JP2807326B2 - Lubricating oil for motor-integrated compression refrigerators - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel lubricating oil for an electric motor-integrated compression refrigerator. More specifically, 1,1,1,2-tetrafluoroethane (hereinafter referred to as chlorofluorocarbon 134a), which can be an alternative to dichlorodifluoromethane (hereinafter referred to as chlorofluorocarbon 12), which is a problem caused by environmental pollution, etc. Has good compatibility with hydrogen-containing CFC compounds and has excellent lubrication performance.
The present invention relates to a lubricating oil for an electric motor-integrated compression type refrigerator mainly containing polyoxylalkylene glycol having low hygroscopicity and high volume resistivity.

[Problems to be solved by conventional technology and invention]

In general, a compression refrigerator 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 in the sealed system. In such a compression refrigerator, although it depends on the type of the apparatus, generally, the temperature is 50 ° C or higher in the compressor, and −40 ° C in the cooler.
Therefore, it is necessary to circulate the refrigerant and the lubricating oil in the system at a temperature of -40 ° C to + 50 ° C without phase separation. If phase separation occurs during operation of the refrigerator, the life and efficiency of the apparatus will be significantly adversely affected. For example, if phase separation occurs between the refrigerant and the lubricating oil in the compressor portion, the movable portion becomes poorly lubricated, causing seizure or the like, and significantly shortening the life of the device. On the other hand, if phase separation occurs in the evaporator, there is a disadvantage that heat exchange efficiency is reduced due to the presence of lubricating oil having a high viscosity.

Conventionally, Freon 12 and the like have been used as refrigerants for compression refrigerators.In recent years, however, the problem of environmental pollution has been clarified, and hydrogen-containing Freon compounds such as Freon 134a have been attracting attention as alternatives. .

As such lubricating oil compatible with Freon 134a, polyoxyalkylene glycol compounds are known. For example, Urcon LB-165 and Urcon LB-525 (both manufactured by Union Carbide, trade names) [“Research
Disclosure No. 17463 (October 1978)], and particularly recently, Japanese Patent Application Laid-Open Nos. 2-102296 and 1-225903.
Various compounds have been proposed in JP-A-5-132 and JP-A-2-132176-9. Further, polyalkylene glycols having at least two hydroxyl groups in one molecule have been proposed (US Pat. No. 4,755,316, JP-A-1-256594, JP-A-1-2711491, and JP-A-2-84491). Gazette).

On the other hand, it has been proposed to use chlorofluorocarbon 134a and a compound capable of dissolving the same in an absorption refrigerator (Japanese Patent Application Laid-Open No. 56-1981).
No. 79175). However, this absorption refrigerator has a completely different mechanism from the above-described compression refrigerator, and the tetraethylene glycol dimethyl ether described in the example of the above publication has a remarkably low viscosity. Is not suitable as a lubricating oil.

Many compression refrigerators used in electric refrigerators, electric freezers, etc. have a structure in which an electric motor and a compressor are integrated for the purpose of preventing leakage of refrigerant, etc. Touch the electrodes.

Conventionally, mineral oil has been used as this lubricating oil, and has a high volume specific resistivity at 80 ° C. of about 10 ¹⁵ Ωcm, which is an electrical insulating property. However, polyoxyalkylene glycol, which exhibits good compatibility with Freon 134a, has a specific volume resistivity at 80 ° C.
Since it has low electrical insulation and a high risk of electric leakage when it is less than 10 ¹⁰ Ωcm, it cannot be used as a lubricating oil for a compression refrigerator with an integrated motor.

Thus, the compatibility with Freon 134a is sufficiently good,
At present, no lubricating oil for a motor-integrated compression refrigerator having excellent electrical insulation performance and lubrication performance has been found yet.

The present invention satisfies such demands, and has good compatibility with hydrogen-containing Freon compounds such as Freon 134a, which can be a substitute for Freon 12 or other Freon compounds that are difficult to decompose, which are particularly problematic for environmental pollution. The object of the present invention is to provide a lubricating oil for an electric motor-integrated compression type refrigerator having good lubrication performance and low hygroscopicity.

[Means for solving the problem]

The present inventors have conducted intensive studies to develop a lubricating oil for a motor-integrated compression refrigerator having excellent compatibility with hydrogen-containing fluorocarbon compounds such as fluorocarbon 134a, lubrication performance, moisture absorption performance and electrical insulation performance. Stacked. As a result, those having a specific structure of polyoxyalkylene glycol whose specific volume resistivity at 80 ° C. is 1 × 10 ¹⁰ Ωcm or more,
It has been found that it can be adapted to the purpose. The present invention has been completed based on such findings.

That is, the present invention relates to the general formula Wherein R ¹ is an alkyl group having 1 to 10 carbon atoms or an aliphatic hydrocarbon group having 1 to 10 carbon atoms having bonding sites 2 to 6, R ² is an alkylene group having 4 carbon atoms, and R ³ is a carbon atom An alkyl group of 1 to 10, n is an integer of 1 to 6, o and p are each an integer of 0 or more,
q is an integer of 1 or more, and the average value of (o + p + q) × n is 4 to 40, q / (o + p + q) is 0.1 or more, and o / (o + p
+ Q) is a number that satisfies the condition of 0.2 or less. And the volume resistivity at 80 ° C. is 1 × 10
An object of the present invention is to provide a lubricating oil for a motor-integrated compression refrigerating machine containing a polyoxyalkylene glycol derivative purified to ¹⁰ Ωcm or more as a main component.

