JPH02305893A - Lubricating oil for compression refrigerating machine - Google Patents

Abstract

PURPOSE:To improve the compatibility with hydrofluorocarbon 134a and the lubricity by incorporation of a specified polyoxyalkylene glycol derivative as an effective constituent. CONSTITUTION:A 2-4C alkylene oxide (e.g. ethylene oxide) is polymerized in the presence of water and an initiator comprising an alkali hydroxide to give a polyoxyalkylene glycol having terminal hydroxyl groups of formula I (wherein p is 6 to 80; R<2> is 2-4C alkylene), and the terminal hydroxyl groups are methyl- etherified, etc., thus giving a polyoxyalkylene glycol derivative (A) of formula II (wherein R<1> and R<3> are each methyl: m is p) (e.g. a polyoxyalkylene glycol dimethyl ether). Component A is mixed, if necessary, with a polyoxyalkylene derivative (B) having terminal hydroxyl groups in such an amount that the terminal hydroxyl groups account for at most 30mol% of the total terminal groups, thus giving the title lubricating oil having a kinematic viscosity (100 deg.C) of 2-50cSt.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel lubricating oil for compression type refrigerators. More specifically, the present invention particularly provides 1, 1, 1.
The present invention relates to a lubricating oil for compression type refrigerators, which has good compatibility with 2-tetrafluorobutane (hereinafter referred to as 70-134a) and has excellent lubrication performance, and whose main component is a polyoxyalkylene glycol derivative.

[Prior Art] A compression type refrigerator generally includes a compressor, a condenser, an expansion valve, and an evaporator, and has a structure in which a liquid mixture of refrigerant and lubricating oil circulates within this closed system. In general, this kind of compression is performed in a refrigerator, although it depends on the type of equipment.
The temperature in the compressor is over 5000℃, and the temperature in the cooler is 14℃.
Since the temperature is around 0℃, the refrigerant and lubricating oil are usually -4℃.
It is necessary to circulate within this system without phase separation at temperatures in the range 0 to +50°C. If phase separation occurs, it will have a significant negative impact on the lifespan and efficiency of the device. For example, if phase separation occurs between the refrigerant and lubricating oil in the compressor, the moving parts will suffer from poor lubrication, causing seizures and other problems, which will significantly shorten the life of the equipment.On the other hand, if phase separation occurs in the evaporator, , the presence of highly viscous lubricating oil reduces the efficiency of heat exchange.

In addition, lubricating oil for refrigerators is used for the purpose of lubricating the moving parts of refrigerators, so lubrication performance is naturally important, especially since the inside of the compressor is at high temperature. It is required to have the following. The required viscosity varies depending on the type of compressor used, usage conditions, etc., but it is usually preferable that the viscosity of the lubricating oil before mixing with the refrigerant is in the range of 2 to 50 sen≠Stokes at a temperature of 100°C. . If the viscosity is lower than the above-mentioned value, the oil film becomes thin and lubrication is likely to occur, and if it is higher, the efficiency of heat exchange decreases. In addition, since lubricating oil for refrigerators is used cyclically over a wide temperature range from high to low temperatures, it is preferable that it has a high viscosity index, and is usually required to have a viscosity index of 40 or more. Low hygroscopicity is required to prevent valve blockage due to freezing on the valve.

Conventionally, Freon 12 has been widely used as a refrigerant in compression type refrigerators, and various mineral oils and synthetic oils that meet the above-mentioned required characteristics have been used as lubricating oils. However, as CFC-12 has the potential to cause environmental pollution such as depleting the ozone layer, regulations have recently become stricter around the world.
0n134a has started to attract attention. Which Freon 134a has little risk of destroying the ozone layer, and can be used without changing the structure of conventional refrigerators.
It is preferable as a refrigerant for compression type refrigerators, as it can be substituted for 70 N12.

