JP2000087060A - Polyether-based lubricating base oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve anti-oxidation stability and heat stability of a base oil by making the base oil contain a specific polyether-based lubricating base oil and a phenol-based or amine-based antioxidant. SOLUTION: A base oil is obtained by mixing 0.01-5 wt.%, preferably 0.05-3 wt.% of a phenol-based or amine-based antioxidant with a specific polyether- based lubricating base oil represented by the formula having 15-200 cSt, preferably 20-150 cSt, an unsaturation degree of not more than 0.05 meq/g, preferably not more than 0.04 meq/g, a peroxide value of not more than 10.0 meq/kg, preferably not more than 5 meq/kg and a carbonyl value of not more than 100 weight ppm, preferably not more than 50 weight ppm, where, in the formula, X is a mono-ol or a residual group obtained by removing hydroxy groups from a polyol, (AO)n is a polyoxyalkylene obtained by polymerization of an alkyleneoxide having not less than 3 carbon atoms or copolymerization of ethylene oxide and an alkyleneoxide having not less than 3 carbon atoms, R is H or a 1-4C alkyl and (n) is not less than 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polyether-based lubricating base oil.

[0002]

2. Description of the Related Art Ordinary lubricating oils consist of a lubricating base oil and additives. Lubricating base oils require several functions besides lubricity. Recently, the base oil itself of lubricating oil has been improved in function, but as functions that are particularly demanded, long life, especially high temperature and long life, which is resistant to deterioration even at high temperatures, low temperature startup, oxidation stability And the like.

As one of synthetic lubricating base oils, there is polyether (polyalkylene glycol). Polyether derivatives have high viscosity index, low pour point, do not generate sludge and varnish, have excellent shear stability, have low corrosiveness and permeability to metals and resins, and have excellent load resistance. It is used as a hydraulic oil or metal working oil because of its excellent characteristics.

[0004]

However, polyether derivatives have a disadvantage that they are basically inferior in oxidation stability and heat stability. Accordingly, an object of the present invention is to provide a polyether-based lubricating base oil having excellent oxidation stability and heat stability.

[0005]

Accordingly, the present inventors have conducted intensive studies and have developed a polyether-based lubricating base oil having excellent oxidation stability. That is, the present invention provides the following general formula (1)

X ｛-O- (AO) _n -R｝ _p (1) wherein X represents a residue obtained by removing a hydroxyl group from a monool or a polyol, and (AO) _n represents a group having 3 or more carbon atoms. Represents a polyoxyalkylene group formed by polymerization of alkylene oxide or copolymerization of ethylene oxide and alkylene oxide having 3 or more carbon atoms, R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n represents 2 or more. And p represents the valence of X. A lubricating base oil having a degree of unsaturation of 0.05 meq / g or less, a peroxide value of 10.0 meq / kg or less, and a carbonyl value of 100 ppm by weight or less. And a lubricating composition containing the same and an antioxidant.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The lubricating base oil of the present invention comprises a polyether represented by the following general formula (1):