The main component of the lubricating oil of the present invention is a polyoxyalkylene glycol derivative represented by the general formula (I).
Here, R ¹ in the general formula (I) represents an alkyl group having 1 to 10 carbon atoms or an aliphatic hydrocarbon group having 1 to 10 carbon atoms having a bonding site of 2 to 6, while R ³ represents 1 carbon atom. Represents up to 10 alkyl groups. These alkyl groups having 1 to 10 carbon atoms may be linear, branched or cyclic. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, various butyl groups, various pentyl groups, various octyl groups, various nonyl groups, various decyl groups, cyclopentyl groups, cyclohexyl groups, and the like. Can be mentioned. If the alkyl group has more than 10 carbon atoms, the compatibility with Freon 134a will decrease. The preferred alkyl group has 1 to 6 carbon atoms.

When both R ¹ and R ³ are alkyl groups, R ¹ and R ³ may be the same or different. Further, when n is 2 or more, a plurality of R ^{3 in} one molecule may be the same or different.

When R ¹ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms having bonding sites 2 to 6, the aliphatic hydrocarbon group may be a chain-like one or a cyclic one. Good. Examples of the aliphatic hydrocarbon group having two bonding sites include an ethylene group, a propylene group, a butylene group, a pentylene group,
Examples include an octylene group, a nonylene group, a decylene group, a cyclopentylene group, and a cyclohexylene group. Examples of the aliphatic hydrocarbon group having 3 to 6 binding sites include trimethylolethane; trimethylolpropane;
Glycerin; pentaerythritol; sorbitol; 1,
Residues obtained by removing hydroxyl groups from polyhydric alcohols such as 2,3-trihydroxycyclohexane and 1,3,5-trihydroxycyclohexane can be mentioned.

When the carbon number of this aliphatic hydrocarbon exceeds 10, fluorocarbon
The compatibility with 134a decreases. The preferred carbon number of the aliphatic hydrocarbon is 2 to 6.

R ² in the general formula (I) is an alkylene group having 4 carbon atoms, and specific examples include an ethylethylene group; a 1,1-dimethylethylene group; a 1,2-dimethylethylene group; Group; 2-methylpropylene group; tetramethylene group. The alkylene group having 4 carbon atoms in one molecule may be the same, or may contain two or more types of alkylene groups.

N in the general formula (I) is an integer of ^{1 to} 6, and is determined according to the number of R ¹ binding sites. For example, when R ¹ is an alkyl group, n is 1, and R ¹ is a bonding site 2, 3, 4, 5, or 6
N is an aliphatic hydrocarbon group having
It will be 2,3,4,5 or 6.

Further, o and p are integers of 0 or more, q is an integer of 1 or more, and the average value of (o + p + q) × n is in the range of 4 to 40, preferably 6 to 30, and q / (o + p + q) is 0.1 or more, preferably 0.2 or more, and o / (o + p + q)
Is a number that satisfies the condition of 0.2 or less, preferably 0.1 or less.

If the average value of (o + p + q) × n is smaller than 4, sufficient lubricity cannot be obtained, and if it is larger than 40, sufficient compatibility cannot be obtained. Also, q / (o + p + q) is 0.
If it is less than 1, sufficient lubricity cannot be obtained. o / (o +
If (p + q) exceeds 0.2, sufficient electrical insulation cannot be obtained.

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

(A) Method: Ethylene oxide, propylene oxide and butylene oxide are reacted (polymerized) using a C1-C10 mono- to hexavalent alcohol or an alkali metal salt thereof as an initiator to obtain a compound represented by the general formula: (Wherein R ¹ , R ² , o, p and q are the same as above, and M is hydrogen or an alkali metal). After obtaining a polymer represented by the following formula, The desired polyoxyalkylene glycol derivative represented by the general formula (I) is obtained.

Method (b): Ethylene oxide, propylene oxide, and butylene oxide are reacted (polymerized) with water or an alkali hydroxide as an initiator to obtain a compound represented by the general formula: [Wherein R ² is the same as described above, r and s are each an integer of 0 or more, t is an integer of 1 or more, and the average of r + s + t is 4 to 40, and t (r + s + t) is 0.1 or more, r / (r + s +
t) is a number satisfying the condition of 0.2 or less, and M is hydrogen or an alkali metal. After obtaining a polymer represented by the formula, by etherifying both ends, the general formula Wherein R ⁴ is an alkyl group having 1 to 10 carbon atoms, and R ² and R
³ , r, s and t are the same as above. An oxyoxyalkylene glycol derivative represented by the following formula is obtained.

(C) Method: C 1-10 in the presence of an acid catalyst such as BF ₃ , SnCl ₄ , SbCl ₅
The polymerization of ethylene oxide, propyne oxide and a cyclic ether (particularly tetrahydrofuran) using a di- to hexahydric alcohol of the formula [Wherein R ¹ , R ² , o, p and r have the same meaning as described above. After obtaining a polymer represented by the following formula, the terminal is etherified to obtain a polyoxyalkylene glycol derivative represented by the general formula (I).

In these production methods, in order to etherify the hydroxyl group of a polyoxyalkylene glycol having a hydroxyl group at a terminal or a derivative thereof, this is usually converted into an alkali metal salt (such as a sodium salt), and then added to the alkali metal salt. A method of reacting an alkyl halide or a sulfate of 1 to 10 or a hydroxyl group of the polyoxyalkylene glycol or a derivative thereof is converted into a sulfonate or a halide, and then an aliphatic alcohol having 1 to 10 carbon atoms or A technique such as reaction of the alkali metal salt is employed.

