol ester obtained using

Kinematic viscosity at 40"C 25 cst, pour point -50°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 4° Sample 7 DPET (dipentaerythritol) as neopentyl polyol, butanoic acid as fatty acid and a mixture of 2-ethylhexanoic acid (molar ratio of fatty acids is 95:5)
neopentyl polyol ester obtained using

Kinematic viscosity at 40°C 61 cst, pour point -40°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 4.2° Sample 8 DPET (dipentaerythritol) as neopentyl polyol, as fatty acid Mixture of butanoic acid and isohebbutanoic acid (molar ratio of fatty acids is 80:20)
neopentyl polyol ester obtained using

Kinematic viscosity at 40°C 63cst, pour point -42.5°C
, the average number of carbon atoms in fatty acids per hydroxyl group in neopentyl polyol is 4.6°.Sample 9 TPET (dipentaerythritol) is used as neopentyl polyol, and pentanoic acid, 2-methylbutanoic acid, and 2-ethylbutanoic acid are used as fatty acids. A neopentyl polyol ester obtained using a mixture (molar ratio of fatty acids: 50:25:25).

Kinematic viscosity 202cs t at 40"C, pour point -27.5°
C. The average number of carbon atoms in fatty acids per hydroxyl group in neopentyl polyol is 5.25° Sample 10 DTMP (ditrimethylolpropane) is used as neopentyl polyol, and pentanoic acid, 2-methylbutanoic acid, and 3-methylleftanoic acid are used as fatty acids. Neopentyl polyol ester obtained using a mixture (molar ratio of fatty acids: 65:30:5).

40"C kinematic viscosity 23 cst, pour point -45°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 5° Sample 11 TPET (tripentaerythritol) and Tetra PET as neopentyl polyol (Tetrapentaerythritol) (Mole ratio of neopentyl polyol is 50:50), mixture of pentanoic acid, 2-methylbutanoic acid and 3-methylbutanoic acid as fatty acids (Mole ratio of fatty acids is 65:30:5) neopentyl polyol ester obtained using

Kinematic viscosity at 40°C 306 cs t, pour point -20°C,
The average number of carbon atoms in fatty acids per hydroxyl group in neopentyl polyol is 5°.Sample 12 A mixture of PET (pentaerythritol) and DPET (dipentaerythritol) as neopentyl polyol (the molar ratio of neopentylboliol is 50:5
0), neopentyl polyol ester obtained using a mixture of pentanoic acid, 2-methylbutanoic acid and 3-methylbutanoic acid (the molar ratio of fatty acids is 65:30:5) as the fatty acid.

40"C kinematic viscosity 32 cst, pour point -45°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 5° Sample 13 DPET (dipentaerythritol) as neopentyl polyol, 2- as fatty acid A mixture of methylpropanoic acid and isohebbutanoic acid (the molar ratio of fatty acids is 30
: Neopentyl polyol ester obtained using 70).

Kinematic viscosity at 40°C 65 cst, pour point -45°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 6.1° Sample 14 DPET (dipentaerythritol) as neopentyl polyol, as fatty acid A mixture of 2-methylpropanoic acid and isohebbutanoic acid (the molar ratio of fatty acids is 10
Neopentyl polyol ester obtained using :90).

Kinematic viscosity at 40°C 67 cst, pour point -45°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 6.7° Sample 15 DPET (dipentaerythritol) as neopentyl polyol, as fatty acid Mixture of heptanoic acid and isohebbutanoic acid (molar ratio of fatty acids is 50:50)
) neopentyl polyol ester obtained using

Kinematic viscosity at 40°C 68 cst, pour point -45°C, average number of carbon atoms of fatty acid per hydroxyl group of neopentyl polyol is 7° Sample 16 DPET (dipentaerythritol) as neopentyl polyol, 2- as fatty acid Neopentyl polyol ester obtained using ethylhexanoic acid.