X ｛—O— (AO) _n —R｝ _p (1) In the general formula (1), X represents a residue obtained by removing a hydroxyl group from a monool or a polyol. As the monol, for example, methanol, ethanol, propanol,
2-propanol, butanol, 2-butanol, pentanol, 2-pentanol, 3-pentanol, isopentyl alcohol, 2-methyl-4-pentanol,
Hexanol, secondary hexanol, isohexanol,
Heptanol, secondary heptanol, octanol, 2-
Ethylhexanol, secondary octanol, isooctanol, nonanol, secondary nonanol, 1-decanol,
Isodecyl alcohol, secondary decanol, undecanol, secondary undecanol, 2-methyldecanol, lauryl alcohol, secondary dodecanol, 1-tridecanol, isotridecyl alcohol, secondary tridecanol,
Myristyl alcohol, secondary tetradecanol, pentadecanol, secondary pentadecanol, cetyl alcohol, palmityl alcohol, secondary hexadecanol, heptadecanol, secondary heptadecanol, stearyl alcohol, isostearyl alcohol, Octadecyl alcohol, oleyl alcohol, behenyl alcohol, eicosanol, docosanol, tetracosanol, hexacosanol, octacosanol, myristyl alcohol, rasserol, tetratriacontanol,
Allyl alcohol, cyclopentanol, cyclohexanol, 2-butyl octanol, 2-butyl decanol, 2-hexyl octanol, 2-hexyl decanol, 2-hexyl decanol, 2-octyl decanol, 2-octyl dodecanol, 2- Octyltetradecanol, 2-decyldodecanol, 2-decyltetradecanol, 2-decylhexadecanol, 2-dodecyltetradecanol, 2-dodecylhexadecanol,
Alcohols such as 2-dodecyloctadecanol, 2-tetradecyloctadecanol, 2-tetradecylicosanol, 2-hexadecyloctadecanol and 2-hexadecylicosanol; phenol, cresol, ethylphenol, and tersha Rubutylphenol, hexylphenol, octylphenol, nonylphenol,
Phenols such as decylphenol, undecylphenol, dodecylphenol, tridecylphenol, tetradecylphenol, phenylphenol, benzylphenol, styrenated phenol, p-cumylphenol and the like can be mentioned.

Examples of the polyol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,2-butanediol, neopentyl glycol, 1,6-hexanediol, 1,2-octanediol, and 1,8-octanediol. Octanediol, isoprene glycol, 3-methyl-1,5-pentanediol, sorbite, catechol, resorcin, hydroquinone, bisphenol A, bisphenol F, hydrogenated bisphenol A,
Diols such as hydrogenated bisphenol F and dimer diol; glycerin, trioxyisobutane, 1,2,3-
Butanetriol, 1,2,3-pentanetriol,
2-methyl-1,2,3-propanetriol, 2-methyl-2,3,4-butanetriol, 2-ethyl-
1,2,3-butanetriol, 2,3,4-pentanetriol, 2,3,4-hexanetriol, 4-propyl-3,4,5-heptanetriol, 2,4-dimethyl-2,3 Trihydric alcohols such as 4-pentanetriol, pentamethylglycerin, pentaglycerin, 1,2,4-butanetriol, 1,2,4-pentanetriol, trimethylolethane and trimethylolpropane; pentaerythritol, erythritol,
2,3,4-pentane tetrol, 2,3,4,5-hexane tetrol, 1,2,4,5-pentane tetrol, 1,3,4,5-hexane tetrol, diglycerin, sorbitan Pentahydric alcohols such as adonitol, arabitol, xylitol and triglycerin; hexahydric alcohols such as dipentaerythritol, sorbitol, mannitol, iditol, inositol, darcitol, talose and allose; Examples thereof include polyglycerin and dehydration condensates thereof. p is a valence of X, and a number of 1 to 8 is preferable.

X may be a residue of a compound derived from the above monol or polyol. Examples of such a compound include sodium alcoholate and potassium alcoholate of the above-mentioned monol or polyol.

Of these, if the valence p of X is too large, the molecular weight of the obtained polyether becomes too large, and the viscosity becomes too high for use as a lubricating base oil. Is preferably 1 to 3. In particular, X
Has preferably 1 to 8 carbon atoms, more preferably 1
~ 4. Preferred as monol or polyol are methanol, ethanol, propanol, 2-
Propanol, n-butanol, 2-butanol, ethylene glycol, propylene glycol, bisphenol A, glycerin and the like.

R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R is preferably a hydrogen atom or a methyl group.

(AO) _n represents an alkylene oxide having 3 or more carbon atoms or a polyoxyalkylene group formed by polymerization of ethylene oxide and an alkylene oxide having 3 or more carbon atoms. Examples of the alkylene oxide having 3 or more carbon atoms include propylene oxide, butylene oxide, α-olefin oxide, styrene oxide and the like. As the alkylene oxide having 3 or more carbon atoms, propylene oxide is most preferable.