The lubricating oil of the present invention contains the polyoxyalkylene glycol derivative represented by the general formula (I) thus obtained as a main component. The polyalkylene glycol derivative may be used alone. Or two or more types may be used in combination.

Further, the lubricating oil of the present invention desirably has a kinematic viscosity at 40 ° C. of 5 to 50 cSt, preferably 10 to 40 cSt in order to maintain an oil film thickness required for lubrication. Therefore, it is preferable to select a raw material, an initiator, and reaction conditions so as to produce a polyoxyalkylene glycol derivative having this viscosity range. However, the viscosity of the compound outside the above kinematic viscosity range may be adjusted within the kinematic viscosity range by mixing several kinds.

However, the polyoxyalkylene glycol derivative thus obtained has a volume resistivity at 80 ° C. of 1
Since it is less than × 10 ¹⁰ Ωcm, it may not be used as lubricating oil for an electric motor-integrated compression refrigerator because electric insulation may be insufficient and electric leakage may occur.

Therefore, in the present invention, it is necessary to use a polyoxyalkylene glycol derivative having a specific volume resistivity at 80 ° C. of 1 × 10 ¹⁰ Ωcm or more, preferably 2 × 10 ¹⁰ Ωcm or more. For that purpose, the crude polyoxyalkylene glycol derivative prepared by the above-mentioned method is purified by a suitable means so as to have a desired volume specific resistivity.

There are various methods for purifying such a crude polyoxyalkylene glycol derivative so that the volume resistivity at 80 ° C. is 1 × 10 ¹⁰ Ωcm or more. There are a method of bringing the glycol derivative into contact with the cation exchange resin and the anion exchange resin, and a method of washing the crude polyoxyalkylene glycol derivative with water purified by the cation exchange resin and the anion exchange resin.

Generally, a strong acid ion exchange resin having a sulfonic acid group and a weak acid ion exchange resin having a carboxyl group are known as cation exchange resins, and a strongly basic ion exchange resin having a quaternary ammonium group is known as an anion exchange resin. An ion exchange resin and a weakly basic ion exchange resin having an amino group are known. The combination of the cation exchange resin and the anion exchange resin used in the above method is preferably any combination of strong acid-strong basic, weak acid-weak basic or weak acid-strong basic. Strongly acidic ion exchange resins and strongly basic ion exchange resins have a high efficiency of improving electrical insulation, but have disadvantages such as a large amount of regenerating agent required for regeneration of the ion exchange resin. It is preferable to select a combination of ion exchange resins to be used in consideration of the electrical insulation properties of the oxyalkylene glycol derivative and regeneration of the ion exchange resin. Further, by taking a method of contacting the cation exchange resin with a weakly acidic ion exchange resin and then contacting the strongly acidic ion exchange resin, a weakly acidic ion exchange resin which can be easily regenerated can be used.
Similarly, as a method of contacting with an anion exchange resin, a method of contacting with a weakly basic ion exchange resin and then contacting with a strongly basic ion exchange resin can be used. However, it is difficult to obtain a desired effect with a weakly acidic-weakly basic combination of ion exchange resins. In many cases, the ion exchange resin is commercially available in the form of a salt, but the cation exchange resin can be converted to the H form and the anion exchange resin can be converted to the OH form by a known method.

In the above purification, the crude polyoxyalkylene glycol derivative may be brought into contact with the ion exchange resin as it is or dissolved in a solvent. The water-soluble polyoxyalkylene glycol derivative is usually used by dissolving it in water, but the poorly water-soluble polyoxyalkylene glycol derivative is used with an organic solvent compatible with water, such as methanol-water and acetone-water. It is preferable to use it by dissolving it in a mixture of water.

The amount of the ion exchange resin to be used is not particularly limited as long as the ion exchange amount of the ion exchange resin is larger than the ion amount contained in the target crude polyoxyalkylene glycol derivative. It is preferable to use an ion exchange resin corresponding to an ion exchange amount of 5 times or more of the ions contained in.

As a method for contacting the ion-exchange resin with the crude polyoxyalkylene glycol derivative, a batch method and a flow method can be used, but a flow method is preferable because the effect of improving electrical insulation is large.

When the polyoxyalkylene glycol derivative is catalyzed with the ion exchange resin, the contact may be made with the cation exchange resin and then with the anion exchange resin, or vice versa. Alternatively, the polyalkylene glycol derivative may be catalyzed in a state where the cation exchange resin and the anion exchange resin are mixed. Among them, the use in a mixed state is preferable because the effect of improving the electrical insulation is large. When the desired effect cannot be obtained by a single contact of the polyalkylene glycol derivative with the cation exchange resin and the anion exchange resin,
It is preferable to make contact twice or more.

The temperature at which the polyoxyalkylene glycol derivative is brought into contact with the ion exchange resin is not particularly limited as long as it is lower than the temperature at which the ion exchange resin decomposes. The effect of improvement can be enhanced.

The polyoxyalkylene glycol derivative that has been brought into contact with the ion exchange resin is heated under normal pressure or reduced pressure to remove the solvent and water.

