JPH0314894A - Lubricating oil for compression refrigerating machine - Google Patents

Abstract

PURPOSE:To obtain the subject lubricating oil improved both in lubricating performance and in the compatibility at any service temperature with hydrofluorocarbon 134a, a refrigerant that can substitute for chlorofluorocarbon 12 by using a specified polyoxyalkylene glycol derivative as principal constituent. CONSTITUTION:A 2-4C alkylene oxide (e.g. ethylene oxide) is polymerized in the presence of an initiator (e.g. water) to give a polyoxyalkylene glycol having terminal OH groups of formula I (wherein (p) is 6 to 80 on average; R<2> is 2-4C alkylene). The terminal OH groups of the polyoxyalkylene glycol are etherified and/or esterified to give a polyoxyalkylene glycol derivative (A) of formula II (wherein R<1> is 1-10C alkyl, acyl or aliphatic hydrocarbon group having 2 to 6 bonding sites, and R<3> is 1-10C alkyl or acyl, provided that both of R<1> and R<3> are not methyl at the same time; (n) is 1 to 6; (m) is a number to provide an average of (m)X(n) of a 6 to 80). The subject lubricating oil having a viscosity (100 deg.C) of 2-50cSt is obtained by using component A as principal constituent and mixing it, as required, with additives (B), such as an antifoaming agent, a lubricant, and an extreme-pressure additive.

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 focuses on 1,1,1.
The present invention relates to a lubricating oil for compression type refrigerators, which has good compatibility with 2-tetrafluoroethane (hereinafter referred to as Freon 134a) and has excellent lubrication performance, and whose main component is a polyoxyalkylene glycol derivative.

[Conventional technology]

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 such compression type refrigerators, although it depends on the type of equipment, generally,
Temperatures above 50°C in the compressor and -4°C in the cooler
Since the temperature is around 0°C, the refrigerant and lubricating oil are usually -
without phase separation at temperatures ranging from 40 to +50″C.
It is necessary to circulate within this system. 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, operating conditions, etc., but it is generally preferable that the viscosity of the lubricating oil before mixing with the refrigerant is in the range of 2 to 50 centistokes 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.

Furthermore, since lubricating oil for refrigerators is used cyclically over a wide temperature range from high to low temperatures, it is preferable that the lubricating oil has a high viscosity index, and a viscosity index of 40 or more is usually required.
Other performance requirements include low hygroscopicity to prevent the expansion valve from clogging due to freezing.

Conventionally, Freon 12 has been widely used as a refrigerant in compression type refrigerators, and various mineral oils and oils that meet the above-mentioned required characteristics have been used as lubricating oils. However, as Freon-12 has the potential to cause environmental pollution such as destroying the ozone layer, its regulations have recently become stricter worldwide, and for this reason, Freon-134a is attracting attention as a new refrigerant. Ta. This Freon 134a is preferable as a refrigerant for compression type refrigerators because it has little risk of destroying the ozone layer and can be substituted for Freon 12 without changing the structure of conventional refrigerators. .

When the above-mentioned Freon 134a is used instead of Freon 12 as a refrigerant in a compression type refrigerator, the lubricating oil naturally has excellent compatibility with the Freon 134a and has lubricating performance that satisfies the above-mentioned required performance. However, the lubricating oil that has been used together with conventional Freon 134a has poor compatibility with Freon 134a.
A new lubricant suitable for 34a will be required. in this case,
Particularly in automotive air conditioners, when replacing fluorocarbons,
It is desired to make almost no changes to the structure of the equipment, and it is not desirable to make large changes to the structure of the current equipment for lubricating oil. Therefore, Freon 13
A lubricating oil having very good compatibility with 4a is required.

Examples of lubricating oils that are compatible with Freon 134a include Urukon LB-, which is based on polyalkylene glycols.
165 and Urukon LB-5 2 5 (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. It has been reported that it does. [“Research 3 Discrowji + - (Rese
arch Disclosure) J No. 17463 (October 1978)].

However, these lubricating oils are polyalkylene glycol derivatives in which polypropylene glycol has a hydroxyl group at one end and an n-butyl ether bond at the other end, and has 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-5 2 5 undergoes phase separation from Freon 134a at room temperature (U.S. Pat. No. 4,755,316). number specification)
.

On the other hand, polyglycols having at least two hydroxyl groups in the 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 Laid-Open No. 79175/1983), but this absorption refrigerating machine is the object of the present invention. The mechanism is completely different from that of a compression refrigerator.
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.