When (AO) _n is constituted by copolymerization of two or more alkylene oxides, the form of copolymerization may be block polymerization, random polymerization or a mixture of block polymerization and random polymerization. If (AO) _{n is} a polyoxyalkylene chain composed entirely of block polymerization, the fluidity may be deteriorated. Therefore, (AO) _n is a polyoxyalkylene chain composed of random polymerization or It is preferable that the polyoxyalkylene chain partially includes a random polymerization. n represents a number of 2 or more, preferably 2 to 300, and more preferably 5 to 200.

The polyether represented by the general formula (1) used in the present invention must have a degree of unsaturation of 0.05 meq / g or less. Further, it is preferably at most 0.04 meq / g, more preferably at most 0.03 meq / g, most preferably at most 0.02 meq / g. This is because when producing a polyether represented by the general formula (1) containing an oxyalkylene group having 3 or more carbon atoms, such as an oxypropylene group, represented by the general formula (1), propylene oxide causes a side reaction to form an allyl group. In some cases, when an allyl group is formed, the thermal stability of the lubricant itself is reduced. In addition, it forms a polymer and causes sludge, and is liable to be oxidized, thereby generating peroxide. When the peroxide is generated, it is decomposed to generate a carbonyl group, which reacts with the lubricating oil additive and the metal surface to cause deterioration and rust.

The peroxide value is preferably 10.0 meq / kg or less, more preferably 5.0 meq / kg or less, most preferably 1.0 meq / kg. The carbonyl value is preferably 100 ppm by weight or less, more preferably 50 ppm by weight or less, and most preferably 20 ppm by weight or less.

In order to produce the polyether represented by the general formula (1) having a low degree of unsaturation, the reaction temperature at the time of reacting propylene oxide is preferably 120 ° C. or lower, more preferably 110 ° C. It is better to do the following. If an alkaline catalyst is used in the production, if an inorganic adsorbent such as activated carbon, activated clay, bentonite, dolomite, or aluminosilicate is used to remove the catalyst, the degree of unsaturation should be reduced. Can be. Further, when producing or using the lubricant of the present invention, contact with oxygen as much as possible or use of an antioxidant together can also prevent an increase in peroxide value or carbonyl value. In addition, it is also effective to distill low-molecular-weight allyl compounds by performing steam distillation under reduced pressure or the like.

The degree of unsaturation, peroxide value and carbonyl value are values measured by a standard fat and oil analysis test method established by the Japan Oil Chemists' Society.

Although the molecular weight of the polyether represented by the general formula (1) used in the present invention is not particularly limited, the molecular weight and the viscosity tend to be proportional. , Molecular weight 300-3.0
About 00 is preferable.

The kinematic viscosity of the polyether represented by the general formula (1) used in the present invention is not particularly limited. However, if the viscosity is too low, the sealing property is poor and the lubricating performance may be reduced. , The energy efficiency becomes worse. Therefore, the kinematic viscosity at 40 ° C. is preferably 15 to
200 cSt, more preferably 20 to 150 cSt.

When the polyether represented by the general formula (1) used in the present invention wherein R is an alkyl group having 1 to 4 carbon atoms, a compound containing chlorine such as methyl chloride is used as a starting material. However, since chlorine erodes the metal surface, the smaller the chlorine content, the better.
It is preferably at most 00 ppm, more preferably at most 50 ppm.

The method for producing the polyether represented by the general formula (1) used in the present invention is not particularly limited, and may be a conventional method for producing a polyether. For example, an alkylene oxide having 3 or more carbon atoms (eg, propylene oxide) or a mixed alkylene oxide mixed with ethylene oxide is added to an alcohol such as methanol as a starting material in the presence of an alkali catalyst such as sodium hydroxide or potassium hydroxide. 100-150 ° C, pressure 0-10kg
/ Cm ² .