When the above-mentioned 70-N 134a is adopted as a refrigerant in a compression type refrigerator instead of 70-N 12, it naturally has excellent compatibility with this Freon 134a as a lubricating oil and can satisfy the above-mentioned required performance. A product with excellent lubrication performance is required, but the lubricating oil that has been used with conventional 70N 12 has poor compatibility with 70N 134a; therefore, a new lubricant suitable for Freon 134a is needed. becomes. In this case, especially in automotive air conditioners, it is desirable to make almost no changes to the structure of the equipment when replacing fluorocarbons, and it is not desirable to make major changes to the structure of the current equipment for lubricating oil. , Therefore, Freon 1
A lubricating oil having very good compatibility with 34a is required.

Examples of lubricating oils that are compatible with Freon 134a include Urukon LB-, which is made of polyalkylene glycol.
165 and Urcon LB-525 (both manufactured by Union Carbide, trade names) are known, and these lubricating oils are compatible with Freon 134a in all composition ratios at low temperatures of at least -50°C. has been reported.

C “Research 0 Days Closer”
Disclosure) J No. 17463 (1978
(October)].

However, these lubricating oils are polyalkylene glycol derivatives having a hydroxyl group at one end of polypropylene glycol and an n-butyl ether bond at the other end, and have relatively good compatibility with Freon 134a at low temperatures. However, the compatibility is not sufficient at high temperatures; for example, it is known that Urukon LB-525 causes phase separation from Freon 134a at room temperature (US Pat. No. 4,755,316 F!A1m). book).

On the other hand, polyglycols having at least two hydroxyl groups in one molecule have been proposed as having good compatibility with Freon 134a (U.S. Pat. No. 4,755,3
Specification No. 16). However, this polyglycol does not necessarily have sufficient compatibility, and since the number of hydroxyl groups in one molecule is large, it has the drawbacks of increased hygroscopicity and decreased viscosity index. Increased hygroscopicity leads to an increase in the amount of dissolved water in the refrigerant-lubricating oil mixture, which can result in ice blockage of the expansion valve, and a decrease in the viscosity index, which increases the amount of dissolved water in the refrigerant-lubricating oil mixture This may lead to an increase in viscosity and reduce heat exchange efficiency.

In addition, when a mixture of polyglycol and Freon is heated from a low temperature to a high temperature, the mixture that was generally phase-separated changes to
It is known that they exhibit a temperature dependence in which they become compatible and then undergo phase separation.

On the other hand, it has been proposed to use Freon 134a and a compound capable of dissolving it in an absorption refrigerating machine (Japanese Patent Application Laid-Open No. 79175/1983), but this absorption refrigerating machine is not the object of the present invention. The mechanism is completely different from that of other compression refrigerators.
Moreover, the tetraethylene glycol dimethyl ether described in the Examples has an extremely low viscosity and is therefore unsuitable as a lubricating oil for compression refrigerators.

As described above, a lubricating oil for compression type refrigerators that has sufficiently good compatibility with Freon 134a and has excellent lubrication performance has not yet been found, and its development is strongly desired. Ta.

[Problems to be Solved by the Invention] The present invention has been developed to meet these demands, and to improve the compatibility with Freon 134a, which can be a substitute for Freon 12, which is a refrigerant that has become a problem in terms of environmental pollution, over the entire operating temperature range. This was done for the purpose of providing a lubricating oil for compression type refrigerators that is both good and has excellent lubrication performance.

[Means for Solving the Problems] The present inventors have discovered that 1. Developing a lubricating oil for compression type refrigerators that is excellent in all aspects;
As a result of intensive research for this purpose, we discovered that scales whose main component is a polyoxyalkylene glycol derivative having a specific structure are suitable for the above purpose, and based on this knowledge, we have completed the present invention. .

That is, the present invention is based on the general formula % formula % (1) (where R1 is an alkyl group having 1 to 10 carbon atoms, an acyl group, or an aliphatic hydrocarbon group having 2 to 6 bonding sites, R
2 is an alkylene group having 2 to 4 carbon atoms, and R3 is an alkylene group having 1 to 1 carbon atoms.
0 alkyl group or acyl group, n is an integer of 1 to 6, m is a number such that the average value of m x n is 6 to 80) A compressed type whose main component is a polyoxyalkylene glycol derivative represented by The company provides lubricating oil for refrigerators.

The present invention will be explained in detail below.

The lubricating oil of the present invention has a polyoxyalkylene glycol derivative represented by the general formula % () as a main component.