Next, the case where the crude polyoxylalkylene glycol derivative is washed with purified water will be described. In the case of contacting with an ion exchange resin for purifying water, the contact may be made with a cation exchange resin and then with an anion exchange resin, or vice versa. Further, the cation exchange resin and the anion exchange resin may be contacted in a mixed state. Of these, the use of a mixed state is preferable because the effect of improving electrical insulation is large. Water purified in this way (pure water)
In order to wash the polyoxyalkylene glycol derivative by the method described above, it may be performed as it is or by adding a solvent. Here, examples of commonly used solvents include benzene, toluene, various xylenes, diethyl ether, chloroform, carbon tetrachloride and the like. The amount of pure water used for washing is generally 1 to the polyoxyalkylene glycol derivative.
It is about 20 times. When a desired effect cannot be obtained by one washing, it is desirable to perform two or more washings.

Further, the lubricating oil of the present invention has a kinematic viscosity at 40 ° C. of 5 to maintain the oil film thickness necessary for lubrication as described above.
It is desirable to be in the range of 50 cSt, preferably 10 to 40 cSt.

The lubricating oil of the present invention contains the purified polyoxyalkylene glycol derivative thus obtained as a main component. At this time, the polyoxyalkylene glycol derivative may be used alone or in combination of two or more. Furthermore, in order to improve the performance of other lubricating oils, they can be used in combination with these.

The lubricating oil of the present invention also includes various additives used in conventional lubricating oils, for example, load-bearing additives, chlorine scavengers, antioxidants, metal deactivators, defoamers, cleaning and dispersing agents. Agent, viscosity index improver, oil agent, anti-wear additive, extreme pressure agent,
Rust inhibitors, corrosion inhibitors, pour point depressants and the like can be added as desired.

Examples of the load-bearing additive include organic sulfur compounds such as monosulfides, polysulfides, sulfoxides, sulfones, thiosulfates, sulfurized fats and oils, thiocarbonates, thiophenes, thiazoles, and methanesulfonic acid esters. Series, phosphoric acid monoesters,
Phosphate esters such as phosphoric diesters and phosphoric triesters (tricresyl phosphate), and phosphites such as phosphite monoesters, phosphite diesters, and phosphite triesters Thiophosphates such as thiophosphate triesters, fatty acids such as high aliphatic acids and hydroxyaryl fatty acids, and fatty acids such as carboxylic acid-containing polyhydric alcohol esters and acrylates Organic compounds such as ester compounds, chlorinated hydrocarbons, chlorinated carboxylic acid derivatives, and other organic chlorine compounds, fluorinated aliphatic carboxylic acids, fluorinated ethylene resins, fluorinated alkylpolysiloxanes, and fluorinated graphite Alcohols, alcohols such as higher alcohols, naphthenates (lead naphthenate), fats Salts (fatty acid lead), thiophosphates salts (zinc dialkyldithiophosphate), thiocarbamates salts, organomolybdenum compounds, organotin compounds, organogermanium compounds, are those of the metal compound-based, such as boric acid ester.

Examples of the chlorine scavenger include glycidyl ether group-containing compounds, epoxidized fatty acid monoesters, epoxidized oils and fats, and epoxycycloalkyl group-containing compounds.
Examples of antioxidants include phenols (2,6-di-tert-butyl-p-cresol), aromatic amines (α-
Naphthylamine). Examples of the metal deactivator include a benzotriazole derivative. As antifoaming agents, silicone oil (dimethylpolysiloxane),
There are polymethacrylates and the like. Detergents include sulfonates, phenates, succinimides and the like. Examples of the viscosity index improver include polymethacrylate, polyisobutylene, an ethylene-propylene copolymer, and a styrene-diene hydrogenated copolymer.

〔Example〕

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Reference Example 1 (Preparation of H-type strongly acidic ion exchange resin) 200 ml of strongly acidic ion exchange resin (Diaion PK216 (Na type) manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) was packed in a glass column, and 3N hydrochloric acid aqueous solution was added. Exchange water 400ml, 2N saline 2
, 400 ml of ion-exchanged water were flowed in this order. In addition, 3
600 ml of N hydrochloric acid, 400 ml of ion-exchanged water, 600 ml of 2N saline, and 400 ml of ion-exchanged water were flowed twice in this order. Subsequently, 1000 ml of 3N aqueous hydrochloric acid and ion-exchanged water 2 were flowed in this order to obtain an H-type strongly acidic ion-exchange resin.

Reference Example 2 (Preparation of OH type strong basic ion exchange resin) Strong base anion exchange resin (manufactured by Mitsubishi Kasei Kogyo Co., Ltd.
200 ml of Diaion PA316 (Cl type) is packed in a glass column, 1N aqueous sodium hydroxide solution 4, ion-exchanged water
400ml, 1N ammonium sulfate aqueous solution 400ml, ion exchange water 40
0 ml, 3N aqueous hydrochloric acid, and 400 ml of ion-exchanged water were flowed in this order. Further, 600 ml of 1N sodium hydroxide aqueous solution, 400 ml of ion-exchanged water, 600 ml of 3N saline and 400 ml of ion-exchanged water were flowed twice in this order. Then, 1000 ml of a 1N aqueous solution of sodium hydroxide and hydrochloric acid and about 2 of ion-exchanged water were allowed to flow to obtain an OH-type strongly basic ion-exchange resin.

Reference Example 3 (Preparation of Mixed Type Ion Exchange Resin) 100 ml each of H type strong acid ion exchange resin and OH type strong basic ion exchange resin prepared by the operations of Reference Examples 1 and 2 were mixed and filled in a glass column. Thus, a mixed ion exchange resin was obtained.