The lubricating base oil of the present invention can be used as a lubricating base oil or a grease base oil. The lubricating base oil of the present invention can be used by mixing with another lubricating base oil. Other lubricating base oils include, for example, mineral oil, poly-α-olefin, polyisobutylene (polybutene), diester, polyol ester, hindered ester, phosphate ester, silicate ester, polyalkylene glycol, polyphenyl ether, silicone Fluorinated compounds, alkylbenzenes and the like.

The mixing ratio of the lubricating base oil of the present invention to these other lubricating base oils is not particularly limited. However, in order to take advantage of the characteristics of the lubricating base oil of the present invention, other lubricating base oils may be used. Is preferably used at not more than 80% by weight.

When the lubricating base oil of the present invention is used in combination with a phenol-based or amine-based antioxidant, it is possible to exhibit oxidative stability over a long period of time. As the phenolic antioxidant, a hindered phenolic antioxidant having a tertiary butyl group or a tertiary pentyl group in the molecule is particularly preferable. For example, 2,6-di-ter
t-butylphenol, 2,6-di-tert.-butyl-p-cresol, 2,6-di-tert.-butyl-4-methylphenol, 2,6-di-tert.-butyl-4-ethyl Phenol, 2,4-dimethyl-6-
tert.-butylphenol, 4,4′-methylenebis (2,6-di-tert.-butylphenol),
4,4'-bis (2,6-di-tert.-butylphenol), 4,4'-bis (2-methyl-6-ter
-butylphenol), 2,2'-methylenebis (4-methyl-6-tert.-butylphenol),
2,2'-methylenebis (4-ethyl-6-tert.
-Butylphenol), 4,4′-butylidenebis (3
-Methyl-6-tert.-butylphenol), 4,
4'-isopropylidenebis (2,6-di-tert.
-Butylphenol), 2,2'-methylenebis (4-
Methyl-6-cyclohexylphenol), 2,2′-
Methylene bis (4-methyl-6-nonylphenol),
2,2′-isobutylidenebis (4,6-dimethylphenol), 2,6-bis (2′-hydroxy-3′-t
tert.-butyl-5'-methylbenzyl) 4-methylphenol, 3-tert.-butyl-4-hydroxyanisole, 2-tert.-butyl-4-hydroxyanisole, 4,4'-thiobis (3-methyl -6-t
ert. -Butylphenol), 4,4′-thiobis (2-methyl-6-tert.-butylphenol),
2,2′-thiobis (4-methyl-6-tert.-butylphenol), 2,6-di-tert. -Butyl-
α-dimethylamino-p-cresol, 2,6-di-t
ert. -Butyl-4 (N, N'-dimethylaminomethylphenol), bis (3,5-di-tert.-butyl-4-hydroxybenzyl) sulfide, tris {(3,5-di-tert.-butyl) 4-hydroxyphenyl) propionyl-oxyethyl diisocyanurate, tris (3,5-di-tert.-butyl-4-)
(Hydroxyphenyl) isocyanurate, 1,3,5-
Tris (3 ′, 5′-di-tert.-butyl-butyl-4-hydroxybenzoyl) isocyanurate, bis {2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert. -Butylphenyl disulfide, 1,3,5-tris (4-di-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetraphthaloyl-di (2,6-dimethyl-4) -Tert.-butyl-3-hydroxybenzylsulfide), 6- (4-hydroxy-3,5-di-tert.-butylanilino) -2,4-bis (octylthio) -1,3,5-triazine, , 2-thio-
{Diethyl-bis-3- (3,5-di-tert.-butyl-4-hydroxyphenyl)} propionate,
N, N'-hexamethylenebis (3,5-di-ter
t. -Butyl-4-hydroxy-hydrocinamide),
3,5-di-tert. -Butyl-4-hydroxy-benzyl-phosphoric acid diester, bis (3-methyl-4-hydroxy-5-tert.-butylbenzyl) sulfide, bisphenol A, alkylated bisphenol A, polyalkylated bisphenol A, etc.