In the formula, R1 is an alkyl group having 1 to 10 carbon atoms, an alkyl group or an aliphatic hydrocarbon group having 2 to 6 bonding sites, R2
is an alkylene group having 2 to 4 carbon atoms, and R3 is an alkylene group having 1 to 10 carbon atoms.
an alkyl group or an acyl group, n is an integer of 1 to 6, m is m
This is a number such that the average value of xn is 6 to 80.

The alkyl group may be linear, branched, or cyclic. Specific examples of the alkyl group include methyl group,
Examples include ethyl group, n-propyl group, isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, cyclopentyl groups, /chlorohexyl groups, etc. can.

If the number of carbon atoms in this alkyl group exceeds 10, Freon 134
The compatibility with a decreases and phase separation occurs. The preferred alkyl group has 1 to 6 carbon atoms.

Further, the alkyl group portion of the acyl group may be straight, branched, or cyclic. Specific examples of the alkyl group moiety of the acyl group include methyl group, ethyl group, n-propyl group, isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, and various nonyl groups. , cyclopentyl group, cyclohexyl group, etc. The number of carbon atoms in the acyl group is 1
When it exceeds 0, the compatibility with Freon 134a decreases, causing phase separation. The preferred number of carbon atoms in the acyl group is 2
~6.

When R1 and R3 are an alkyl group or an acyl group, R1 and R3 may be the same or different.

Roughly speaking, when n is 2 or more, a plurality of R3s in one molecule may be the same or different.

When R+ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms and having 2 to 6 bonding sites, this aliphatic hydrocarbon group may be chain-like or cyclic. good.

Examples of the aliphatic hydrocarbon group having two bonding sites include ethylene group, propylene group, butylene group, pentylene group, hexylene group, hexylene group, octylene group, nonylene group, te/lene group, cyclopentylene group, and cyclohexylene group. Examples include silene group. Examples of aliphatic hydrocarbon groups having 3 to 6 bonding sites include trimethylolpropane, glycerin, pentaerythritol, sorbitol, 1,2.3-trihydroxycyclohexane, and 1,3.5-trihydroxycyclohexane. Examples include residues obtained by removing the hydroxyl group from polyhydric alcohols such as.

When the number of carbon atoms in this aliphatic hydrocarbon group exceeds 10, the compatibility with 70-ton 134a decreases and phase separation occurs. The preferred carbon number is 2 to 6.

R2 in the general formula (I) is an alkylene group having 2 to 4 carbon atoms, and examples of the oxyalkylene group as a repeating unit include an oxybutylene group, an oxybutylene group, and an oxybutylene group. The oxyalkylene groups in one molecule may be the same or two or more types of oxyalkylene groups may be included, but those containing at least oxypropylene units in one molecule are preferable, and in particular, oxyalkylene units Those containing 50 mol% or more of oxypropylene units are preferred.

In the general formula (I), n is an integer of 1 to 6 and is determined depending on the number of bonding sites of R'. For example, when R+ is an alkyl group or an acyl group, n is 1, and R1 is the bonding site 2.
In the case of aliphatic hydrocarbon groups having 3.4.5 and 6, n becomes 2.3.4.5 and 6, respectively. Also,
m is a number such that the average value of mXn is 6 to 80, and mxn
If the average value of is outside the above range, the object of the present invention cannot be fully achieved.

The polyoxyalkylene glycol derivative represented by the general formula (I) used in the lubricating oil of the present invention can be produced by the following various methods.

(A) Method: 2 carbon atoms such as ethylene oxide and propylene oxide
~4 alkylene oxides are polymerized using water or alkali hydroxide as an initiator to form a compound of the general formula 8%) (in the formula, p is a number with an average value of 6 to 80, and R2 has the same meaning as above) After obtaining a polyoxyalkylene glycol having hydroxyl groups at both ends represented by, by etherifying or esterifying both hydroxyl groups of this product, or by etherifying one hydroxyl group and esterifying the other hydroxyl group. According to the general formula 8 formula % ([[) (R3 and R4 in the formula are an alkyl group or an acyl group having 1 to 1 o carbon atoms, and they may be the same or different from each other. , R2 and p have the same meanings as above) A polyoxyalkylene glycol derivative represented by the following is obtained.