Production Example 1 9.0 g of powdered sodium methoxide was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid inlet tube.
(0.17 mol) and toluene (50 g) were added and sealed, and the mixture was heated to 106 ° C., and 100 g of a mixture of propylene oxide and 1,2-epoxybutane (molar ratio: 1: 1) was stirred through a liquid introducing tube for 8 hours. It was pressed into an autoclave. After cooling the autoclave to room temperature, 34 g (0.24 mol) of methyl iodide was added while further cooling in ice water. The autoclave was gradually heated to 90 ° C. with stirring, and then reacted at 90 ° C. for 4 hours. Transfer the reaction mixture to a glass 300 ml flask,
After heating under reduced pressure to distill off excess methyl iodide and toluene, the precipitated sodium iodide was removed by centrifugation. After 100 ml of water and 200 ml of methanol were added to the solution to dissolve it, the solution was passed through a column of the cation exchange resin prepared in Reference Example 1 at a speed of about 20 ml / min.
Was passed through the column of the anion exchange resin prepared in the above at a speed of about 20 ml / min. Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column. This solution was passed twice through a column of the mixed ion exchange resin prepared in Reference Example 3 at a speed of about 20 ml / min.

After concentrating the obtained solution by a rotary evaporator, it was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.3 mmHg) to obtain 91 g of a target polyoxyalkylene glycol dimethyl ether. This compound had lost the infrared absorption spectrum (3450 cm ^-1 ) based on the hydroxyl group. The kinematic viscosity of this compound was 17.03 cSt (40 ° C), 4.23 cSt
(100 ° C.) and the viscosity index was 162. Further, the average molecular weight was 660. The average molecular weight was measured using GPC (gel permeation chromatography) (standard substance: polyethylene glycol). The average molecular weights of the following Production Examples and Reference Examples were measured in the same manner.

Production Example 2 11.7 g of powdery sodium methoxide was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid introduction tube.
(0.22 mol) and 30 g of toluene were added, and the mixture was sealed, heated to 106 ° C., and 130 g of a mixture of propylene oxide and 1,2-epoxybutane (molar ratio 1: 1) was added to the mixture through a liquid introduction tube at 11.5 g with stirring.
It was pressed into the autoclave over time. After cooling the autoclave to room temperature, 48 g (0.34 mol) of methyl iodide was added while further cooling in ice water. The autoclave was gradually heated to 90 ° C. with stirring, and then reacted at 90 ° C. for 4 hours. The reaction mixture was transferred to a 300-ml glass flask, heated under reduced pressure to remove excess methyl iodide and toluene, and then centrifuged to remove precipitated sodium iodide. After adding 100 ml of water and 200 ml of methanol to the solution and dissolving it, the solution was passed through a column of the cation exchange resin prepared in Reference Example 1 at a speed of about 20 ml / min. The column of the exchange resin was passed at a speed of about 20 ml / min. Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column. Also,
This solution was passed twice through a column of the mixed ion exchange resin prepared in Reference Example 3 at a speed of about 20 ml / min.

After the solution was concentrated by a rotary evaporator, the solution was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.2 mmHg) to obtain 115 g of a desired polyoxyalkylene glycol dimethyl ether. This compound had lost the infrared absorption spectrum (3450 cm ^-1 ) based on the hydroxyl group. The kinematic viscosity of this compound is 21.00 cSt (40 ° C), 4.94 cSt (100 ° C),
The viscosity index was 171 and the average molecular weight was 743.

Production Example 3 5.5 g of powdery sodium methoxide (0.5 g) was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid introduction tube.
10 mol) and 30 g of toluene, sealed, heated to 106 ° C, and autoclaved under stirring with 130 g of a mixture of propylene oxide and 1,2-epoxybutane (molar ratio 1: 1) from the liquid introduction tube for 11.5 hours. Press-fit. After cooling the autoclave to room temperature, 25 g (0.18 mol) of methyl iodide was added while further cooling in ice water. The autoclave was gradually heated to 90 ° C. with stirring, and then reacted at 90 ° C. for 4 hours. Transfer the reaction mixture to a glass 300 ml flask,
After heating under reduced pressure to distill off excess methyl iodide and toluene, the precipitated sodium iodide was removed by centrifugation. The solution was added with 200 ml of toluene, and washed five times with 500 ml of pure water. The pure water used at this time was passed through the cation exchange resin column prepared in Reference Example 1 at a rate of about 20 ml / min, and then passed through the anion exchange resin column prepared in Reference Example 2 at about 20 ml / min. After passing through the same column of a cation exchange resin and a column of an anion exchange resin, it was prepared in Reference Example 3. The mixture was passed through a mixed ion exchange resin column twice at a speed of about 20 ml / min.

After the solution was concentrated by a rotary evaporator, it was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.3 mmHg) to obtain 101 g of the desired polyoxyalkylene glycol dimethyl ether. This compound had lost the infrared absorption spectrum (3450 cm ^-1 ) based on the hydroxyl group. The kinematic viscosity of this compound is 46.62 cSt (40 ° C), 9.06 cSt (100 ° C),
The viscosity index was 180 and the average molecular weight was 1260.