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image

Embedded image (In the formula, Me represents a methyl group, t-Bu is ter
t. Represents a -butyl group, R represents a monovalent hydrocarbon group, and R 'represents a divalent hydrocarbon group. ) And the like.

As the amine-based antioxidant, an aromatic amine-based antioxidant is particularly preferred. For example, naphthylamine antioxidants such as 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine and phenyl-2-naphthylamine Agent; N, N'-diisopropyl-
p-phenylenediamine, N, N'-diisobutyl-p
-Phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N, N'-di-β-naphthyl-p-
Phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-cyclohexyl-
N'-phenyl-p-phenylenediamine, N-1,3
Phenylenediamine antioxidants such as -dimethylbutyl-N'-phenyl-p-phenylenediamine, dioctyl-p-phenylenediamine, phenylhexyl-p-phenylenediamine, phenyloctyl-p-phenylenediamine; dipyridylamine, diphenylamine,
p, p'-di-n-butyldiphenylamine, p, p '
-Di-tert. -Butyldiphenylamine, p, p '
-Di-tert. -Pentyldiphenylamine, p,
p'-dinonyldiphenylamine, p, p'-didecyldiphenylamine, p, p'-didodecyldiphenylamine, p, p'-distyryldiphenylamine, p,
Examples thereof include diphenylamine-based antioxidants such as p′-dimethoxydiphenylamine, 4,4′-bis (4-α, α-dimethylbenzoyl) diphenylamine, and p-isopropoxydiphenylamine.

The amount of these phenolic or amine-based antioxidants to be added is not particularly limited. However, if the amount is too small, the antioxidant effect is not sufficient, and if the amount is too large, there is no effect corresponding to the added amount and there is a technical meaning. , Preferably 0.01 to 5% by weight, more preferably 0.05 to 3% by weight, based on the lubricating base oil of the present invention.

The lubricating base oil of the present invention can be used in combination with other lubricating oil additives as required. Representative lubricating oil additives include oil agents, friction modifiers, extreme pressure agents, other antioxidants, detergents, dispersants, viscosity index improvers, defoamers, rust inhibitors, pour point depressants And the like.

Examples of the oily agent include fatty acids such as capric acid, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid, linoleic acid and linolenic acid, lauryl alcohol, myristyl alcohol , Palmityl alcohol, stearyl alcohol, alcohols such as oleyl alcohol, laurylamine, myristylamine, palmitylamine, stearylamine, amines such as oleylamine,
Examples include amides such as laurylamide, myristylamide, palmitylamide, stearylamine, and oleylamine.

As the friction modifier, for example, capric acid (mono, di, tri) glyceride, caproic acid (mono,
Di, tri) glyceride, caprylic acid (mono, di, tri)
Glyceride, lauric acid (mono, di, tri) glyceride, myristic acid (mono, di, tri) glyceride, palmitic acid (mono, di, tri) glyceride, stearic acid (mono, di, tri) glyceride, oleic acid (mono) ,
Esters such as di- and tri-glycerides; metal salts such as oxymolybdenum dialkyl dithiocarbamate and oxymolybdenum dialkyl dithiophosphate; polyol ethers such as glycerin monooleyl ether; and polyethers.