Method (B): An alkylene oxide having 2 to 4 carbon atoms is polymerized using m alcohols having 1 to 10 carbon atoms or an alkali metal salt thereof as an initiator, and the formula 8 is %() (RS in the formula is is an alkyl group having 1 to 10 carbon atoms, and R
2 and p have the same meanings as above), which has an ether bond at one end and a hydroxyl group at the other end, is obtained, and then the hydroxyl group of this is converted into an ether. By the conversion or esterification, a polyoxyalkylene glycol derivative represented by the general formula % (in which R8, R1, R6 and p have the same meanings as above) can be obtained.

Method (C): Using a divalent to hexavalent polyhydric alcohol having 1 to 10 carbon atoms or an alkali metal salt thereof as an initiator, an alkylene oxide having 2 to 4 carbon atoms is polymerized to obtain the general formula % formula % () (R6 in the formula has 1 to 1 carbon atoms and has 2 to 6 bonding sites.
0 aliphatic hydrocarbon group, r is an integer of 2 to 6, q is qXr
After obtaining a polyoxyalkylene glycol derivative having a hydroxyl group at the terminal represented by (the average of which is 6 to 80, and R2 has the same meaning as above), the hydroxyl group of this product is etherified or esterified. As a result, a polyoxyalkylene glycol derivative represented by the general formula % (in which R2, R3, R6, q and r have the same meanings as above) is obtained.

In these production methods, in order to esterify the hydroxyl group of polyoxyethylene glycol or its derivatives having a hydroxyl group at the end, the polyoxyethylene glycol usually has a carbon number of 1 to 10.
aliphatic carboxylic acid, or its reactive derivative such as its acid anhydride, acid halide, or ester, or after converting the hydroxyl group of the polyoxyethylene glycol or its derivative into a sulfonic acid ester or halide, For example, the method of reacting the carboxylic acid or its salt is used.

Specific examples of the carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, and cyclohexanecarboxylic acid.

In addition, when performing esterification using the carboxylic acid or its acid anhydride, or when performing esterification by transesterification using the ester of the carboxylic acid, usually sulfuric acid or pH
An acid catalyst such as luenesulfonic acid is used, while amines are usually used as the dehydrohalogenating agent when esterifying with an acid halide.

On the other hand, in order to etherify the hydroxyl group of a polyoxyalkylene glycol or a derivative thereof having a hydroxyl group at the end, the polyoxyalkylene glycol is usually reacted with an alkali metal such as sodium metal or an alkali metal salt of a lower alcohol such as sodium methoxide. to obtain an alkali metal salt of the polyoxyalkylene glycol or its derivative; A method is usually used in which the hydroxyl group of the derivative is converted into a sulfonic acid ester or halide, and then reacted with an aliphatic alcohol having 1 to 10 carbon atoms or an alkali metal salt thereof.

In the polyoxyalkylene glycol derivative of the present invention obtained in this manner, the bonding mode of the oxyalkylene units is usually group-tail in the case of oxypropylene units and oxybutylene units, but head-to-head and tail-to-tail. The binding style may also be slightly distorted. The lubricating oil of the present invention has the thus obtained polyoxyalkylene glycol derivative represented by the general formula (1) as a main component.
They may be used alone or in combination of two or more. In addition to the polyoxyalkylene glycol derivative represented by the general formula (1), the lubricating oil also contains a polyoxyalkylene glycol derivative having a hydroxyl group at the terminal, with a content of the hydroxyl group relative to all terminal groups. Even if it is contained, it can be suitably used as long as the proportion is 30 mol% or less. If the content of this hydroxyl group exceeds 30 mol%, hygroscopicity increases and the viscosity index decreases, which is not preferable.

It should be noted that polyoxyalkylene glycol derivatives in which R1 and R3 in the general formula (I) are aromatic systems cannot achieve the object of the present invention, although the reason is not clear.