Production Example 4 11.7 g of powdery sodium methoxide was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid introduction tube.
(0.22 mol) and toluene (50 g) were added, the mixture was sealed, heated to 106 ° C., and 130 g of 1,2-epoxybutane was injected into the autoclave via a liquid introduction tube for 10 hours with stirring. After cooling the autoclave to room temperature, 37 g (0.26 mol) of methyl iodide was added while further cooling in ice water. The autoclave was gradually heated to 90 ° C. with stirring, and then reacted at 90 ° C. for 4 hours. The reaction mixture was transferred to a 300-ml glass flask, heated under reduced pressure to remove excess methyl iodide and toluene, and then centrifuged to remove precipitated sodium iodide. After adding 100 ml of water and 200 ml of methanol to the solution and dissolving it, the solution was passed through a column of the cation exchange resin prepared in Reference Example 1 at a speed of about 20 ml / min. About 20 ml /
Minutes. Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column. This solution was passed twice through the mixed ion exchange resin column prepared in Reference Example 3 at a speed of about 20 ml / min.

After the solution was concentrated by a rotary evaporator, the solution was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.7 mmHg) to obtain 68 g of the desired polyoxybutylene glycol dimethyl ether. This compound had lost the infrared absorption spectrum (3450 cm ^-1 ) based on the hydroxyl group. The kinematic viscosity of this compound was 15.56 cSt (40 ° C.), 3.82 cSt (100 ° C.), the viscosity index was 142, and the average molecular weight was 581.

Production Example 5 14 g of powdered sodium methoxide (0.2 g) was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid introduction tube.
6 mol) and 30 g of toluene, sealed, heated to 106 ° C., and stirred with 130 g of 1,2-epoxybutane through a liquid inlet tube.
It was pressed into the autoclave over 0 hours. After cooling the autoclave to room temperature, 53 g (0.37 mol) of methyl iodide was added while further cooling in ice water. The autoclave was gradually heated to 90 ° C. with stirring, and then reacted at 90 ° C. for 4 hours. The reaction mixture was transferred to a 300-ml glass flask, heated under reduced pressure to remove excess methyl iodide and toluene, and then centrifuged to remove precipitated sodium iodide. After 100 ml of water and 200 ml of methanol were added to the solution to dissolve the solution, the solution was passed through a cation resin exchange column prepared in Reference Example 1 at a speed of about 20 ml / min. The resin was passed through an exchange column at a rate of about 20 ml / min. Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column. This solution was passed twice through the mixed ion exchange column prepared in Reference Example 3 at a speed of about 20 ml / min.

The solution is concentrated by a rotary evaporator, and heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.3 mmHg) to obtain a desired polyoxybutylene glycol dimethyl ether.
125 g were obtained. This compound had lost the infrared spectrum (3450 cm ^-1 ) based on the hydroxyl group. The kinematic viscosity of this compound was 28.28 cSt (40 ° C.), 5.18 cSt (100 ° C.), the viscosity index was 114, and the average molecular weight was 657.

Production Example 6 Methanol (6.4 g, 0.2 mol), tetrahydrofuran (32.4 g, 0.45 mol) and boron trifluoride-diethyl ether complex 0.9 g (6.3 mmol) were added to a 300 ml stainless steel autoclave equipped with a stirrer and a liquid inlet tube. Heated to 35-45 ° C and stirred with propylene oxide
78.3 g (1.35 mol) was injected through a liquid introduction tube over 7 hours, and the mixture was further aged at 30 to 35 ° C. for 5 hours. The reaction mixture was transferred to a glass 300 ml flask, heated under reduced pressure to remove unreacted tetrahydrofuran and propylene oxide, and then a 5% aqueous sodium carbonate solution was added. After removing water, 150 ml of toluene was added and the solid was filtered. The filtrate was transferred to a glass 500 ml flask, and 77 g (0.4 mol) of a 28% by weight sodium methoxide methanol solution was added.
Upon heating, methanol and toluene were distilled off. The reaction product was transferred to a 200 ml stainless steel autoclave, and 68 g (0.48 mol) of methyl iodide was added while cooling with ice water. The autoclave was gradually heated to 90 ° C. with stirring, and then reacted at 90 ° C. for 4 hours.

The reaction mixture was transferred to a 300 ml glass flask, and heated under reduced pressure to remove excess methyl iodide, and then centrifuged to remove precipitated sodium iodide. Liquid to water 10
After 0 ml and 200 ml of methanol were added and dissolved, the solution was passed through the column of the cation exchange resin prepared in Reference Example 1 at a speed of about 20 ml / min. The column was passed through at a rate of about 20 ml / min.
Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column. This solution was passed twice through a column of the mixed ion exchange resin prepared in Reference Example 3 at a speed of about 20 ml / min.

After the solution was concentrated by a rotary evaporator, it was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.3 mmHg) to obtain 103 g of the desired polyoxyalkylene glycol dimethyl ether. This compound had lost the infrared spectrum (3450 cm ^-1 ) based on the hydroxyl group. The kinematic viscosity of this compound was 21.01 cSt (40 ° C.), 4.82 cSt (100 ° C.), the viscosity index was 159, and the average molecular weight was 701.

Reference Example 4 4.8 g of powdery sodium methoxide (0. 0 g) was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid introduction tube.
(088 mol) and 30 g of toluene, the mixture was sealed, heated to 106 ° C., and 100 g of propion oxide was injected into the autoclave from the liquid introduction tube for 8 hours with stirring. After cooling the autoclave to room temperature, 15 g (0.11 mol) of methyl iodide was added while further cooling in ice water. The autoclave was gradually heated to 90 ° C. with stirring, and then reacted at 90 ° C. for 4 hours. The reaction mixture was transferred to a 300-ml glass flask, heated under reduced pressure to remove excess methyl iodide and toluene, and then centrifuged to remove precipitated sodium iodide. After adding 100 ml of water and 200 ml of methanol to the solution and dissolving it, the solution was passed through a column of the cation exchange resin prepared in Reference Example 1 at a speed of about 20 ml / min. The column of the exchange resin was passed at a speed of about 20 ml / min. Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column.