Examples of extreme pressure agents include sulfurized olefins,
Sulfurized paraffin, Sulfurized polyolefin, Sulfurized lard, Sulfurized fish oil, Sulfurized whale oil, Sulfurized soybean oil, Sulfurized pinene oil, Sulfurized phenol, Sulfurized alkylphenol, Sulfurized fatty acid, Dialkyl polysulfide, Dibenzyl disulfide, Diphenyl disulfide, Polyphenylene sulfide, Alkyl mercaptan, Alkylsulfone Acid, dithiocarbamate, 1,3,4-thiadiazole derivative,
Thiuram disulfide, butyl (thio, dithio) phosphate, hexyl (thio, dithio) phosphate, octyl (thio, dithio) phosphate, 2-ethylhexyl (thio, dithio) phosphate, nonyl (thio, dithio) phosphate, decyl (thio, dithio) ) Phosphate, lauryl (thio, dithio) phosphate, myristyl (thio, dithio) phosphate, palmityl (thio,
Dithio) phosphate, stearyl (thio, dithio) phosphate, oleyl (thio, dithio) phosphate,
(Thio, dithio) phosphates such as phenyl (thio, dithio) phosphate and cresyl (thio, dithio) phosphate.

Examples of the sulfur-based antioxidant include dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl thiodipropionate, and distearyl- β, β′-thiodibutyrate, 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, 2-benzimidazole disulfide, dilauryl sulfide, amylthioglycolate and the like.

Examples of the phosphorus-based antioxidant include triphenyl phosphite, trinonyl phenyl phosphite, triisodecyl phosphite, diphenyl isodecyl phosphite, phenyl diisotridecyl phosphite, trioctadecyl phosphite, and tridecyl phosphite. Phyte, diphenylnonylphenylphosphite, trilauryltrithiophosphite, tris (cyclohexylphenyl) phosphite, bis (2-ethylhexyl) phosphite, diisodecylpentaerythritol diphosphite, distearylpentaerythritol diphosphite, tetraphenyldipropylene Glycol diphosphite and the like.

Examples of the metal salt system include nickel dithiocarbamate, zinc-2-mercaptobenzimidazole and the like.

Examples of the detergent include calcium sulfonate, calcium phenate, calcium salicylate, magnesium sulfonate, magnesium phenate, magnesium salicylate, barium sulfonate, barium phenate, and barium salicylate. Examples of the dispersant include polyalkenyl succinimide, polyalkenyl succinimide boride, benzylamine and the like. Examples of the viscosity index improver include poly (meth) acrylate, polyisobutylene, polystyrene, ethylene-propylene copolymer, styrene-isobutylene copolymer and the like.

When the lubricating base oil of the present invention is used as a grease base oil, a thickener is blended. As the thickener, for example, organic non-soap such as soap-based or complex soap-based thickener, terephthalate-based thickener, urea-based thickener, polytetrafluoroethylene, fluorinated ethylene-propylene copolymer and the like And a non-soap inorganic thickener.

These thickeners may be used alone,
Further, two or more kinds may be combined. The amount of the thickener is not particularly limited, but is usually preferably 3 to 40% by weight, more preferably 5 to 20% by weight, based on the base grease comprising the base oil and the thickener. The consistency of the base grease comprising the base oil and the thickener is not particularly limited, but is usually 10
It is about 0 to 500. Further, the various additives described above can be added as needed.

The lubricating base oil of the present invention can be used as a lubricating base oil or grease base oil for any use. For example, industrial lubricating oil, turbine oil, machine oil, bearing oil, compressor oil, hydraulic oil, hydraulic oil, internal combustion engine oil, gear oil, automatic transmission oil (ATF), continuously variable continuously variable transmission oil ( CVT
Oil), transaxle fluid, metalworking oil, lubricating oil for textiles and the like. It can also be used as a base oil for various greases such as sliding bearings, rolling bearings, gears, universal joints, torque limiters, constant velocity joints (CVJs) for automobiles, ball joints, wheel bearings, constant velocity gears, and transmission gears. . Above all, hydraulic oil,
It can be preferably used as gear oil, metal working oil, compressor oil, lubricating oil for fibers and the like.