In this way, a lubricating oil for compression type refrigerators that has sufficiently good compatibility with Freon 134a and has excellent lubrication performance,
At present, it has not yet been discovered, and its development has been strongly desired.

[Problem to be solved by the invention]

In response to these demands, the present invention has developed a refrigerant that has good compatibility with Freon 134a, which can be a substitute for Freon 12, which is a refrigerant that has become a problem due to environmental pollution, over the entire operating temperature range, and has excellent lubrication performance. This was developed for the purpose of providing a lubricating oil for compression type refrigerators.

[Means to solve the problem]

As a result of extensive research in order to develop a lubricating oil for compression type refrigerators that has both excellent compatibility with Freon 134a and lubrication performance, the present inventor has developed a polyoxyalkylene glycol mK substance having a specific structure. We have discovered that the main component is suitable for the above purpose, and based on this knowledge, we have completed the present invention.

That is, the present invention provides general formula R'+{OR'h○R'). (1) (Rl in the formula
is an alkyl group or acyl group having 1 to 10 carbon atoms, 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 alkyl group or acyl group having 1 to 10 carbon atoms. Base. n is an integer from 1 to 6. m is rrlX
The average value of n is a number from 6 to 80. ) A lubricating oil for compression type refrigerators is provided which mainly contains a polyoxyalkylene glycol derivative represented by:

The present invention will be explained in detail below.

The lubricating oil of the present invention is mainly composed of a polyoxyalkylene glycol derivative represented by the general formula R1 (OR) (1).

Rl in the formula is an alkyl group having 1 to 10 carbon atoms. Acyl group or aliphatic hydrocarbon group having 2 to 6 bonding sites H
z is an alkylene group having 2 to 4 carbon atoms, R3 is 1 to 1 carbon number
0 alkyl or acyl groups. n is an integer from 1 to 6, m
is a number such that the average value of mXn is 6 to 80.

The alkyl group may be linear, branched chain, or cyclic. Specific examples of the alkyl group include methyl group,
Ethyl group, n-probyl group. Isobrobyl group, various butyl groups. Examples include various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, cyclobentyl groups, and cyclohexyl groups.

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.

Furthermore, the alkyl group portion of the acyl group is linear. It may be either chain-like or circular. 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, various nonyl groups, cyclopentyl groups. Examples include cyclohexyl group. 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 RI and R3 are an alkyl group or an acyl group, R1 and R' may be the same or different.

Furthermore, when n is 2 or more, multiple R3s in one molecule may be the same or different. When Rl 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, heptylene group, octylene group. Nonylene group, decylene group, cyclopentylene group. Examples include cyclohexylene group. Examples of the aliphatic hydrocarbon group having 3 to 6 bonding sites include trimethylolpropane, glycerin, and pentaerythritol. Examples include residues obtained by removing hydroxyl groups from polyhydric alcohols such as sorbitol, 1,2,3-1-lihydroxycyclohexane, and 1,3,5-}lyhydroxycyclohexane. When the number of carbon atoms in this aliphatic hydrocarbon group exceeds 10, the compatibility with Freon 134a decreases and phase separation occurs. The preferred carbon number is 2 to 6.

Rz 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 oxyethylene group, an oxypropylene 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 preferred, especially oxyalkylene units. Those containing 50 mol% or more of oxypropylene units are preferred.

n in the general formula (1) is an integer of 1 to 6, and is determined according to the number of binding sites of Rl. For example, when Rl is an alkyl group or an acyl group, n is 1, and Rl is the bonding site 2,
For aliphatic hydrocarbon groups having 3, 4.5 and 6, n is 2, 3, 4.5 and 6, respectively. In addition, m is a number such that the average value of mXn is 6 to 80, and m
If the average value of Xn deviates from the above range, the object of the present invention cannot be fully achieved.

The polyoxyalkylene glycol derivative represented by the general formula (1) 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 brobylene oxide
~4 alkylene oxide is polymerized using water or alkali hydroxide as an initiator to form the general formula H→OR"}-OH
(II) (in the formula, p is a number with an average value of 6 to 80, and R! has the same meaning as above) After obtaining a polyoxyalkylene glycol having hydroxyl groups at both ends, By etherifying or esterifying both of the hydroxyl groups of a substance, or by etherifying one hydroxyl group and esterifying the other hydroxyl group, the general formula R'-+OR"}t-OR' (I[[) (R3 and R4 in the formula are an alkyl group or an acyl group having 1 to 10 carbon atoms, and they may be the same or different, and Rt and p have the same meanings as above. A polyoxyalkylene glycol derivative represented by the following formula is obtained.

