Biodegradable lubricating oil composition

Abstract

A biodegradable lubricating oil composition of the invention includes a component (A) that is an ester obtained by reacting a linear saturated aliphatic carboxylic acid and a linear aliphatic dicarboxylic acid with a polyhydric alcohol, a component (B) that is an ester obtained by reacting a linear saturated aliphatic carboxylic acid with a polyhydric alcohol, and a component (C) that is a phosphate amine salt obtained by reacting an acidic phosphate with an alkylamine, in which the linear saturated aliphatic carboxylic acid of the component (A) is formed of a linear saturated aliphatic carboxylic acid having 8 carbon atoms and a linear saturated aliphatic carboxylic acid having 10 carbon atoms, and a molar amount of the linear saturated aliphatic carboxylic acid having 8 carbon atoms is larger than a molar amount of the linear saturated aliphatic carboxylic acid having 10 carbon atoms.

1 . A biodegradable lubricating oil composition comprising:
 a component (A) that is an ester obtained by reacting a linear saturated aliphatic carboxylic acid and a linear aliphatic dicarboxylic acid with a polyhydric alcohol, the ester having a kinematic viscosity at 40 degrees C. in a range from 400 mm 2 /s to 1000 mm 2 /s and an acid value of 0.5 mgKOH/g or less;   a component (B) that is an ester obtained by reacting a linear saturated aliphatic carboxylic acid with a polyhydric alcohol, the ester having an acid value of 0.5 mgKOH/g or less; and   a component (C) that is a phosphate amine salt obtained by reacting an acidic phosphate with an alkylamine, wherein   the linear saturated aliphatic carboxylic acid in the component (A) is formed of a linear saturated aliphatic carboxylic acid having 8 carbon atoms and a linear saturated aliphatic carboxylic acid having 10 carbon atoms, and   a molar amount of the linear saturated aliphatic carboxylic acid having 8 carbon atoms is larger than a molar amount of the linear saturated aliphatic carboxylic acid having 10 carbon atoms.   
     
     
         2 . The composition according to  claim 1 , wherein
 the linear saturated aliphatic carboxylic acid in the component (A) is formed of the linear saturated aliphatic carboxylic acid having 8 carbon atoms in a range from 60 mol % to 90 mol % and the linear saturated aliphatic carboxylic acid having 10 carbon atoms in a range from 10 mol % to 40 mol %.   
     
     
         3 . The biodegradable lubricating oil composition according to  claim 1 , wherein
 the biodegradable lubricating oil is a gear oil or a bearing oil.   
     
     
         4 . A process for lubricating a step-up gear of a wind power generator, comprising contacting the biodegradable lubricating oil composition according to  claim 3  with the step-up gear. 
     
     
         5 . A step-up gear of a wind power generator comprising, thereon, the biodegradable lubricating oil composition according to  claim 1 . 
     
     
         6 . The composition according to  claim 1 , wherein the polyhydric alcohol of component (A) is a hindered polyol selected from the group consisting of neopentyl glycol, 2-ethyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, trimethylol ethane, trimethylol propane, trimethylol butane, trimethylol pentane, trimethylol hexane, trimethylol heptane, pentaerythritol, 2,2,6,6-tetramethyl-4-oxa-1,7-heptanediol, 2,2,6,6,10,10-hexamethyl-4,8-dioxa-1,11-undecanediol, 2,2,6,6,10,10,14,14-octamethyl-4,8,12-trioxa-1,15-pentadecanediol, 2,6-dihydroxymethyl-2,6-dimethyl-4-oxa-1,7-heptanediol, 2,6,10-trihydroxymethyl-2,6,10-trimethyl-4,8-dioxa-1,11-undecanediol, 2,6,10,14-tetrahydroxymethyl-2,6,10,14-tetramethyl-4,8,12-trioxa-1,15-pentadecanediol, di(pentaerythritol), tri(pentaerythritol), tetra(pentaerythritol), and penta(pentaerythritol). 
     
     
         7 . The composition according to  claim 1 , wherein the linear saturated aliphatic carboxylic acid of component B is formed of a linear saturated aliphatic carboxylic acid having from 6 to 12 carbon atoms. 
     
     
         8 . The composition according to  claim 1 , wherein the component (B) has a kinematic viscosity at 40 degrees C. of from 20 mm 2 /s to 40 mm 2 /s. 
     
     
         9 . The composition according to  claim 1 , wherein the acidic phosphate of component (C) is of formula (1): 
       
         
           
           
               
               
           
         
         wherein X 1  is a hydrogen atom or an alkyl group having 6 to 20 carbon atoms, and X 2  is an alkyl group having 6 to 20 carbon atoms. 
       
     
     
         10 . The composition according to  claim 1 , wherein a content of phosphorous in component (C) is from 150 to 500 mass ppm based on a total amount of the composition. 
     
     
         11 . The composition according to  claim 1 , wherein the alkylamine of component C is a dialkylamine or trialkylamine. 
     
     
         12 . The composition according to  claim 1 , wherein a content of the component (C) is from 0.2 to 1 mass %, based on a total amount of the composition. 
     
     
         13 . The composition according to  claim 1 , further comprising a component (D), which is a sulfur compound. 
     
     
         14 . The composition according to  claim 13 , wherein the component (D) is a sulfur compound (D-1) blended with a sulfur compound (D-2),
 and wherein   the sulfur compound (D-1) does not comprise a polysulfide condensation of —S—S—S— or more in a molecule and comprises 15 mass % or more of sulfur atoms (S) in the molecule, and   the sulfur compound (D-2) is a trihydrocarbyl thiophosphate of formula (2)
   (RO—) 3 P═S  (2),
 
 wherein R is a hydrocarbyl group having 6 to 20 carbon atoms.