The lubricating oil of the present invention desirably has a viscosity of 2 to 50 centistokes, preferably 5 to 30 centistokes, at a temperature of 100°C in order to maintain the oil film thickness necessary for lubrication. The lubricating oil of the present invention also contains various additives that are conventionally used in lubricating oils, such as load-bearing additives, chlorine scavengers, antioxidants, metal deactivators, antifoaming agents, detergent dispersants, and viscosity additives. Index improvers, oil agents, anti-wear additives, extreme pressure agents, rust preventives, corrosion inhibitors, pour point depressants, etc.
It can be added as desired.

The load-bearing additives mentioned above include monosulfides, polysulfides, sulfoxides, sulfones, thiosulfinates, sulfurized oils and fats, thiocarbonate a, thiophenes, thiazoles, methanesulfonic acid esters, etc. Compounds, phosphate monoesters, phosphoric diesters, phosphoric triesters (tricresyl phosphate), phosphorous monoesters, phosphorous diesters, Phosphite esters such as phosphoric triesters, thiophosphoric esters such as thiophosphoric triesters, higher fatty acids, hydroxyaryl fatty acids, carboxylic acid-containing polyhydric alcohol esters, metal soaps, etc. Fatty acid-based products, fatty acid ester-based products such as polyhydric alcohol esters and acrylic acid esters, chlorinated hydrocarbons, organic chlorine-based products such as chlorinated carboxylic acid derivatives, and 7-substituted aliphatic carboxylic acids. , fluorinated ethylene resins, fluorinated alkyl polysiloxanes, organic fluorine-based products such as fluorinated graphite, alcohol-based products such as higher alcohols, naphthenates (lead naphthenate),
Fatty acid salts (fatty acid lead), thiophosphates (zinc dialkyldithiophosphate), thiocarbamates, organic molybdenum compounds, metal compounds such as tin compounds, organic germanium compounds, boric acid esters, chlorine scavengers Examples include glycidyl ether group-containing compounds, epoxidized fatty acid monoesters, epoxidized fats and oils, epoxycycloalkyl group-containing compounds, and antioxidants include phenol* (2,6-ditertiarybutyl-p-cresol), aromatic group amines (α-s7tylamine),
As metal deactivators, benzotriazole derivatives,
Antifoaming agents include silicone oil (dimethylpolysiloxane), polymethacrylates, and cleaning and dispersing agents include sulfonates, phenates, succinimides,
Examples of the viscosity index improver include polymethacrylate, polyisobutylene, ethylene-propylene copolymer, and styrene-diene hydrogenated copolymer.

The lubricating oil of the present invention has excellent compatibility with refrigerants and lubrication performance, and is used for compression type refrigerators. Unlike conventional lubricating oils, it has good compatibility with Freon 134a, so it is particularly suitable for use as a refrigerant with Freon 134a. It is suitable for use in compression type refrigerators that use In addition, for the purpose of improving compatibility with refrigerants,
It can also be used by mixing it with other compression type refrigerating oil.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

Production Example 1 In a glass 200mQ three-necked flask equipped with a stirrer and a dropping funnel, Uniloop MB- manufactured by Nippon Oil & Fats Co., Ltd.
11 (polyoxypropylene glycol mono-n-butyl ether, average molecular fi 1000) 509, Viridi 79
．． 5g (0,12-F-1), ethyl ether 100I
After adding 9.4yC of acetyl chloride under stirring at room temperature,
0.12 mol) was added from the dropping funnel over 30 minutes.

After heating and refluxing for 2 hours, the reaction mixture was cooled to room temperature, then transferred to a separating funnel, and 50 mQ each of saturated brine was added.
Washed 5 times using After distilling off the ether, it was dried at 100°C for 1 hour under reduced pressure with a vacuum pump to obtain 49.09% of the target acetate ester of Uniloop MB-11.

Production Example 2 In a glass 300mQ three-necked flask equipped with a stirrer and a distillation head, Uniloop MB- manufactured by Nippon Oil & Fats Co., Ltd.
11759 and 50 ml of toluene were added, and about 20 ml of toluene was distilled off while heating and stirring to remove moisture. next,
Distillation / After removing the throat and installing the condenser and dropping funnel, add pyridine 11°99 (0.15 mo/L,),
50 mQ of toluene was added. While stirring at room temperature, 16.0 g (0.15 mol) of n-butyryl chloride was added from the dropping funnel through the dropping funnel.
Added over 1/2 minute. After heating and refluxing for 4 hours, the mixture was cooled to room temperature, and then the reaction mixture was transferred to a separating funnel and washed five times with 50 ml each of saturated brine. After distilling off toluene, the residue was dried under reduced pressure with a vacuum pump at lOOoC for 1 hour to obtain 70.59 of the target n-butyric acid ester of Uniloop MB-11.