Method (B): Using a monohydric 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 form a polymer with the general formula R'-{-OR''}70 H ( IV) (
R5 in the formula is an alkyl group having 1 to 10 carbon atoms, and R2
After obtaining a polyoxyalkylene glycol monoalkyl ether having an ether bond at one end and a hydroxyl group at the other end, the hydroxyl group is etherified. Or, by esterification, the general formula RS-+OR"斤OR' (V) (R in the formula!
．． R3. A polyoxyalkylene glycol derivative represented by (RS and p have the same meanings as above) is obtained.

Method (C): An alkylene oxide having 2 to 4 carbon atoms is polymerized using a divalent to hexavalent polyhydric alcohol having 1 to 10 carbon atoms or an alkali metal salt as an initiator to form a compound of the general formula R'-E-{ ORLhOH), (Vl)(
In the formula, R' is an aliphatic hydrocarbon group having 1 to 10 carbon atoms and having 2 to 6 bonding sites, r is an integer of 2 to 6, q is a number such that the average of qXr is 6 to 80, and Rz is After obtaining a polyoxyalkylene glycol derivative having a hydroxyl group at the terminal represented by (having the same meaning as above), the hydroxyl group of this product is etherified or esterified to obtain the general formula Rh-{-{OR'hOR3] , (■) (in the formula, R'', R', Rh, q and r have the same meanings as above) is obtained.

In these production methods, in order to esterify the hydroxyl group of a polyoxyalkylene glycol or a derivative thereof having a hydroxyl group at the end, the polyoxyalkylene glycol usually has 1 to 1 carbon atoms.
10 aliphatic carboxylic acids. or a method of reacting a reactive derivative thereof such as an acid anhydride, an acid halide, or an ester, or a method in which the hydroxyl group of the polyoxyalkylene glycol or its derivative is converted into a sulfonic acid ester or halide, and then the carboxylic acid Alternatively, a method of reacting a salt thereof can be used.

Specific examples of the carboxylic acid include formic acid, acetic acid, propionic acid, m-acid. Valeric acid. Caproic acid, caprylic acid, capric acid. Examples include cyclohexanecarboxylic acid.

In addition, when performing esterification using the carboxylic acid or acid anhydride, or when performing esterification by transesterification using the ester of the carboxylic acid, an acid such as sulfuric acid or p-}luenesulfonic acid is usually used. A catalyst is used, whereas in the case of esterification using an acid halide, amines are usually used as the dehydrohalogenation agent.

On the other hand, in order to etherify the hydroxyl group of a polyoxyalkylene glycol or its derivatives 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. After obtaining the alkali metal salt of the polyoxyalkylene glycol or its derivative,
In addition, an alkyl halide having 1 to 10 carbon atoms. A method of reacting sulfuric acid esters or sulfonic acid esters,
Alternatively, a method is usually used in which the hydroxyl group of the polyoxyalkylene glycol or its 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 thus obtained polyoxyalkylene glycol derivative of the present invention, the bonding mode of the oxyalkylene units is usually one head in the case of oxypropylene units and oxybutylene units, but one head and one tail. A small amount of binding mode may also be included. The lubricating oil of the present invention has the thus obtained polyoxyalkylene glycol derivative represented by the general formula (1) as a main component, but this polyoxyalkylene glycol derivative may be used alone. Alternatively, two or more types may be used in combination. Moreover, the lubricating oil contains, in addition to the polyoxyalkylene glycol derivative represented by the general formula (I),
A polyoxyalkylene glycol derivative having a hydroxyl group at the terminal can be suitably used even if it is contained as long as the content of the hydroxyl group is 30 mol % or less based on all the terminals. 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.

Furthermore, it is desirable that the lubricating oil of the present invention has a viscosity in the range 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 contains various additives conventionally used in lubricating oils, such as load-bearing additives, chlorine scavengers, antioxidants, metal deactivators, antifoaming agents, detergent dispersants, and viscosity index improvers. Agents, oil agents, anti-wear additives, extreme pressure agents, rust preventives, corrosion inhibitors, pour point depressants, etc. can be added as desired.