This solution was passed twice through a column of the mixed ion exchange resin prepared in Reference Example 3 at a speed of about 20 ml / min.

After the solution was concentrated by a rotary evaporator, it was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.3 mmHg) to obtain 96 g of polyoxybutylene glycol dimethyl ether. This compound had lost the infrared absorption spectrum (3450 cm ^-1 ) associated with the hydroxyl group. The kinematic viscosity of this compound is 22.64 cSt (40 ° C.), 6.37 cSt (100 ° C.), and the viscosity index is 260
And the average molecular weight was 849. .

REFERENCE EXAMPLE 5 4.0 g of powdered sodium methoxide (0.3 g) was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid inlet tube.
(074 mol) and 30 g of toluene were sealed, heated to 106 ° C., and 100 g of propion oxide was injected into the autoclave via a liquid introduction tube for 8 hours with stirring. After cooling the autoclave to room temperature, 13 g (0.092 mol) of methyl iodide was added while further cooling in ice water. The autoclave was gradually heated to 90 ° C. with stirring, and then reacted at 90 ° C. for 4 hours. The reaction mixture was transferred to a 300-ml glass flask, heated under reduced pressure to remove excess methyl iodide and toluene, and then centrifuged to remove precipitated sodium iodide. After adding 100 ml of water and 200 ml of methanol to the solution and dissolving it, the solution was passed through a column of the cation exchange resin prepared in Reference Example 1 at a speed of about 20 ml / min. The column of the exchange resin was passed at a speed of about 20 ml / min. Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column. This solution was passed twice through a column of the mixed ion exchange resin prepared in Reference Example 3 at a speed of about 20 ml / min.

After the solution was concentrated by a rotary evaporator, it was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.3 mmHg) to obtain 93 g of polyoxypropylene glycol dimethyl ether. This compound had lost the infrared absorption spectrum (3450 cm ^-1 ) based on the hydroxyl group. The kinematic viscosity of this compound was 33.09 cSt (40 ° C.), 7.68 cSt (100 ° C.), and the viscosity index was 213.
And the average molecular weight was 1095.

Reference Example 6 Unilube MB-11 (polyoxypropylene glycol monobutyl ether, average molecular weight 10
00) 100 g was dehydrated by heating at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.4 mmHg).

Reference Example 7 6.2 g (0.083 mol) of n-butanol was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid inlet tube.
72 g (1 mol) of tetrahydrofuran and 0.9 g (6.3 mmol) of boron trifluoride-diethyl ether complex are added, and the mixture is heated to 35 to 45 ° C., and stirred with 44 g of ethyleoxide.
(1 mol) from the liquid introduction tube over 7 hours.
Aged at 30-35 ° C for 5 hours. 300 ml of reaction mixture made of glass
After transferring to a flask and heating under reduced pressure to remove unreacted tetrahydrofuran and ethylene oxide, a 5% aqueous sodium carbonate solution was added. After removing water, 150 ml of toluene was added and the solid was filtered. After 100 ml of water and 200 ml of methanol were added to the filtrate to dissolve the solution, the solution was passed through a column of the cation exchange resin prepared in Reference Example 1 at a speed of about 20 ml / min. The column of the exchange resin was passed at a speed of about 20 ml / min. Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column. This solution was passed twice through a column of the mixed ion exchange resin prepared in Reference Example 3 at a speed of about 20 ml / min. After the solution was concentrated by a rotary evaporator, it was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.3 mmHg) to obtain 103 g of the desired polyoxyalkylene glycol monobutyl ether. The kinematic viscosity of this compound is 168.0c
St (40 ° C) 31.44 cSt (100 ° C), viscosity index is 231,
The average molecular weight was 2530.

Reference Example 8 100 g of polyoxyalkylene glycol was obtained in the same manner as in Production Example 3 except that washing with pure water was performed twice.
The kinematic viscosity of this compound is 45.25 cSt (40 ° C), 8.95 (100
° C), the viscosity index was 183 and the average molecular weight was 1245.

REFERENCE EXAMPLE 9 4.0 g of powdered sodium methoxide (0.3 g) was placed in a 300 ml stainless steel autoclave equipped with a stirrer and a liquid introduction tube.
(074 mol) and 30 g of toluene, sealed, heated to 106 ° C., and 100 g of a mixture of propion oxide and 1,2-epoxybutane (99: 1) was injected into the autoclave via a liquid introduction tube for 8 hours with stirring. did. After cooling the autoclave to room temperature, it is further cooled in ice water while adding methyl iodide.
13 g (0.092 mol) were added. Autoclave with stirring
After gradually heating to 90 ° C., the reaction was carried out at 90 ° C. for 4 hours.
The reaction mixture was transferred to a glass 300 ml flask and heated under reduced pressure to remove excess methyl iodide and toluene.
The precipitated sodium iodide was removed by centrifugation.
After adding 100 ml of water and 200 ml of methanol to the solution and dissolving it, the solution was washed with a column of the cation exchange resin prepared in Reference Example 1.
The solution was passed through the column of the anion exchange resin prepared in Reference Example 2 at a speed of about 20 ml / min. Further, the mixture was passed through the same cation exchange resin column and anion exchange resin column. This solution was used in Reference Example 3
The mixture was passed through the column of the mixed ion exchange resin prepared in step 2 twice at a speed of about 20 ml / min.