Production Example 3 Imbutyryl chloride 16.0 instead of n-butyryl chloride
Isobutyric acid ester 749 of Uniloop MB-11 was obtained by carrying out exactly the same operation as in Production Example 2 except that 9 (0.15 mol) was used.

Reference example 1 16.9 g of benzoyl chloride (0
, 12 mol) was carried out in exactly the same manner as in Production Example 1 to prepare benzoic acid ester 57 of Uniloop MB-11.
．． I got 09.

Reference Example 2 In a glass 200mα three-necked flask equipped with a stirrer and a dropping funnel, Uniloop MB- manufactured by Nippon Oil & Fats Co., Ltd.
11sog, potassium hydroxide 7.99 (0.14 mol)
, 80 ml (l) of toluene was added, and while stirring the toluene under reflux, 15.29 (0.12 mol) of benzyl chloride was added from the dropping funnel over 30 minutes. After that, it was heated and refluxed for 4 hours, and then cooled to room temperature. Then, the reaction mixture was transferred to a separatory funnel and washed 5 times with 50 ml of saturated brine (100 ml each). After distilling off the toluene, the reaction mixture was washed under reduced pressure with a vacuum pump (0,1 mmH, 100°0. After drying for 1 hour, remove the benzyl ether of Purpose and Suluniroof'MB-11.
9. I got Oy.

Production example 4 Glass 300 mI equipped with stirrer and distillation head
Polyoxypropylene glycol mono-n-butyl ether (average molecular weight 1120) was added to an I'E two-flask.
659 and 70 mα of toluene were added, and about 20 ml of toluene was distilled off while heating and stirring to remove moisture. After cooling, 2
8% by weight sodium methoxide solution in methanol 259
(0.13 mol) and heated to methanol and approx.
0 mQ of toluene was distilled off. After cooling, the distillation head was removed, and a cooler and dropping funnel were attached.
ethyl iodide 309 (0.19 mol) while stirring at °C.
was added from the dropping funnel over 30 minutes. The mixture was heated and stirred at 50°C for 1 hour, 70°C for 3 hours, and 105°C for 1.5 hours, and then cooled to room temperature. The reaction mixture was then transferred to a separatory funnel and washed five times with 50 m/1 each of saturated brine. After distilling off toluene, the residue was dried at 100° C. for 11 hours under reduced pressure with a vacuum pump to obtain 58 g of the desired ethyl ether derivative of polyoxypropylene glycol mono-n-butyl ether.

Production Example 5 Instead of polyoxypropylene glycol mono-n-butyl ether, polyoxypropylene glycol having hydroxyl groups at both ends (average molecular weight 1100)6! Using M,
A methanol solution of 281% sodium metkind, 509 (0.27 mol) and 60 g of ethyl iodide, respectively.
Except for using (0.38 mol), the same operation as in Production Example 4 was carried out to obtain 62 g of the desired polyoxypropylene glycol diethyl ether.

Production Example 6 Using polyoxypropylene glycol (average molecular weight 1000) derivative 659 having three hydroxyl groups in one molecule obtained by polymerizing propylene oxide using glycerin as an initiator instead of polyoxypropylene glycol mono-n-butyl ether, A methanol solution of 28% sodium methoxide and ethyl iodide were added to
The desired polyoxypropylene glycol triethyl ether derivative 619 was obtained by carrying out exactly the same operation as in Production Example 4, except that 909 (0.58 mol) and 909 (0.58 mol) were used.

Production example 7 Glass 300m1+ equipped with stirrer and distillation head
Add 50 y of Sannix PP-1000 manufactured by Sanyo Chemical Industries, Ltd. (polyoxypropylene glycol with hydroxyl groups at both ends, average molecular weight 1000) and 80 y of toluene to a three-necked flask, and add about 20 ml of toluene while heating and stirring.
Water was removed by distilling mQ off.