Kinematic viscosity at 40°C 156 cst, pour point -35°C
, the average number of carbon atoms in fatty acids per hydroxyl group in neopentyl polyol is 8°.Sample 17 A polyalkylene glycol compound CI represented by the following formula.

HO(CH,CHO)ヮH Kinematic viscosity at 40°C 34cst, pour point -42.5°C.

Sample 18 A polyalkylene glycol compound CHl C4H90(CLCHO)+ represented by the following formula. H 40″C kinematic viscosity 36cst, pour point -55°C0 Sample 19 Polyalkylene glycol compound CH represented by the following formula.

80 (CHzCHO)+J Kinematic viscosity at 40°C 73cst, pour point -45°C0 Example 1 ■! Place each sample shown in Table 1 in a glass autoclave.
5 parts by weight, Freon 134a 85 parts by weight, or 0 Table 1
60 parts by weight of each of the samples shown in Figure 1 and 40 parts by weight of Freon 134a were added, and the compatibility at -60°C to 100°C was examined. The results are shown in Table 1 below.

Table 1 Comparative Example 1 The compatibility of the samples shown in Table 2 was investigated in the same manner as in Example 1 (■). The results are shown in Table 2.

Table 2 Example 2 10g of each sample shown in Table 3 was placed in a 100d beaker, and 2
It was placed in a constant temperature and humidity chamber at 0° C. and 60% humidity, and changes in weight were examined after 24 hours. The results are shown in Table 3.

Table □ Comparative Example 2 Using the samples shown in Table 4, 24
Changes in weight (water absorption) after time were examined.

The results are shown in Table 4.

As is clear from Table 4, the increase in weight is significantly greater than in Example 2, and the water absorption is high.

Table Example 3 One measure of electrical insulation is volume resistivity. Table 5
The volume resistivity of each sample shown in 70% humidity and measurement temperature 3
Measurement was performed at 0°C using a method using a direct current amplifier according to JIS C-2101. Atohanchist T as a microcurrent meter
R-8601 (manufactured by Atopan Test Co., Ltd.) was used, and Adhantes) TR-44 (manufactured by Atopan Test Co., Ltd.) was used as a cell for measuring liquid resistance. The applied voltage was 100μ. The results are shown in Table 5.

Table 5 Comparative Example 3 The volume resistivity of each sample shown in Table 6 was investigated in the same manner as in Example 3. The results are shown in Table 6.

As is clear from Table 6, the polyalkylene glycol compounds were all inferior in volume resistivity to the neopentyl polyol ester compound of the present invention.

Table 6 Example 4. Comparative Example 4 15 parts by weight of each sample shown in Table 7 and Freon 134a8 were placed in a 100d stainless steel (StlS-316) autoclave.
5 parts by weight were added, and one each of steel, copper, and aluminum metal pieces (50 x 25 x 1.5 pieces) were added, sealed, and heated at 150°C for 14 days (336 hours).

After the heating test was completed, the Freon 134a was removed by vacuum degassing, and the viscosity and appearance of the refrigerator lubrication side after the test were evaluated. In addition, the metal pieces were washed with toluene and ethanol, and changes in weight were measured. The results are shown in Table 7.

Furthermore, the stability of comparative products against Samples 17 to 19 was investigated using the same method. It was found that all of these had a larger viscosity change rate than the compounds of the present invention, and the influence of metals was also large. The test results are shown in Table 7.

Procedural amendment (spontaneous) October 24, 1990 (038) Asahi electric transformation engineering Business KK formula Target of correction Detailed description of the invention in the specification 6 Contents of correction (1) 6-2 lines from the bottom of statement 6 [Also, Jitrime Tyrolpropane...can be used.

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Claims (1)

[Claims] A lubricant for refrigerators using a chlorine-free fluorocarbon refrigerant, characterized by containing a neopentyl polyol ester of a fatty acid having 2 to 6 carbon atoms.