Examples of the load-bearing additives include monosulfides, polysulfides, sulfoxides, sulfones, thiosulfinates, sulfurized oils and fats, thiocarbonates, and thiophenes. Thiazoles. Organic sulfur compound-based products such as methanesulfonic acid esters, phosphoric acid ester-based products such as phosphoric acid monoesters, phosphoric acid diesters, phosphoric acid triesters (tricresyl phosphate), phosphorous acid monoesters, etc. Phosphite esters such as esters, phosphite diesters and phosphite triesters, thiophosphoric acid esters such as thiophosphoric triesters, higher fatty acids, and hydroxyaryl fatty acids. Carboxylic acid-containing polyhydric alcohol esters, fatty acid-based products such as metal soaps, polyhydric alcohol esters, fatty acid ester-based products such as acrylic esters, organic compounds such as chlorinated hydrocarbons, and chlorinated carboxylic acid derivatives. Chlorinated ones, fluorinated 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. Organotin compounds, organogermanium compounds. Metal compounds such as boric acid esters, chlorine scavengers include glycidyl ether group-containing compounds, epoxidized fatty acid monoesters, and epoxidized fats and oils. Epoxycycloalkyl group-containing compounds and antioxidants include phenol [(2,6-ditertiarybutyl-p-cresol), aromatic amines (α-naphthylamine),
As metal deactivators, penzotriazole derivatives,
Silicone oil (dimethylpolysiloxane) is used as an antifoaming agent. Polymethacrylates, detergents and dispersants include sulfonates, phenates, and succinimides; viscosity index improvers include polymethacrylates, polyisobutylene, ethylene-propylene copolymers, and styrene-diene hydrogenated copolymers. Can be mentioned.

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 lubricating oils for compression refrigerators. [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 Uniloop MB-1 manufactured by Nippon Oil & Fats Co., Ltd. was placed in a glass 200d three-necked flask equipped with a stirrer and a dropping funnel.
1 (polyoxypropylene glycol mono-n-butyl ether, average molecular weight 1000) 50 g, pyridine 9.5
g (0.12 mol), ethyl ether 100 ml
After adding 9.4 g of acetyl chloride (
0.12 mol) was added from the dropping funnel over 30 minutes.

After heating and refluxing for 2 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 parts each of saturated brine. After distilling off the ether, the mixture was heated to 100°C under reduced pressure with a vacuum pump. After drying for 1 hour, 49.0 g of the desired acetate ester of Uniloop MB-11 was obtained.

Production Example 2 Uniloop MB-1 manufactured by Nippon Oil & Fats Co., Ltd. was placed in a glass 300d three-necked flask equipped with a stirrer and a distillation head.
75 g of 1 and 50 g of toluene were added, and about 20 g of toluene was distilled off while heating and stirring to remove moisture. Next, after removing the distillation head and attaching the condenser and dropping funnel, 11.9 g (0.15 mol) of pyridine and 5 mol of toluene were added.
Added 0sei. n-Butyryl chloride l6. under stirring at room temperature.
0 g (0.15 mol) was added from the dropping funnel over 30 minutes. Heat for 4 hours. After refluxing, the reaction mixture was cooled to room temperature, then transferred to a separatory funnel, and saturated brine was added. 5 each
Washed 5 times with M. After distilling off toluene, the mixture was dried at 100''C for 1 hour under reduced pressure with a vacuum pump to obtain 70.5 g of the target n-butyric acid ester of UNILUBE MB-11.

Production Example 3 Isobutyryl chloride 16.0 instead of n-butyryl chloride
Production Example 2 except that g (0.15 mol) was used.
Exactly the same operation as above was performed to obtain 74 g of isobutyric acid ester of UNILUBE MB-11.

Reference example 1 16.9 g of benzoyl chloride (0
．． The benzoic acid ester of UNILUBE MB-11 57 was prepared in exactly the same manner as in Production Example 1 except that 12 mol) was used.
．． Obtained 0g.

Reference example 2 Glass 200 with stirrer and dropping funnel attached
50 g of Unilube MB-11 manufactured by Nippon Oil & Fats Co., Ltd. was placed in a ml three-necked flask. Potassium hydroxide 7.9g (0.1
4 mol) and 80 ml of toluene were added thereto, and while the toluene was heated under reflux and stirred, 15.2 g (0.12 mol) of benzyl chloride was added from the dropping funnel over 30 minutes. Then heat for 4 hours. After refluxing, the reaction mixture was cooled to room temperature, and then transferred to a separating funnel and washed five times with 50 d each of saturated brine. After distilling off the toluene, use a vacuum pump under reduced pressure (
0. 1+mnl{g), 1 0 0°C, 1
After drying for hours, 49.0 g of the desired benzyl ether of UNILUBE MB-11 was obtained.