After cooling, 28% by weight sodium methoxide in methanol solution 259 (0.13 mol) was added and heated to give meta/-
and about 20 ml of toluene were distilled off.

After cooling, the contents are transferred to a stainless steel 300mQ container with a stirrer.
Transfer to an autoclave and add methyl iodide 36.8y (0,
After adding 26 mol) and sealing, the temperature was raised from 50°C to 70°C over 4.5 hours while stirring, and the reaction was carried out at 85°C for 4 hours. After cooling to room temperature, the reaction mixture was poured with 100 ml of water.
1! , dissolved in a mixture of 200 ml of methanol and 200 mA of cation exchange resin.

Then, it was passed through an anion exchange resin 200mAO column.

After distilling off the solvent, the solvent was removed under reduced pressure using a vacuum pump (o, 1 mmHg).
), dried at 100°C for 11 hours to obtain the desired dimethyl ether derivative of Sannix PP-1000 42.5
I got a 9. This derivative had an infrared absorption spectrum (3450 cm-) based on hydroxyl groups that had disappeared.

Production Example 8 Completely the same as Production Example 7 except that Nissan Uniol D-1200 (polyoxypropylene glycol with hydroxyl groups at both ends, average molecular weight 1200) 609 manufactured by NOF Corporation was used instead of SANNIX PP-1000. 49 g of dimethyl ether derivative of Nirasan Uniol D-1200 was obtained. In this derivative, the infrared absorption spectrum (3450 crV') based on hydroxyl groups disappeared.

Examples 1 to 8, Comparative Examples 1 to 6 The compatibility of the compounds obtained in Production Examples 1 to 8 and Reference Examples 1 to 2 and the raw material polyglycol of Production Example 114.5.6 was measured.

Add a predetermined amount of sample to a pressure-resistant glass ampoule at a concentration of 10% and 20% by weight based on Freon 134a (1,1,1,2-tetrafluoroethane), and connect this to the vacuum piping and Freon 134a gas piping. did. The ampoule was vacuum degassed at room temperature, cooled with liquid nitrogen, and a predetermined amount of 70 tons 134a was collected. Next, the ampoule was sealed, and the temperature was raised from -40°C in a constant temperature bath, and the temperature at which phase separation started was measured.

The higher the phase separation temperature is, the more preferable it is. The results are shown in Table 1.

[Effects of the Invention] The lubricating oil for compression type refrigerators of the present invention mainly contains a polyoxyalkylene glycol derivative having a structure in which the hydroxyl groups at both ends of the polyoxyalkylene glycol are etherified or esterified. It has good compatibility with 70N 134a, which is attracting attention as a substitute for Freon 12, which has become a problem due to environmental pollution, over the entire operating temperature range, and has excellent lubrication performance. Therefore, it is extremely suitable as a lubricating oil for compression refrigerators that use the Freon 134a.

Furthermore, the polyoxyalkylene glycol derivative is
For the purpose of improving compatibility with refrigerants, it can also be used by mixing with other lubricating oils for compression type refrigerators.

Patent applicant: Idemitsu Kosan Co., Ltd. Representative: Patent attorney Fujibe Kubota.

□,.

Procedural amendment (voluntary) June 6, 1990

Claims (1)

[Claims] 1 General formula R^1-[-(OR^2)_m-OR^3]_n (R^1 in the formula is an alkyl group having 1 to 10 carbon atoms, an acyl group, or a bonding site) Aliphatic hydrocarbon group having 2 to 6 R^2
is an alkylene group having 2 to 4 carbon atoms, and R^3 is an alkylene group having 1 to 4 carbon atoms.
10 alkyl or acyl groups, n is an integer of 1 to 6, m
is a number whose average value of m×n is 6 to 80.) A lubricating oil for compression type refrigerators containing a polyoxyalkylene glycol derivative as a main component. 2. The lubricating oil according to claim 1, wherein the compression type refrigerator uses 1,1,1,2-tetrafluoroethane as a refrigerant.