After the solution was concentrated by a rotary evaporator, it was heated at 100 ° C. for 1 hour under reduced pressure of a vacuum pump (0.3 mmHg) to obtain 94 g of polyoxyalkylene glycol dimethyl ether. This compound had lost the infrared absorption spectrum (3450 cm ^-1 ) based on the hydroxyl group. The kinematic viscosity of this compound is 22.53 cSt (40 ° C.), 5.21 cSt (100 ° C.), and the viscosity index is 174.
And the average molecular weight was 803.

Examples 1 to 4 The compatibility of the polyoxyalkylene glycols obtained in Production Examples 1, 3, 4, and 6 was measured.

The measurement of the compatibility was performed as follows. That is, a predetermined amount of a sample is added to a pressure-resistant glass ampoule so as to be 10% by weight and 20% by weight with respect to Freon 134a (1,1,1,2-tetrafluoroethane), and this is added to a vacuum pipe and Freon 134a.
The ampule was connected to a gas pipe, degassed at room temperature under vacuum, cooled with liquid nitrogen, and a predetermined amount of Freon 134a was collected. Next, the ampoule was sealed, the temperature was raised from -40 ° C in a thermostat, and the temperature at which phase separation started was measured. The higher the phase separation temperature,
It is preferable as a lubricating oil for refrigerators. First result
It is shown in the table.

Examples 5 to 9 and Comparative Examples 1 to 3 The specific volume resistivity of the compounds obtained in Production Examples 1, 3, 4, 5, 6 and Reference Examples 6, 7, 8 was measured by the following procedure. First, the sample was dried under reduced pressure (0.3-0.8 mmHg) at 100 ° C for 1 hour,
The sample was placed in a liquid cell for measuring the volume resistivity in a thermostat at 80 ° C. After the sample was kept in a constant temperature bath at 80 ° C. for 40 minutes, the measurement was performed at an applied voltage of 250 V using a super insulation meter (manufactured by Yokogawa Hewlett Packard KK, type 4329A). Further, the water content immediately after the measurement was measured by a Karl Fischer moisture meter. The results are shown in Table 2.

Examples 10 to 14 and Comparative Examples 4 to 6 In order to evaluate the lubricity of the compounds obtained in Production Examples 2, 3, 5, 6 and Reference Examples 4, 5, and 9, a Falex wear resistance test was performed. The block was AISI1137 steel and the pin was SAE3135 steel, and the amount of wear after one hour at a load of 300 pounds and a pin rotation speed of 600 rpm was measured. The results are shown in Table 3.

Examples 15 to 17 and Comparative Examples 7, 8 The hygroscopicity of the compounds obtained in Production Examples 1, 4, 6 and Reference Examples 4, 6 was measured by the following procedure. First, a 30 g sample is weighed 36 m
m, 76 mm deep in a glass container. Further, a stirrer was put therein, and put in a thermo-hygrostat kept at a temperature of 25 ° C. and a relative humidity of 75% to absorb moisture. After a lapse of a predetermined time, the sample was taken out of the thermo-hygrostat, capped and stirred for 5 minutes, and then the water content was measured by a Karl Fischer water content measuring device (model CAO2, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.). The results are shown in Table 4.

[Effect of the Invention] The lubricating oil of the present invention has good compatibility with a hydrogen-containing Freon refrigerant such as Freon 134a, and has excellent lubricity and electrical insulation properties, and is used in electric motors such as electric refrigerators and electric freezers. It is suitably used as a lubricating oil for an integral compression refrigerator.

The lubricating oil of the present invention has good water solubility with a hydrogen-containing Freon refrigerant as described above. Here, as the hydrogen-containing Freon, other than Freon 134a, 1,1-dichloro 2,2,2
-Trifluoroethane (Freon 123); 1-chloro-1,1-
Difluoroethane (CFC 142b); 1,1-difluoroethane (CFC 152a); chlorodifluoromethane (CFC2
2) Or trifluoromethane (CFC23).

Further, the lubricating oil of the present invention can be used by being mixed with other lubricating oils for compression refrigeration machines for the purpose of improving the compatibility with the refrigerant or the electric insulation.

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) C10M 107/34 C10M 105/18 C10N 20:00 C10N 40:30 C10N 60:00 C09K 5/04 CA (STN ) WPI / L (QUESTEL)

Claims (3)

(57) [Claims] (1) General formula Wherein R ¹ is an alkyl group having 1 to 10 carbon atoms or an aliphatic hydrocarbon group having 1 to 10 carbon atoms having bonding sites 2 to 6, R ² is an alkylene group having 4 carbon atoms, and R ³ is a carbon atom An alkyl group of 1 to 10, n is an integer of 1 to 6, o and p are each an integer of 0 or more,
q is an integer of 1 or more, and the average value of (o + p + q) × n is 4 to 40, q / (o + p + q) is 0.1 or more, and o / (o + p
+ Q) is a number that satisfies the condition of 0.2 or less. And the volume resistivity at 80 ° C. is 1 × 10
Lubricating oil for motor-integrated compression refrigerators containing a polyoxyalkylene glycol derivative purified to ¹⁰ Ωcm or more 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. 3. In the general formula (I), R ² represents an ethylethylene group; a 1,1-dimethylethylene group; a 1,2-dimethylethylene group; a 1-methylpropylene group; a 2-methylpropylene group or a tetramethylene group. The lubricating oil for an electric motor-integrated compression refrigerator according to claim 1 or 2, wherein