Production Example 4 Into a glass 300/d three-necked flask equipped with a stirrer and a distillation head, 65 g of polyoxypropylene glycol mono-n-butyl ether (average molecular weight 1120),
Add 70 d of toluene and heat it while stirring to add about 2 d of toluene.
Water was removed by distilling off 0 ml. After cooling, 28% by weight
Sodium methoxide methanol? 25g of liquid (0
．． 13 monole) and heat to dissolve methanol and approx.
0d of toluene was distilled off. After cooling, the distillation head was removed, a cooler and a dropping funnel were attached, and 30 g (0.19 mol) of ethyl iodide was heated at 50°C and stirred.
was added from the dropping funnel over 30 minutes.

After heating and stirring at 50"C for 1 hour, 70°C for 3 hours, and 105°C for 1.5 hours, the reaction mixture was cooled to room temperature.Then, the reaction mixture was transferred to a separating funnel, and saturated brine, each Washed 5 times using 50d.

After distilling off toluene, under reduced pressure with a vacuum pump, at 100°C, 1
Ethyl ether derivative of the desired polyoxypropylene glycol mono-n-butyl ether 58
I got g.

Production Example 5 Instead of polyoxypropylene glycol mono-n-butyl ether, 65 g of polyoxypropylene glycol (average molecular weight 1100) having hydroxyl groups at both ends was used,
28% by weight sodium methoxide methanol solution, 50g (0.27 mol) each of ethyl iodide, 6
Except for using 0 g (0.38 mol), the same operation as in Production Example 4 was performed to obtain 62 g of the target polyoxypropylene glycol diethyl ether.

Production Example 6 Using 65 g of a polyoxypropylene glycol (average molecular weight 1000) derivative 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, 28% by weight sodium methoxide in methanol solution, 50g each of ethyl iodide (0%
．． 26 moles). The same operation as in Production Example 4 was carried out except that 90 g (0.58 mol) was used, and the desired polyoxypropylene glycol triethyl ether derivative 6 was obtained.
1g was obtained.

Production Example 7 Stirrer. Glass 300 with distillation head attached
ml three-necked flask, Sannix PP-1000 (polyoxypropylene glycol with hydroxyl groups at both ends, average molecular weight 1000) manufactured by Sanyo Kagyo Co., Ltd. 5
0g. }80 ml of toluene was added, and water was removed by distilling off about 201 d of toluene while heating and stirring.

After cooling, 25 g (0.13 mol) of a 28% by weight methanol solution of sodium methoxide was added, and the mixture was heated to distill off methanol and about 20 parts of toluene.

After cooling, the contents were transferred to a stainless steel 300d autoclave with a stirrer and 36.8 g of methyl iodide (
After adding 0.26 mol) and sealing, the temperature was raised from 50°C to 70"C over 4.5 hours while stirring, and then heated to 85°C.
It reacted for 4 hours. After cooling to room temperature, the reaction mixture was diluted with 1 part of water.
00d, dissolved in a mixture of 200all of methanol, 200d of cation exchange resin, then 200d of anion exchange resin.
0- column.

After distilling off the solvent, reduce the pressure using a vacuum pump (0.1 mm}
Ig), 100'c, dried for 1 hour to obtain the target dimethyl ether derivative 4 of SANNIX PP-1000.
2.5g was obtained. In this derivative, the infrared absorption spectrum (3450 cm-') based on hydroxyl groups disappeared.

Production Example 8 Completely the same as Production Example 7 except that 60 g of Nissan Uniol D-1200 (polyoxypropylene glycol with hydroxyl groups at both ends, average molecular weight 1200) manufactured by NOF Corporation was used instead of SANNIX PP-1000. 49 g of dimethyl ether m4 of Nissan Uniol D-1200 was obtained. This derivative has an infrared absorption spectrum (3 4 5 0 cm-'
) had 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 polyglycols of Production Examples 1, 4, and 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 Freon 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.

(Blank below) [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 Freon 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.

Claims (2)

[Claims] (1) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R^1 in the formula 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, R^3 is an alkyl group or acyl group having 1 to 10 carbon atoms, n is an integer of 1 to 6, and m is an average value of m x n of 6 to 80. The number is
However, this excludes the case where R^1 and R^3 are both methyl groups. ) A lubricating oil for compression type refrigerators whose main component is a polyoxyalkylene glycol derivative represented by (2) The lubricating oil according to claim 1, wherein the compression type refrigerator uses 1,1,1,2-tetrafluoroethane as a refrigerant.