[0037]

The present invention will be described more specifically with reference to the following examples. In the following examples, “parts” and “%” are based on weight unless otherwise specified. EO is an oxyethylene group, PO is an oxypropylene group, Me is a methyl group,
Bu is an abbreviation for an n-butyl group, G is an abbreviation for a glycerin residue, and the symbol "-" between them represents a block copolymer, and "/" represents a random copolymer. (Production Example) A 10-liter autoclave was charged with 76 g of n-butanol and 28 g of potassium hydroxide as a catalyst. After dissolving the catalyst, the reaction temperature was 125 to 135 ° C., the pressure was 3 to 10 kg / cm ² , and propylene oxide 5 was added.
000 g were reacted. After aging, it was treated with an adsorbent to obtain a product 1 of the present invention. The lubricating base oils of inventive products 2 to 7 and comparative products 1 to 7 shown in Table 1 below were produced in the same manner. In addition,
EO of inventive products 3, 6 and 7 and comparative products 3, 6 and 7
The / PO ratio is 50/50.

The degree of unsaturation, peroxide value and carbonyl value of each sample were measured by a standard fat and oil analysis test established by the Japan Oil Chemists' Society. <Measurement of Unsaturation (meq / g)>
(Cl-acetic acid solution) and allowed to stand in the dark. Thereafter, excess ICl was reduced to iodine, and the iodine content was titrated with sodium thiosulfate to calculate the iodine value. This iodine value was converted to a vinyl equivalent, which was defined as the degree of unsaturation. <Measurement of peroxide value (meq / kg)> Potassium iodide was added to the sample, and the generated free iodine was titrated with sodium thiosulfate. This free iodine was converted to the number of milliequivalents per 1 kg of the sample, which was defined as the peroxide value. <Measurement of carbonyl value (ppm by weight)>
The reaction of dinitrophenyl hydrazine produced chromogenic quinoid ions. The absorbance of this sample at 480 nm was measured and converted to the amount of carbonyl based on a calibration curve previously determined using cinnamaldehyde as a standard substance. <Thermal Stability Test> 10 g of each sample was taken in a glass petri dish, left in a thermostat at 120 ° C. for 24 hours, and the change in weight was measured.

[0039]

[Table 1]

Next, an antioxidant was added to the lubricating base oil, and the thermal stability was similarly evaluated.

[Table 2]

[0041]

The effect of the present invention is to provide a polyether-based lubricating base oil having excellent oxidation stability and heat stability.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kimiyoshi Nanami 7-2-35 Higashiogu, Arakawa-ku, Tokyo Asahi Denka Kako Co., Ltd. (72) Yoshio Minowa 7-2-35 Higashiogu, Arakawa-ku, Tokyo No. Asahi Denka Kogyo Co., Ltd. (72) Inventor Ayako Mikichi

Claims (4)

[Claims] 1. A compound represented by the following general formula (1): X ｛—O— (AO) _n —R｝ _p (1) wherein X is a residue obtained by removing a hydroxyl group from a monool or a polyol. And (AO) _n represents a polyoxyalkylene group formed by polymerization of an alkylene oxide having 3 or more carbon atoms or copolymerization of ethylene oxide and an alkylene oxide having 3 or more carbon atoms, and R represents a hydrogen atom or a carbon atom having 1 carbon atom. Represents an alkyl group of 4 to 4, n represents a number of 2 or more, and p represents a valence of X. A lubricating base oil having a degree of unsaturation of 0.05 meq / g or less, a peroxide value of 10.0 meq / kg or less, and a carbonyl value of 100 ppm by weight or less. . 2. X is methanol, ethanol, propanol, 2-propanol, n-butanol, 2-butanol, ethylene glycol, propylene glycol,
The lubricating base oil according to claim 1, which is a residue obtained by removing a hydroxyl group from bisphenol A or glycerin. 3. The lubricating base oil according to claim 1, wherein (AO) _n is a polyoxyalkylene chain formed by homopolymerization of propylene oxide or copolymerization of ethylene oxide and propylene oxide. 4. A lubricating composition comprising the lubricating base oil according to claim 1, and a phenolic or amine-based antioxidant.